VARA,Pactor4 versus Mercury

[Supermagnum]

Are there any studies comparing VARA and Pactor4 to this new modem? I want to see how it stands up to the current standards when it comes to speed and reliability in high noise environments.

[porkiedev]

I'd also love to see a comparison like this. I'm very happy to have an open source alternative to VARA and Pactor. If there were benchmarks that put Mercury against VARA and Pactor, it may encourage people to develop tools with support for Mercury, and I'd love to see how this changes the digital space of amateur radio.

I'm not qualified to benchmark mercury; however, FWIW, I fed my Yaesu FT-897D into a dummy load with an RTLSDR on the receive side. Even just from the tiny bit of RF leakage, I was able to decode CQFRAME packets with Mercury. The signal was hardly even visible on the waterfall, and mercury measured the SNR at -8, but I still got a decode. This doesn't really show much, but maybe you'll find it interesting.

Ultimately, proper benchmarks would be awesome!

[rafael2k]

Thanks @Supermagnum and @porkiedev. We are indeed evaluating on how to do a meaningful comparison. Concerning Pactor 4, we don't really have the hardware to obtain the experimental data.

[Supermagnum]

There is data one can compare against here:
https://winlink.org/sites/default/files/downloads/a_winlink_digital_mode_performance_comparison_based_on_the_ionis_sim_hf_vhf_channel_simulator_-_november_2_2020_0.pdf

For the hardware:
https://github.com/ARSFI/HFSimulator/tree/master

relevant options:

1. gr-watterson (dedicated Watterson HF channel model OOT module)

https://github.com/noahthurston/gr-watterson
Built specifically to implement the Watterson model (the same math behind PathSim and the IONOS simulator) as native GNU Radio blocks — developed by EpiSys Science. This is the closest direct equivalent to "IONOS/PathSim as a GNU Radio block."

2. gr-channels (built into GNU Radio core)

https://github.com/gnuradio/gnuradio/blob/master/gr-channels/include/gnuradio/channels/channel_model.h
Ships with every GNU Radio install (channels.channel_model / channel_model2). It gives you AWGN, frequency offset, sample-rate offset, and a generic multipath/Rician-Rayleigh FIR tap model — good for general fading but it's not a purpose-built Watterson/CCIR HF model like gr-watterson is. You'd need to hand-tune the tap delays/Doppler manually to approximate CCIR Good/Moderate/Poor.