Many SDR radios have relatively long latency in their transmit and receive audio paths. It would be ideal if the transmit to receive and receive to transmit times were a little longer to accommodate SDR latencies.
VARA already has incorporated delay specifically designs for SDRs.
Just FYI : VarAC has no control over that. Once the modem signals VarAC to Key the PTT, it dosn't provide a method to tell it "wait with the sounds for a little while". Its all managed by the modem.
What SDR are you having issues with? The Flex 6xxx, Apache and SunSDR's have been tested and working well. last year we did some extensive testing with Irad and Jose to work out TX/RX delays in VARA HF by doing some quantitative with special VARA HF software. Changes were made. I personally run a Flex 6500 and Apache Labs Anan 7000DLE daily with VarAC and have had zero latency issues. There are also several SunSDR users too.
I use two radios regularly used for digital: Apache Labs ANAN 7000DLE and ANAN 100. Both have Protocol 1 installed and I have seen issues with both PowerSDR and Thetis. I was only having problems connecting to Flex radios. After reducing the size of the audio buffer which probably adds both receive and transmit audio latency, I have not seen the problem as often but still have a few disconnects from Flex radios. I use an IC-7300 for portable digital and have never seen this issue with the 7300.
VARA already has incorporated delay specifically designs for SDRs.
Just FYI : VarAC has no control over that. Once the modem signals VarAC to Key the PTT, it dosn't provide a method to tell it "wait with the sounds for a little while". Its all managed by the modem.
73s
Irad
What SDR are you having issues with? The Flex 6xxx, Apache and SunSDR's have been tested and working well. last year we did some extensive testing with Irad and Jose to work out TX/RX delays in VARA HF by doing some quantitative with special VARA HF software. Changes were made. I personally run a Flex 6500 and Apache Labs Anan 7000DLE daily with VarAC and have had zero latency issues. There are also several SunSDR users too.