Searching \ for 'EE: IR receiver with range >8m ?' 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/io/sensors.htm?key=rang
Search entire site for: 'IR receiver with range >8m ?'.

Truncated match.
PICList Thread
'EE: IR receiver with range >8m ?'
2004\05\04@033721 by Aadu Adok

flavicon
face
hi,

I have to know when something crosses 30 metres long line. If the
distance was less than 8m, then I would use Everlight's IR receiver,
ELIRM8601 for example (which responds to 38khz modulated IR signal).

But I have to cover 30 metres. Any ideas? Laserdiodes?

thanks,
aadu adok

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email spam_OUTlistservTakeThisOuTspammitvma.mit.edu with SET PICList DIGEST in the body

2004\05\04@045549 by Russell McMahon

face
flavicon
face
> I have to know when something crosses 30 metres long line. If the
distance was less than 8m, then I would use Everlight's IR receiver,
ELIRM8601 for example (which responds to 38khz modulated IR signal).
But I have to cover 30 metres. Any ideas? Laserdiodes?
>


Some modest lensing would almost certainly allow this - easily tried.
Failing that, visible laser pointers would do it with ease, but visibility
may not be what you want. That said, if the transmitter is recessed in a
wider blackened housing  and the receiver similarly, then it could be made
that a laser dot would only be visible when you were being detected.  If you
don't want the red dot to give the game away as they walk through then IR is
the way.

Glass has varying attenuation at IR depending on composition but it would be
easy to try some cheap glass lenses and see what happens - possibly at
transmitter end only. The aim is to produce a parallel (more or less) beam
of diameter equal to the lense diameter. An ordinary red high efficiency LED
makes an extremely bright night time beam at tens of metres - an IR remote
LED and lense should do similar. .


       RM

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email .....listservKILLspamspam@spam@mitvma.mit.edu with SET PICList DIGEST in the body

2004\05\04@064336 by Mike Harrison

flavicon
face
On Tue, 4 May 2004 10:37:30 +0300, you wrote:

>hi,
>
>I have to know when something crosses 30 metres long line. If the
>distance was less than 8m, then I would use Everlight's IR receiver,
>ELIRM8601 for example (which responds to 38khz modulated IR signal).
>
>But I have to cover 30 metres. Any ideas? Laserdiodes?
>
>thanks,
>aadu adok

Laser diodes will probably not help - you get more overal power from IR diodes.
Some powerful IR LEDs and some reasonable optics to narrow the beam and the receiver's field of view
should get you the range you need, but it will need solid mounting to keep it aligned.
--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email listservspamKILLspammitvma.mit.edu with SET PICList DIGEST in the body

2004\05\04@111748 by Shawn Wilton

flavicon
face
Why don't you just go with RF?  Is there some reason you absolutely have
to use IR over such a great distance?

Aadu Adok wrote:

{Quote hidden}

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email EraseMElistservspam_OUTspamTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

2004\05\04@115456 by Russell McMahon

face
flavicon
face
> Why don't you just go with RF?  Is there some reason you absolutely have
> to use IR over such a great distance?

Read again and you'll see that it's a "break the beam" 'intruder' detection
system. RF could be used, but in a different mode (eg radar)


> > I have to know when something crosses 30 metres long line. If the
> > distance was less than 8m, then I would use Everlight's IR receiver,
> > ELIRM8601 for example (which responds to 38khz modulated IR signal).
> > But I have to cover 30 metres. Any ideas? Laserdiodes?

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email listservspamspam_OUTmitvma.mit.edu with SET PICList DIGEST in the body

2004\05\04@115912 by Shawn Wilton

flavicon
face
Crap, missed that part of the email.  If it's an intruder detection
system, I would use a laser, or even directional IR module made for such
a purpose (has been mentioned).  A laser based system is going to much
more effective than an IR based system and you can bounce the beam
around using simple reflectors.

-Shawn


Russell McMahon wrote:

{Quote hidden}

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email KILLspamlistservKILLspamspammitvma.mit.edu with SET PICList DIGEST in the body

2004\05\05@045932 by Aadu Adok

flavicon
face
> A laser based system is going to much more effective than an IR based
> system and you can bounce the beam around using simple reflectors.
>
> -Shawn

howdy,
as lasers use visible light (650nm), what would you use for detecting
part? typical photo-diode? how does it make a difference if ligth is
coming from laser or from sun? by filtering?

thanks,
aadu adok

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

2004\05\05@052710 by Mike Harrison
flavicon
face
On Wed, 5 May 2004 11:59:14 +0300, you wrote:

>> A laser based system is going to much more effective than an IR based
>> system and you can bounce the beam around using simple reflectors.
>>
>> -Shawn
>
>howdy,
>as lasers use visible light (650nm), what would you use for detecting
>part? typical photo-diode? Yes.
>how does it make a difference if ligth is
>coming from laser or from sun? by filtering?
By optics - put the detector down a tube, so it only sees light from a specific direction. Also, using a modulated beam and AC amplifier will filter out any ambient light effects..

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

2004\05\05@063054 by Russell McMahon

face
flavicon
face
>>as lasers use visible light (650nm), what would you use for detecting
>>part? typical photo-diode?

>Yes.

>>how does it make a difference if ligth is
>>coming from laser or from sun? by filtering?

>By optics - put the detector down a tube, so it only sees light from a
specific direction.
>Also, using a modulated beam and AC amplifier will filter out any ambient
light effects..

Let me push the IR receiver barrow again again again.
IF the IR receiver works OK its going to be far far easier than rolling you
own with a laser. It's easy to try the IR receiver, it's cheap enough, and
if it doesn't work then by all means move onto a laser and PIN diode (or
similar) receiver. Making receivers work well in sunlight is a non trivial
task (based on my experience). Shielding the receiver down a longish tube
certainly helps. IR filters don't help much against sunlight as the sun has
the original patent on IR transmission and lets you know it. You can make
detector circuits which dynamically bias themselves to allow for "DC" light
levels but they are not without their problems. You then have to modulate
the laser and make an Ac receiver and amplifier and detector and .... . The
IR receiver module has thus inside it already.

TRY and IR receiver with a lense and a remote. See how far you can get. IF
that's not enough, try a lense at both ends. (Or do a little theory to see
how good it should be.) IF the IR receiver doesn't work, then make life
difficult for yourself and use a laser.


   Russell McMahon

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

2004\05\05@082159 by Aadu Adok

flavicon
face
> Let me push the IR receiver barrow again again again.
> IF the IR receiver works OK its going to be far far easier
ok. let's see if I got it right:

* turn IR led on/off every 13us (to get 38khz)
* receive modulated beam with IR receiver module (TSOP, ELIRM8601, etc..
with TTL level output)
* if the beam is uninterrupted, there will be logical 1 on receiver
output
* if the beam is broken, there will be 0 on receiver output

or am I missing something?

thanks,
aadu adok

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

2004\05\05@083236 by Hazelwood Lyle

flavicon
face
{Quote hidden}

Not quite..
I have used a few different brands of IR receiver, and have found:
1.You'll get a high signal when clear, and a low signal when IR is present.
  i.e. an active-low signal.
2.Just modulating at 38 khz is not enough, constant 38Khz will only give a brief
  active signal.. the flashing will have to be gated with a slower pulse to give
  a matching (inverted) output at the receiving end.

If you read the datasheet of the receiver carefully, this information is usually included there.


Good Luck,
Lyle

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

2004\05\05@083857 by Wouter van Ooijen

face picon face
> * turn IR led on/off every 13us (to get 38khz)
> * receive modulated beam with IR receiver module (TSOP,
> ELIRM8601, etc..
> with TTL level output)
> * if the beam is uninterrupted, there will be logical 1 on receiver
> output
> * if the beam is broken, there will be 0 on receiver output
>
> or am I missing something?

Yes, the requirement that the modulation has periodic breaks, for
instance a 500 Hz on/off. See datasheets (as always).

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: http://www.voti.nl
consultancy, development, PICmicro products

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

2004\05\05@084936 by Russell McMahon

face
flavicon
face
part 1 1786 bytes content-type:text/plain; (decoded 7bit)

ok. let's see if I got it right:

* turn IR led on/off every 13us (to get 38khz)
* receive modulated beam with IR receiver module (TSOP, ELIRM8601, etc..
with TTL level output)
* if the beam is uninterrupted, there will be logical 1 on receiver
output
* if the beam is broken, there will be 0 on receiver output

or am I missing something?

It's very slightly more complex than that. Most IR receivers (certainly all
I have seen) require the 38 KHz to be 'modulated' to maintain lock. So if
you eg turn the 38 kHz on and off at a slower rate (eg 1 kHz) then the
output should be a 1 kHz square wave. If you just send "DC" (ie permanent 38
kHz) the receiver output reacts as if there is no signal. NBNBNB This
behaviour is not in any data sheet I have seen (although it may be in some I
have not seen ;-) ) - I guess they assume people will be sending data of
some sort.

Also, the sending signal to the LED does NOT have to be a 38 kHz square
wave - it can be shorter bursts of IR energy at a 38 kHz rate. This allows
you to send a LARGE pulse to the LED and then leave it off for the remainder
of the 26 microsecond frame and cool down and recover its breath. This
allows a much larger effective energy input as the systems tends to care
only that it has seen "something" each 26 uS period or not. Presumably there
is some lower time limit that  the receiver needs and presumably this is
(possibly) in the data sheet. Starting with 50/50 can't hurt.

I've attached some IR receiver circuits that Jinx provided just  to lure you
to the dark side. Don't do it though - use a commercial module :-)



       Russell McMahon


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




part 2 4753 bytes content-type:image/gif; (decode)

2004\05\05@135538 by Mike Harrison

flavicon
face
On Wed, 5 May 2004 15:20:56 +0300, you wrote:

>> Let me push the IR receiver barrow again again again.
>> IF the IR receiver works OK its going to be far far easier
>
>ok. let's see if I got it right:
>
>* turn IR led on/off every 13us (to get 38khz)
>* receive modulated beam with IR receiver module (TSOP, ELIRM8601, etc..
>with TTL level output)
>* if the beam is uninterrupted, there will be logical 1 on receiver
>output
>* if the beam is broken, there will be 0 on receiver output
>
>or am I missing something?

Probably.

The reason for saying 'probably' rather than 'yes'  that is that some IR receiver modules need to
see a modulated carrier for best performance, so I'd reccommend modulating the 38KHz at around 1KHz,
i.e. a 1ms burst of 38khz, a 1ms gap etc. This would give a 1KHz squarewave when the beam is intact,
and a logic high when no beam is present. This could be done in one chip with a 556.


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

2004\05\05@182645 by Peter L. Peres

picon face
>Read again and you'll see that it's a "break the beam" 'intruder'
>detection system. RF could be used, but in a different mode (eg radar)

Microwave barriers work fine over such distances (and much greater than
that). The available gain at the receiver is much larger and the
transmitter and receiver are on opposite sides, not on the same (as in
radar).

Peter

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

More... (looser matching)
- Last day of these posts
- In 2004 , 2005 only
- Today
- New search...