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I want to know if anyone here has fed audio to their tx’s via a basic radio tuned to an existing radio station’s frequency. Here’s where I’m going; I know you can feed a tx with audio from computers, cd players, Ipods, record players etc.
I have an idea to feed audio from my ‘A’ transmitter, which is currently set on 1440 AM, to a ‘B’ transmitter a mile or so away-within range of the ‘A’ tx’s audio signal. At the ‘B’ tx, I’d hook it up to a basic AM/FM radio set on its dial to the aforementioned 1440 AM and “wala”. In this set up I’d be using a basic radio as the audio source for the ‘B’ tx to extend my coverage. In theory this set up could work for a ‘C’, ‘D’ and ‘E’ tx placed within the circumference of the others. Placed properly apart it could work, right? Minimal fluttering between the tx’s notwithstanding it seems plausible that it could work seamlessly.
In the past week, I received great response to my query about clustering. (Not to go there again. I got it… It will work.) As mentioned I’ll let you know how that experiment goes in (2) weeks time. However, the above-mentioned goals of using my ‘A’ and ‘B’ tx’s in the manner I described seems like a viable option for getting around having to purchase those ridiculously high $400 Barix boxes to link the audio between two seperate tx’s.
Total posts : 45366Of all the ways discussed here for synching the audio on separated transmitters, your suggestion may never have been made. It sounds like it will work, and it may be an elegant solution.
Total posts : 45366If you can get enough separation between the transmitter antenna and the radio receiving antenna it should work ok.
The problem being that if the receiving radio is in close proximity to the transmitter antenna, the front end of the receiver could be swamped out by the strong signal from the transmitter and block the signal.
You might have to go so far as to install a snap-on RF choke core on the audio cable at the radio to keep the RF from coming in that way.
Total posts : 45366This is simliar in how a licensed station with a distant located translator works.
Although a translator does more than repeat audio, it does one of two other things. Either it “walks” the main station frequency received to another frequency with tuned circuits and then to a final amp, or it generates the new frequency itself and the power and on/off states of the translator are controlled by the incoming RF signal from the main transmitter.
This is mostly found in FM band stations, though there are AM stations using FM translators, it is the latter that uses translators that generate their own frequency.
The concept of it all is your using one transmitter’s received signal to pick up audio and send out on another transmitter on another frequency. And indeed as suggested, make sure the frequencies selected for use are separated enough to prevent interference to the intended received signal.
RFB
Total posts : 45366As someone who has played with repeaters for 40 years,I can tell you that you will lose a lot of audio fidelity for every repeater you go thru. Its sorta like the audio cassette,make a copy,not too bad,now make a copy of the copy…yuk! It can be improved if the audio can be passed perfectly flat response thru the repeaters,but there is still losses and added noise. FM to AM works pretty good,just dont try going back to FM…again…yuk! A link should feed all the remote transmitters at once. Best system I ever saw was distributed by dedicated leased lines to 15 sites,all sounded great. Modern day best would be a microwave link or wi-fi or plain internet,each with their own inherent problems.
Total posts : 45366i had the wacky idea to use an sca source to feed and sync a network of part 15 am and fm transmitters. muzak used sca for years till they went to satellite. i’m guessing a lot of the sca sub carriers now go un used and could be utilized for this if you found a receptive engineer.
Total posts : 45366SCA has a limited audio bandwidth, sort of like AM radio itself, or maybe less. It probably would work for feeding AM transmitters, but would be poor for feeding FM transmitters.
Total posts : 45366“SCA has a limited audio bandwidth”
Not really. If you have ever installed a “muzak” system like I have, and plugged in a set of high quality headphones into the SCA receiver, that audio quality is darn near like mono FM, and is more than adequate for regular FM audio and excellent for AM modulation.
Perhaps this might shed some insights.
http://www.owlradio.org/sca.html
RFB
Total posts : 45366“I can tell you that you will lose a lot of audio fidelity for every repeater you go thru.”
This is only applicable if your audio is being demodulated, runs through audio circuits feeding another transmitter’s audio input circuitry, which is common for two way repeater systems such as that used in the HAM radio world.
With translators it does not work that way. Most are utilizing frequency conversion which is direct, no demodulating or remodulating are involved.
The only time the mod/demod method is used is when a FM translator is repeating an AM station. A direct frequency conversion would not only be impractical, but the modulation mode would be incompatible.
But your correct. By the time you repeat so many times through demod and remod, you will loose audio quality. Though I am not sure exactly what the ratio would be if the specifications of each receiver and transmitter are unknown or vary from one to another, nor if the audio degradation would even be noticed in 3Khz voice bandwidth. But for semi hi-fi audio or brick wall filtered audio like that of FM and AM, it would not take very much to degrade that audio quality down to muffled garble.
RFB
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