| FT8 - dziwny komunikat |
| Nie odpowiedziałem na zadanie. SQ9JXB pisze: Dam przykład: pasmo 60m, 5.357.000 , STx 1400Hz, a radio pokazuje 5.356.500. Dlaczego? Myślę, że poprawna odpowiedź jest w dokumencie "FT8 Operating Guide - G4iFB", punkt 7.9 http://www.g4ifb.com/FT8_Hinson_tips_for_HF_DXers.pdf: The Fake It setting can QSY the main VFO on transmit if it needs to compensate for a difference in the audio frequencies generated (see below), and QSY back to the original VFO frequency on receive. The ‘difference in audio frequencies generated’ comes about because very low or very high audio frequences are likely to be attenuated by your transmitter’s audio filtering. Most amateur sideband transmitters have a restricted audio range of approximately 200 Hz to 3 kHz, sufficient for intelligible speech, similar to the telephone. Therefore, WSJT-X and JTDX can move the transmit VFO HF or LF in 500 Hz steps while generating audio at the same number of 500Hz steps in the opposite direction. Those steps cancel out e.g. moving 500 Hz HF on the VFO but 500 Hz LF on the audio gets your transmitted signal back to the same place on the band, the exact same RF frequency. So why bother? The idea is that audio is always generated around the middle of the rig’s audio range. Dobrze myślę? 73 de SQ6GTL |