Teledyne LeCroy QPHY-BroadR-Reach - Manual (Page 30)

Test 5 - Transmitter Power Spectral Density (PSD)
This test calculates the PSD of the transmitter and checks to see if it is outside of the specified mask
described in Section 5.4.4. This test will also measure the maximum PSD value for informational
purposes. The DUT is required to be placed in test mode 5 for this test.
What is Measured:
A FFT of the acquired signal is calculated and then averaged using a boxcar filter. The FFT is then tested
against the provided mask in Figure 5.5 of Section 5.4.4.
Test Methodology:
The oscilloscope is set to acquire 1 Mpts at 10 GS/s. The PSD is calculated by performing a FFT on the
acquired signal. A boxcar filter of length 60 is applied to the FFT. A pass/fail mask test is then performed
using the PSD and the specified mask. A passing result indicates that the entire PSD is contained within
the mask. P1 measures the maximum of the FFT for informational purposes. The test will run until a
passing result is measured or 300 sweeps have been performed.
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