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Maxim > Design Support > Technical Documents > Application Notes > T/E Carrier and Packetized > APP 3670
Keywords: RL, Return Loss, LIU, Line Interface Unit, SCT, Single Chip Transceivers, DS3150, DS3151,
DS3152, DS3153, DS3154, DS3251, DS3252, DS3253, DS3254, DS3170, DS3171, DS3172, DS3173,
DS3174, DS3181, DS3182, DS3183, DS3184
APPLICATION NOTE 3670
Measuring Return Loss Using the Advantest
R3132 Spectrum Analyzer
Dec 14, 2005
Abstract: This application note contains the basic operating procedures needed to help engineers
measure return loss using the Advantest® R3132 spectrum analyzer (or similar spectrum analyzer), and
should give them enough information to measure return loss in the laboratory. While the specific key-
press operations apply only to the R3132, the basic procedures can be useful for all spectrum analyzers.
It is not an all-encompassing tutorial, and some basic knowledge of spectrum-analyzer operation is
needed.
Return-Loss Requirements
For E3, ITU G.703, and ETS 300-686, specify the input return-loss requirements shown in Table 1 and
the output return-loss requirements shown in Table 2.
Table 1. Input-Port Minimum Return Loss
Frequency Range (kHz) Return Loss (dB)
860 to 1720 12
1720 to 34,368 18
34,368 to 51,550 14
Table 2. Output-Port Minimum Return Loss
Frequency Range (kHz) Return Loss (dB)
860 to 1720 6
1720 to 51,550 8
Measuring Return Loss on Dallas Semiconductor LIUs
The test setup and procedures for measuring E3 return loss are described in subclauses A.2.5 and A.2.6
of the ETS 300-686 specification. The test configuration in Figure 1 is designed to measure the input
return loss and verify compliance with the requirements shown in Table 1. The output return-loss
configuration is similar, with the same equipment connected to the transmitter output instead of the
receiver input.
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