Teledyne LeCroy QPHY-10GBase-T - Manual (Page 23)

QPHY-10GBASE-T Operator’s Manual
Test 5 - Transmitter Power Spectral Density
The purpose of this test is to verify that the power spectral density of the transmitter is within the
conformance limits as defined in section 55.5.3.4 of the IEEE 802.3-2008 specification.
This test uses Test Mode 5.
W HAT I S M EASURED
The power spectral density is measured by taking the FFT of the ERES of the differential signal
C1-C2
T EST M ETHODOLOGY
The signal output using Test Mode 5 is acquired by the oscilloscope. The scope is configured to
perform an averaged FFT on C1-C2, with the ERES function performed on C1-C2 to condition
the signal. The FFT is compared to the mask defined by the standard in the mask file
10GBASET_PSD.msk.
D EFAULT P ASS C ONDITION :
The test passes if all points in the FFT are within the mask after averaging at least 50
acquisitions. If the test does not pass prior to acquiring 200 waveforms, a test failure is reported.
Figure 10 – Transmitter Power Spectral Density Test Results
Shown on this screen:
• F3 = FFT(ERES(F2)), where F2 = C2-C1
• Pass/Fail testing is setup, with Q1 = Pass if all points in F3 are in the mask
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