TX synchronisation at special Pluto-setup
Posted: Tue Sep 29, 2020 12:58 pm
Hi,
I’d like to ask for the following additional feature / option :
But first a description about what I did:
I developed a small add-on board for the Pluto which delivers some pretty accurate 40Mhz to the Pluto (Tailor Winfield VCTCXO) – I have a small board-documentation at the Amsat board….
From this 40MHz VCTCXO I also derive on the same board the 25MHz for the LNB.
The board is currently in use by ~ 10 users.
It can be locked to an external GPSDO to get down to the last Hz – in this case everything is fine – no deviation at Pluto or LNB, RIT/XIT=0.
But in this setup the GPSDO is not really necessary!
We have the Beacon!
Because now everything is based on one single oscillator and while using the beacon correction, we know the (small, ~1-2Hz) deviation of this oscillator.
The missing part is: Calculating the relative beacon deviation (relative!, everything is linear in the mixing process) and correct the transmit frequency by this factor (usually << 1ppm).
This additional option in beacon/pluto mode would make it possible to correct RX and TX by the beacon without the need for a GPSDO.
What do you think?
I know – this would be only of use for guys using the special setup, that LO for the pluto and LNB are derived from the same oscillator…
Any chance this option could be added in an upcoming version?
73 Michael – DL2FW
I’d like to ask for the following additional feature / option :
But first a description about what I did:
I developed a small add-on board for the Pluto which delivers some pretty accurate 40Mhz to the Pluto (Tailor Winfield VCTCXO) – I have a small board-documentation at the Amsat board….
From this 40MHz VCTCXO I also derive on the same board the 25MHz for the LNB.
The board is currently in use by ~ 10 users.
It can be locked to an external GPSDO to get down to the last Hz – in this case everything is fine – no deviation at Pluto or LNB, RIT/XIT=0.
But in this setup the GPSDO is not really necessary!
We have the Beacon!
Because now everything is based on one single oscillator and while using the beacon correction, we know the (small, ~1-2Hz) deviation of this oscillator.
The missing part is: Calculating the relative beacon deviation (relative!, everything is linear in the mixing process) and correct the transmit frequency by this factor (usually << 1ppm).
This additional option in beacon/pluto mode would make it possible to correct RX and TX by the beacon without the need for a GPSDO.
What do you think?
I know – this would be only of use for guys using the special setup, that LO for the pluto and LNB are derived from the same oscillator…
Any chance this option could be added in an upcoming version?
73 Michael – DL2FW