Searching \ for '[EE]: Amateur radar?' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/index.htm?key=amateur+radar
Search entire site for: 'Amateur radar?'.

Exact match. Not showing close matches.
PICList Thread
'[EE]: Amateur radar?'
2001\08\04@181224 by Sean Breheny

face picon face
Hi all,

One thing that I was wondering recently is this: why, with all of the
varied and interesting amateur radio operation modes, do we not see
amateur radar, either weather radar or air-surveillance radar? Yes, I
know about the small doppler speed-only units by Ramsey but I'm talking
about  someting that provides both speed and range.

Compared to EME or some of the satelite modes, it really wouldn't require
very sophistocated equipment.

After an extensive search on the net, I only found one reference to this,
and IIRC it was a question on an amateur radio newsgroup about whether it
was legal to do, and the consensus was yes. It would seem to me that it
would be leagal, too, since pulsed modes are allowed on amateur radio
bands which are right next to bands used by both the FAA and National
Weather Service.

Sean

--
http://www.piclist.com hint: To leave the PICList
spam_OUTpiclist-unsubscribe-requestTakeThisOuTspammitvma.mit.edu


2001\08\04@182918 by David VanHorn

flavicon
face
>
>After an extensive search on the net, I only found one reference to this,
>and IIRC it was a question on an amateur radio newsgroup about whether it
>was legal to do, and the consensus was yes. It would seem to me that it
>would be leagal, too, since pulsed modes are allowed on amateur radio
>bands which are right next to bands used by both the FAA and National
>Weather Service.

Ya know...
A microwave-inclined storm-spotter like me might be interested in such a
project.
Lots of microcontroller room here, controlling the antenna and such.
Lots of interesting analog stuff too.

How to begin though?

NWS is complaining already, about interference from people using marine
radars on cars.


--
Dave's Engineering Page: http://www.dvanhorn.org

I would have a link to http://www.findu.com/cgi-bin/find.cgi?KC6ETE-9 here
in my signature line, but due to the inability of sysadmins at TELOCITY to
differentiate a signature line from the text of an email, I am forbidden to
have it.

--
http://www.piclist.com hint: To leave the PICList
.....piclist-unsubscribe-requestKILLspamspam@spam@mitvma.mit.edu


2001\08\04@210235 by Sean Breheny

face picon face
Hi Dave,

I've got to ask: why do people use marine radar on cars?!

I have a real tendency to have too many irons in the fire, and I'm very
busy right now, so this will have to go on the "long term projects" list.
However, I had some ideas on how it might be done relatively cheaply.

First of all, my primary interest was toward the aircraft side (I think
it would be REALLY amazing to have a display on your computer screen in
real time of all the aircraft in, say ,a 30 miles radius!) so my ideas
may not be as relevant to the weather version, although that interests
me, too.

I was thinking of using a bunch of Mini circuits ERA amplifiers in
parallel (with hybrids to combine power) as the output amp, providing
only around 100mW depending on how many I wanted to parallel.
Since these can be had for only a few dollars a piece and go up to about
20mW power. Some similar parts from minicircuits would also
make a nice LNA for the receive side.

I would mount an upconverter and a downconverter right up on the back of
the antenna (probably a small dish). I would feed the TX signal and RX
signal to/from the converters with regular coax, using a baseband of
about 1 MHz. Since A to D and D to A converters can easily sample at several
megasamples/sec, the outgoing signal could be generated by a D to A
connected to a high-speed DSP chip, and the incoming signal could be
processed by an A to D and another DSP chip. This way, a change of coding
scheme or decoding algorithm would be only a software change. I'm fairly
certain this would work for simple pulses, but I'm not sure if DSP chips
have enough horsepower for doppler extraction from pulse compressed
coding schemes (like Barker codes) which we might need to make up for the
low output power.

Finally, some PICs could be used to control steppers or other servos to
tilt the antenna horizontally/vertically. I was thinking of using
something around 5GHz, so a relatively small dish (perhaps a 2 to 3 feet
diameter) could be used.

Sean


On Sat, 4 Aug 2001, David VanHorn wrote:

{Quote hidden}

--
http://www.piclist.com hint: To leave the PICList
.....piclist-unsubscribe-requestKILLspamspam.....mitvma.mit.edu


2001\08\04@211519 by David VanHorn

flavicon
face
At 09:01 PM 8/4/01 -0400, Sean Breheny wrote:
>Hi Dave,
>
>I've got to ask: why do people use marine radar on cars?!

Because they don't make radar units for cars.
:)


>First of all, my primary interest was toward the aircraft side (I think
>it would be REALLY amazing to have a display on your computer screen in
>real time of all the aircraft in, say ,a 30 miles radius!) so my ideas
>may not be as relevant to the weather version, although that interests
>me, too.

Probably similar application.
I think doppler is out of the reach of the hobbyist, but a good look at
storm structure would be achievable.

>I was thinking of using a bunch of Mini circuits ERA amplifiers in
>parallel (with hybrids to combine power) as the output amp, providing
>only around 100mW depending on how many I wanted to parallel.
>Since these can be had for only a few dollars a piece and go up to about
>20mW power. Some similar parts from minicircuits would also
>make a nice LNA for the receive side.

I can check with my local microwave ham, I'm sure there are simpler devices
to hack.


>I would mount an upconverter and a downconverter right up on the back of
>the antenna (probably a small dish). I would feed the TX signal and RX
>signal to/from the converters with regular coax, using a baseband of
>about 1 MHz.

I'd be inclined to go with 70 MHz, and use TV receiver components

>  Since A to D and D to A converters can easily sample at several
>megasamples/sec, the outgoing signal could be generated by a D to A
>connected to a high-speed DSP chip, and the incoming signal could be
>processed by an A to D and another DSP chip. This way, a change of coding
>scheme or decoding algorithm would be only a software change. I'm fairly
>certain this would work for simple pulses, but I'm not sure if DSP chips
>have enough horsepower for doppler extraction from pulse compressed
>coding schemes (like Barker codes) which we might need to make up for the
>low output power.

Interesting.


>Finally, some PICs could be used to control steppers or other servos to
>tilt the antenna horizontally/vertically. I was thinking of using
>something around 5GHz, so a relatively small dish (perhaps a 2 to 3 feet
>diameter) could be used.

Makes sense.
I'd like a small beamwidth to get high resolution.
This is one problem with marine radars. They have a thin but tall fan beam,
because ships roll around a lot. That makes them less than stellar for
mapping clouds, where things change with height.

10 or 24 would shrink that antenna, but I don't know yet what the rain
attenuation would be like.



--
Dave's Engineering Page: http://www.dvanhorn.org

I would have a link to http://www.findu.com/cgi-bin/find.cgi?KC6ETE-9 here
in my signature line, but due to the inability of sysadmins at TELOCITY to
differentiate a signature line from the text of an email, I am forbidden to
have it.

--
http://www.piclist.com hint: To leave the PICList
EraseMEpiclist-unsubscribe-requestspam_OUTspamTakeThisOuTmitvma.mit.edu


2001\08\04@215135 by Mike Kendall

flavicon
face
A small commercial marine radar that runs off 13.6vdc may only use 40watts
average power, but the peak pulsed power from the magnetron is huge.  Alot
of the newer units have TX up and the majority of the circuitry is on the
mast.  Military radars are classified as surface search and air search.
Taking a marine band surface search radar and using it to find airplanes
just doesn't work out all that well.  You would need an antenna designed for
the job, for example an "orange peel" antenna.  All I can say is that it
would be a monumental project.  The performance of the system would be no
easy task and I'd not sell it to anyone as I'd be afraid of someone running
into another plane under IFR conditions and then sueing you for any money
you previously made and may make in the future.  There must be some catch,
otherwise Furuno would be making them.
Mike
{Original Message removed}

2001\08\05@224135 by Scott Stephens

picon face
Subject: [EE]: Amateur radar?

>One thing that I was wondering recently is this: why, with all of the
>varied and interesting amateur radio operation modes, do we not see
>amateur radar, either weather radar or air-surveillance radar?

The robotics folks seem to have more of an interest in it and sonar.

>but I'm talking about  someting that provides both speed and range.
...
>it really wouldn't require very sophistocated equipment.

I've been waiting for alarm systems that discriminate between intruders,
pets, and homeowners, and respond accordingly 8^)
It would be very discouraging to come back from vacation to be assaulted by
your 'smart' home after you find your dog has starved and the burglers have
been fed and watered.

Hey, maybe the feds at Los Alamos could use some radar and RFID tags to keep
track of our nuclear warhead designs and disk drives with the instructions
to disarm them? On a TV congressional hearing show I watched a few months
back, they (DOE management) complained the RF radiated by cameras might make
too much noise for their bug/counter-elint efforts. Spies might bug their
meetings, or observe their research. Uh, OK.

Of course all the high-tech in the world is no use against damaged moral.
Finding scientists and engineers too stupid to notice the hypocrisy and beat
managment in a race to the bottom, yet smart enough to be even a little
effective is tough to do. I have often heard that in 'public service' or
government jobs, the pay is less because of the perk of honor and duty - the
warm fuzzy patriotic feeling. Guess that's not enough; even the FBI can't
keep guns and laptops that aren't bolted down.

I suppose even those in the private sector would even like to believe the
honor of their employees would prevent them from turning to the competition
for a better price.

Once I was working as a technician at a lab bolting down PC's with chains,
adhesive pads and superglue. An intern (no, not a pretty managment
thong-snapper, but an exploited, underpaid recent grad) came up and remarked
that the way they defeated that method at their school was to inject acetone
under the adhesive pad with a syringe. Lucky I found out how to remove those
nasty glue pads when I was requested to move the equipmeent from someone,
without busting what they were glued to.

Its not that crooks usualy know more about crime than  those the chains are
meant to keep honest from temptations. I mean the locks and chains, and bugs
and cameras project an identity. They shout and scream in their silent
vigilence "I don't trust you - you are not honorable or worthy of trust".
They declair a double standard, shouting - "You are the child, I am the
parent; you are the inmate, I am the warden, you are the sheep, I am the
farmer, you are the prey, I am the predator".

This is why there is a nameless, denied, inherint aversion to video cameras,
and it is why the media and government insist otherwise. Defacto double
standard, inequality, and a self-fullfilling prophecy.

The FBI didn't want polygraphs for this reason. How can they feel like elite
guardians of justice and freedom when they are being questioned like
criminals? Asked embarassing questions (have you ever wanted to sell out?
lusted after another male? a child? an animal?) for stress responses, probed
like rats in an experiment? And how does a scientist, that sees,  as Feynman
described, the threads in the tapestry that run through the whole of
creation, feel when a bunch of armed gorillas, lead by an alpha male that
has no more moral compass than Joey Stalin treat them like a treasonous
public enemy? Probably feels like selling out to the 'enemy' that, like the
Pigs in Orwell's "Animal Farm", look strangely like the evil farmers!

I recently read a thesis (allens-masters-m2.pdf from
http://www.ai.mit.edu/projects/leglab/robots/robots.html ) where the author
dedicated it to his parents and sisters for 'believing' in him. Believing in
him? Who cares if they are 'believed' in!?!? There once was prophet that
would do no miracles where the people didn't believe in him, and demanded
faith from his 'believers'. The social plasma is nonlinear - the individuals
trajectory in society is self-consistent and self-reinforcing with their
beliefs and attitudes, and the identity society projects on them;
psychologist call it 'wish fullfilment', or self-fullfilling prophecy. Those
children in the prison-like 'schools' with metal detectors, barred windows,
armed guards and clever head games are most malleable.

The Konformist (http://www.konformist.com - sorry, couldn't find the
reference) internet conspiracy rag had a story some parents who had a
suprize party arranged for their daughter, with the help of a local TV
station. They wired the house for video while the girl was at school. The
parents were quite embarrased to discover their daughter had an unusauly
self-gratifying method of feeding the dog alone after school, with a part of
her anatomy other than her hand! I wonder how attitudes and self-images were
affected? No, I don't want to know.

Hey, we should sell bugs and video cameras to the government! Think of it -
arrogant bureaucrats babysitting their irresponsible 'children', Attitudes,
expectations and moral degenerating until - ? Like selling crack cocain to
your enemy! If you try to take your enemy's vice, he will count his vice a
virtue, and cling to it. If you allow your enemy to abuse his vice to his
tolerance, like an addict, it will either destroy him or cause change. What
did the Clinton's lawyer say in his defense at his impeachment, 'They
(Republicans) want to impeach him 'TOO' much'. In other words, the
Republicans are selectively finding fault to humiliate their opponents for
political gain rather than systemic integrity. So instead the Democrats
choose to 'normalize', excuse, embrace corruption - if its by the 'alpha
male' anyways.

Lifes full of so many simple ironies. Oh my, I am ranting again.

>After an extensive search on the net, I only found one reference to this,

Check da patent server, and the references at http://www.aetherwire.com

>and IIRC it was a question on an amateur radio newsgroup about whether it
>was legal to do, and the consensus was yes. It would seem to me that it
>would be leagal, too, since pulsed modes are allowed on amateur radio
>bands which are right next to bands used by both the FAA and National
>Weather Service.

For some info on interference caused by radar-like signals -
www.its.bldrdoc.gov/pub/ntia-rpt/01-383/01-383.pdf
www.its.bldrdoc.gov/pub/ntia-rpt/01-384/all_appendices.pdf
"APPENDIX A. TUTORIAL ON USING AMPLITUDE PROBABILITY DISTRIBUTIONS
TO CHARACTERIZE THE INTERFERENCE
OF ULTRAWIDEBAND TRANSMITTERS TO NARROWBAND RECEIVERS"

Scott

****************************************************************
Freedom is pursuing your carrot, not running from a stick.
The mob only rules what its members are allowed to achieve.
Physics - the manifold ways the odds always get even...
****************************************************************

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2001\08\05@224149 by Scott Stephens

picon face
>I was thinking of using a bunch of Mini circuits ERA amplifiers in
>parallel (with hybrids to combine power) as the output amp

If its radar, why not avalanche impulse generators? Checkout the Zetex app
note "The ZTX415 Avalanche Mode Transistor
An Introduction to Characteristics, Performance and Applications: for
transistorized pulse forming and Marx genererators. You can use type 2n2222
transistors (and some others) in this mode, if you don't wan't to caugh up
$20 for Zetex ones, for non-aerospace apps.

For radars I like the idea of impulse better than CW, matched filters better
than chirps. But I don't speak from experience. Be sure to look up radars on
the patent server and checkout the impulse radio company I posted links to
in the past.

>Finally, some PICs could be used to control steppers or other servos to
>tilt the antenna horizontally/vertically. I was thinking of using
>something around 5GHz, so a relatively small dish (perhaps a 2 to 3 feet
>diameter) could be used.

Come on, be bold. Figure out how to use common ferrites or piezo materials
(perhaps glass or TiO ceramic?) To build a phased array scanner. Plenty of
examples out there!

Scott

****************************************************************
Freedom is pursuing your carrot, not running from a stick.
The mob only rules what its members are allowed to achieve.
Physics - the manifold ways the odds always get even...
****************************************************************

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads


2001\08\06@045443 by Alan B. Pearce

face picon face
>I've got to ask: why do people use marine radar on cars?!

To jam speed cameras ????

--
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


2001\08\06@052635 by J.Feldhaar

flavicon
face
Hi all,

another tack on the issue: what about the bandwidth required for good
distance resolution, assuming a pulse or a chirp is used, considering the
mandatory use of multi kilowatts of peak power needed for the 30 miles
range earlier mentioned in this thread...??

I personally have considered doing just this and I have not found an
amateur frequency range where this would be permitted...even the 5 GHz
band

Comments?

Greets,
Jochen Feldhaar DH6FAZ

"Alan B. Pearce" schrieb:

> >I've got to ask: why do people use marine radar on cars?!
>
> To jam speed cameras ????
>
> --
> 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


2001\08\06@095536 by David VanHorn

flavicon
face
At 09:52 AM 8/6/01 +0100, Alan B. Pearce wrote:
> >I've got to ask: why do people use marine radar on cars?!
>
>To jam speed cameras ????

Nope, won't work, wrong band.

They use it to map storms locally.

--
Dave's Engineering Page: http://www.dvanhorn.org

I would have a link to http://www.findu.com/cgi-bin/find.cgi?KC6ETE-9 here
in my signature line, but due to the inability of sysadmins at TELOCITY to
differentiate a signature line from the text of an email, I am forbidden to
have it.

--
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


2001\08\06@100250 by Matt Bennett

flavicon
face
"J.Feldhaar" wrote:
>
> Hi all,
>
> another tack on the issue: what about the bandwidth required for good
> distance resolution, assuming a pulse or a chirp is used, considering the
> mandatory use of multi kilowatts of peak power needed for the 30 miles
> range earlier mentioned in this thread...??
>
> I personally have considered doing just this and I have not found an
> amateur frequency range where this would be permitted...even the 5 GHz
> band
>
> Comments?
>
> Greets,
> Jochen Feldhaar DH6FAZ

Ummm... What's "good resolution?"

From _Intoduction to Radar Systems_ by Merrill I. Skolnik- the error in
the time delay of a pulse (using rising and falling edges of the pulse)
can be written (Eq. 11.5):

Rise time error=(t/(4BE/No))^(1/2), where B is the bandwidth, E is the
signal energy, No is the noise power per unit bandwidth and t is the
pulse width.

The range error would be 1/2*time error*c) (1/2 since radar is 2-way,
but that also means that your power recieved goes down as a factor of
1/r^4)

A chirp would get you a greater effective power on the target-
increasing E.

As to peak power required and so forth, I direct the curious to chapter
2 of the same book, where the radar equation is discussed in some detail
(50+ pages).

That's your range resolution, but azimuth resolution is a factor of your
antenna and range.  I'm particularly fascinated by synthetic aperture
radar- while the range resolution is still a factor of system bandwidth,
azimuth resolution is *independent* of range with a focused SAR.
Depends on a moving radar (or target) and you can't make an image in
"real time" but it is fascinating anyway.

Matt Bennett

--
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


2001\08\06@101243 by Mike Kendall

flavicon
face
Here's one for thought, if it is used on the amatuer bands, how will the ID
be done  for the station every (I think I remember it as 10 minutes)?  Will
there be a CW station ID every 10minutes?
Mike
{Original Message removed}

2001\08\06@103822 by Mike Kendall

flavicon
face
If someone was interested in doing what was mentioned, electronics now
magazine had a "radar gun calibrator" article in the 80's.  It uses a gunn
diode and feedhorn setup.  I guess you'd have to cut a hole in the grill of
your hotrod and know for sure what band the local yocals were using on their
radar guns.
Mike
{Original Message removed}

2001\08\06@105317 by Douglas Butler

flavicon
face
About a year ago I pulled a radar-thingy out of the dump.  It is called
a "Whistler Radar" model WR-108 US Patent# 3735402.
It is small suitcase sized and hangs on a shoulder strap.  Most of the
volume is occupied by a parabolic reflector antenna.  It has jacks for
12V and headphones, and has one knob and an analog meter labeled 0 to 1
nautical mile.
Does anyone know what I have got?  It is a little corroded but could
probably be gotten working, if I knew what it is supposed to do.  The
company doesn't seem to exist anymore and I haven't had time to track
down the patent number.

Sherpa Doug

> {Original Message removed}

2001\08\06@105335 by Matt Bennett

flavicon
face
Mike Kendall wrote:
>
> Here's one for thought, if it is used on the amatuer bands, how will the ID
> be done  for the station every (I think I remember it as 10 minutes)?  Will
> there be a CW station ID every 10minutes?
> Mike

Heck, that's easy- just CW modulate the transmitted signal with your ID
in morse code. Takes some time away from your scanning, but otherwise,
it's no problem.

Matt Bennett

--
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


2001\08\06@110136 by David VanHorn

flavicon
face
At 10:31 AM 8/6/01 -0400, Douglas Butler wrote:
>About a year ago I pulled a radar-thingy out of the dump.  It is called
>a "Whistler Radar" model WR-108 US Patent# 3735402.
>It is small suitcase sized and hangs on a shoulder strap.  Most of the
>volume is occupied by a parabolic reflector antenna.  It has jacks for
>12V and headphones, and has one knob and an analog meter labeled 0 to 1
>nautical mile.
>Does anyone know what I have got?  It is a little corroded but could
>probably be gotten working, if I knew what it is supposed to do.  The
>company doesn't seem to exist anymore and I haven't had time to track
>down the patent number.

This is a man-portable radar system.
I vaguely remember seeing ads for this..

Where's the dump? :)

--
Dave's Engineering Page: http://www.dvanhorn.org

I would have a link to http://www.findu.com/cgi-bin/find.cgi?KC6ETE-9 here
in my signature line, but due to the inability of sysadmins at TELOCITY to
differentiate a signature line from the text of an email, I am forbidden to
have it.

--
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


2001\08\06@113404 by Alan B. Pearce

face picon face
>Heck, that's easy- just CW modulate the transmitted signal with your ID
>in morse code. Takes some time away from your scanning, but otherwise,
>it's no problem.

Or use it in the chirp. There used to be a marine beacon transponder unit
that did this to identify itself on a marine radar screen. I never actually
saw the display, but understand that you got this line of dots and dashes on
the PPI with the closest point being where the beacon was situated.

--
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


2001\08\06@130239 by Douglas Butler

flavicon
face
{Quote hidden}

On Cape Cod.  There is lots of recreational marine stuff in our dumps.

What I can't figure out is how it would be used.  I suppose you could
aim it at a target (it may have had a sighting device on top) and turn
the knob until you heard a signal on the headphones, then read the range
off of the meter.  That seems cumbersome, and explains why I have only
ever seen one of these.

Sherpa doug

{Quote hidden}

--
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


2001\08\06@131002 by Sean Breheny

face picon face
Hi All,

If I do attempt this, I really should get a copy of Skolnik's book. I
took a course on radar while getting my BS in EE, and a lot of the
references were to Skolnik (we even got some photocopies of chapters out
of the book) but I don't recall seeing that particular equation. Thanks
for the info!

I did some "back of the envelope" calculations which showed that in a
1MHz bandwidth, with a dish which gives about 1m^2 effective area (a
little more than 2 feet diameter,if your feed is very good in delivering
a unifrom dish illumination), running about 10 watts peak power (just
sending simple pulses about 2 microseconds long or so), with a mediocre
receiver (NF=3dB), and a large target (50m^2 RCS, equivalent to a 737 or
larger), you could get out to 24 miles. Better NF or higher power
increase range according to the 4th root of power.

Since I was suggesting only 100mW output power (since I haven't been able
to find a convenient way to cheaply produce a lot more at 5GHz), that
would give a range of 24 divided by the 4th root of 100 (10/0.1) or about
7 miles.

Using a better coding scheme (other than just simple pulses) would help
a fair bit. Linear FM chirps (as mentioned by a few posters) or another
form of pulse compression (phase codes, where you send a long burst of
binary or trinary or higher-order phase modulation and then use a proper
matched filter on the other end) could probably double the range without
having to do anything extremely fancy.

As for ID, I was thinking of just stopping the radar-type emission every
10 minutes and just turning on the transmitter in CW mode and sending CW
id, then resuming the scan.

Finally, on the subject of weather radar, I'd like to ask the experts
here something: How does weather radar obtain the component of wind (or
droplet) velocity perpendicular to the direction of radar beam
propagation? In other words, the doppler freq only tells you how fast the
object is moving toward or away from you. When dealing with aircraft, you
have to track the individual plane in order to get the other component
(that is, subtract its last position form the current one). Its seems to
me as  though this isn't possible with  WX radar since there is no target
to track, you are  getting an echo from millions of water dropplets
throughout a whole area.

Sean


On Mon, 6 Aug 2001, Matt Bennett wrote:

{Quote hidden}

--
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


2001\08\06@141714 by John Ferrell

flavicon
face
I think it appeared on the cover of Radio & Electronics Magazine in the
50's, maybe 60's.
No telling what it might be worth on EMBAY If you could pair it with a copy
of the magazine...

John Ferrell
6241 Phillippi Rd
Julian NC 27283
Phone: (336)685-9606
Dixie Competition Products
NSRCA 479 AMA 4190  W8CCW
"My Competition is Not My Enemy"



{Original Message removed}

2001\08\06@142812 by Mike Kendall

flavicon
face
If the antenna actually rides on the backpack wearers device, I'd shy away
from it. If the antenna is seperately mounted, this would not apply.  I
heard that some of the origional police officers involved with speed trap
radars did not fare too well.  Apparantly,  due to the size of the radar gun
electronics, it was mounted in the back seat and aimed past the police
officers face between the driver and passenger  seats.  There were cases of
the side of the police officer's face becoming cancerous over time.  I just
heard this as a factoid/word of mouth.  If the radar unit was built in the
50's/60's, this might not have been considered when designing the unit.
{Original Message removed}

2001\08\06@143038 by David VanHorn

flavicon
face
>
>What I can't figure out is how it would be used.  I suppose you could
>aim it at a target (it may have had a sighting device on top) and turn
>the knob until you heard a signal on the headphones, then read the range
>off of the meter.  That seems cumbersome, and explains why I have only
>ever seen one of these.

That's more or less what I remember.

--
Dave's Engineering Page: http://www.dvanhorn.org

I would have a link to http://www.findu.com/cgi-bin/find.cgi?KC6ETE-9 here
in my signature line, but due to the inability of sysadmins at TELOCITY to
differentiate a signature line from the text of an email, I am forbidden to
have it.

--
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


2001\08\06@143411 by David VanHorn

flavicon
face
>
>Finally, on the subject of weather radar, I'd like to ask the experts
>here something: How does weather radar obtain the component of wind (or
>droplet) velocity perpendicular to the direction of radar beam
>propagation? In other words, the doppler freq only tells you how fast the
>object is moving toward or away from you. When dealing with aircraft, you
>have to track the individual plane in order to get the other component
>(that is, subtract its last position form the current one). Its seems to
>me as  though this isn't possible with  WX radar since there is no target
>to track, you are  getting an echo from millions of water dropplets
>throughout a whole area.

That's what you get.
And if the rain is dense enough, you go blind behind it.

--
Dave's Engineering Page: http://www.dvanhorn.org

I would have a link to http://www.findu.com/cgi-bin/find.cgi?KC6ETE-9 here
in my signature line, but due to the inability of sysadmins at TELOCITY to
differentiate a signature line from the text of an email, I am forbidden to
have it.

--
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


2001\08\06@152837 by Douglas Butler

flavicon
face
> From: Sean Breheny [KILLspamshb7KILLspamspamCORNELL.EDU]
......
> Finally, on the subject of weather radar, I'd like to ask the experts
> here something: How does weather radar obtain the component
> of wind (or
> droplet) velocity perpendicular to the direction of radar beam
> propagation? In other words, the doppler freq only tells you
> how fast the
> object is moving toward or away from you. When dealing with
> aircraft, you
> have to track the individual plane in order to get the other component
> (that is, subtract its last position form the current one).
> Its seems to
> me as  though this isn't possible with  WX radar since there
> is no target
> to track, you are  getting an echo from millions of water dropplets
> throughout a whole area.
>
> Sean

This might be a little out of the realm of amateur weather radar, but
there is a technique I know of to measure the speed of silt particles in
seawater using a laser.

You split the laser into two beams that converge on the area of interest
and create an interference pattern.  Now you have alternating light and
dark bands in the water.  As particles move through the bands their
reflected light flickers at a rate indicating speed, though direction is
ambiguous.  By using three beams each modulated at different frequencies
the 2D direction can be found.

The water sample measured is about one meter from the end of the
instrument, and by sliding lenses a small volume can be scanned.  Using
radar beams in place of lasers a larger area might be scanned in the
air.

Sherpa Doug

--
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


2001\08\06@180641 by Olin Lathrop

face picon face
> How does weather radar obtain the component of wind (or
> droplet) velocity perpendicular to the direction of radar beam
> propagation?

It doesn't.


********************************************************************
Olin Lathrop, embedded systems consultant in Littleton Massachusetts
(978) 742-9014, RemoveMEolinTakeThisOuTspamembedinc.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


2001\08\06@203228 by Ashley Roll

flavicon
face
Hi,

You can find the patent at http://www.delphion.com/details?&pn=US03735402__

not sure how much info you'll be able to get from it without subscribing,
but it has an overview of the device.

Ash

> {Original Message removed}

2001\08\06@230654 by Brandon Fosdick

flavicon
face
Douglas Butler wrote:
> This might be a little out of the realm of amateur weather radar, but
> there is a technique I know of to measure the speed of silt particles in
> seawater using a laser.

Laser Velocimetry. Its used in wind tunnels too, except with dust in
moving air. There are two problems with it though, 1. tracking lots of
particles takes an enourmous amount of computing power, not to mention
the video capture requirements; 2. Near particles can obscure far
particles. Normally you don't think of a dust particle being big enough
to obscure anything, but since they're bright they can take up several
pixels, which will obscure other particles, or at least make the
boundary ambiguous. And then when the two particles seperate again, you
have to figure out which one is which. Tracking millions of water
droplets would be a big task.

--
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


2001\08\06@234115 by Peter Wintulich

flavicon
face
Hello,

I rember a unit like this for sale a few years ago from a surplus place.
It was a point to point (line of site) voice link used as a pair one at each end.

>>> spamBeGonedbutlerspamBeGonespamIMETRIX.COM 08/07/01 12:01AM >>>
About a year ago I pulled a radar-thingy out of the dump.  It is called
a "Whistler Radar" model WR-108 US Patent# 3735402.
It is small suitcase sized and hangs on a shoulder strap.  Most of the
volume is occupied by a parabolic reflector antenna.  It has jacks for
12V and headphones, and has one knob and an analog meter labeled 0 to 1
nautical mile.
Does anyone know what I have got?  It is a little corroded but could
probably be gotten working, if I knew what it is supposed to do.  The
company doesn't seem to exist anymore and I haven't had time to track
down the patent number.

Sherpa Doug

--
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


2001\08\07@020414 by David VanHorn

flavicon
face
At 01:08 PM 8/7/01 +0930, Peter Wintulich wrote:
>Hello,
>
>I rember a unit like this for sale a few years ago from a surplus place.
>It was a point to point (line of site) voice link used as a pair one at
>each end.

I've seen those too, Gemstar, I think was the name
24 GHz, and it looked like a headlight.

--
Dave's Engineering Page: http://www.dvanhorn.org

I would have a link to http://www.findu.com/cgi-bin/find.cgi?KC6ETE-9 here
in my signature line, but due to the inability of sysadmins at TELOCITY to
differentiate a signature line from the text of an email, I am forbidden to
have it.

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.


2001\08\07@105531 by Eric Strauts

flavicon
face
> You can find the patent at http://www.delphion.com/details?&pn=US03735402__
>
> not sure how much info you'll be able to get from it without subscribing,
> but it has an overview of the device.
>
> Ash

Try looking at http://www.uspto.gov/patft/ You can view the whole
patent and print it from saved .TIFF image files without any
subscription nonsense. You need a .TIFF viewer plug in for your
Web browser but the site has links in the help to a very good and
small one (180k download) called Alternatiff.

Don't use the Quicktime plug-in. It unexpectedly wants to magnify
the image and won't let you print or save image files.

Eric

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.


2001\08\07@112703 by Douglas Butler

flavicon
face
       The underwater machine I saw used a single photomultiplier tube as the
detector, only one pixel!  I suspect the operation was different than
the laser velocimetry you describe.
       At the time I was working on the next instrument over, a diffractometer
which measured silt particle size.

Sherpa Doug

> {Original Message removed}

2001\08\07@120159 by eter William Green

flavicon
face
you may have seen a laser doppler system (LDV) which is based on a frequency shift.
this is a point measurement system.

the other method described sounds like partical image velocimetry (PIV), which allows you to map out an entire velocity field.

both of these have been around for some time.  you may want to take a look at dantec's site for some more info (it's a commercial system but they have explanations of the principles)  http://www.dantecmt.com/lda/princip/index.html

-pete


On Tue, 7 Aug 2001, Douglas Butler wrote:

>         The underwater machine I saw used a single photomultiplier tube as the
> detector, only one pixel!  I suspect the operation was different than
> the laser velocimetry you describe.
>         At the time I was working on the next instrument over, a diffractometer
> which measured silt particle size.
>
> Sherpa Doug
>
> > {Original Message removed}

2001\08\07@135620 by Peter L. Peres

picon face
>> How does weather radar obtain the component of wind (or
>> droplet) velocity perpendicular to the direction of radar beam
>> propagation?
>
> It doesn't.

I think that it can try if the target is larger than a single echo. The
angle of the general droplet movement is different for each successive
echo from a larger target so a computer could figure the speed and the
vector from several echo's doppler content. I think that normal stationary
weather radar does this already but I am not sure.

Peter

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.


More... (looser matching)
- Last day of these posts
- In 2001 , 2002 only
- Today
- New search...