I would like to generate stable volts from 0 to 5 and to minimize Gibbs phenomenon without losing measurement data. I get much sudden peaks in Raspberry Pi 1/2 which I can control by adding low-pass and/or high-pass filters after Raspberry but this is losing too much measurement data. These peaks correspond to Gibbs phenomenon and they are not because of a wiring problem and not because of Nyquist frequency.
I can detect the phenomenon with the sampling rates 500 MHz and 200 MHz by having the signal from Raspberry Pi 1/2 with standard ADCs (testing next week with a set of other ADCs). Here some pictures from 354 and 322 LeCroy Oscilloscopes (cheap) with 500 MHz and 200 MHz respectively when sigma delta ADC:
To increase the rate cannot minimize the source of the phenomenon. Processing of the data does not affect the creation of the event.
I want to affect the formation of this event by affecting the ADC converter. The default converters of Raspberry cause much such an event. One thread about some basics.
- sigma delta ADCs, review here
- non-sigma delta ADCs: MCP3008 (10 bit, 200 kHz), ADS1113 (16 bit, 860 Hz)
- I2C: PCF8591 discussed here
- ADS1113/4/5 (can be a good ones)
There must be better precision ADC converters. Better options
- SAR (Successive Approximation) ADCs
Frequency and precision
I cannot give any answer about the frequency because it is determined by the internals of Raspberry Pi 1/2 where the limiting components are most likely ADCs. Low-pass filter works but it loses quite much data. Probably, the precision of 12 bits is ok.
Which precision ADC converters are good for Raspberry Pi in minimizing the sudden peaks?