Jackson Labs PHASE STATION 53100A, User Manual

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PhaseStation 53100A User’s Manual V1.04 25-Apr-2022 187
/overlap
For maximum reliability on slower host PCs, overlapped FFT processing during phase noise
measurement is turned off by default in TSERVE. Specifying the
/overlap option can significantly
improve the speed required for low-noise measurements to converge, at the risk of possible
data overruns.
Specifying the
/overlap
option on the TSERVE command line is equivalent to checking the
Overlapped acquisition
checkbox in the
Additional options
page of the 53100A acquisition
dialog.
/phasedec
/phaserate
These options determine the default sample rate for frequency and phase-difference
data streamed to TCP/IP clients connected to the data port.
When a client initially establishes a Telnet connection to the TSERVE command port, it
inherits various global settings including the
/phaserate
parameter. In this case, the
/phaserate
parameter becomes the phaserate value for measurements initiated by that
client. This value can be displayed with the show phaserate command or modified with
the set phaserate command at any time prior to starting a measurement. Using either
of these techniques, you can set the phase rate to 1 reading per second to conserve
network bandwidth and/or disk space for use with extremely stable sources.
Conversely, measurements of drift-prone sources may require phase data rates of 100
or 1000 readings per second to avoid acquisition failures.
The choice of phase data rate also determines the baseband measurement bandwidth
for frequency and phase stability. In TSERVE, the equivalent noise bandwidth (ENBW) is
half of the
/phaserate interval, or 50 Hz by default. (Note that the PhaseStation 53100A
driver limits the minimum bandwidth to 5 Hz, even when /phaserate:1 is used.)
The
/phasedec
parameter provides some additional flexibility by allowing you to specify
a larger-than-normal decimation ratio for the post-detection phase data. Its default
value is 2, corresponding to the default
Output decimation
property on the
Additional
options
page of the PhaseStation 53100A acquisition dialog. The nominal phase rate
options of 1, 10, 100, and 1000 readings per second are based on the default
/phasedec
value of 2. Setting /phasedec to larger values reduces the overall rate at which
frequency and phase-difference data is streamed to TSERVE clients and any output file
specified with the
/file
parameter, and also determines the tau0 interval for the
show
adev command. Regardless of any changes to
/phasedec, t
he equivalent noise
bandwidth is still determined by the phaserate value that was in effect when the
measurement began.