GPS debug display
It is possible to enable a view of the live GPS discipline parameters for debug purposes by
pressing the ‘g’ key once.
Then the screen appears as below.
To explain these five debug parameters in turn:
1. The first parameter (1 here) is the cumulative frequency measurement error since GPS
discipline began. Remember that frequency measurement in a 1 second interval has a 1 Hz
resolution. So when you see “1” here it does not mean that the frequency is 1 Hz wrong.
But if you see a number larger than 1, this means that some accumulated frequency error
has occurred; if the Cal #2 parameter is non-zero it will gradually act to remove any
accumulated error, reducing it to 0.
2. Frequency measurement in the last 1 second interval. When GPS discipline has homed in
on the correct adjustment amount, this measurement will alternate between 9,999,999 and
10,000,000 with an average therefore of exactly 9,999,999.5 Hz.
3. 27407 is just the current value of the internal 16-bit counter used for the frequency
measurement. It will reduce by 1 every 2 seconds (0.5 Hz per second, to reflect the 0.5Hz
offset from 10.000000 MHz).
4. Fourthly, 466 / 3650 (in this case) is the current adjustment amount, and the constant 3650
to remind you that the adjustment amount is expressed in 3650’th of a Hz at 9,999,999.5
Hz.
5. The last parameter (7 in this case) is the current step size, the amount the adjustment is
adjusted, after every 1 second measurement period. The minimum value is the value
expressed in Cal #1.
ProgRock2 manual 1.00b
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