Lambda SR1, Operation Manual, Page: 46 / 317

SR1 Operation Manual 46
© 2014 Stanford Research Systems
high amplitude during the burst cycle. For externally triggered bursts the Burst On Time specifies the
number of cycles the sine is output at the high amplitude following a trigger.
Lo Amplitude specifies the burst "Lo Amplitude" as a fraction of the nominal waveform amplitude.
Synchronous Burst Sine, Repetition Rate = 6 cycles, Burst On Tim e = 2cycles
The green burst indicator will flash when the burst is triggered in either the Ext. Gated or Ext. Triggered
modes. The red burst error indicator will flash in the externally triggered mode to indicate a rate error
condition.
Noise
The noise waveform outputs random noise with an almost-gaussian amplitude probability density
function with several options. (A true gaussian probability density function has finite probability for any
amplitude, no matter how large, which is impractical for a physical device.)
Amplitude controls, as with all SR1 waveforms, the peak value of the noise output. The crest factor of
the noise waveform, the ratio of the peak value to the rms value of the noise, is approximately 4.
The Repeat checkbox governs the repetition interval of the generated noise. If not checked the repeat
interval is sufficiently long that it won't observable under most conditions. If, however, it is desired for the
noise to repeat after a fixed interval, check the Repeat box and enter the Repeat interval below it. If
Repeat is selected, the noise waveform produces a generator trigger each time a waveform repeat is
initiated.
The Pink checkbox specifies that the noise output should be filtered by a 3 dB/octave "pinking" filter.
While the power contained in a white noise signal is linearly proportional to the measurement bandwidth,
pink noise will have equal power in equal logarithmic frequency intervals, e.g. the power contained in the
100 Hz to 200 Hz interval will be the same as the power contained in the 10 kHz to 20 kHz interval.
White or Pink noise can be further filtered according to the controls in the filter group.