I experienced difficulty connecting to VarAC users running SDR's on two occasions while testing version 3. In both cases, repeated attempts to connect to these users failed, but they could connect to me without difficulty. I also use an SDR.
I was suspicious, since I have never experienced the "latency connection issue" described in the VARA-HF "manual". I used latency monitor, https://www.resplendence.com/downloads, a nice software tool for identifying the cause(s) of latency. Running latency monitor identified an issue with ndis.sys, which is a network driver issue. Apparently, a recent Windows 10 update updated something.
I won't go through all of the "detective" work. I isolated the issue to the Intel network adapter. Searching the Intel driver site, I found an updated driver for the ethernet adapter. This driver was NOT identified by the Windows update process, or by the Dell driver update process. I downloaded the driver directly from Intel and installed it--latency issue solved.
Latency monitor is a good tool for identifying any issues that might cause issues with "real-time" pc audio.
Fixing the latency of my PC fixed my issue with connecting, even with the unmodified version of VARA-HF. I should have been suspicious, since I have connected with Gary and other SDR users before. I'm sure the modified version also makes connecting better. I've been using only SDR's for years, so am very familiar with latency issues. I'm glad Jose made changes to VARA-HF to make it more tolerant.
Larry as an FYI, with both myself running an SDR a SunSDR2DX and with Gary NC3Z who was using either a 7300 or possibly his Flex6500 you could not connect with either, is why I posted that message on the forum regarding" This would be a great mode but" which you responded about the latency Monitor. All SDR rigs have some latency it's just the fact of design. some a bit more than others. Jose has made couple changes in the Vara HF modem application which has help ALOT! I think Irad sent you the test / Beta update for Vara HF 4.5.2 When you get a chance to install those files, please email me so we can test your connection to both Gary NC3Z and myself again. I am pretty sure that will resolve the issue with the handshake connection. When both Gary and I connected to you we both were running the updated 4.51 or 4.5.2 version of Vara HF. Neither of us would have connected prior to that most likely. AS I understand and think Jose will be releasing an updated version of VaraHF soon. My PC latency is very low- Hower the software to control radio and the fact my SDR uses a mechanical relay adds some latency to the equation, another good test would be W2JON also an older Flex 5000 again a mechanical relay switching TX/RX.
Please move it.
Great post Larry. With your permission i will move it to a new troubleshooting section.