Convert IR remote to RF remote

Try something like

Cool. This looks just like the one I had seen except smaller and cheaper (less range 20m instead of 30m but that won't be a problem). The best thing, computronics isn't far from where I live, but I didn't even know it existed. I will have to go there tommorow and see what other cool stuff they have. So let me see if I have this correct. I should be able to connect the Code input pin of the transmitter to the IR LED in the remote and connect the Digital Output pin of the reciever to the phototransistor in the deck and I'm done? Obviously connecting power and ground too. Should I leave the IR LED in the circuit or remove it? Same with the phototransistor? What should I use for the antenna? Just a piece of wire 30-35cm long? Is 3kb/s fast enough?

Cheers

Matthew

"Matthew Gunn"

** Doubt it is quite as easy as that.

IR remote transmitters modulate the light beam at around 40 kHz - ie the control code is actually sent as bursts of 40 kHz pulses, not just simple LED on and off pulses. So you will need to pass the LED drive voltage through a low pass filter prior to the Tx unit to remove the 40 kHz part.

Also, an IR receiver's photo detector is tuned to respond to the same 40 kHz frequency only - so recovered data pulses from a radio Rx will have to be fed in just after the IR units input stage.

You will need a CRO to have a hope of sorting this all out.

............ Phil

convert an

frequency

didn't

the

in

Hi Matthew, I don't think you will be able to connect the IR led output directly to the RF transmitter as the led is usually modulated @ around 40khz. Also connecting the output of the reciever to the photodiode probably won't work as there is normally a 40khz filter/amplifier for the photodiode receive circuit.

You would probably need to drive the transmitter from the unmodulated signal and connect the output of the reciever after the amplifier/filter.

Most RF signals are also coded with something like a manchester code to improve reliability so I don't even like the idea of RF transmission of the unmodulated signal.

I think you will find the answer to your question is "near impossible". Regards, Dean.

Shit. Oh well. Looks like I'll have to make do how it is. I never have understood why manufacturers put an IR remote in a car stereo. I could understand a RF remote but IR is a joke. The only line of sight to the deck is out the hatchback, between the two seats. This doesn't really allow many situations where I can actually use the remote to do anything.

Cheers anyway

Matthew

** You better not buy a radio control system for models then - most just switch the carrier on and off with a simple pulse position modulation with a 50 Hz repetition rate. The FM variety just shift the frequency up a few kHz with the same modulation pattern.

No way that could ever work reliably ..........

............ Phil

What about if the data rate were faster, say 120kb/s or higher? I don't think such a thing exists but I will look if it is viable. I don't really want to mess around too much inside the deck itself, but i was thinking if the data rate was fast enough, the RF signal could replace the IR signal directly. Does this sound right?

Matthew

** Find a Tx/Rx combo that can handle a 50 kb/d data rate and you have it made - just drive a IR led from the output of the Rx to optically drive the IR unit in the car from a metre or so away.

............. Phil

What about if the data rate was faster, say 120 kb/s or more? If the data rate was fast enough, it could replace the IR signal with the RF one couldn't it? If that is the case I will have to look for something with faster data rates. I don't really want to go poking around too much inside the deck itself so I was hoping for a simple solution at least at the reciever end. I don't mind so much playing around with the remote 'cause they are nice and cheap.

Matthew

Sorry I didn't think it posted the first time.

Matthew

Great idea. I could mount the RF reciever on the cargo barrier between the seats and it will have a good "view" of the deck. Then I don't even need to open the deck up. Now the question is, does anyone know where I would find a Tx/Rx combo that can handle 50 kb/s data rate?

Matthew

have it

optically drive

between

even

where I

These modules can do 200kbit/sec:

Perhaps you could also consider an IR repeater? Place the IR receiver of the repeater in a good location (such as the roof area between the sun visors?) and have the IR transmitter sitting in the boot with your stereo. That way it's passive and you're not modifying anything except the car (slightly :) )

most

modulation

frequency up

Actually I think you will find that most OLD radio control systems for models use simple PPM and any corruption of the stream might only cause the servo to jitter briefly until the next stream comes along (I designed the RC encoder for Silicone Chip transmitter). New RC control systems use PCM to improve reliability and have error detection. Regards, Dean.

= evil context snipper - grrrrrrrrrr

** Err - that is just what I wrote.

Except that PPM ( in either AM or FM versions ) is still the most common method in use by far.

** So it works reliably - despite in band interference - because of code repetition.

Guess what an IR remote does too ???

................ Phil

Old model remote control systems used PPM, New and advanced systems use PCM, ever wondered why ??.

Also the IR remote stops transmitting as soon as you release the switch therefore it's not continuous repetiton. PPM systems were used for analogue systems not for digital code transmissions that if corrupted could cause very strange actions like turning the CD player off. All the RF links for things like car alarms use some kind of coding like a manchester code.

Regards, Dean.

** Now the snipping MANIAC snips out the ENTIRE context !!!!

So I will put it all back:

** Err - that is just what I wrote.

Except that PPM ( in either AM or FM versions ) is still the most common method in use by far.

** So it works reliably - despite in band interference - because of code repetition.

Guess what an IR remote does too ???

** And new ones still do - since the method has proven to work so well. ** Well, since PPM works so well, fixing it not one of them. ** But code repetition it is.

** IR and PCM radio control systems use code repetition too. ** Manchester code simply allows the clock frequency to be extracted from the code.

Guarding against data errors requires redundancy - or repetition.

Now piss off - you PITA know nothing pedant.

............. Phil

Maybe you would like to advise us all why PCM is used over PPM then if not for improved reliability (stops servo jitter).

Manchester code transmits 01 for logic 0 and 10 for a logic 1 so there are a number of illegal codes which can be rejected, therefore guarding against data errors.

Anyway as your obviously not a very nice person I no longer care to enlighten you.

Dean.

Anyway as your obviously not a very nice person I no longer care to

** A PITA wanker like you cound not "enlighten" a dead dog .

Bugger off.

........... Phil

which, if your plant isnt an integrator, is a real problem - and even if the plant is an integrator, its often still a bad thing. eg look at the lengths astronomers go to to reduce cogging torque in scanning telescope positioning systems.

yep. built-in redundancy. Although its generally only the first element in providing one of Claude Shannons so-called noiseless binary communication channel. I once did some work on a military remote firing device for explosives that could detect and correct 9-bit errors, in a

16-bit data stream. Turns out that inadvertently firing off bloody great piles of high explosive is to be avoided :)

Empirical evidence suggests he's a quasi-sentient used colostomy bag. Dont let his drivel put you off posting useful information, others read NGs too.

Cheers Terry