Post by thread:B/W

At 08:07 AM 8/14/97 -0500, you wrote: > I would guess that a source that gave off >gamma's at about the same energy level as the UV light would work fine. Eh ? You can't have a gamma anywhere near the energy of UV as far as I know its impossible. The gamma is higher frequency electromagnetic radiation than UV and would likely go straight through the cell with out ionising it - ie dislodging the charge. Remember energy level and frequency are not separable when it comes to electromagnetic radiation - be careful - there is no safe dose of Gamma OR UV for that matter - but you can sit in front of a bar heater for as long as you like ;) >Wonder what kind of shielding the package adds? At Gamma frequencies - NONE - ZERO - ZILTCH. >Probably the best method would to be to etch a hole in the package and use >a light. Why not paste it to the face of a really old Black and White monitor, leave the monitor brightness turned up to maximum (after you've tweaked the EHT up about 20% - BEFORE it ARCS) and leave them there for about 3 days and check what percentage of bits were cleared - ie do a before and after statistical test - OH and don't forget to turn off the deflection coils - so you'd better paste the chips to where the beam center would be. Make sure you are far away from the jigged up monitor - ie put it in the garden shed. If the kittens have two heads or start talking to congress or making phone calls then don't blame me but send me a 20% commission when you sell them to the National Enquirer ;) Rgds Mike Perth, Western Australia

At 02:16 PM 8/14/97 -0400, you wrote: >At 08:07 AM 8/14/97 -0500, you wrote: > >> I would guess that a source that gave off >>gamma's at about the same energy level as the UV light would work fine. > >Eh ? You can't have a gamma anywhere near the energy of UV as far as I >know its impossible. That may be true I havent looked it up in my old Nuclear Physics books. >The gamma is higher frequency electromagnetic >radiation than UV and would likely go straight through the cell with >out ionising it - ie dislodging the charge. There is allways a probability of interaction depending on the matter that the gamma passes through (i.e. lead has a higher probability than aluminum). If this were not true, why would we need shielding arround nuclear reactors for gamma radiation? Also how could we measure the levels? To get the required flux to dislodge the charge, you would need to increase the incident flux (higher dose), or increase the time (higher dose). > >Remember energy level and frequency are not separable when it comes >to electromagnetic radiation Gammas are not electromagnetic in the normal fasion. There is a wide energy band of gammas that differ in energy (and frequency) depending on the isotope that generated them. >- be careful - there is no safe dose >of Gamma OR UV for that matter Sure there is according to the US 10CFR20 regulations from DOE. Dose is something like 5 REM (radiation equivalent to man) per year for adults over 18 years of age (the formula is a little more complex). BTW that is above background, you allready get some exposure just from naturally occuring radioactive decay, and from outerspace. >- but you can sit in front of a bar >heater for as long as you like ;) > I agree wholeheartely! >>Wonder what kind of shielding the package adds? > >At Gamma frequencies - NONE - ZERO - ZILTCH. > Well, everything does a little. Polyethelye does offer some sheilding. I belive ceramic IC packages offer more than plastic packages (that's why we uses them in radiation hardened products). Enough nuclear physics, lets get back to PIC's. Norm

At 02:03 PM 8/14/97 -0500, you wrote: >There is allways a probability of interaction depending on the matter that >the gamma passes through (i.e. lead has a higher probability than >aluminum). The higher the frequency the lower the level of interaction, the memory cell in EPROMS is *designed* to be erased by a particular band of UV, lower frequencies have less effect and so do higher frequencies - the trick with X-rays is a frequency that is higher than UV such that it wll penetrate the packaging but low enough to STILL have some value in erasing the cell, this will taper off radically as frequency goes up. Lead (like most things) are less effective the higher frequency you go. For very high frequency gamma rays (ie high energy) you need progressively thicker lead (or other dense material) for shielding, like spent U238 (just make sure there are no neutron sources ;-) >Gammas are not electromagnetic in the normal fasion. Rubbish - from low frequency RF, through visible light, UV, Xray, Gamma its ALL electromagnetic radiation - there is no distinction. There is a wide >energy band of gammas that differ in energy (and frequency) depending on >the isotope that generated them. They differ in frequency hence they differ in energy, if you are talking about beta decay then thats different - thats an electron which can be expelled with differing energies - but its not EM. >>- be careful - there is no safe dose >>of Gamma OR UV for that matter > >Sure there is according to the US 10CFR20 regulations from DOE. I reject the regulation - it is only a reference for convenience, there is NO safe DOSE of radiation. > Dose is >something like 5 REM (radiation equivalent to man) per year for adults over >18 years of age (the formula is a little more complex). BTW that is above >background, you allready get some exposure just from naturally occuring >radioactive decay, and from outerspace. The rule is DON'T add to background radiation, any ionising radiation will be harmful given enough time. You never know when that one particular gene gets hit to force a cell to go cancerous - its a statistical phenomena, therefore there is NO SAFE dose - don't be misled by an out of date idea about what radiation is. Heck they still transport strong magnets in lead boxes for crying out loud ! >Well, everything does a little. Polyethelye does offer some sheilding. In practical terms the package of a PIC will provide NONE AT GAMMA frequencies - it provides near 100% shielding against UV since its opaque and UV is just above visible. Gamma is way above visible, it so happens the attenuation is probably less that 0.0001% comments ???? > I >belive ceramic IC packages offer more than plastic packages (that's why we >uses them in radiation hardened products). Hang on - there are other issues here about radiation hardening, ceramic packages provide negligible shielding - that is NOT radiation hardening. Ceramic packages are generally more useful for better sealing and better heat transfer - shielding is definitely negligible for GAMMA rays, though it 'might' have some benefit against low energy beta particles. >Enough nuclear physics, lets get back to PIC's. We've only had enough when its cleared up Norm, otherwise we will all end up glowing in the dark and coughing up blood due to ignorance ;-) Rgds Mike Perth, Western Australia There is no a'priori reason that the ultimate truth will be interesting or even useful, those moments of frustration during philosophical debate would be replaced by the sheer terror which accompanies true knowledge. Unsubscribe message should go here - please :)

Why is the window in the erasable devices ( EPROM) a small separately made piece of quarts. Why isn't the whole upper side of the component made of a large block of it. That would make the production cheaper. Erasure can be made even through plexiglas for 5..10 times before it goes 'black' to UV. And there is even some UV detectors packed in plastics, who stay functionary for years. This kind of package could make OTP's obsolete. -------------------------------------------------------------------------- PTM, spam_OUTpasi.mustalahtiTakeThisOuTutu.fi, .....ptmustaKILLspam@spam@utu.fi, http://www.utu.fi/~ptmusta Lab.ins. (mikrotuki) ATK-keskus/Mat.Luon.Tdk OH1HEK Lab.engineer (PC support) Computer Center OI7234 Mail: Turun Yliopisto / Fysla, Vesilinnantie 5, 20014 Pt 02-3336669, FAX 02-3335632 (Pk 02-2387010, NMT 049-555577) --------------------------------------------------------------------------

At 04:20 PM 8/15/97 +301000, you wrote: >> ...there is NO safe DOSE of radiation. > Ok, this _has_ become tedious but I can't resist. hehe - Such is life... > Mike, given that the risk of carcinogenesis when exposed > to ionising radiation cannot be eliminated, how would > you evaluate and manage the threats posed by the various > beneficial uses of such radiation? Thats a very good question, I've not been in this situation so let me think about it for a while. Though please specify are you talking about diagnostic X-rays OR tracer isotopes OR radiation therapy OR something else ? >Unsubscribe message would waste space here - no thanks :P Ah ha - what beautiful irony - your comment used up that bandwidth ! Rgds :) Mike Perth, Western Australia

At 09:31 AM 8/15/97 +0300, you wrote: >Why is the window in the erasable devices ( EPROM) a small separately made >piece of quarts. Why isn't the whole upper side of the component made of >a large block of it. That would make the production cheaper. No - quartz is not that easy to work, ceramic tops seal better, I think the relative coefficients of thermal expansion would be one reason. Erasure can >be made even through plexiglas for 5..10 times before it goes 'black' to >UV. And there is even some UV detectors packed in plastics, who stay >functionary for years. This kind of package could make OTP's obsolete. Could be dozens of reasons, we can speculate. Doesn't plexiglas attentuate the short wavelengths of UV we need for erasure ? Rgds mike perth, Western Australia

>>Sure there is according to the US 10CFR20 regulations from DOE. > >I reject the regulation - it is only a reference for convenience, there >is NO safe DOSE of radiation. > >> Dose is >>something like 5 REM (radiation equivalent to man) per year for adults over >>18 years of age (the formula is a little more complex). BTW that is above >>background, you allready get some exposure just from naturally occuring >>radioactive decay, and from outerspace. > >The rule is DON'T add to background radiation, any ionising radiation >will be harmful given enough time. You never know when that one particular Mike, if there is NO SAFE DOSE you better stop living, but quick! Who knows when you might get cancer. This gets back to the "reliability" thread which discussed probability of harm based upon statistics. If you aren't willing to risk a little, you end up at a dead-end. Better stop being capitalistic, too. (Oh wait, you're from DOWN THERE, I forgot, sorry, didn't mean to imply you already were). >We've only had enough when its cleared up Norm, otherwise we will >all end up glowing in the dark and coughing up blood due to ignorance ;-) Norm and I went to college together for a year. You picked the wrong guy to discuss Nuclear Physics with - you'll lose! He's even more of a geek than me! (Norm- ignore that comment or I'll get the rest of the dorm after you <G> Say, you get the homecoming flyer this week? Going?) Andy ================================================================== Andy Kunz - Montana Design - 409 S 6th St - Phillipsburg, NJ 08865 Hardware & Software for Industry & R/C Hobbies "Go fast, turn right, and keep the wet side down!" ==================================================================

>Thats a very good question, I've not been in this situation so let >me think about it for a while. Though please specify are you talking >about diagnostic X-rays OR tracer isotopes OR radiation therapy OR >something else ? What does it matter? All are beneficial. Also, I happen to believe that nuclear armaments are a wonderful lifesaver due to the fact that they have prevented major war for the past 50 years. But that isn't politically correct on the bottom of the world, so here comes another debate... <G> Andy ================================================================== Andy Kunz - Montana Design - 409 S 6th St - Phillipsburg, NJ 08865 Hardware & Software for Industry & R/C Hobbies "Go fast, turn right, and keep the wet side down!" ==================================================================

At 07:59 AM 8/15/97 -0400, you wrote: >Mike, if there is NO SAFE DOSE you better stop living, but quick! Who >knows when you might get cancer. Hey Andy you've misunderstood. I am saying that we should NOT be misled into thinking there is such a notion as a safe DOSE of radiation, if people have the illusion there is, then they will not be as quick to object about those waste dumps which 'only give off safe doses', would you want a 'SAFE DOSE' waste dump next to your primary school ? Radiation exposure is like being shot at with lots of small powerful bullets - even one does damage, and the effects are accumulative. So therefore there is no SAFE dose of radiation - ie Don't accept the notion that even small number of bullets hitting you is safe ! >This gets back to the "reliability" thread which discussed probability of >harm based upon statistics. If you aren't willing to risk a little, you >end up at a dead-end. Having the appreciation there is NO safe dose does not mean you don't take a risk - especially if you already have cancer and are considering radiation therapy as ONE of the potential treatments - I am saying its up to the persons own commonsense and is not subject to a dehumanising formula which has no basis in reality and can never be tested by experiment. If I was to get cancer I would only consider radiation therapy as a last resort - its like removing a growth by shooting at it. Especially since there are many other treatments for a vast majority of cancers which are nowhere near as indiscriminant as firing radiation at it. >Better stop being capitalistic, too. (Oh wait, you're from DOWN THERE, I >forgot, sorry, didn't mean to imply you already were). Sorry Andy - I don't know what you are referring to here - please explain ? >>We've only had enough when its cleared up Norm, otherwise we will >>all end up glowing in the dark and coughing up blood due to ignorance ;-) > >Norm and I went to college together for a year. You picked the wrong guy >to discuss Nuclear Physics with - you'll lose! He's even more of a geek >than me! (Norm- ignore that comment or I'll get the rest of the dorm after >you <G> Say, you get the homecoming flyer this week? Going?) Well I hope the College training was comprehensive because some of the things Norm has said are tangential to basic facts about electromagnetic radiation - maybe he's forgotten Maxwell and Debroglie. Back in 1986 I was chief engineer and radiation officer for a local company - we used Cesium 137 and Cobalt 60 sources for measureing iron ore flow rates in a processor controlled feedback system. Even though I was at University back in late 70's we still had to undergo a significant crash course in the whole field - the most notable issue being that any ionising radiation is accumulative - so don't ADD to that already in the background. Rgds mike Perth, Western Australia

At 07:59 AM 8/15/97 -0400, you wrote: >>>Sure there is according to the US 10CFR20 regulations from DOE. >> >>I reject the regulation - it is only a reference for convenience, there >>is NO safe DOSE of radiation. >> That is true if you also subscribe to the theory that there are no safe cars, planes, trains, electromagnetic waves, air, sun, etc. >>> Dose is >>>something like 5 REM (radiation equivalent to man) per year for adults over >>>18 years of age (the formula is a little more complex). BTW that is above >>>background, you allready get some exposure just from naturally occuring >>>radioactive decay, and from outerspace. >> >>The rule is DON'T add to background radiation, any ionising radiation >>will be harmful given enough time. You never know when that one particular > OK if this is so, then we should all live at sea level. < set sarcasim flag> And we all know how many mutants there are in places like Denver due to the higher background levels of radiation now don't we. <clear sarcasim flag> >Mike, if there is NO SAFE DOSE you better stop living, but quick! Who >knows when you might get cancer. It is true that exposure to ionizing radiation will slightly increase your chances of cancer but the increase is a low %. It is also true that if you walk up and down stairs you increase the probability that you will fall. I don't know about you, but I don't avoid stairs. They can be quite usefull. I am carefull using them but still use them. This does not mean that you should not worry about limiting your exposure. You are a fool if you "PLAN" to get (or worse don't plan not to get) your leagal dose limit of radiation. > >This gets back to the "reliability" thread which discussed probability of >harm based upon statistics. If you aren't willing to risk a little, you >end up at a dead-end. > >Better stop being capitalistic, too. (Oh wait, you're from DOWN THERE, I >forgot, sorry, didn't mean to imply you already were). > I'm not touching this one :-) >>We've only had enough when its cleared up Norm, otherwise we will >>all end up glowing in the dark and coughing up blood due to ignorance ;-) > Well, coughing up blood can happen but ask the Russians how much exposure it takes. As for glowing, glowing comes from radioactive decay. If you got radiated to the point that you glowed, you wouldn't care anymore because you would have allready died. >Norm and I went to college together for a year. You picked the wrong guy >to discuss Nuclear Physics with - you'll lose! He's even more of a geek >than me! (Norm- ignore that comment or I'll get the rest of the dorm after >you <G> Say, you get the homecoming flyer this week? Going?) > Thanks for the vote of confidence Andy. I might have been offended except for the "more of a geek than me" line :-) Norm

At 08:03 AM 8/15/97 -0400, you wrote: >>Thats a very good question, I've not been in this situation so let >>me think about it for a while. Though please specify are you talking >>about diagnostic X-rays OR tracer isotopes OR radiation therapy OR >>something else ? > >What does it matter? All are beneficial. Wrong. 1. Diagnostic X-rays can be harmful if equipment is not frequently checked and since its accumulative they can also cause cancers, check your local statistics if you don't believe me. Many people were X-rayed too often for diagnosis and now have X-ray induced cancers. 2. Tracer isotopes not necessarily beneficial in all cases. Very dangerous and easy to misuse in diagnostic circumstances. 3. Radiation therapy - see other post - this is like removing something by shooting lots of bullets - still very messy and dangerous. >Also, I happen to believe that nuclear armaments are a wonderful lifesaver >due to the fact that they have prevented major war for the past 50 years. You forget there has already been a nuclear war the second bomb of which was completely unnecessary. And we almost had conflict on several occasions due to failing systems in USA and USSR. Now we have lots of fissile material, the danger of annihalation is not over by any means. Its more likely that good commercial sense prevented war not the presence of missiles - many hotheads on both sides were too eager to use them at the earliest opportunity. >But that isn't politically correct on the bottom of the world, so here >comes another debate... <G> Not a debate just an improved understanding - feel free to email me privately if you like :) rgds mike Perth, Western Australia

At 08:55 AM 8/15/97 -0400, you wrote: >At 07:59 AM 8/15/97 -0400, you wrote: > >>Mike, if there is NO SAFE DOSE you better stop living, but quick! Who >>knows when you might get cancer. > >Hey Andy you've misunderstood. I am saying that we should NOT be misled >into thinking there is such a notion as a safe DOSE of radiation, if >people have the illusion there is, then they will not be as quick to >object about those waste dumps which 'only give off safe doses', would >you want a 'SAFE DOSE' waste dump next to your primary school ? Remeber the US law says for persons over 18years old. The law would not alow the dump by the primary school. > >Radiation exposure is like being shot at with lots of small powerful >bullets - even one does damage, and the effects are accumulative. So >therefore there is no SAFE dose of radiation - ie Don't accept the >notion that even small number of bullets hitting you is safe ! > Which leads me back to your first error, that the radiation will not interact with the PIC. If it interacts with people then it will with the semiconductor material in the PIC. How is the question. You said it would pass right through. If it passes through a PIC, then it will pass through you too. {Quote hidden}> >Well I hope the College training was comprehensive because some of the >things Norm has said are tangential to basic facts about electromagnetic >radiation - maybe he's forgotten Maxwell and Debroglie. Back in 1986 I >was chief engineer and radiation officer for a local company - we used >Cesium 137 and Cobalt 60 sources for measureing iron ore flow rates in >a processor controlled feedback system. Even though I was at University >back in late 70's we still had to undergo a significant crash course in >the whole field - the most notable issue being that any ionising radiation >is accumulative - so don't ADD to that already in the background. > Well, I think we must have misunderstood each other. I was pointing out that gammas act like particles not waves like other (what most people referto as) elctromagnetic radiation. For example, you use wave theory for determining the characteristics of a cell phone RF system. You use particle theory for gammas. BTW my nuclear course work was at the graduate level and I worked in the feild for over 5 years before leaving for better carrer oportunity. BTW, I think we may have strayed enough off topic to stop using the PIClist. We can continue via private e-mail if you like. Norm

OK Guys this is the last one on the PICLIST - all else private please :) At 08:01 AM 8/15/97 -0500, you wrote: >>>I reject the regulation - it is only a reference for convenience, there >>>is NO safe DOSE of radiation. > >That is true if you also subscribe to the theory that there are no safe >cars, planes, trains, electromagnetic waves, air, sun, etc. No Norm - accepting there is a notion of a 'safe dose' of radiation is like saying its ok to be shot a certain number of times. For some reason you and Andy are over-reacting and confusing risks of ionising radiation with necessary aspects of living in this society - I don't think its normal to accept the notion that radiation has a safe dose. All I am pointing out Norm/Andy is the *illusion* of a Safe Dose ! >>>The rule is DON'T add to background radiation, any ionising radiation >>>will be harmful given enough time. You never know when that one particular > >OK if this is so, then we should all live at sea level. < set sarcasim flag> >And we all know how many mutants there are in places like Denver due to the >higher background levels of radiation now don't we. <clear sarcasim flag> No. I am referring to the desire not to spread isotopes or indulge in unnecessary X-rays etc. Don't you have a Radon controversy in USA, if you had the option of working in the basement or in an upstairs study - then are you saying "Gee the Radon is a Safe Dose so I'll work in the basement". If it was me I wouldn't let my kids in the basement ever. >>>We've only had enough when its cleared up Norm, otherwise we will >>>all end up glowing in the dark and coughing up blood due to ignorance ;-) >> > >Well, coughing up blood can happen but ask the Russians how much exposure >it takes. As for glowing, glowing comes from radioactive decay. If you >got radiated to the point that you glowed, you wouldn't care anymore >because you would have allready died. True. I was joking. I don't think any sane individual will so easily accept some government regulation so easily - didn't they inject children in USA with 'safe doses' as part of an experiment a few years ago. And who says the government knows any better about radiation now, they thought they did back then in the 70's. Rgds Mike Perth, Western Australia

This is my last one on the list also At 11:20 AM 8/15/97 -0400, you wrote: >OK Guys this is the last one on the PICLIST - all else private please :) > > >>That is true if you also subscribe to the theory that there are no safe >>cars, planes, trains, electromagnetic waves, air, sun, etc. > >No Norm - accepting there is a notion of a 'safe dose' of radiation is >like saying its ok to be shot a certain number of times. For some >reason you and Andy are over-reacting and confusing risks of ionising >radiation with necessary aspects of living in this society - I don't >think its normal to accept the notion that radiation has a safe dose. > >All I am pointing out Norm/Andy is the *illusion* of a Safe Dose ! > What I am trying to say is that it's no worse at limited levels than lots of other things. Yeah car accidents are different. You don't have a little car accident every time you drive. Air pollution, second hand smoke, etc are the same. You get a little damage from each exposure and overtime if the exposure is high enough it can cause problems. Most people pannic because they don't understand radiation. Comments like "cough up blood, and glow" to us who know are obviously severe situations but to thoes uneducated in such things they are frightening. I belive that you do understand the phenomon but thik you are exagerating the real risk. (Sorry but those who are tired of this, will hear no more from me on this on the list.)

>No Norm - accepting there is a notion of a 'safe dose' of radiation is >like saying its ok to be shot a certain number of times. For some Actually, it _is_ safe to be shot. It depends upon caliber, distance, projectile type, etc. Just like radiation. How can you reasonably sit in front of a CRT and write what you do. Aren't there Euro standards are EMI??? >No. I am referring to the desire not to spread isotopes or indulge in >unnecessary X-rays etc. Don't you have a Radon controversy in USA, if you >had the option of working in the basement or in an upstairs study - then >are you saying "Gee the Radon is a Safe Dose so I'll work in the basement". >If it was me I wouldn't let my kids in the basement ever. Only in certain parts. WHere I live we have a _lot_ of uranium deposits, hence the radon. It is only a problem if you have a well-sealed basement, and it's only a problem with enviro-whackos and similar subhumans. Andy ================================================================== Andy Kunz - Montana Design - 409 S 6th St - Phillipsburg, NJ 08865 Hardware & Software for Industry & R/C Hobbies "Go fast, turn right, and keep the wet side down!" ==================================================================

> OK if this is so, then we should all live at sea level. > <set sarcasim flag> > And we all know how many mutants there are in places like Denver > due to the higher background levels of radiation now don't we. > <clear sarcasim flag> Well, I always thought Elway was too good to be the result of natural genetics. ;) But, Norm, your sarcasm is misplaced. First, there is a distinct difference between mutagenesis and carcinogenesis (which your "four years of post-graduate studies in Nuclear Physics" should have elucidated). Second, the relationship between exposure to ionising radiation due to altitude and the incidence of various types of cancer and birth defects is well documented. The most extreme example being, of course, people who work on aeroplanes in flight. ___Bob

>> No Norm - accepting there is a notion of a 'safe dose' of radiation is >> like saying its ok to be shot a certain number of times. > > Actually, it _is_ safe to be shot. It depends upon caliber, distance, > projectile type, etc. Just like radiation. The discussion concerns _ionising_ radiation. The proper analogy would be "its ok to be shot in the left temple with a small calibre handgun at close range". Hmm... After you, Andy. The effects of radiation are both statistical and cumulative. Therefore, there is no dose of radiation (however small) that is risk free and so could be called 'safe'. The exposure limits that are set by regulatory authorities are _not_ safe doses, they are 'acceptable risk doses' (where, curiously, the determination of acceptable risk is often made by those same authorities). In practice, the determination of acceptable risk is usually made with reference to some other form of exposure to radiation. For example, an annual exposure equivalent to one chest x-ray may be deemed to constitute an acceptable risk, and so the corresponding equivalent dose is called 'safe'. Of course, this process is specious because while the two exposures carry the same risk, no consideration has been given to the harm or benefit that accrues from each exposure. > How can you reasonably sit in front of a CRT and write what you do. > Aren't there Euro standards are EMI??? I accept the risk of sitting in front of a CRT because it benefits me to do so. The benefit does not _eliminate_ the risk, it merely _outweighs_ it. The existence of a government standard or regulation does not constrain physics to behave accordingly. > Only in certain parts. Where I live we have a _lot_ of uranium deposits, > hence the radon. It is only a problem if you have a well-sealed basement A well-sealed basement increases risk by allowing radon gas to accumulate. A well-ventilated basement decreases risk by allowing radon gas to disperse. A well-ventilated basement does not eliminate risk. ___Bob

> The effects of radiation are both statistical and cumulative. > > Therefore, there is no dose of radiation (however small) that is > risk free and so could be called 'safe'. ........... > ___Bob > I am not expert in this subject, though I know we get some level of harmful radiation in daily regular life from sun to CRTs. Moreover, in a conference, the dean of college of engineering at Idaho State University, the other nuclear dump state, claiming daily dose of radiation increasing the life expectancy and lowering cancer rate:)! He was suggesting to get daily radiation pills with vitamins. Don't lough I am not joking. I didn't buy his argument but the story is true, he was statistically making some points. I would like make couple of points here. If you don't claim that radiation is good you don't get funding from DOE. Therefore you'll never be a dean nor governor in the state of Idaho. Second point is that whenever you talk about fuzzy concepts there will always be different evaluations. Since nothing is crisp and it'll keep going and going. Aydin

Andy Kunz wrote: > Also, I happen to believe that nuclear armaments are a wonderful lifesaver > due to the fact that they have prevented major war for the past 50 years. <sigh> How can you say such irrational things? You cannot PROVE a NEGATIVE argument. If I take an aspirin and my headache goes away, the observation of relief does not prove a relationship. You would need to conduct double blind experiments to establish a statistical probability of a causal link. It is not a 'fact' that the possession of nuclear arms by various countries has prevented a major war. It is a fact that various countries possess nuclear arms. It is a fact that no major war has occured. You cannot demonstrate a relationship between these. If you wish to hold, as an article of faith, that there is a relationship, then that is fine. But your original statement is untenable. > But that isn't politically correct on the bottom of the world, so here > comes another debate... <G> <sigh> How can you say such irrational things? Andy, you are treading on VERY dangerous ground here. You seem to be confusing Australia and New Zealand. If you persist in this misrepresentation you photo WILL be posted at all ports of entry. Please remember that Ansell is an Australian company. ;) Of course, due to the fact that Americans are ignorant of geography and of world affairs your confusion is to be expected. ___Bob

Aydin Yesildirek wrote: > In a conference, the dean of college of engineering at Idaho State > University, the other nuclear dump state, claiming daily dose of > radiation increasing the life expectancy and lowering cancer rate! I don't know to what the Dean was refering (and, as you point out, he was probably not a disinterested observer) but... Human cells have very extensive and effective mechanisms for detecting and repairing the genetic damage caused by ionising radiation. Some researchers believe that these mechanisms are much more extensive than would be expected given the amount of genetic damage that actually occurs naturally. That is, the benefit of these mechanisms to the organism is outweighed by their cost, and so there should be no selective pressure in favour of them. An explanation for this discrepancy (which may not, of course, actually exist as it depends upon somewhat speculative inter- pretation of various data) is that the background radiation flux has, in the past, been at much higher levels than today. ___Bob PS: I have found that engineers have great difficulty understanding biological systems and processes. I would give little credence to anything a 'dean of engineering' said in relation to life expectancy and cancer rates!

At 10:49 AM 8/17/97 +0000, you wrote: {Quote hidden}>Andy Kunz wrote: > >> Also, I happen to believe that nuclear armaments are a wonderful lifesaver >> due to the fact that they have prevented major war for the past 50 years. > > <sigh> How can you say such irrational things? > > You cannot PROVE a NEGATIVE argument. > > If I take an aspirin and my headache goes away, the observation of > relief does not prove a relationship. You would need to conduct > double blind experiments to establish a statistical probability of > a causal link. > > It is not a 'fact' that the possession of nuclear arms by various > countries has prevented a major war. It is a fact that various > countries possess nuclear arms. It is a fact that no major war > has occured. You cannot demonstrate a relationship between these. > > If you wish to hold, as an article of faith, that there is a > relationship, then that is fine. But your original statement is > untenable. > While it is true that it would be near to impossible to PROVE that nuclear weapons prevented WW III, I think that a very strong case can be made that they did. After all, isn't this how ALL historical argumentation must be done, since historical experimentation can't be done and rarely does an event get repeated in history under the same conditions, or especially under conditions which allow it to be a "double blind" test. For instance, if a man runs into a bank with a gun and threatens to rob it, and I take out a gun and show him that I have it, and he then runs out of the bank, MOST people would agree that he probably ran out when he saw that I had comparable armament and that he was taking a much more substantial risk than if he were challenging an unarmed group of people. Yet, according to your argument, I should not assume that he ran out because I pulled the gun. No, I can't prove that he did, it is just the best explanation that anyone can come up with for why he left. Sean

At 11:27 PM 8/16/97 -0400, you wrote: > For instance, if a man runs into a bank with a gun and threatens to >rob it, and I take out a gun and show him that I have it, and he then runs >out of the bank, MOST people would agree that he probably ran out when he >saw that I had comparable armament and that he was taking a much more >substantial risk than if he were challenging an unarmed group of people. Hey Sean wakeup, The unfortuanate fact is history show that when people/armies have comparable armaments - they use em, seems to make no difference. For most hothead robbers - you show em a gun and they'll try and shoot you first - armed guards don't stop ALL robberies by stupid people. There are several reasons we didn't have WW3 (so far) mainly commercial but, we NOW have more danger of WW3 scenario BECAUSE of failing systems, this would not be the case if we didn't STILL have nuclear weapons. May I suggest that such a discussion you send it private to Robert Lunn and not to the piclist... If you really need to reply to me - please make it private. Rgds Mike Perth, Western Australia

On 17 Aug 97 at 10:49, Robert Lunn wrote: > Andy Kunz wrote: > > > Also, I happen to believe that nuclear armaments are a wonderful lifesaver > > due to the fact that they have prevented major war for the past 50 years. > > <sigh> How can you say such irrational things? > > You cannot PROVE a NEGATIVE argument. Its a tongue-in-cheek empirical *observation*. If he said it'll stop it for another fifty years... that would be crystal ball gazing. > > If I take an aspirin and my headache goes away, the > observation of relief does not prove a relationship. You > would need to conduct double blind experiments to establish > a statistical probability of a causal link. I would think that including 50% placebos in packs on aspirin would not prove popular with the public. Bayer might like it as a cost cutting solution though <g> Does a double blind experiment in this study lead to a doubly blinding headache? <bg> > > It is not a 'fact' that the possession of nuclear arms by > various countries has prevented a major war. It is a fact > that various countries possess nuclear arms. It is a fact > that no major war has occured. You cannot demonstrate a > relationship between these. To extend this argument to its ultimate conclusion, postulate what might happen if *all* countries possessed nuclear armaments, ranging in scale from small, dirty terrorist style bombs to cruise missile/ICBM. How safe would you feel? > > If you wish to hold, as an article of faith, that there is a > relationship, then that is fine. But your original > statement is untenable. > Aaarrrghh! the faith word again. > > But that isn't politically correct on the bottom of the world, so here > > comes another debate... <G> Aaarrrghh! PC is a bug caught from the USA politik. We're sick of it! > > <sigh> How can you say such irrational things? > > Andy, you are treading on VERY dangerous ground here. You > seem to be confusing Australia and New Zealand. If you Are Kiwis PC Bob? > persist in this misrepresentation you photo WILL be posted > at all ports of entry. Please remember that Ansell is an > Australian company. ;) Ansell, the company that make balloons and, um, 'lifestyle' products, or Ansett, the plane company? They both *might* be relevant, in strangely different ways... > > Of course, due to the fact that Americans are ignorant of > geography and of world affairs your confusion is to be > expected. > That sweeping statement should cop some flak. I'll let the one's it targets take care of that though. MikeS <mikesmith_ozKILLspamrelaymail.net> === For PICLIST help (including "unsubscribe" instructions), === send an e-mail containing the single phrase "help piclist" === to: .....listservKILLspam.....mitvma.mit.edu

-----Original Message----- From: Andre Abelian <andrespam_OUTcompufire.com> To: Lawrence Lile <@spam@lilelKILLspamtoastmaster.com>; pic microcontroller discussion list <KILLspamPICLISTKILLspamMITVMA.MIT.EDU> Date: Friday, March 12, 1999 6:27 PM Subject: Re: mplab 3.4 vs 4.0 >> The biggest advantage of MPlab 4.00 is that it crashes every 5 to 10 >> minutes. DON't use it - even Microchip told me to download v3.99 and delete >> 4.00. > > >I have been using version 4.0 came with MPLAB-ICE on CD >so far so good didn't see any problem with it. my second PC >is setup for picmaster didn't see any problem Either. > >Andre Abelian. You are lucky, then. Using Windows 95 Yet? My problems started as soon as I upgraded. It also doesn't help that I am using an obsolete ICEPIC - I doubt the ICEPIC software is as stable as MPLAB-ICE.. WIN95 (A.K.A. LOSE95) is not happy about serial communications and is jealous of anything that must get that close to it's precious hardware. I can literally start MPLAB, open a project, start the ICEPIC or PICStart programmer, and get a general protection fault within thirty seconds of starting the program almost every time. Microchip admits this is a big problem for some users on some machines and promised to do better next time. BTW has MCHIP ever gotten that WINDOWS NT version running? I'd switch to WIN NT in a minute if they do. I hear that, after the initial hairpulling and teeth gnashing it can be much more stable than LOSE95 (A.K.A WIn95)

> BTW has MCHIP ever gotten that WINDOWS NT version running? I'd switch to > WIN NT in a minute if they do. I hear that, after the initial hairpulling > and teeth gnashing it can be much more stable than LOSE95 (A.K.A WIn95) I'am using NT4.0 SP4, MPLAB 4.0 and the PICSTART plus. Works fine for me (16F84 and 16C73A) M. -- Standard PS: English is not my native language ------------------------------------------------------------------------------- RemoveMEMartin.SanderTakeThisOuThimh1.hi.bosch.de Robert Bosch Multimedia-Systeme GmbH & Co. KG MU/EMS3 P.O. Box 77 77 77 31132 Hildesheim Germany Tel: +49 5121 494374 ------------------------------------------------------------------------------- commercial: spamBeGoneMartin.SanderspamBeGonetouch-screen.de ------------------------------------------------------------------------------- privat: TakeThisOuTprivatEraseMEspam_OUTmartin-sander.de http://www.martin-sander.de -------------------------------------------------------------------------------

>>Where can is the [NT] serial patch [for PICStart+] located? http://www.microchip.com/10/Tools/picmicro/program/picstart/index.htm John Clark, Software Engineer EraseMEJohnCinter-intelli.com (317) 715-8175 (voice & fax) Interactive Intelligence, Inc. 3500 DePauw Blvd., Suite 1060 Indianapolis, IN 46268-1136 http://www.inter-intelli.com {Quote hidden}> -----Original Message----- > From: Norm [SMTP:RemoveMEnsiegelEraseMEEraseMEEXECPC.COM] > Sent: Tuesday, March 16, 1999 9:31 AM > To: RemoveMEPICLISTspam_OUTKILLspamMITVMA.MIT.EDU > Subject: Re: MPLAB/WIN95/WIN NT (was mplab 3.4 vs 4.0) > > John Clark wrote: > > >Works like a champ for me too. > > > >NT Server 4.0 Sp4 > >MPLAB 4 + serial patch > >PICStart+ > > > > Where can is the serial patch located?

Hi, I am trying to build a robot that navigates around obstacles, and I want to take input from a B/W video camera, probably infrared. I will scan the screen, and if a region is dark, i will avoid it (grass reflects infrared very well). I will get the sync pulses with an inverter, since the sync is negative, the inverter output will be positive during sync. Any ideas how to distinguish the, say, +0.8 V of a light area from the, say, +0.2 volts of a dark region? -Mike Lapson <RemoveMElapson25TakeThisOuTspamhotmail.com> ________________________________________________________________________ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com -- http://www.piclist.com hint: To leave the PICList EraseMEpiclist-unsubscribe-requestspamspamBeGonemitvma.mit.edu>

Yeah, use a damn fast comparator. Don't forget to clamp your video to a fixed reference level (using sync tip is common) so that changes in average brightness don't shift your level (most cameras have AC coupled outputs) You realize that your data rates will be -really- high... As for using just an inverter to extract sync, the total video signal spans but 1V, hardly enough to get a reliable sync extraction from a mere inverter, particularly if it's threshold is 1/2VCC or the .6V of a TTL gate. You really should use a sync sep chip or an unused section of your video threshold comparator for reliable triggering of the scanning software. Michael Lapson wrote: {Quote hidden}> > Hi, > > I am trying to build a robot that navigates around obstacles, and I want to > take input from a B/W video camera, probably infrared. I will scan the > screen, and if a region is dark, i will avoid it (grass reflects infrared > very well). I will get the sync pulses with an inverter, since the sync is > negative, the inverter output will be positive during sync. > Any ideas how to distinguish the, say, +0.8 V of a light area from the, say, > +0.2 volts of a dark region? > > -Mike Lapson > <RemoveMElapson25KILLspamhotmail.com> -- http://www.piclist.com hint: To leave the PICList piclist-unsubscribe-requestSTOPspamspam_OUTmitvma.mit.edu>

Michael Lapson wrote: > Hi, > > I am trying to build a robot that navigates around obstacles, and I want to > take input from a B/W video camera, probably infrared. I will scan the > screen, and if a region is dark, i will avoid it (grass reflects infrared > very well). I will get the sync pulses with an inverter, since the sync is > negative, the inverter output will be positive during sync. > Any ideas how to distinguish the, say, +0.8 V of a light area from the, say, > +0.2 volts of a dark region? Hints: Op-Amp and A->D {Quote hidden}> > > -Mike Lapson > <spamBeGonelapson25STOPspamEraseMEhotmail.com> > ________________________________________________________________________ > Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com > > -- > http://www.piclist.com hint: To leave the PICList > KILLspampiclist-unsubscribe-requestspamBeGonemitvma.mit.edu -- * | __O Thomas C. Sefranek EraseMEtcsEraseMEcmcorp.com |_-\<,_ Amateur Radio Operator: WA1RHP (*)/ (*) Bicycle mobile on 145.41, 448.625 MHz ARRL Instructor, Technical Specialist, VE Contact. hamradio.cmcorp.com/inventory/Inventory.html http://www.harvardrepeater.org -- http://www.piclist.com hint: To leave the PICList @spam@piclist-unsubscribe-request@spam@spam_OUTmitvma.mit.edu>

Mike Wrote > Hi, > > I am trying to build a robot that navigates around obstacles, and I want to > take input from a B/W video camera, probably infrared. I will scan the > screen, and if a region is dark, i will avoid it (grass reflects infrared > very well). I will get the sync pulses with an inverter, since the sync is > negative, the inverter output will be positive during sync. > Any ideas how to distinguish the, say, +0.8 V of a light area from the, say, > +0.2 volts of a dark region? > As someone else commented, this is a lot of processing to extract the information from a video signal, even if the sensing is rudimentary. I am using a single line CCD, that way the processing is within the PICs capability and the PIC generates the control sequences, not the other way around. I have been able to use cheap processors (PICs) by not only using the single line CCDs but also negative feeding back analog levels pre-adc from stored results to cancel out unwanted artifacts. Also generate youre own I/R light source and sync to that, great at noise/interference suppression. _____________________________ Lance Allen Technical Officer Uni of Auckland Psych Dept New Zealand http://www.psych.auckland.ac.nz _____________________________ -- http://www.piclist.com hint: To leave the PICList spamBeGonepiclist-unsubscribe-requestKILLspammitvma.mit.edu>

All of Robert's comments are good. As a way around these problems you may want to consider a video imager that is easier to talk to. I just bought a digital camera called "WWF Slam Cam" from McFrugles (spelling?) for $14.99 US. They were originally marketed for $29.99. Inside the camera is an imager made by VVL (VLSI Vision Ltd) in the UK. http://www.vvl.co.uk/ The imager in the camera is a VV6300. The Web site has information on the VV6301 which appears to be very similar. What is nice about this imager is that it is very easy to communicate with. First, of all the resolution is only 120 lines of 160 pixels each. (Well, what did you expect for $15). This limits what you can see but the PIC can't handle much more data than this anyway. Second, the video comes from the imager as 8 bits per pixel either delivered 4 or 8 bits at a time. The A/D is internal to the imager! Third, all the control and status is done using an I2C 2-line serial interface. The I2C sets things like clock rates and the way the video is output. Last, this is a low power, 5-volt only part with no complicated signal voltages required. The Slam Cam has an 8052 in it (boo). It is just longing for a PIC :-) Actually, I got 2 of the cameras. Some day I hope to do stereo video with them... -- Richard Robert Rolf wrote: {Quote hidden}> > Yeah, use a damn fast comparator. > > Don't forget to clamp your video to a fixed reference level (using sync > tip is common) so that changes in average brightness don't shift your > level (most cameras have AC coupled outputs) > > You realize that your data rates will be -really- high... > > As for using just an inverter to extract sync, the total video signal > spans but 1V, hardly enough to get a reliable sync extraction from > a mere inverter, particularly if it's threshold is 1/2VCC or the .6V > of a TTL gate. You really should use a sync sep chip or an unused > section > of your video threshold comparator for reliable triggering of the > scanning software. > > Michael Lapson wrote: > > > > Hi, > > > > I am trying to build a robot that navigates around obstacles, and I want to > > take input from a B/W video camera, probably infrared. I will scan the > > screen, and if a region is dark, i will avoid it (grass reflects infrared > > very well). I will get the sync pulses with an inverter, since the sync is > > negative, the inverter output will be positive during sync. > > Any ideas how to distinguish the, say, +0.8 V of a light area from the, say, > > +0.2 volts of a dark region? > > > > -Mike Lapson > > <TakeThisOuTlapson25.....TakeThisOuThotmail.com> > > -- > http://www.piclist.com hint: To leave the PICList > TakeThisOuTpiclist-unsubscribe-requestKILLspamspammitvma.mit.edu -- http://www.piclist.com hint: To leave the PICList .....piclist-unsubscribe-requestRemoveMEmitvma.mit.edu>

Hi, You might like to check out the sensor that is used in the Gameboy camera. It has a 128x128 pixel resolution and incorporates image processing on the chip. The device is a M64283FP made by Mitshubishi Electric Corp. Check out http://homepages.paradise.net.nz/~vkemp/gbcam.htm Gary ---------------------------------------------------------------- Email: RemoveMEgary.fowlerspamBeGonedsto.defence.gov.au Phone: +61 8 8259 5767 Fax: +61 8 8259 5672 RF Countermeasures, Electronic Warfare Division Defence Science & Technology Organisation PO Box 1500 Salisbury, South Australia 5108 ---------------------------------------------------------------- -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]: PIC only [EE]: engineering [OT]: off topic [AD]: advertisements

"Alan B. Pearce" wrote: > > >The Slam Cam has an 8052 in it (boo). It is just longing for a PIC :-) > >Actually, I got 2 of the cameras. Some day I hope to do stereo video > >with them... > > Ahh, to make a competitor to the virtual car someone else here was playing > with??? No, I just seem to enjoy giving myself headaches by looking at 3-D images. A friend of mine commented the other day that the problem with field sequential video (such as these cameras would be used for) gives her a headache that does not go away with practice -- unlike SIRDS and other 3-D schemes. > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]: PIC only [EE]: engineering [OT]: off topic [AD]: advertisements -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]: PIC only [EE]: engineering [OT]: off topic [AD]: advertisements

> No, I just seem to enjoy giving myself headaches by looking at 3-D > images. A friend of mine commented the other day that the problem with > field sequential video (such as these cameras would be used for) gives > her a headache that does not go away with practice -- unlike SIRDS and > other 3-D schemes. There's an interesting machine called "Felix The Helix", which consists of a transluscent helix, like a post-hole borer, that has coloured lasers shone on it from underneath to produce moving 3D images. Do a search for "felix the helix" and you'll find a few sites and pictures. Seen it only on TV but looks impressive, if like the sort of contraption you'd have expected in the days of mechanical televisions -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

A parallel port will not be too slow for this, but under normal PC operation its timing will be too inconsistent. I have tried (and succeeded) to drive a small linear CCD using a bit banged parallel port, but using an assembly+C program that took over all interrupts from the OS (and caused it to lose time etc). Video signal can be generated in the same way, but it is easier to get an older CGA card that has a RCA B/W NTSC output jack on it. You may have to run through junk to find one, I have one and it is irreplaceable. One thing that can be tried is to make a RS232 port output at least large characters and bar graphs. Using 256K speed gives about 4 usec per bit which allows 13 bits in each line (assuming 52 usec visible scan in PAL). The vertical resolution is 300 lines which is enough for certain bar graphs and other such applications. I once did all the figuring. I'd use a PLL built from CMOS chips to generate the H sync signal, by locking to the 312th harmonic of the V signal which was generated by RS232 RTS. This might even work under some OS as long as you can write the serial interrupt routine for it (hint hint: open source or open architecture required). But I never got around to try it out. Note that 312 = (625 - 1)/2 = 256 + 56 ~= 256 + 64 (which simplifies the divider feedback). NTSC uses 525 lines and you get to do your own numbers. BTW you can make a PLL for this with a 12 bit PIC ;) The image will not be interlaced properly and it will have some flicker unless the PLL generates serration pulses and the computer can delay by 1/2 line in software when appropriate. hope this helps, Peter -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

Just run the video signal through a notch filter. The filter should be set for 4.43 MHz for PAL or 3.58 MHz for NTSC. Regards Stuart Sean H. Breheny wrote: {Quote hidden}> > Hi all, > > Quick video question: I want to try taking a color video signal and use a > high speed comparator to compare the brightness of pixels to some set value > (trying to detect a dark object against a light background). I want to > reject the color information in this process (luma only). How can I do > this? I know it must be fairly simple since B/W TV's can accept color signals. > > Thanks, > > Sean > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

> Quick video question: I want to try taking a color video signal and use a > high speed comparator to compare the brightness of pixels to some set value > (trying to detect a dark object against a light background). I want to > reject the color information in this process (luma only). How can I do > this? I know it must be fairly simple since B/W TV's can accept color signals. If you have access to an S-Video type input, you can split off the luma signal and just let the color info spill onto the floor. If you have to split a combined (composite) signal, you will tend to get inferior results. (they make cables which go from s-video to dual RCA type connectors, one for chroma, one for luma) -Steve -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

Hi Stuart, Thanks! Could I low pass filter it instead of using a notch filter? It might be a bit simpler. How do old B/W TVs reject the color subcarrier? Since they didn't know about it when they designed them, they couldn't have used a notch filter for 3.58 MHz (yes, I'm dealing with an NTSC signal). Also, in response to Stephen, unfortunately, I will be using a cheap little CCD board camera, so I don't think it will have S-video output. Sean At 04:47 PM 11/29/00 +1100, you wrote: >Just run the video signal through a notch filter. The filter should be >set for 4.43 MHz for PAL or 3.58 MHz for NTSC. >Regards >Stuart -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

At 12:33 AM 11/29/00 -0500, Sean H. Breheny wrote: >Hi all, > >Quick video question: I want to try taking a color video signal and use a >high speed comparator to compare the brightness of pixels to some set value >(trying to detect a dark object against a light background). I want to >reject the color information in this process (luma only). How can I do >this? I know it must be fairly simple since B/W TV's can accept color signals. You're already there. NTSC carries chroma on a subcarrier. The baseband signal is only lumiance and sync. B/W TVs don't pay any attention to the subcarrier, and neither should you. -- Where's dave? http://www.findu.com/cgi-bin/find.cgi?kc6ete-9 -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

Hi Dave, Thanks,but I want to ask a further question because I don't totally understand how that's true. If I'm looking at an NTSC color composite video signal, isn't the subcarrier just added in to the signal? If so, why wouldn't a comparator pick it up (i.e., if the B/W video level is -0.25, and the subcarrier instantaneous voltage is 0.5 V, then why doesn't the comparator act like the level is 0.25 V ?) Thanks, Sean At 01:29 AM 11/29/00 -0500, you wrote: {Quote hidden}>At 12:33 AM 11/29/00 -0500, Sean H. Breheny wrote: > >Hi all, > > > >Quick video question: I want to try taking a color video signal and use a > >high speed comparator to compare the brightness of pixels to some set value > >(trying to detect a dark object against a light background). I want to > >reject the color information in this process (luma only). How can I do > >this? I know it must be fairly simple since B/W TV's can accept color >signals. > >You're already there. >NTSC carries chroma on a subcarrier. >The baseband signal is only lumiance and sync. >B/W TVs don't pay any attention to the subcarrier, and neither should you. > > >-- >Where's dave? http://www.findu.com/cgi-bin/find.cgi?kc6ete-9 > >-- >http://www.piclist.com hint: The list server can filter out subtopics >(like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

"Sean H. Breheny" wrote: > Thanks! Could I low pass filter it instead of using a notch filter? It Yes, if you don't mind loosing some of your resolution. > might be a bit simpler. How do old B/W TVs reject the color subcarrier? Trap filter (not quite as deep as a notch but sufficient). > Since they didn't know about it when they designed them, they couldn't > have used a notch filter for 3.58 MHz (yes, I'm dealing with an NTSC signal). Depends on when/how it was made. The really cheap TV's don't bother with a filter, and you'll see all kinds of dot crawl from strong color information. (Color bars are really good for showing this). Better ones do have this filter, and the really good ones use a 'comb' filter to cleanly remove the color info without affecting the B&W bandwidth. The NTSC signal was designed to be compatible with old B&W TV's so the color phase changes every scan line so that you end up with a four field sequence in NTSC. This visually averages out the color info dots since every second field (odds and evens) has opposite chroma polarity. 3.579545Mhz /227.5= 15734.263 H rate /262.5 =59.94Hz=V rate You will notice that the color subcarrier is 'interlaced' just like the scan lines. > > Also, in response to Stephen, unfortunately, I will be using a cheap little > CCD board camera, so I don't think it will have S-video output. You could wiretap the luminance info since it is processed separately from the chroma and usually combined at the output stage. You may be able to just cut a trace to nuke the chroma addition function so that you get B&W only output, with full bandwidth. Chip info is available on the Sony and Sharp semi sites. If you poke around the last transistor at the output you'll probably find a SMT cap that is coupling the chroma signal into the base. Remove it and you have a B&W camera. Don't forget to gate your 'dark compartor' since sync is blacker than black. And be sure to clamp your video so that scene brightness changes don't throw off your comparator setpoints. Robert -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

In message <4.3.2.7.2.20001129003122.00c607d0EraseMEpostoffice2.mail.cornell.e> du>, Sean H. Breheny <RemoveMEshb7EraseMEspam_OUTCORNELL.EDU> writes >Hi all, > >Quick video question: I want to try taking a color video signal and use a >high speed comparator to compare the brightness of pixels to some set value >(trying to detect a dark object against a light background). I want to >reject the color information in this process (luma only). How can I do >this? I know it must be fairly simple since B/W TV's can accept color signals. The colour (color for you!) encoding systems were designed to be backwards compatible with B/W TV's - the colour is encoded on a 4.44361875Mz sub-carrier (for PAL) and 3.58?Mz for NTSC. An old B/W set will simply not display anything from this sub-carrier, later sets also include a notch filter to remove the chroma from the video path, as do colour sets in their luminance processing. All you need is a simple notch filter, or it may just work without doing anything!. -- Nigel. /--------------------------------------------------------------\ | Nigel Goodwin | Internet : @spam@nigelgRemoveMEEraseMElpilsley.co.uk | | Lower Pilsley | Web Page : http://www.lpilsley.co.uk | | Chesterfield | Official site for Shin Ki and New Spirit | | England | Ju Jitsu | \--------------------------------------------------------------/ -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

Hi Robert, Thanks for the info. I am going to gate the comparator by simply having my code (PIC, of course :-) just reject the input during sync periods (I will have an LM1881 sync separator in the circuit to tell the PIC when the sync is happening). I'm not sure what you mean by "clamp", though. If you mean just limit the video signal swing, I don't understand how that would achieve what you are talking about. Sean At 12:04 AM 11/29/00 -0700, you wrote: >Don't forget to gate your 'dark compartor' since sync is blacker >than black. And be sure to clamp your video so that scene brightness >changes don't throw off your comparator setpoints. > >Robert > >-- >http://www.piclist.com hint: The list server can filter out subtopics >(like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

At 02:02 AM 11/29/00 -0500, you wrote: >Hi Dave, > >Thanks,but I want to ask a further question because I don't totally >understand how that's true. If I'm looking at an NTSC color composite video >signal, isn't the subcarrier just added in to the signal? If so, why >wouldn't a comparator pick it up (i.e., if the B/W video level is -0.25, >and the subcarrier instantaneous voltage is 0.5 V, then why doesn't the >comparator act like the level is 0.25 V ?) The subcarrier is phase modulated, and low amplitude. If this were a problem, you'd see it in a B/W tv, as distortion of the picture. Also, the speed of your comparator is critical here. You could lowpass your video, but this will get you phase distortion. -- Where's dave? http://www.findu.com/cgi-bin/find.cgi?kc6ete-9 -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

> Hi Robert, > > Thanks for the info. I am going to gate the comparator by simply having my > code (PIC, of course :-) just reject the input during sync periods (I will > have an LM1881 sync separator in the circuit to tell the PIC when the sync > is happening). I'm not sure what you mean by "clamp", though. If you mean > just limit the video signal swing, I don't understand how that would > achieve what you are talking about. > Video is normally AC coupled. Clamping, also called DC restoration, rebiases the signal so that the sync tips are at a known voltage. Bob Ammerman RAm Systems (contract development of high performance, high function, low-level software) -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

> Quick video question: I want to try taking a color video signal and use a > high speed comparator to compare the brightness of pixels to some set value > (trying to detect a dark object against a light background). I want to > reject the color information in this process (luma only). How can I do > this? I know it must be fairly simple since B/W TV's can accept color signals. This is very easy if it is a composite signal. The magnitude of that signal is the luminance channel, which is the black and white part. Color, if present, is encoded such that an old black and white TV can just use the luminance and without any knowledge of color. Color requires two additional degrees of freedom. These are encoded as the amplitude and phase shift of a carrier whose frequency is just a bit above the official upper limit of the luminance signal. ***************************************************************** Olin Lathrop, embedded systems consultant in Devens Massachusetts (978) 772-3129, EraseMEolin@spam@embedinc.com, http://www.embedinc.com -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

> >Just run the video signal through a notch filter. The filter should be > >set for 4.43 MHz for PAL or 3.58 MHz for NTSC. > > Thanks! Could I low pass filter it instead of using a notch filter? Yes, the luminance signal is all below the color carrier. But obviously the slower the filter cutoff, the more luminance signal you will be throwing out. This will look like horizontal blurring. > It > might be a bit simpler. How do old B/W TVs reject the color subcarrier? They don't. The beam intensity does get modulated by the color subcarrier, but so what? There is no way you can see this accross the room, and probably not even by carefully examining the picture. The color subcarrier frequency is deliberately just a bit higher than the luminance upper frequency limit. If you had special high performance B+W TV, the color subcarrier would show up as very tightly spaced horizontal ripples. Most old black and white TVs can't resolve this, and your eyes can't either from a normal viewing distance. ***************************************************************** Olin Lathrop, embedded systems consultant in Devens Massachusetts (978) 772-3129, @spam@olinspam_OUT.....embedinc.com, http://www.embedinc.com -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

> Thanks,but I want to ask a further question because I don't totally > understand how that's true. If I'm looking at an NTSC color composite video > signal, isn't the subcarrier just added in to the signal? Yes. > If so, why > wouldn't a comparator pick it up (i.e., if the B/W video level is -0.25, > and the subcarrier instantaneous voltage is 0.5 V, then why doesn't the > comparator act like the level is 0.25 V ?) It would if the comparator is fast enough. The color subcarrier was meant to be unnoticeable to humans watching old B+W TVs at a normal viewing distance. It is not necessarily unnoticable to a custom circuit that analyses the video signal. ***************************************************************** Olin Lathrop, embedded systems consultant in Devens Massachusetts (978) 772-3129, spamBeGoneolinEraseMEembedinc.com, http://www.embedinc.com -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

Most Video circuits are AC coupled (especially cheap cameras). This means that level you've chosen to detect (say .8V) will move as the AVERAGE scene brightness changes. Clamping uses the sync signal to force the known black part of the video (just after sync) to a fixed level. It can also be as simple as a diode that gets biased on for sync tips since the relationship between sync (0V) and video is supposed to be constant. The LM1881 has a clamp output (back porch) which you'd use to turn on a transistor switch for to force your downstream (past the AC coupling cap) video to black level (0v since you want to keep your dynamic range as wide as possible for noise considerations). If you look a changing video scene with a scope you will see that the trace moves around as the average scene brightness changes. This will play havoc will your comparator setpoint unless you clamp the video (having striped it of the chroma subcarrier before you do this). Robert "Sean H. Breheny" wrote: {Quote hidden}> > Hi Robert, > > Thanks for the info. I am going to gate the comparator by simply having my > code (PIC, of course :-) just reject the input during sync periods (I will > have an LM1881 sync separator in the circuit to tell the PIC when the sync > is happening). I'm not sure what you mean by "clamp", though. If you mean > just limit the video signal swing, I don't understand how that would > achieve what you are talking about. > > Sean > > At 12:04 AM 11/29/00 -0700, you wrote: > >Don't forget to gate your 'dark compartor' since sync is blacker > >than black. And be sure to clamp your video so that scene brightness > >changes don't throw off your comparator setpoints. > > > >Robert > > > >-- > >http://www.piclist.com hint: The list server can filter out subtopics > >(like ads or off topics) for you. See http://www.piclist.com/#topics > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

David VanHorn wrote: > > At 02:02 AM 11/29/00 -0500, you wrote: > >Hi Dave, > > > >Thanks,but I want to ask a further question because I don't totally > >understand how that's true. If I'm looking at an NTSC color composite video > >signal, isn't the subcarrier just added in to the signal? If so, why > >wouldn't a comparator pick it up (i.e., if the B/W video level is -0.25, > >and the subcarrier instantaneous voltage is 0.5 V, then why doesn't the > >comparator act like the level is 0.25 V ?) > > The subcarrier is phase modulated, and low amplitude. It's not low amplitude if he's shooting against a strong colored background. The subcarrier can be a large as the video signal for 'saturated' color backgrounds. > If this were a problem, you'd see it in a B/W tv, as distortion of the > picture. NO! What you see is 'dot crawl'. Ever look at color bars on a B&W TV? Check out the boundaries between the bars to see what I mean.(TV dependant of course. The cheaper the TV the more likely you'll see the crawling). > Also, the speed of your comparator is critical here. Yes, it should be fast, but that also depends on what he's trying to detect. A flying insect or an intruder. > You could lowpass your video, but this will get you phase distortion. Not enough to be an issue here. -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

The color subcarrier frequency is chosen such that the black and white dots produced by the color subcarrier appear as white and black dots in the next frame. Your eye then averages these out removing the effects of the color subcarrier on b/w television receivers. Harold On Wed, 29 Nov 2000 01:05:36 -0500 "Sean H. Breheny" <shb7spamBeGoneCORNELL.EDU> writes: {Quote hidden}> Hi Stuart, > > Thanks! Could I low pass filter it instead of using a notch filter? > It > might be a bit simpler. How do old B/W TVs reject the color > subcarrier? > Since they didn't know about it when they designed them, they > couldn't > have used a notch filter for 3.58 MHz (yes, I'm dealing with an > NTSC signal). > > Also, in response to Stephen, unfortunately, I will be using a cheap > little > CCD board camera, so I don't think it will have S-video output. > > Sean > > At 04:47 PM 11/29/00 +1100, you wrote: > >Just run the video signal through a notch filter. The filter should > be > >set for 4.43 MHz for PAL or 3.58 MHz for NTSC. > >Regards > >Stuart > > -- > http://www.piclist.com hint: The list server can filter out > subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics > > FCC Rules Online at http://hallikainen.com/FccRules Lighting control for theatre and television at http://www.dovesystems.com ________________________________________________________________ GET INTERNET ACCESS FROM JUNO! Juno offers FREE or PREMIUM Internet access for less! Join Juno today! For your FREE software, visit: dl.http://www.juno.com/get/tagj. -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

On Wed, 29 Nov 2000 00:04:57 -0700, Robert Rolf wrote: > >Depends on when/how it was made. The really cheap TV's don't bother >with a filter, and you'll see all kinds of dot crawl from strong >color information. (Color bars are really good for showing this). >Better ones do have this filter, and the really good ones use a >'comb' filter to cleanly remove the color info without affecting >the B&W bandwidth. Many *good* color TVs had comb filters as well. They got a better picture by separating the color and luminance early on using the comb filter to remove the color signal from the composite and then subtracting the result from the composite again to get the chroma. Much of the good color data can be derived from the sideband signals of the color subcarrier that are sort of interleaved throughout the spectrum with the luminance and are lost with a simple notch, or trap filter. This would be the higher detail color data that spills over like that. Dan -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

Speaking of Comb filers... I was looking at televisions at Best Buy and one of them boasted a "Digital Comb Filter". How can this be? Isn't the comb filter deep in analog territory? What can be digital about it? These were NTSC televisions, not the HDTV variety either. On Wed, 29 Nov 2000, Dan Larson wrote: {Quote hidden}> On Wed, 29 Nov 2000 00:04:57 -0700, Robert Rolf wrote: > > > > >Depends on when/how it was made. The really cheap TV's don't bother > >with a filter, and you'll see all kinds of dot crawl from strong > >color information. (Color bars are really good for showing this). > >Better ones do have this filter, and the really good ones use a > >'comb' filter to cleanly remove the color info without affecting > >the B&W bandwidth. > > Many *good* color TVs had comb filters as well. They got a better picture > by separating the color and luminance early on using the comb filter to remove > the color signal from the composite and then subtracting the result from the > composite again to get the chroma. Much of the good color data can be derived > from the sideband signals of the color subcarrier that are sort of interleaved > throughout the spectrum with the luminance and are lost with a simple > notch, or trap filter. This would be the higher detail color data that spills over > like that. > > Dan > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics > > > -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

In message <RemoveMEPine.GSO.4.21.0011291618400.4374-100000@spam@spamBeGoneisis.visi.com>,> Matthew Fries <.....freeze@spam@EraseMEVISI.COM> writes >Speaking of Comb filers... I was looking at televisions at Best Buy and >one of them boasted a "Digital Comb Filter". How can this be? Isn't the >comb filter deep in analog territory? What can be digital about it? > >These were NTSC televisions, not the HDTV variety either. It's quite simple, all the processing is done digitally inside chips, they just implement a comb filter algorithm in the software - probably using a DSP. -- Nigel. /--------------------------------------------------------------\ | Nigel Goodwin | Internet : .....nigelgRemoveMElpilsley.co.uk | | Lower Pilsley | Web Page : http://www.lpilsley.co.uk | | Chesterfield | Official site for Shin Ki and New Spirit | | England | Ju Jitsu | \--------------------------------------------------------------/ -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

----- Original Message ----- From: Nigel Goodwin <.....nigelgSTOPspam@spam@LPILSLEY.CO.UK> To: <PICLISTEraseME@spam@MITVMA.MIT.EDU> Sent: Wednesday, November 29, 2000 6:10 PM Subject: Re: [EE]: Video: Color to B/W conversion {Quote hidden}> In message <RemoveMEPine.GSO.4.21.0011291618400.4374-100000spamBeGoneisis.visi.com>,> > Matthew Fries <spamBeGonefreezeKILLspam@spam@VISI.COM> writes > >Speaking of Comb filers... I was looking at televisions at Best Buy and > >one of them boasted a "Digital Comb Filter". How can this be? Isn't the > >comb filter deep in analog territory? What can be digital about it? > > > >These were NTSC televisions, not the HDTV variety either. > > It's quite simple, all the processing is done digitally inside chips, > they just implement a comb filter algorithm in the software - probably > using a DSP. At video frequencies!! ?? !! Bob Ammerman RAm Systems (contract development of high performance, high function, low-level software) -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

Bob Ammerman wrote: > From: Nigel Goodwin <nigelgspam_OUT@spam@LPILSLEY.CO.UK> > To: <spamBeGonePICLIST@spam@MITVMA.MIT.EDU> > Sent: Wednesday, November 29, 2000 6:10 PM > Subject: Re: [EE]: Video: Color to B/W conversion > > Matthew Fries <RemoveMEfreezeEraseMEKILLspamVISI.COM> writes > > >Speaking of Comb filers... I was looking at televisions at Best Buy and > > >one of them boasted a "Digital Comb Filter". How can this be? Isn't the > > >comb filter deep in analog territory? What can be digital about it? > > > > > >These were NTSC televisions, not the HDTV variety either. > > > > It's quite simple, all the processing is done digitally inside chips, > > they just implement a comb filter algorithm in the software - probably > > using a DSP. > > At video frequencies!! ?? !! Yep. It's a trivially simple algorithm. Sample line at a minimum of 4*Fsc, delay one H, subtract new samples from delayed line samples and output. The early comb filters used an ultrasonic subcarrier (10.7Mhz was common) into a glass slab that bounced the signal back and forth numerous times to get the delay they needed. That what those funny tall (2cm), thin (.5cm) brightly color slabs were for. Robert -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

Except that what you mention, while it may be discrete-time signal processing, doesn't qualify as DSP, and it especially doesn't qualify as "using A DSP" because that implies an actual DSP processor. Sean At 09:58 PM 11/29/00 -0700, you wrote: {Quote hidden}>Yep. It's a trivially simple algorithm. Sample line at a minimum of >4*Fsc, delay one H, subtract new samples from delayed line samples and >output. The early comb filters used an ultrasonic subcarrier (10.7Mhz >was common) into a glass slab that bounced the signal back and forth >numerous times to get the delay they needed. That what those funny >tall (2cm), thin (.5cm) brightly color slabs were for. > >Robert > >-- >http://www.piclist.com hint: The list server can filter out subtopics >(like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

On Wed, 29 Nov 2000 18:49:29 -0500, you wrote: >----- Original Message ----- >From: Nigel Goodwin <nigelg@spam@LPILSLEY.CO.UK> >To: <EraseMEPICLISTRemoveMESTOPspamMITVMA.MIT.EDU> >Sent: Wednesday, November 29, 2000 6:10 PM >Subject: Re: [EE]: Video: Color to B/W conversion > > >> In message <RemoveMEPine.GSO.4.21.0011291618400.4374-100000KILLspamTakeThisOuTisis.visi.com>,> >> Matthew Fries <spamBeGonefreeze@spam@VISI.COM> writes >> >Speaking of Comb filers... I was looking at televisions at Best Buy and >> >one of them boasted a "Digital Comb Filter". How can this be? Isn't the >> >comb filter deep in analog territory? What can be digital about it? >> > >> >These were NTSC televisions, not the HDTV variety either. >> >> It's quite simple, all the processing is done digitally inside chips, >> they just implement a comb filter algorithm in the software - probably >> using a DSP. > >At video frequencies!! ?? !! Yes - take a look at any PC video capture card - you won't see any big analogue delay lines or filters - all done digitally. Check out the Brooktree website for data if you want to read more. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

> Bob Ammerman wrote: > > From: Nigel Goodwin <RemoveMEnigelgspam_OUTLPILSLEY.CO.UK> > > To: <PICLISTspamMITVMA.MIT.EDU> > > Sent: Wednesday, November 29, 2000 6:10 PM > > Subject: Re: [EE]: Video: Color to B/W conversion > > > Matthew Fries <spam_OUTfreezespam_OUTspam_OUTVISI.COM> writes > > > >Speaking of Comb filers... I was looking at televisions at Best Buy and > > > >one of them boasted a "Digital Comb Filter". How can this be? Isn't the {Quote hidden}> > > >comb filter deep in analog territory? What can be digital about it? > > > > > > > >These were NTSC televisions, not the HDTV variety either. > > > > > > It's quite simple, all the processing is done digitally inside chips, > > > they just implement a comb filter algorithm in the software - probably > > > using a DSP. > > > > At video frequencies!! ?? !! > > Yep. It's a trivially simple algorithm. Sample line at a minimum of > 4*Fsc, delay one H, subtract new samples from delayed line samples and > output. The early comb filters used an ultrasonic subcarrier (10.7Mhz > was common) into a glass slab that bounced the signal back and forth > numerous times to get the delay they needed. That what those funny > tall (2cm), thin (.5cm) brightly color slabs were for. > > Robert > Ah... the light goes on. I was envisioning a typical FIR/IIR type digital filtering with multiple poles... Bob Ammerman RAm Systems (contract development of high performance, high function, low-level software) -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

> Speaking of Comb filers... I was looking at televisions at Best Buy and > one of them boasted a "Digital Comb Filter". How can this be? Isn't the > comb filter deep in analog territory? What can be digital about it? Think of the comb filter as a mathematical formula. It can be realized (approximated) by either analog or digital means. In this particular case the bandwidth is fairly high so a digital implementation is not trivial. ***************************************************************** Olin Lathrop, embedded systems consultant in Devens Massachusetts (978) 772-3129, olinspam_OUTembedinc.com, http://www.embedinc.com -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

Sean, small BW TV's don't do anything about rejecting color, but they do reject it because they usually do not have the bandwidth to display it, either in the IF or in the video amplifier sections. Professional monitors do have rejection circuitry and the bandwidth and when the former does not work then the color signal manifests itself in a very peculiar disturbance pattern on the monitor (you can tell immediately what is on). The reverse is also true, high resolution color images rendered on a monitor while using composite video signal (CVBS) can have image details that are b/w appear in color on a monitor because their features generate color carrier frequencies in the Y channel. So the way to get rid of color is to use a simple tank circuit (LCR) tuned to 3.57 MHz (in America), with a 6dB bandwidth of about 350 kHz (which is about 10% of Fo). However due to the items detailed above, you also need to limit the bandwidth of the video signal before comparing, to lower than 3.57-(0.35/2) MHz. The best way is, to modify the source of video signal so it does not output color or burst at all. Then you have all the bandwidth and no filtering problems. This is trivial in most cases (find the YC mixer in the camera or VCR and remove the color signal coupling capacitor - this works in most cases). TV tuners can be tuned 'low'. This puts the color signal on the high attenuation upper slope of the SAW filter and will remove color (and possibly sound in single IF TV tuner/if units). Use the AFC control to do this on an assembled set. good luck, Peter -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listservspamBeGone.....mitvma.mit.edu with SET PICList DIGEST in the body

"Peter L. Peres" wrote: GUESSED? Speculated? Mispoke? > Sean, small BW TV's don't do anything about rejecting color, but they do > reject it because they usually do not have the bandwidth to display it, > either in the IF or in the video amplifier sections. If this were true Peter, you wouldn't have any sound. For most TV standards the sound carrier is ABOVE the chroma carrier so any bandwidth constraint in the IF that killed the color carrier would also kill the sound carrier. For NTSC sound is at 4.5Mhz, color at 3.58Mhz. > Professional monitors > do have rejection circuitry and the bandwidth and when the former does not > work then the color signal manifests itself in a very peculiar disturbance > pattern on the monitor (you can tell immediately what is on). That pattern (herringbone or 'stipe noise') occurs when the raw luma video signal (vertical stripes in a scene) produces frequencies that match the color subcarrier. Modern cameras trap this out so that you rarely see this effect. > The reverse is also true, high resolution color images rendered on a > monitor while using composite video signal (CVBS) can have image details > that are b/w appear in color on a monitor because their features generate > color carrier frequencies in the Y channel. A trick that the old Apple II computer expoited to simplify it's video circuitry. > So the way to get rid of color is to use a simple tank circuit (LCR) tuned > to 3.57 MHz (in America), with a 6dB bandwidth of about 350 kHz (which is > about 10% of Fo). However due to the items detailed above, you also need > to limit the bandwidth of the video signal before comparing, to lower than > 3.57-(0.35/2) MHz. > > The best way is, to modify the source of video signal so it does not > output color or burst at all. Then you have all the bandwidth and no Removing color "burst" will simply make a color TV display a B&W image. It will do NOTHING to prevent the color subcarrier from being included in the video signal. > filtering problems. This is trivial in most cases (find the YC mixer in > the camera or VCR and remove the color signal coupling capacitor - this But this is removing the chroma signal, not necessarily the burst, and you may be surprised to find that you can get great 'color black' signal (composite sync with burst) by breaking the one path, without actually affecting the other (I know, it happened to me in an old Sony camera). > works in most cases). TV tuners can be tuned 'low'. This puts the color > signal on the high attenuation upper slope of the SAW filter and will > remove color (and possibly sound in single IF TV tuner/if units). Use the > AFC control to do this on an assembled set. The simplest solution is an LC low pass filter, if resolution loss is tolerable. Otherwise a parallel LC trap tuned to the color subcarrier. Robert -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email spam_OUTlistservKILLspammitvma.mit.edu with SET PICList DIGEST in the body

Thanks to all who responded about the video question. As it turns out, I can tolerate a reduction in resolution (in fact, it will actually help me by preventing a single dark pixel from being detected as a whole dark object), so I plan on using a low pass filter with a cutoff somewhere around 1 MHz (I have to figure out exactly how much resolution reduction I can tolerate). I tried a very quick test of the idea a few days ago, just using a fast comparator (without sync gating or DC restoration, as I said, just a very crude test) and it looks like this will probably work. I have to wait a couple of weeks or so until I get a chance to actually try a better experiment. As for DC restoration, I'm afraid I don't understand what is being suggested. My thought was to capacitively couple the input, sample the signal level when the LM1881 says that the negative sync tip should occur(or just use a negative peak detector), and then use an op-amp to set the average level such that the negative tip ends up where I want it (the inverting input would be connected to the sampled voltage, the non-inverting input to a voltage reference, and the output would go to the signal line via a resistor. A small capacitor would go from output to inverting input to allow constant feedback for high frequencies). When I see the circuit for the Dirt Cheap Frame Grabber (which Mike suggested), however, my circuit seems WAY too complicated. I don't understand how that guy's circuit (just the capacitor, 2 resistors, a diode, and a 2N2222) does what he says,or what is necessary. He talks about the capacitor clamping the voltage. I don't see any way that the cap is going to affect the average level (which it must because the average level is changing and we don't want it to). Thanks again, Sean -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

> As for DC restoration, I'm afraid I don't understand what is being > suggested. My thought was to capacitively couple the input, sample the > signal level when the LM1881 says that the negative sync tip should > occur(or just use a negative peak detector), You shouldn't use the sync tip for DC restoration. It can work if you're always receiving video from the same known device, but I would definitely not use it accross video sources. The scan line front porch is provided for the purpose of DC restoration. It occurs after the sync tip and before the displayable part of the scan line. This is also where the color burst is, so you have to be a little careful. You can also use the back porch, but usually finding the front porch is a little easier with simple circuitry. ***************************************************************** Olin Lathrop, embedded systems consultant in Devens Massachusetts (978) 772-3129, RemoveMEolinRemoveMEEraseMEembedinc.com, http://www.embedinc.com -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

Sean H. Breheny wrote: {Quote hidden}> > Thanks to all who responded about the video question. As it turns out, I > can tolerate a reduction in resolution (in fact, it will actually help me > by preventing a single dark pixel from being detected as a whole dark > object), so I plan on using a low pass filter with a cutoff somewhere > around 1 MHz (I have to figure out exactly how much resolution reduction I > can tolerate). > > I tried a very quick test of the idea a few days ago, just using a fast > comparator (without sync gating or DC restoration, as I said, just a very > crude test) and it looks like this will probably work. I have to wait a > couple of weeks or so until I get a chance to actually try a better experiment. > > As for DC restoration, I'm afraid I don't understand what is being > suggested. My thought was to capacitively couple the input, sample the > signal level when the LM1881 says that the negative sync tip should > occur(or just use a negative peak detector), and then use an op-amp to set > the average level such that the negative tip ends up where I want it (the > inverting input would be connected to the sampled voltage, the > non-inverting input to a voltage reference, and the output would go to the > signal line via a resistor. A small capacitor would go from output to > inverting input to allow constant feedback for high frequencies). > > When I see the circuit for the Dirt Cheap Frame Grabber (which Mike > suggested), however, my circuit seems WAY too complicated. I don't > understand how that guy's circuit (just the capacitor, 2 resistors, a > diode, and a 2N2222) does what he says,or what is necessary. He talks about > the capacitor clamping the voltage. I don't see any way that the cap is > going to affect the average level (which it must because the average level > is changing and we don't want it to). > > Thanks again, > > Sean Sean, see if you can find a TV trades textbook, an older one will be better. These simple circuits have been used for many years for finding the sync pulses, dc restoration, black/white level detection etc etc. Any good TV textbook will have chapters devoted to this with simple circuits, formulas and examples. If you are going to be doing a lot of work with video signal this may be worth getting. -Roman -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

On Sun, 3 Dec 2000 18:17:16 -0500 Olin Lathrop <KILLspamolin_piclistspamBeGoneEMBEDINC.COM> writes: {Quote hidden}> > As for DC restoration, I'm afraid I don't understand what is being > > suggested. My thought was to capacitively couple the input, sample > the > > signal level when the LM1881 says that the negative sync tip > should > > occur(or just use a negative peak detector), > > You shouldn't use the sync tip for DC restoration. It can work if > you're > always receiving video from the same known device, but I would > definitely > not use it accross video sources. The scan line front porch is > provided for > the purpose of DC restoration. It occurs after the sync tip and > before the > displayable part of the scan line. This is also where the color > burst is, > so you have to be a little careful. You can also use the back > porch, but > usually finding the front porch is a little easier with simple > circuitry. > > By the way, waveforms for NTSC television are shown in section 73.699 of the FCC rules. This is available as text (without the images) at www.hallikainen.com/cgi-bin/section.pl?section=73.699 and as a pdf (with images) at frwebgate.access.gpo.gov/cgi-bin/get-cfr.cgi?TITLE=47&PART=73&SECT ION=699&TYPE=PDF Watch for URL wrap. Also, on the pdf, you may have to save the file, then rename it with pdf extension to view it. Harold FCC Rules Online at http://www.hallikainen.com/FccRules/ ________________________________________________________________ GET INTERNET ACCESS FROM JUNO! Juno offers FREE or PREMIUM Internet access for less! Join Juno today! For your FREE software, visit: dl.http://www.juno.com/get/tagj. -- http://www.piclist.com hint: To leave the PICList piclist-unsubscribe-requestspammitvma.mit.edu

>After explosion it looks like a lot of neat things can be done with it. Exploded, that's a good one ;) I would have said dismantled. I have also acquired a 1.3 megapixel camera from a mobile phone - which was in a more exploded state, in this case discarded from a passing car and run over by an unknown number of vehicles. One of my colleagues who bicycles almost everywhere picked it up. The phone appears to be a Samsung D500, and the claim is that this is a colour camera. I have got it out of what was left of the case, apparently undamaged, despite the trauma the rest of the phone suffered. It appears to be a variant of the standard 1/4, 1/3, 1/2" cmos sensors with a controller on the back. I managed to find a circuit for the phone on a Russian website, which confirms it has the seemingly ubiquitous I2C control bus and 8 bit parallel video out bus. However researching these little cameras shows there is no standardisation in the registers used to control them. It seems that it probably has anywhere between 64 and 80 registers to control all the camera functions. The one thing I don't seem to be able to find is any data on this particular camera. The circuit appears to give it a part number of AXK8l24115S and any googling with that number just returns me to the circuit diagrams. It would be nice to be able to use this in a project where the normally available ones on little circuit boards are too big. This one is just the chip size as the footprint with a flexible PCB coming out the back, making for a smaller cross section than any of the ones one can purchase. Does anyone here have any knowledge of Samsung product sources that might help me please? TIA