26-06-2019, 07:26 AM
Hi
"WSPR is also at least 10-12 dB more sensitive than FT8 ..." Well, this depends on the actual propagation. WSPR is good across smooth paths, but terrible when traveling across distorted paths. If it is only about sensitivity please choose JT9-30, Opera4H or WSPR15.
There is actually a rather interesting picture of the FT4 sensitivity vs. propagation, see https://physics.princeton.edu/pulsar/k1j...otocol.pdf page 5. Unfortunately, I haven't found similar simulations for the other modes. But the simulations clearly show that there is a dramatic loss of sensitivity vs. different propagation models, i.e. path irregularities. Also the duration of the mode negatively affects the sensitivity, if not subject to Additive White Gaussian Noise (AWGN). I have seen a similar set of simulations for FT8, but unfortunately I don't have the picture, that shows e.g. FT8 subject to highly disturbed ionospheric conditions has so poor sensitivity that the curve is flat all the way beyond 0 dB.
Here is a link to a presentation I made at the 2018 RSGB Convention about beacons and PI4 https://www.youtube.com/watch?v=jFcCncceSN4 A part of the presentation addresses the above path irregularities.
Bottom line: there is no single mode that is best for everything - it all depends.
Bo
"WSPR is also at least 10-12 dB more sensitive than FT8 ..." Well, this depends on the actual propagation. WSPR is good across smooth paths, but terrible when traveling across distorted paths. If it is only about sensitivity please choose JT9-30, Opera4H or WSPR15.
There is actually a rather interesting picture of the FT4 sensitivity vs. propagation, see https://physics.princeton.edu/pulsar/k1j...otocol.pdf page 5. Unfortunately, I haven't found similar simulations for the other modes. But the simulations clearly show that there is a dramatic loss of sensitivity vs. different propagation models, i.e. path irregularities. Also the duration of the mode negatively affects the sensitivity, if not subject to Additive White Gaussian Noise (AWGN). I have seen a similar set of simulations for FT8, but unfortunately I don't have the picture, that shows e.g. FT8 subject to highly disturbed ionospheric conditions has so poor sensitivity that the curve is flat all the way beyond 0 dB.
Here is a link to a presentation I made at the 2018 RSGB Convention about beacons and PI4 https://www.youtube.com/watch?v=jFcCncceSN4 A part of the presentation addresses the above path irregularities.
Bottom line: there is no single mode that is best for everything - it all depends.
Bo