LeCroy WaveSurfer 400 Series Service Manual page 55

Press Clear Sweeps.
Measure for at least 50 sweeps, and then press Stop to halt the acquisition.
Record the four mean parameter values in Table 4, and compare the test
results to the limits in the test record.
Recall Noise - 10mv.lss or set Input gain to 10 mV/div. on all 4 Channels
Record the measurements (mean of 1,2,3,4) in Table 4, and compare the
results to the limits in the test record.
Rev. D Sept 2007 Performance Verification 5-15