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TimeHub 5500 TL1 Reference Manual
209
Performance Monitoring
097-55501-02 Issue 5: June 2003
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5
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SSSSSSSSSSSS SSSS S SSSSS SSSSSSS S SSS S SSSSS
44
Time Deviation
This measurement is displayed in ns and measures an input port’s Time Deviation
(TDEV). TDEV is the input’s port’s RMS value of second difference of phase
deviation expressed in time units for various averaging times.
The mathematical formula for TDEV computation is based on Type II of the
Efficient Algorithms for Computing Time Variance (TVAR) and TDEV.
TDEV values are computed based on 98 average phase deviation values separated
by
τ
, the averaging time. Therefore, measurement time is 98 times the averaging
time. For example, a 16 second TDEV value is based on 1,568 seconds of phase
measurements in the immediate past.
The command format is:
RTRV-PM[-TSG]:[<tid>]:CLK-a:<ctag>::TDEV;
Response Format:
<sid> <date> <time>
M <ctag> COMPLD
"CLK a-b:TDEV-a,<monval>,<status>"...
;
The parameters which will be displayed in the response are listed below.
Parameter Value Description
CLK-a a = 0 to 4 Input port number of active clock card 555xx-01 (5 input)
a = 0 to 8 Input port number of active clock card 555xx-02 (9 input)
Parameter Value Description
CLK a-b a = 1 or 2 Clock card from which data was collected
b = 1 to 4
Input port number of clock card from which
data was collected
TDEV-a a = 1S, 4S, 16S, 64S,
256S, 1024S
Performance monitoring measurement type,
where a is the averaging time (refer to Table I
for details). Variable a can also be
appended to TDEV in RTRV-PM to obtain a
response for only that measurement time
<monval> Calculated values for averaging times in ns
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