The sample rate is how often the A/D (analog to digital converter) samples the
vibration. A very common value is 1024 which means that the seismograph
samples 1024 times per second for each channel. The sample rate is a very
important setting. The seismograph should sample at least 4 times the
highest expected frequency. At 1024, this means the highest expected
frequency should not exceed approximately 256 hertz.
Where the frequencies are expected to be very low, the sample rate can be
lowered which will proportionally change the duration. For example, if the
seismograph is set to sample at 1024 for 4 seconds, changing the sample rate to
512 will change the duration to 8 seconds. This will also change the high
frequency limit from 256 to 128 Hz. |