
The most simple way to determine your particular crystals frequency is to 
hook an accurate frequency counter to the orange LED and just type frequency in.

This procedure is for those who have no reference and want to bootstrap Loran-C timing.

Hardware setup is as usual, and an oscilloscope is really useful to make your 
antenna is catching signals well, as this procedure depends on a good
signal to noise ratio.

Try to remove all switching power supplies, as they tend to radiate violently.

Determine your crystal frequency roughly with "coarse". Look at the included image !
The crystals on STM32F4 are specified for 80 ppm, so a +-100ppm range is scanned.
It will take some time, make sure signal is stable during the whole time.

The most intense peak will give you roughly your crystal frequency, 
in this case +73ppm. Set this with "1000,073 kHz".

This coarse measurement can be flashed as start value by typing:
compiletoflash : init init 1000,073 kHz ;

Now you can go on with fine tuning by usage of "calfreq".
