SDS2102X Plus Enhanced Bit Function

[mawyatt]

I've been spending some time with SDS2102X Plus and did some experiments to "see" how the Enhanced Bits function behaves.

Test setup used the DSO AWG set to 50 ohms, 1MHz at 2mvptp, DSO set to 50 ohms, 0.5mv/div, 20ms/div on Channel 1. In the 3 screen captures below, F1 is the normal FFT (FFT(C1)), average 4, 0dBM reference and 20db/div, Center Freq 1MHz, span 1MHz, F2 is the same as F1 except it's the FFT of the "eres" function (FFT(eres(C1)).

The 1st screen capture has Enhanced Bits set to 1.0, 2nd to 2.0 and 3rd to 3.0.

Note how the noise floor drops (Marker 2 @ 1.1MHz) with the Enhanced Bits and how it drops faster than the signal level (Marker 1 @ 1MHz), this improves the SNR. Also note how F2 has the noise floor showing notches in the 3rd capture on either side of 1MHz!!

Does anyone know the algorithms used by Siglent in the SDS2102X Plus DSO for the Enhanced Bits function (eres)?

Best,

Here's 3 more with the input at about -93dBm and the reference level at -40dBm.

[Performa01]

Here is a LeCroy document explaining ERES vs. HiRes:
https://teledynelecroy.com/doc/differences-between-eres-and-hires

Even though Siglent calls their resolution enhancement technique "Eres", hence very similar to the LeCroy thing, there is no evidence that it's actually the same as LeCroy's implementation. It might just as well be an ordinary HiRes...

[mawyatt]

Thanks so much for the info (and the excellent discussion on the FFT use).

So it appears the ERES function is a FIR linear phase filter and the waveform is selectively filtered based upon nearest neighbor samples and thus somewhat of a correlation result.

It's so nice to have all these features and capability in a modest priced DSO, the more I work with the SDS2102X Plus the more impressed I am

Best,

[mawyatt]

Just did a few more experiments with the FFT function of the SDS2102X Plus.

This is the "average" of the FFT of the waveform in F1 and the FFT of the waveform "average". The waveform is a small 1mvpp (-69dBvrms) input at 1MHz, and not very "clean".

F1 is doing an average after the FFT, and F2 is doing an FFT of the {average of the waveform}, thus F1 is a Frequency Domain average. Note how F2 has a significantly lower noise floor, and the harmonics are lower.

Best,