Downsampling can bias data
When a data is read into diaggui, it is downsampled either on NDS or in DTT to a rate as low as possible but with a nyquist frequency greater than the stop frequency requested for analysis.
When this rate is lower than the true data rate of the stream, the value is biased. For instance, a 524k data stream with constant value of 1000.0 gives the following values at different stop frequencies:
Stop Frequency (HZ) | output value |
---|---|
128,000 | 1000.0 |
100,000 | 1000.2 |
900 | 1012.2 |
200 | 1015.3 |
This might be an NDS 1 bug.
Edited by Erik von Reis