Option 100 Fault Location and SRL 4-9
Making SRL Measurements
How to Make and Interpret SRL Measurements
Table 4-1 shows the effects of a connector mismatch on the measurement
of a −35 dB SRL spike.
Table 4-1 Measurement Results with Varying Connector Mismatches
As indicated by Table 4-1, the best true SRL measurement is made when
the contribution of the connector is minimized by
• a good calibration (see “Verifying the Calibration” on page 4-5)
• a high-quality connector and connection (see Chapter 2, "Cable
Preparation")
• a connector model which provides the lowest corrected connector
response
The effects of the connector response can be minimized with the built-in
connector model and the corrected connector response can be measured
while the SRL measurement is being made. For some connectors, a
response correction of up to 15 dB or more improvement is possible with
the built-in connector model.
NOTE The maximum extent to which the effects of the connector response can
be removed is to the accuracy and repeatability of the analyzer system
(including the effects of test lead cable stability and quality). The
accuracy of the system is given by the system directivity of the analyzer
(which can be determined from the trace with a load connected after
calibration).
For determining measurement uncertainty, use the value of the system
directivity and the connector response. See “SRL Measurement
Uncertainty vs Connector Fault” on page 9-8.
Corrected Connector Return
Loss
SRL Total Measured
−53 dB −35 dB −34 dB
−42 dB −35 dB −31.8 dB
−35 dB −35 dB −29 dB
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