KA9Q auto-rx frequency offset correction question

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G1_Chris

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Dec 4, 2024, 8:41:21 PM12/4/24
to radiosonde_auto_rx
First, hi there.
I am trying the KA9Q + auto-rx setup with an Airspy Mini and firstly,  I think this KA9Q + Auto-Rx is a fantastic idea and seems to work great. I do have a problem I can't resolve however.
The Airspy Mini I received is out of spec. I calculated the frequency error to be about 3.7 ppm. Not good. Spec says 0.5 ppm and I have raised a ticket with Itead. But that's another issue for another place.
The problem I have is that I have tried adding the error correction into auto-rx config file, but it has no effect at all. I'm guessing that's just how it is....for now.
What I am wondering though, is if anyone has found a way to make a frequency ppm correction work with KA9Q + Auto-Rx + Airspy? Perhaps a file in the KA9Q directory can be changed? Perhaps it's coming in upcoming changes to auto-rx once more is understood how better to link with the options in KA9Q?
I have noticed the word "correction' is used in some of the KA9Q files where the math is done for frequency (I think). Eg. in the KA9Q file airspy.c from line 418 onwards. I have no Idea what I'm doing with this coding stuff so I dare not touch it, but it does appear to my ignorant mind that at least the KA9Q software is capable of applying an offset correction.
Any help would greatly appreciated,
Chris

Clayton Smith

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Dec 5, 2024, 1:23:22 AM12/5/24
to radiosonde_auto_rx
Hi Chris,

Until recently, there was a bug in ka9q-radio which caused the "calibrate" setting to be ignored for AirSpy receivers. That was fixed in https://github.com/ka9q/ka9q-radio/pull/64.

But you'll have to wait a while before upgrading ka9q-radio, because Auto-RX has not yet been updated to take into account another recent change in ka9q-radio. You can follow this pull request to keep up to date with progress on that issue: https://github.com/projecthorus/radiosonde_auto_rx/pull/947

Once Auto-RX supports the latest ka9q-radio, you should be able to add something like "calibrate = 3.7e-6" to your rad...@airspy-autorx.conf file.

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