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C Commands Summary
MiLLennium Command Descriptions Manual 87
FREQUENCY_OUT
This command allows the user to specify the frequency of the output pulse train available at the variable frequency
(VARF) pin of the I/O strobe connector. This command has no effect on the operation of the GPSCard; it is only
provided for user-determined applications.
The frequency (in Hertz) is calculated according to formulas which require three input parameters (n,k,p), such
that:
if k =1 or p =1: VARF = 0
if n =1 and k ≠ 1, p ≠ 1: VARF =
if n ≠ 1, k ≠ 1, p ≠ 1: VARF =
The possible range of output frequencies is 0 - 5 MHz. As a reference, some n, k and p selections and their
corresponding frequency outputs are listed in Table C-3:
Table C-3 VARF Range
The resultant waveform is composed of active-high pulses with a repetition rate as defined above, and a jitter of 50
ns. The pulse width has a range of 100 ns - 51.25 µs, and is calculated as follows:
pulse width (ns) = (n + 1) * 50
The command has two syntactical forms. One is to define a frequency, and the other is to disable this function.
Syntax 1:
Example:
frequency_out 2,4,8
Syntax 2:
n k p VARF (Hz)
1 1 1 0 (Minimum)
1024 65 536 65 536 0.004 652 065
1 65 536 65 536 0.004 656 612
1 4000 5000 1
2 4 8 312 500
1 2 2 5 000 000 (Maximum)
FREQUENCY_OUT N K P
Command Range Values Description
FREQUENCY_OUT - Command
N 1 - 1024 Variable integer
K 1 - 65,536 Variable integer
P 1 - 65,536 Variable integer
FREQUENCY_OUT keyword
Command Range Values Description
FREQUENCY_OUT - Command
keyword disable The keyword “DISABLE” is the only one defined at this time.
20 000 000,,
kp×
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20 000 000 n 1–()×,,
nkp××
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