2017-09-15, 10:34 PM
(2017-09-15, 09:05 PM)Sailoog Wrote: I think calibration software is working right.
Cheap dongles have bigger variation with temperature. Connect your dongle for 1 or 2 hours and then calibrate.
The ppm tolerance is +/-7 ppm.
OP calibration method is based on GSM stations and is quite accurate. You need a visual confirmation of your calibration with gqrx or "take a look button".
There is another method, disable AIS reception, open a terminal and type "rtl_test -p" you will get something like this every 10 seconds:
real sample rate: 2048184 current PPM: 90 cumulative PPM: 90
run this for hours until the PPM value stabilizes.
Do I wait for Current PPM and Cumulative PPM to match? Or do I use the Cumulative PPM for the value after running for a few hours. I've started running this and am piping the output to a log file so I can share after a while.
The dongle has been plugged in all day, so temperature shouldn't be a huge issue at this point.