Macro: SmplRate

These radio buttons select one of 4 popular sample rates: 11025, 22050, 44100, or 48000 Hz. Selecting one of these buttons also forces the Rate Adjust control (below) to the same value. The default is 48000 samples per second (Hz) if your card supports it, otherwise 44100 samples per second.

The sample rate determines the time resolution and extent of the waveform display, as well as the frequency resolution and extents of the Spectrum and Spectrogram ( Sgram) displays.

Daqarta acquires 1024 samples per display. For a waveform, the resolution is the reciprocal of the sample rate. The resolutions and X-axis extents for 0-1023 samples are:

11025 Hz = 90.703 msec per sample, 92.88 msec max.
22050 Hz = 45.351 msec per sample, 46.44 msec max.
44100 Hz = 22.676 msec per sample, 23.22 msec max.
48000 Hz = 20.833 msec per sample, 21.31 msec max.

For a spectrum, those 1024 samples become 512 spectral lines ranging from 0 (DC) to just under half the sample rate (known as the Nyquist frequency). The resolution is the sample rate divided by 1024. The resolutions and X-axis extents for lines 0-511 are:

11025 Hz = 10.77 Hz per line, 5501.73 Hz max.
22050 Hz = 21.53 Hz per line, 11003.47 Hz max.
44100 Hz = 43.07 Hz per line, 22006.93 Hz max.
48000 Hz = 46.88 Hz per line, 23953.31 Hz max.

The astute observer will note that higher sample rates give better time resolution but narrower overall axis time for waveforms, while lower sample rates give better resolution and lower overall frequency range for spectra.

If you change the sample rate, you may need to adjust certain Generator controls. In particular, Burst durations are stored internally as sample counts, based upon the sample rate in effect when they were originally set. For example, if you set a High duration of 0.100 sec with a sample rate of 44100 Hertz, it is stored as 4410 samples. Changing the sample rate to 22050 Hz doesn't change the number of samples, but it doubles the effective duration because each sample takes twice as long.

Similarly, Slow Factor and Step Size in the Random / Step Timing dialog are stored as sample counts, so halving the sample rate would also double the effective times.

Note that sample rate controls are disabled during averages.

Macro Notes:

SmplRate=44100 sets the Sample Rate to 44100 samples per second.

See also X-Axis Control Dialog

• Back to CPM Spectrum
• Ahead to Sample Rate Adjust
• Daqarta Help Contents
• Daqarta Help Index
• Daqarta Downloads
• Daqarta Home Page
• Purchase Daqarta

Questions? Comments? Contact us!