Products > Test Equipment

Hacking the Siglent SDM3055 Bench DMM

<< < (27/35) > >>

alexvg:
Hi.
I'm working on the measurement processing.

Here you could find my latest results

Kleinstein:
The noise is a bit higher than for the 34470, but this is not such a surprise: the 34470 is a 7 digit meter and the SDM3055 is 5.5 digits only. In the 1000 V range the resolution is 10 mV for the display. So the noise level is well below the display resolution.

I think the higher noise is from a different (e.g. 1:1000 or maybe 1:500) divider. The divider can be the dominant noise source for the 1000 V and 100 /200 V range.

alexvg:
I'm working hard "try-hard" to enhance my "1 PLC" measurement.

My best result is actually
std.dev = 364.9uV
span = 13547.5uV

Measurement settings :
- DMM at 1000V DC
- 2,5V with PDVS2mini
- 50HZ power-line

The Keysight 34470A at 1PLC (auto-zero during 43 mins) provides :
std.dev = 133.6uV
span = 1149uV

Kleinstein:
The 1000 V range has a very hard stand to get low noise. Chances are the divider is 1:1000 (maybe 1:500) and the divider alone would have quite some noise. So a factor of Sqrt(10) higher noise compared to the meters that can use a divider 1:100 and 10 V range to follow is kind of normal.
There is a bit possible advantage compared to many other meters in that the AZ mode may still be able to do contineous sampling.
The fair comparison may be at a fixed reading rate of lets say some 25 readings per second. With the KS34470 (and many other meters in AZ mode) this would be 1 PLC. With the SD Chip based (and thus ADC with differential input) meters this may be already 2 PLC.

The RMS noise looks good, but the span is quite a bit larger. Is this in an non AZ mode ?

alexvg:
Hi,
I cannot implement an « AZ mode » with the DMM Siglent SDM3055. Why ? Because I need to permanently and continuously resample source ADC data to 50 or 60Hz (the DMM doesn’t have power-line sync).
I’ve already tried to implement this AZ mode without a very good result, the integrated electronic could not provides enough feature. But I’ve tried… However the resampling always provides the better result !

Internal ADC have a clock rate variation of +/-4%, it's not very precise.
Ideally an PLL connected to the power-line could provide the perfect clock rate... But it's a dream.

I’m using the 1000V DC range because it is very hard to get good results. I try-hard, I work hard !

About the measurement of my processing. I really provide a 1PLC with 50 (or 60) measures per second. All PLC measurements provided with my processing have a settling time of 3ms.
Original Siglent software provides 800ms settling time in slow rate (5 values/sec),  80ms in middle rate (50 values/sec) and 26.7ms in fast rate (150 values/sec).

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod