Re: FT8 and power levels


jeanrenier2004
 

Hi Mitchel,

My experience using the uBIT-X in FT8 mode is quite similar.

The uBIT-X has a remarkably sensitive receiver, on a good day I can "hear" FT8 signals from New Zealand (about as far as one can get from Belgium) at -24dB S/N.  Its transmitter is of course limited to QRP levels, I am typically running at 5...6W (continuous, not PEP) into a simple (not so good) 20m dipole. 

FT8 is a great mode inasmuch it gives a more or less objective measurement of the S/N on both sides.  Of the 100+ QSO I made during the past months the average difference between received S/N at my end and the received S/N at the other end is as much as 15dB (in favor of the other guy).  Some are as low as 0dB, some as much as 24dB.

Since the same transmission path, including both antennas, is used for both directions I come to believe that a lot of OMs are transmitting FT8 at 100...200W, levels, some even over 1000W.  Not entirely the intent of Joe Taylor with WSJT-X, but I am afraid it is one of these facts of life. 
It means that I don't even try anymore to make a QSO with a station that come in with a S/N of less than -10dB.  On good days I can still reach out to NE USA and Canada. 

73,  ON4JRT/Jean.


Op 20/01/2021 om 00:54 schreef Mitchel Rought:

A question of curiosity about FT8 and the level of power being used, I have a uBITX v6.2 with a usb dongle running approx.5-7 watts into either a  cobweb, 20m hexbeam, or a 20m delta loop, all antennas are run through a tuner and average < 1.1 swr at the digital freq.
I have made contacts and the average report I get back is anywhere from -13 to-26db
I am curious what everyone else is doing and seeing
thanks in advance

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