C H A P T E R 7 – T E S T S A N D T E S T C O N D I T I O N S
AT5600 User Manual 98-119 issue 14 Page 132
7.23. RLOS – Return Loss
Where Used
The Return loss test measures the impedance mismatch between the transformer
and a transmission line of a specified impedance. RLOS is calculated from a
measurement of the complex impedance (Zl) and the specified reference (Zr)
impedance. This test is suitable for audio & telecommunication transformers and
checks the effective input impedance of the transformer in the application.
Measurement Conditions
The load resistor is assumed to be on the fixture, but not shown on the Editor
schematic. It is switched in circuit using an OUT test that must be inserted in the
program before the RLOS test. (The relay patterns associated with inserting and
removing fixture resistors have deliberately not been included in the RLOS test
dialogue for two reasons: a) it would make the dialogue too complicated, and b) it
is not always necessary - e.g. in the case of a fixture where the resistor is
permanently fitted in circuit).
The test voltage is applied to the input winding, and the voltage and current
measured. From the measured results, and the reference impedance value
(specified by the user in the test dialogue), the return loss is calculated.
The impedances used are complex, where:
Please also see
14.6.19 for specific advice on programming the test, and
10.2.22 for test accuracy specification
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