Video Demo: Pactor-III / Vara Throughput Tests


Tony
 

All:

After spending many hours testing VARA, on-air and via the path simulator, it does seem capable of Pactor-III speeds. It will often maintain 3000 bps when subjected to moderate path conditions (simulated and real) which is pretty fast on HF.

After many test runs, I've only seen the modem peak one level higher than 3000 bps for brief moments so it would seem 3k is Vara's limit on HF. If anyone has a screen capture of the modem maintaining higher speeds (ionospheric propagation only please) I'd appreciate it if you can send them my way.

With respect to HF channel adaptation, Pactor-III seems to change speed levels quickly while Vara shifts gears at a slower pace. With frequent dropouts, the slower shifts may add a significant amount of time when transferring large files: could be something the author may be able to tweak?

To demonstrate the similarities of the modes under certain conditions, I recorded a video that shows VARA and Pactor-III being tested minutes apart via VE1YZ's 40 meter gateway. Pactor finishes quicker, but VARA is not far behind.

Video Link: https://www.youtube.com/watch?v=mu1JsUGiyNc

While the video shows what the Vara can do, it should be taken with a grain of salt: being limited to only one Pactor-III modem, I can't run path simulations like I do with VARA and ARDOP so it's difficult come to any real conclusions due to the variable nature of on-air testing.

Tony -K2MO

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