Lambda SR1, Operation Manual, Page: 255 / 317

SR1 Operation 255
© 2014 Stanford Research Systems
2.8.2 SNR Panel
The SNR (Signal to Noise) Quick Measurement uses the Time Domain Detector to measure the Signal
to Noise ratio of the EUT. Noise is measured first by measuring the integrated output of the EUT with the
generator off. (This effectively puts a resistance equal to the output impedance of the generator across
the input of the EUT). The noise value then stored in the dBr reference for each channel. (If a weighting
curve is specified the noise measurement is made with the selected weighting filter in place.)
Subsequent measurements are made with the generator on and the results are expressed as a dB
Signal-to-Noise ratio.
Cabling Configuration
The output of SR1's analog or digital generator is connected to the EUT's input. The output of the EUT is
connected to SR1's analog or digital inputs. The number of inputs and outputs and the connectors used
are specified in the
Setup Panel .
Generator Configuration
The output waveform is set to either Sine or Low Distortion Sine as specified in the panel. For free-run
operation the amplitude and frequency of the generator is set to the frequency and level in the "start"
column of the panel. For swept operation the frequency is swept from the start to stop value for each
amplitude value specified.
Analyzer Configuration
One or both analyzers (depending on the number of output channels specified in the Setup Panel ) are
configured as Time Domain Detectors .
Free Run Configuration
A barchart display is created for each output channel showing the instantaneous SNR.
Sweep Configuration
A graph will be created for each channel showing a graph of SNR vs. Freq for the selected number of
amplitude steps. Log spacing can be selected for both the frequency and amplitude sweeps. The settling
parameters of the SNR measurement can be adjusted directly from the "Settling" tab of the panel.