研究目的
Investigating the occurrence and impact of 100 ns sample clock time jumps in the Keysight 3458A digital multimeter when using its internal sampling clock.
研究成果
Sample clock time jumps in the Keysight 3458A DMM were identified and measured, showing that they can influence high-accuracy measurements involving signal phase. The study suggests identifying DMMs without SCTJs or using parts of the sampled record without jumps for such measurements.
研究不足
The detection of SCTJs requires a clean and stable signal source. Measurements at low signal frequencies or with phase instability can compromise the detection of SCTJs. The phenomenon is not important for all measurements but can influence highest accuracy measurements involving signal phase.
1：Experimental Design and Method Selection:
The study involved detecting and measuring sample clock time jumps (SCTJ) in the Keysight 3458A digital multimeter using its internal clock. A method to identify these jumps by estimating phase changes in the sampled signal was developed.
2：Sample Selection and Data Sources:
Two DMMs were tested over a two-year period. A 3052 Hz signal was sampled using the 1 V range and a 10 s sample burst duration.
3：List of Experimental Equipment and Materials:
Keysight 3458A digital multimeter, arbitrary waveform synthesizer (AWG), Josephson Arbitrary Waveform Synthesizer (JAWS), metrology grade calibrator.
4：Experimental Procedures and Operational Workflow:
The signal frequency was estimated from the sample record using a PSFE algorithm. Phases of sub-records were estimated using a three parameter sine fit procedure. Phase differences were translated to sample time differences to identify SCTJs.
5：Data Analysis Methods:
The phase differences were analyzed to detect SCTJs, with results indicating the timing and occurrence of these jumps.
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