How to null hardware freq errors

simon
Posts: 8
Joined: Sat Feb 20, 2021 5:58 pm

How to null hardware freq errors

#1

Unread post by simon »

Two hardware have error, lnb and oscillator on adalm pluto for qo100.

Assume i warm up adalm pluto long enough to steady temperature and there is "small" freq drift over qso time of few minutes

With qo100 beacon locked, is it true that the software will "auto adjust" value 9.750225000hz to an appropiate number to null out the "combined error of lnb lo and adalm pluto crystal"?

Now, in cw mode, if i send a carrier to sat, and receive water fall is, says, 10khz HIGHER than the dial freq. How can i manually adjust the 8089.500.000hz number (screen attached) to cancel out the tcxo error.
Should it be add or minus 10khz from that number?

Is this perferred over the ppm adjustment? Screen attached

Given either of these adjustment method (ppm or no ppm), the freq are correct for the "average of the system error"

Says, for next 10 minutes into qso, the adlim pluto drift tens to 100hz, making ssb barely audioable

HOW can i use XIT to fine tune in tens of hz during the on going operation over next 10 minutes. May be listen to my downlink to hear own voice correctly.

Before the next qso, use my phone has af genetator software to 1khz near mic. On ssb transmit to sat, should i adjust xit until i got 1khz from down link.

Of course, if adalm pluto drift to much and too quick, i need to replace the tcxo, or even go to gpsdo. Would like to do the software only route first.

Is it true that lnb drift is harmless as the beacon lock will null it?

Many thanks
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jdow
Posts: 800
Joined: Mon Aug 10, 2020 8:17 pm

Re: How to null hardware freq errors

#2

Unread post by jdow »

It cannot be done automatically, if that is what you are looking for. The bottom dialog will allow you to tune out the Pluto's error if you have a precise reference to work with.

{o.o}

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