I'm looking for a little guidance to help ensure I don't severely damage anything. I'm following a patent that I found which involves using a modified CB radio. The CB Radio I'm attempting to use is the Cobra 29LX.
The specific detail from the patent is:
Essentially I need to take the output of a function generator that is producing a square wave of various different frequencies and input it directly into the CB radio input, though I do not want the input signal to be limited and I need to allow it to over-modulate so that it will "produce a pulsed radio wave". Probably sounds crazy but it's worth a shot.CB radios generally include audio filters that limit the audio frequency response to a range of 300 to 2500 cycles. This frequency limitation effectively inhibits and clips off the harmonics in the square wave. To overcome this frequency limitation, modifications are made to the CB radio that widens its bandwidth. Further, the modulation limiter of the CB radio is bypassed allowing the CB radio to over-modulate. Over-modulation produces a pulsed radio wave. When the radio wave is modulated with an audio signal, the audio wave will therefore be pulsed too.
I found the Modulation Limiter is the little zener diode on D11, though I'm not sure about the audio frequency filters that may be in place and how to go about modifying these. Also what would be the best way to directly input the signal from the function generation to the audio input. I saw a post from a couple years ago ([Please login or register to view this link]) for audio injecting so I'm thinking that might be a good start.
Ideally, whichever mods are made can be fairly easily reversed if this whole thing doesn't work out, though I'd important enough of a project that I'm willing to risk the radio if I must.
The full patent for anyone interested is:
U.S. Patent # 5,908,441 - Jun 1, 1999 - [Please login or register to view this link]
Its a rather interesting read and very similar in overall concept to an earlier device made back in the 20's-30's with much success, though this design was even featured on a TED talk not too long ago.
Thank you very much for any assistance here. I dont want to directly talk about what it's for due to rumors going around, but I'm sure you can figure it out and if so, you'll understand the urgency and the potential if this actually works. Anything is worth a try at this point.
Thanks again in advanced!
-Ryan
