Lambda SR1, Operation Manual, Page: 64 / 317

SR1 Operation Manual 64
© 2014 Stanford Research Systems
Phased Sines*
The phased sine waveform consists of two sines, one on channel A and one on Channel B with a
specified phase difference between them. This waveform may not be combined with other waveforms.
Phases may be entered in any 360
º
interval (for instance 0
º
to 360
º
or -180
º
to 180
º
) specified on the
Preferences Panel .
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, i.e. 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.
Noise Filter
None White or Pink noise is directly output without further filtering.
Lowpass The white or pink noise is filtered with a 4th order Butterworth lowpass filter at the
frequency specified in the filter frequency control.