Posted: 3/19/2015 9:14:15 AM EDT
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Full duplex radio Would make for fun in the digi modes. Both sides could at least confirm/73 in JT modes for instance. |
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Full duplex radio Would make for fun in the digi modes. Both sides could at least confirm/73 in JT modes for instance. OMG, the snake oil on this is phenomenal. 
Ooh, I put a receiver and transmitter on the same chip, such a big deal. This has been tried soooo many times it's uncountable. The bottom line is that in a multipath environment you have to detect, characterize and then time and amplitude adjust Every. Single. Reflection. that is larger than say 10dB below the desired signal for cancellation prior to your first receiver amplifier. The only folks who have come close to anything usable are some of the airborne systems because they live in a much simpler multipath environment, not that the backlobes and sidelobes reflecting from the wings and the rest of the aircraft are nothing to sneeze at. Money, time and talent down a rathole, that's what this is. Sorry for the rant, but I've had a lot of people try to sell me this particular type of snake oil for the last 20 or so years and seen literally tens of millions of government dollars wasted chasing it, including this very DARPA program. |
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I have several full duplex radios in front of me, one I have to listen to some one breathing heavily because they don't know the etiquette of turning off their mics. Thanks full duplex for making this possible.  Science!Full duplex in this context is a misnomer. What they are really shooting for is simultaneous transmit and receive on the same frequency, which is a very special case of full duplex. |
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Sorry for the rant, but I've had a lot of people try to sell me this particular type of snake oil for the last 20 or so years and seen literally tens of millions of government dollars wasted chasing it, including this very DARPA program. Pffft. Sounds simple enough. We just need more processing power. A farm of Raspberry Pis should do it. 
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Full duplex in this context is a misnomer. What they are really shooting for is simultaneous transmit and receive on the same frequency, which is a very special case of full duplex. Quoted:
Quoted:
I have several full duplex radios in front of me, one I have to listen to some one breathing heavily because they don't know the etiquette of turning off their mics. Thanks full duplex for making this possible. Science!Full duplex in this context is a misnomer. What they are really shooting for is simultaneous transmit and receive on the same frequency, which is a very special case of full duplex. Its still just plain old duplex. Just like we have been doing for decades. Then end result hasn't changed. Trying to do it on the same frequency is a novel trick to save on spectrum. The title should be about a new way to reduce spectrum. The duplex part is not new or special. |
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How I could see this working would be to have it setup so that it listens for say 20 MS then Transmits for 20 MS
on the same frequency then processing your speech (or data) into chunks that send or rec depending on their slot. The problem is getting it to work in the real world |
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How I could see this working would be to have it setup so that it listens for say 20 MS then Transmits for 20 MS on the same frequency then processing your speech (or data) into chunks that send or rec depending on their slot. The problem is getting it to work in the real world Actually, that is exactly how WiFi does it on the same freq. They call it half duplex. |
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How I could see this working would be to have it setup so that it listens for say 20 MS then Transmits for 20 MS on the same frequency then processing your speech (or data) into chunks that send or rec depending on their slot. The problem is getting it to work in the real world You just described more or less how DMR radio works now, except it times at 30ms. They use the other timeslot to allow a second "channel' on the same freq, but its the same concept. I have been chatting on it all day. |
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Actually, that is exactly how WiFi does it on the same freq. They call it half duplex. Quoted:
Quoted:
How I could see this working would be to have it setup so that it listens for say 20 MS then Transmits for 20 MS on the same frequency then processing your speech (or data) into chunks that send or rec depending on their slot. The problem is getting it to work in the real world Actually, that is exactly how WiFi does it on the same freq. They call it half duplex. Right it's half not full duplex |