I'm creating some sensors that repeat each others' audio feeds over radio in a point-to-point fashion in order to listen much like a distributed baby monitor.

Each sensor has a circuit for a repeater which it uses to repeat radio signals from the others. In this sense it operates like a radio based analog mesh network.

I'm worried though. Will two or more of these point-to-point repeaters experience feedback from each other? Will they experience interference?

  • \$\begingroup\$ Where are you going to set up the repeaters, indoors or outdoors? \$\endgroup\$ – Harry Svensson Jul 13 '19 at 7:41
  • \$\begingroup\$ Outdoors. I'm burying the sensors, but leaving the antenna above ground because I'm assuming a subterranean antenna would be useless. \$\endgroup\$ – Steve Mucci Jul 13 '19 at 8:03
  • \$\begingroup\$ How many channels do you have? \$\endgroup\$ – JRE Jul 13 '19 at 8:22
  • \$\begingroup\$ It almost sounds as if you are reinventing Internet on a very small scale. \$\endgroup\$ – Harry Svensson Jul 13 '19 at 8:46

A repeater usually has seperate transmit and receive frequencies. You would normally only have one repeater for a given transmit/receive frequency pair.

If you have more than one repeater operating on the same frequency pair, then you will get chaos. Multiple transmitters on one frequency is just going to end up blocking all the receivers.

The way a radio system with a repeater works is like this:

  1. You have two frequencies (I'll call them "low" and "high".)
  2. You have a repeater that receives on "low" and transmits on "high." Anything it receives is immediately transmitted.
  3. You have a bunch of regular radios. They transmit on "low" and receive on "high." Note that this is the opposite of the repeater. When a regular radio transmits, it turns off its receiver.
  4. The regular radios have a lockout - they aren't allowed to transmit while they are receiving.

Now, when the channel is free, one of the radios can start transmitting. The repeater broadcasts it to all the other radios. None of the other radios can transmit until the first has finished.

There is always only one transmitter operating on each frequency at any given time.

Your idea of an "analog mesh" would require seperate frequency pairs between each sensor, and the "route" through the mesh would be fixed by the pairs.

If you tried it using just one pair, you'd get transmitters stepping on each other - interference and lost signals is all you'll get.

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