Kieran Sullivan <[email protected]> writes: > Oh, and when someone figures out a good way to calibrate the radio on > the Telemega, please let me know. I’ve been trying to get it right for > a couple of years on and off… :-)
Oh, sorry, I thought we had the process documented but apparently in
manual section 11.8.2 we basically just tell you not to do this
yourself. We should probably add a new appendix to the manual
explaining how to do it with suitable caveats about "don't try this
unless you have the right gear and know what you're doing, or are really
desperate".
In the meantime, if you want to cal a board, you need some way to
accurately measure frequency near 435 Mhz (Keith and I both have
high-end frequency counters locked to GPS disciplined reference
oscillators on our benches). Once you have that, there are two ways you
could go:
First, the ao-bringup/turnon_telemega script in the ao-bringup
subdirectory of our fw/altos repo is our current production script. The
relevant bit is that it calls cal-freq with a device argument and the
SERIAL environment variable set to the board serial number to do the
frequency cal.
The other option is to do it all by hand. Connect to the board over USB
with a terminal program, and the 'c s' command will show you the
currently configured frequency and PLL calibration factor. Use the 'C'
command to generate a steady carrier, measure the actual frequency the
board is transmitting on, and then you can calculate an updated cal
value using the equation:
<desired frequency> / <measured frequency> * <current cal value>
Use 'c f' to set that new cal factor, and 'c w' to write the updated
value to flash. Then use the 'C' command to confirm the board is now
transmitting on the desired frequency.
Hope that helps!
Bdale
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