Delta Sigma modulator reconstruct analog signal

Projects General Guidance
1

Hi,
I'm trying to reconstruct the analog signal that enter to a Delta Sigma modulator ADS1201.

<a href="http://www.ti.com/lit/ds/sbas081/sbas081.pdf ">Datasheet ADS1201</a>

The input signals on the modulator have frequency that start from DC to 100Hz. The output 1 bit stream of the modulator have frequency of 1MHz (the clock of the modulator).

After the modulator should be included a digital low pass filter which acquires only the useful signal and discards the quantization noise, in cascade a decimator to decrease the frequency and increase the number of output bits.

<a href="http://www.ti.com/lit/an/slyt423/slyt423.pdf">How delta-sigma ADCs work, Part 1</a>
<a href="http://www.ti.com/lit/an/slyt438/slyt438.pdf ">How delta-sigma ADCs work, Part 2</a>

After completing all the above procedures I should regain in one pin of Arduino the analog signal that is in the input of the modulator.
I try to do this operation with an oscilloscope but I don't obtain results.

I would be grateful if someone could help me.
Thanks a lot.
Riccardo

2

I admit that I do not really understand the theory behind this modulation. The demodulator schematic suggests to sum up the bits received in sequence (shift register), but I have no clue about the bit weights.

Will a simple RC low pass filter on the modulator output reveal something similar to the input?

3

Hi,
thank you for response.
I tried to use a RC low pass filter and I reconstruct the input signal but it is worst because it is affected by noise (I suppose the noise of quantization error).
I would try to implement the filter and decimator in Arduino, so I can view if the quantization error disappears.
Thank you for your disponibility.
Riccardo