remote decoder.

Thread Starter

lesin akbar

Joined Dec 16, 2007
30
I need to built a device which can detect the frequency coming to it. I shall make it more clearer, ie the remote controlled device i need to built should have a global transmitter, ie i should be able to assign any transmitter for my device. I may even use my TV remote. So for this thing first i need to detect the signal and save it, now whenever the same frequency is found the ckt is activated. So i need to know how am i going to identify that signal.(i know the programing of mc's). Hope the idea is clear. plz help
 

beenthere

Joined Apr 20, 2004
15,819
What you have in mind sounds a bit like a panoramic receiver. It would help if you could narrow the range of frequencies down a bit - modern RF bands cover all the way from 7 Hz up to over 10 GHz. One receiver can only cover a limited range of frequencies.
 

Thread Starter

lesin akbar

Joined Dec 16, 2007
30
Thanx for your fast response. But I only need to decode the IR signals and i think the standard is 38.5 KHz. (eg. TV remote). Now only thing is that i just have to catch a signal, and whenever the same one comes again i need to identify it. Never interested in the data and all, i need only to identify the pattern.
 

beenthere

Joined Apr 20, 2004
15,819
Well, any old phototransistor will see the IR. While the IR turns on and off at around 38 KHZ (don't know how I got onto RF), the control codes are pretty much patterns of variable on and off periods. If you look at a remote with a digital camera, you can see the IR transmitter wink on and off.

As far as recording the pattern and recognizing it later goes, it sounds like a job for a microprocessor and a certain amount of memory for storing/searching those patterns.
 

Søren

Joined Sep 2, 2006
472
Hi,

[...] I only need to decode the IR signals and i think the standard is 38.5 KHz. (eg. TV remote).
Carrier waves for IR-remotes (TV, HiFi or whatever) can be anything from around 25 kHz to 455 kHz.

(K = Kelvin, k = kilo).

[...] Now only thing is that i just have to catch a signal, and whenever the same one comes again i need to identify it. Never interested in the data and all, i need only to identify the pattern.
The pattern IS the data!

Take a look at this page about IR-remotes to learn the difference between the carrier and the data (and then some).
 

Thread Starter

lesin akbar

Joined Dec 16, 2007
30
thank you all for ur valuable responses. I know how to work with micro controllers(AT89C51), so thats not going to be a problem, i hope so. I more doubt , when we press (and hold it like that) a key of a RC of a TV will the pattern be generated periodically , continuously or will it be coming only once ?
 

Thread Starter

lesin akbar

Joined Dec 16, 2007
30
Oops, sorry, i didnt checked the links you've(soren) given. Ive got everything what i need. Thank you again. and thanx for directing me to such a cute chip picaxe 08M.
 
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