[sci.electronics] Universal IR Remote Receiver

hunter@apple.com (Kurt Hunter) (10/26/90)

Does anyone know of a discrete or integrated amplifier circuit that can be 
used to increase the signal of an IR detector diode while preserving all 
the IR signal data?

What I want to do is detect both the IR signal data pattern and it's 
carrier frequency as a TTY logic level signal.  I believe typical data 
pattern frequencies are in the range of about 45ms, while carrier 
frequencies have a range of about 30kHz to 80kHz.

I'm also thinking I will need some filtering in addition to amplification, 
however, I don't want the filtering to block out the carrier frequencies.  
I've been told there are some commercial IR pre-amplifier products that 
amplify, filter and wave-shape an IR signal from a directly connected IR 
detector, unfortunately, these same products also demodulate the signal's 
carrier frequency and that's not what I'm after.  Any suggestions?

If any of this sounds weird, it might be because I'm a professional 
software geek :-) and a very part-time hobbyest hardware nerd.


--
Kurt Hunter                             e-mail: hunter@apple.com
Apple Computer, Inc.                    AppleLink: HUNTER.K

Disclaimer:  This posting is not related to Apple Computer, Inc. in any way.

byron@cc.gatech.edu (Byron A Jeff) (10/27/90)

In article <10955@goofy.Apple.COM> hunter@apple.com (Kurt Hunter) writes:
-Does anyone know of a discrete or integrated amplifier circuit that can be 
-used to increase the signal of an IR detector diode while preserving all 
-the IR signal data?
-
-What I want to do is detect both the IR signal data pattern and it's 
-carrier frequency as a TTY logic level signal.  I believe typical data 
-pattern frequencies are in the range of about 45ms, while carrier 
-frequencies have a range of about 30kHz to 80kHz.
-
-I'm also thinking I will need some filtering in addition to amplification, 
-however, I don't want the filtering to block out the carrier frequencies.  
-I've been told there are some commercial IR pre-amplifier products that 
-amplify, filter and wave-shape an IR signal from a directly connected IR 
-detector, unfortunately, these same products also demodulate the signal's 
-carrier frequency and that's not what I'm after.  Any suggestions?
-Kurt Hunter                             e-mail: hunter@apple.com

I refer you to the March 1987 issue of BYTE magazine pg. 113. Steve Ciarcia
Has a design for a trainable master remote controller. Instead of trying
to do the carrier frequency and pulse detection in analog he samples the
IR signal at a 1 Mhz rate and uses a microcontroller to examine the sample
for the carrier and pulse lengths.

I find it's a much more workable method than all the discrete electronics
because most of the work is done in software instead of hardware.

He uses a simple LM311 comparator circuit to boost the signal and then 
shifts the data into a sift register at 1 Mhz. The shift register is read in 
every 8 microseconds. By taking 32 or so 8 bit samples and analysing them you 
can determine both the carrier frequency and the pulse widths.

I'm in the process of trying to build a circuit along the same lines.
I'm using the TL414 phototransistor and a high power IR LED from Radio
Shack. I'm trying to build a IR copier using the sampling principle.
I plan to detect with the phototransistor, amplify with the LM311 circuit,
sample with a shift register and then drive the IR LED. I'm hoping to
be able to copy the incoming signal with enough precision to drive the
box the original remote drives.

Anyway if anyone is interested I'll send mail and let you know how it
came out.

BAJ
---
Another random extraction from the mental bit stream of...
Byron A. Jeff - PhD student operating in parallel!
Georgia Tech, Atlanta GA 30332   Internet: byron@cc.gatech.edu

jw@mck-csc.mckinsey.com (Jeffrey Weiss) (10/31/90)

In article <15934@hydra.gatech.EDU> byron@cc.gatech.edu (Byron A Jeff) writes:
>In article <10955@goofy.Apple.COM> hunter@apple.com (Kurt Hunter) writes:
>-Does anyone know of a discrete or integrated amplifier circuit that can be 
>-used to increase the signal of an IR detector diode while preserving all 
>-the IR signal data? ...
>
>I refer you to the March 1987 issue of BYTE magazine pg. 113. Steve Ciarcia
>Has a design for a trainable master remote controller. Instead of trying
>to do the carrier frequency and pulse detection in analog he samples the
>IR signal at a 1 Mhz rate and uses a microcontroller to examine the sample
>for the carrier and pulse lengths....
>
>He uses a simple LM311 comparator circuit to boost the signal and then 
>shifts the data into a sift register at 1 Mhz....
You will have a problem if you use this method.  Ciarcia's application 
requires that the receiver be about one inch from the transmitter; it's used
to train a multi-remote.  For any reasonable distance, the photo diode or
transistor puts out precious little signal!  The 311 will not do the trick, a
very highly sensitive and low noise pre-amp is required....and as the original
poster identified, commercially available receivers-in-the-can seem to all
include an assumption of a ~40KHz carrier, and remove this carrier for you.
-- 

jw@mckinsey.com (...mit-eddie!mck-csc!jw)
Jeffrey Weiss

ygrignon@sobeco.com (y.grignon) (11/13/90)

In <10955@goofy.Apple.COM> hunter@apple.com (Kurt Hunter) writes:

>Does anyone know of a discrete or integrated amplifier circuit that can be 
>used to increase the signal of an IR detector diode while preserving all 
>the IR signal data?

Radio Shack has an IR receiver module that you can get for cheap.  I do not
remember if it demodulates the signal or not.

Y. Grignon

lairdkb@mentor.cc.purdue.edu (Kyler Laird) (11/14/90)

In article <1990Nov12.171158.8146@sobeco.com> ygrignon@sobeco.com (y.grignon) writes:
>In <10955@goofy.Apple.COM> hunter@apple.com (Kurt Hunter) writes:
>
>>Does anyone know of a discrete or integrated amplifier circuit that can be 
>>used to increase the signal of an IR detector diode while preserving all 
>>the IR signal data?
>
>Radio Shack has an IR receiver module that you can get for cheap.  I do not
>remember if it demodulates the signal or not.
>
>Y. Grignon

Yes, it does.  The output is a logic (on/off) signal.  So simply using it to
gate the output of an oscillator (555?) should do the trick.  The pulse widths 
I've worked with (if I remeber correctly) are fairly long so timing shouldn't be
a major hangup.

(Oh yeah, I think the output is active low.)

It's a fun little item to have around - I used a 6811 to decode the output.  I'd
like to build a Universal IR _Receiver_ some day.

--kyler

rick@ofa123.fidonet.org (Rick Ellis) (11/16/90)

On <Nov 12 17:11> y.grignon writes:

 y> Radio Shack has an IR receiver module that you can get for cheap.  I do 
 y> not remember if it demodulates the signal or not.

It eliminates the carrier.  Making a sensitive IR receiver that preserves the 
carrier and has a high dynamic range is a difficult problem.
 

--  
Rick Ellis
Internet: rick@ofa123.fidonet.org
Compuserve: >internet:rick@ofa123.fidonet.org
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