24 Jan 2020

2m VHF - WSPR versus FT8

It is some years since I tried WSPR on 144MHz. Although I  managed some reasonable results, drift over the 2 minute transmission slot was a major issue.

FT8 is about 10dB less sensitive than WSPR, but the 15 second TX period means drift does not appear to be an issue at all. With WSPR the window is only 200Hz wide whereas FT8 has a window of at least 2500Hz. All signals within this window can be detected and decoded. Signals on FT8 occupy 50Hz, whereas WSPR signals occupy about 6Hz. FT8 allows 2-way QSOs, but this is not really possible with WSPR.

Overall, I find better results with FT8 than WSPR on VHF. I have even had 2-way FT8 QSOs on 70cm!

With the 15 second TX period there are more aircraft relections too with FT8. I have not tried FT4 which uses 7.5 second TX periods, but is less sensitive. Logically, with even shorter TX periods this should be even better with aircraft scatter when signals can be quite strong.

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