| Products > Test Equipment |
| Hacking the Siglent SDM3055 Bench DMM |
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| 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). |
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