Warren, >I had my 1st THOR4 contact the other day on 30meters. It is very good at very >weak >signals and a lot of noise. How do you compare it with DominoEX and Olivia? >>Warren - K5WGM
That's a good question and I took some time to run each mode through the HF path simulator. I tried to get the bandwidth / word-per-minute rates as close as possible for an apples-to-apples comparison. The wpm rates are approximate. Test #1 In this test, we determined the lowest signal-to-noise ratio possible for each mode (no HF path distortion) SNR @ 3KHz BW. THOR4 14 wpm 173Hz BW -14db SNR OLIVIA 2/125 12wpm 125Hz BW -15db SNR OLIVIA 8/250 17wpm 250Hz BW -15db SNR DominoEX-4 27wpm* 173Hz BW -15db SIR *Slowest DominoEx mode 27wpm. In this test, all modes were tested with a moderate high-latitude (polar ionosphere) disturbance. The SNR was increased to -8bd; 7db above the minimum SNR. THOR4 NO COPY OLIVIA 1/125 100% COPY OLIVIA 8/250 100% COPY DominoEX-4 NO COPY Selective fade test - the type of slow and deep selective fading found on many paths. Same -8db SNR. THOR4 100% COPY OLIVIA 2/125 100% COPY OLIVIA 8/250 100% COPY DominoEX-4 75% COPY Conclusion: The high-latitude simulation was too much for both THOR and Dominio-EX4 which is an indication that they would most likely have difficulty with moderately disturbed polar ionosphere. Both show an intolerance to frequency spreading fouund on these paths. In the selective fade test which emulates notch attenuation sweeping across the spectrum, THOR and OLIVIA did well while DominioEX-4 showed signs of failure indicating this might not be the best mode when selective fading is present. It seems to me that since all 4 modes have nearly the same sensitivity, it would be difficult to tell the difference between them on a stable HF channel. The DominoEX4 mode that did poorly on disturbed paths would be the better choice during quite conditions since it moves along at a much faster 27 wpm. It all depends on conditions at hand. Tony -K2MO
