Stanford Research Systems SR844 User Manual page 125

Data Storage 4-23
Starting and Stopping a Scan
The STRT,STRD, PAUS and REST commands are used to control data storage.
Basically, the STRT command starts data storage after a reset or pause. The PAUS
command pauses data storage but does not reset the buffer. The REST command stops
data storage and resets the buffer data.
Aliasing Effects
In any sampled data stream, it is possible to sample a high frequency signal such that it
will appear to be a much lower frequency. This is called aliasing.
Aliasing occurs whenever the signal being sampled contains components at frequencies
greater than 1/2 the sample rate.
Generally, the highest possible sample rate should be used given the desired storage time.
The lock-in time constant and filter slope should be chosen to attenuate signals at
frequencies higher than 1/2 the sample rate as much as possible.
SR844 RF Lock-In Amplifier