On 27/09/2023 12:40, VA3NCA Wayde via groups.io wrote:
Hi Everyone,
Is there any possibility that a future fw for the u3s could support FST4W beacons? Perhaps with the GSPDO it would have the clock stability to be a pretty nice little FST4W beacon, perhaps even up into some of the HF bands, no?
The minimum requirements for FST4W to be useful is a nice clean signal, the Si5351 is capable of this.
As you realise frequency stability is also required, FST4W decoders do not allow for much drift.
(Another thing that can help is absolute frequency accuracy but stability is more important.)
With the U3 the GPS will not make it more stable, it is set once per calibration cycle, the crystal can drift in between.
The QDX can transmit a signal suitable for spectral width measurement, so therefore the U3S could. It has to have the TCXO or other reference remote so heat does not affect it.
The U3S may have a TCXO fitted, it may be good enough if the TCXO is insulated, it is not so likely to be affected by PA heat.
FST4W is just like WSPR but with extra measurements of the signal. It shows on WSPRnet and could replace WSPR in the U3S.
73 Alan G4ZFQ
