Recording RF signals for later playback...

Fairly green when it comes to developing and building with the arudion so i thought this might be a good way to get started.

I found a TouchTunes Jukebox for sale a while back. I bought it with the intent of gutting it for parts, but being the music junkie i am i have now decided to use it for its intended purpose.

HOWEVER there is a catch. The guy I bought it from had lost the remote. Now instead of buying a new one I thought it would be fun to try and build one off the Arduino. Maybe using the arduino is overkill i dont know.

Fortunately for me the bar down the way from me has the same jukebox with a working control. What I would like to do is build something that would allow me to record the RF signals from the bar jukebox and save them (to a CF card or something [i have a library for that, came with a shield kit i bought a while back) or some other media) so that i can "play them back" for the jukebox i bought.

anyone have any ideas? I know the frequency is 433mhz and i have found a few places to buy the antennas but how to hook it up and how to go about actually recording the signals, well im a little lost.

I would appreciate any help you all could give.

You'd need a matching receiver to be able to receive the signal. You'll need to decode the signal to capture the data in the signal, and record that data. Then, you'll need a matching transmitter to transmit the signal. Finally, you'll need to read the stored data and reconstruct the data stream to be transmitted, and transmit that.

It won't be as simple as recording the incoming signal like you would record a song off the radio.

But, it is possible. The level of effort, I think, would be reduced if you had an oscilloscope and logic analyzer. How much of the working transmitter owner's product you consume while collecting data will influence the length of time it takes to complete the project, too.

LOL good point about drinking while working, fortunately I dont drink.

Like i said i know its a 433Mhz signal, and from what i have been able to research it doesnt seem that the signal is keyed to any specific unit. so i dont understand why i cant just grab the resulting RF burst and then just retransmit that.

Kind of like recording an IR signal to an audio wave form and then playing it back on an iPod with an IR diod wired for connection to the headphone jack.

so i dont understand why i cant just grab the resulting RF burst and then just retransmit that.

Because in order to sample that frequency you would have to digitise it at 1G and have 1G of memory to store it in. The only way of cutting it down is to demodulate it and record the demodulated pulses. That cuts the problem down to size.

annnnnnnnd i have no idea how to do any of that. so maybe this wasnt a good place to jump back into the world of arduino

i have no idea how to do any of that

The only way of cutting it down is to demodulate it

That's what your 433[u]M[/u]Hz receiver does for you.

annnnnnnnd i have no idea how to do any of that. so maybe this wasnt a good place to jump back into the world of arduino

Look at it this way: you are wanting to somehow magically record a device that has a "clock speed" (frequency) approximately 27 times that of the Arduino, which is running at 16 MHz.

This is impossible - research "Nyquist Theorem".

Grumpy_Mike is right; you won't be able to do this with an Arduino (you might not even be able to do it with a standard PC running at 1+ GHz, but you stand a better chance).

Really, what you need to do, is to get access to the transmitter, and get access to the signal train prior to 433 MHz transmitter. Something tells me that the manufacturer of these systems likely made them as difficult to hack as possible (just personal experience with closed media systems like this); you may or may not be able to take a standard 433 MHz receiver and transmitter, and get them to work.

Something else you might try is to contact the manufacturer if they are still around, and see if you can simply buy a transmitter, or if they would be willing to give you some specs or whatnot. Likely the transmitter is expensive, and they are unlikely to give you specs, but it can't hurt to ask; you never know what they will say until you do!

There's also this:

http://www.happcontrols.com/amusement/jukebox/600069001.htm

I suppose that puts a lie to my previous statement about them being difficult to hack - so obviously someone has done it; maybe the information is out there already (ie, maybe somebody has already captured the streams and posted them on an FTP site or something)?

:)

true i hadnt thought about the clock difference. but would it be possible to capture the signal on a laptop running 2.56Ghz if i could figure out some way to attach a 433Mhz antenna and read the incoming data?

this was supposed to be an "easy-ish" way to jump back into the world of arduino. whoops.

all i need to figure out is the command codes prior to RF modulation that can then be programed into an arduino based system for later modulation and broadcast. Maybe i should go back to digging through the net and see if i cant find them somewhere.

anyway guys thanks for the insight.

If you want to record a song that is coming out of a radio, you have two choices. You could record the demodulated signal that the radio created, or you could record the modulated signal that the radio received.

You have the same situation here. You could try to record the signal coming out of the bar's transmitter, or you could get a receiver of the same frequency, and record it's (demodulated) output.

The only way that the Arduino can be used to send a signal to the Jukebox is by attaching a transmitter to it. That transmitter is going to modulate the signal it is given, and the jukebox's receiver is going to demodulate it again.

Therefore the only recording that is going to do you any good is the recording of the demodulated data. That demodulated data is going to be of much lower frequency, and the Arduino should be capable of handling the recording of that data.

but would it be possible to capture the signal on a laptop running 2.56Ghz if i could figure out some way to attach a 433Mhz antenna and read the incoming data

Absolutely 100% no a PC lap top can’t digitise a 400MHz signal no way.

Yes it has a 2.5GHz clock, but that is only inside the chip. There is no way you can digitise signals at that speed and get them into the processor.

I am not absolutely certain (and that universal remote link probably means the rest of this is "wrong"), but from what I read yesterday, it seemed like the "433 MHz" transmitter/receiver combo the TouchTunes jukebox uses isn't a "standard" 433 MHz part; its frequency is "off" by so many KHz that prevents you from using off-the-shelf transmitters/receivers to make such a remote control.

I didn't research it in any great depth, though, and like I said, that universal remote link says something completely different; but then again, the lack of sites and discussion out there about homebrewing such a system (though there are many people asking about it; just no answers) seems to say that to do so will be a difficult proposition.

You might be able to do it if you modded one of those 433 MHz receivers and transmitters to run at the exact frequency of the jukebox (which would require more than a few extra tools most people don't have - frequency counters and signal generators, for instance); then again, maybe I was reading too much into what little I could find, and the frequency is standard...

:)