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All things pertaining to wireless and RF links
By brennen
#33697
OK, I'll admit I don't know the slightest thing about wireless communication on the analog side of things (antennas, especially). I am giving consideration to having a project that uses two nRF24L01's for full-duplex communication (a single 24L01 is half-duplex). Can you run full-duplex communcations over one (preferrably single-ended) antenna? Or does this require a pair of antennas? If you guys can point me to some simple links you might know of, that would be cool too.
By wiml
#33724
Running real full-duplex radio is hard, even if you use two antennas (assuming the antennas are pretty close to each other). The transmitting antenna will swamp any received signal unless the receiver has really good rejection of nearby strong signals.

It's possible to do it; the old analog cell phones did, for example, but their TX and RX frequencies were about 40 MHz apart, and I think they needed specialized SAW filters and stuff to make it all work. Are you sure you can't assign a transmit timeslot and receive timeslot to each device? That would make your life a lot easier. You could switch between tx and rx many times per second, making the connection practically full-duplex on a human timescale.
By brennen
#33741
All things considered, I could certainly make the TX and RX frequencies considerably different (up to around 80 MHz), but given the amount of work it would probably take, I don't necessarily think it's worth it. I was basically just going to try it to see if I could get it going, but I don't think my analog RF skills are quite up to par to pull it off. I suppose I'll just roll it out the easy way. :wink: