Electrical signal measurement device using reference signal

Patent metadata

Field	Value
Publication number	US-10509063-B2
Application number	US-201715824270-A
Country	US
Kind code	B2
Filing date	Nov 28, 2017
Priority date	Nov 28, 2017
Publication date	Dec 17, 2019
Grant date	Dec 17, 2019

Abstract

Systems and methods provide measurement of one or more electrical parameters (e.g., impedance) of a device under test (DUT) using an electrical parameter measurement device (e.g., multimeter, oscilloscope) that includes reference signal circuitry that generates, detects, and processes common mode reference signals. A measurement device may include a known common mode AC reference voltage source coupled to a common input terminal. During measurement of a DUT, circuitry may detect a signal at a voltage test input terminal and a signal at the common input terminal. The circuitry may process the first and second signals to determine one or more electrical parameters of the DUT, which one or more electrical parameters may be used to implement one or more features. The determined electrical parameters may be presented to an operator via a visual indicator device and/or may be communicated to an external device via a wired and/or wireless communications interface.

First claim

The invention claimed is:

1. An electrical parameter measurement device, comprising:
a voltage test input terminal operatively coupled to voltage measurement circuitry of the electrical parameter measurement device;
a common input terminal operatively coupled to the voltage measurement circuitry of the electrical parameter measurement device; and
reference signal circuitry, comprising:
a common mode reference voltage source which, in operation, generates an alternating current (AC) reference voltage having a reference frequency, wherein the common mode reference voltage source is electrically coupled to the common input terminal;
detection circuitry that, in operation,
detects a first signal present at the voltage test input terminal; and
detects a second signal present at the common input terminal; and

processing circuitry that, in operation,
receives the first and second signals from the detection circuitry;
processes the first and second signals; and
determines at least one electrical characteristic of a device under test that is electrically coupled to the voltage test input terminal and the common input terminal based at least in part on the processing of the first and second signals.

2. The electrical parameter measurement device of claim 1 , further comprising:
a display, wherein, in operation, the processing circuitry causes the at least one electrical characteristic to be presented on the display.

3. The electrical parameter measurement device of claim 1 wherein, in operation, the processing circuitry compares a phase of the first signal to a phase of the second signal to determine a measure of impedance of the device under test.

4. The electrical parameter measurement device of claim 1 wherein the common mode reference voltage source is electrically coupled to the common input terminal via a transformer.

5. The electrical parameter measurement device of claim 1 wherein the common mode reference voltage source is directly electrically coupled to the common input terminal.

6. The electrical parameter measurement device of claim 1 wherein the AC reference voltage generated by the common mode reference voltage source has a frequency that is greater than or equal to 500 Hz and less than or equal to 5,000 Hz.

7. The electrical parameter measurement device of claim 1 wherein the electrical parameter measurement device comprises one of an analog multimeter, a digital multimeter, an analog oscilloscope, or a digital oscilloscope.

8. The electrical parameter measurement device of claim 1 wherein, in operation, the processing circuitry determines the presence or absence of a ghost voltage in the device under test based at least in part on the processing of the first and second signals.

9. The electrical parameter measurement device of claim 1 wherein, in operation, the processing circuitry analyzes the first signal to determine a signal magnitude, and determines a loop impedance between the voltage test input terminal and the common input terminal based at least in part on the signal magnitude of the first signal.

10. The electrical parameter measurement device of claim 1 wherein, in operation, the processing circuitry determines at least one of an inductance value or a capacitance value for the device under test based at least in part on the processing of the first and second signals.

11. The electrical parameter measurement device of claim 1 wherein, in operation, the processing circuitry determines whether the device under test is electrically coupled to each of the voltage test input terminal and the common input terminal based at least in part on the processing of the first and second signals.

12. The electrical parameter measurement device of claim 1 wherein the detection circuitry comprises:
a first voltage divider circuit operatively coupled to the voltage test input terminal;
a second voltage divider circuit operatively coupled to the common input terminal;
a first analog-to-digital converter input terminal operatively coupled to an output of the first voltage divider circuit; and
a second analog-to-digital converter input terminal operatively coupled to an output of the second voltage divider circuit.

13. The electrical parameter measurement device of claim 1 wherein the detection circuitry comprises:
a first filter circuit operatively coupled to the voltage test input terminal, wherein, in operation, the first filter circuit passes signals that have a frequency within an expected range of frequencies for the device under test; and
a second filter circuit operatively coupled to the voltage test input terminal, wherein, in operation, the second filter circuit passes signals that have the reference frequency of the common mode reference voltage source.

14. The electrical parameter measurement device of claim 1 wherein the processing circuitry implements a fast Fourier transform (FFT) to obtain a frequency domain representation of the first and second signals.

15. The electrical parameter measurement device of claim 1 wherein the common mode reference voltage source comprises a digital-to-analog converter (DAC).

16. A method of operating an electrical parameter measurement device, the electrical parameter measurement device comprising a housing, voltage measurement circuitry, a voltage test input terminal and a common input terminal operatively coupled to the voltage measurement circuitry, the method comprising:
causing a common mode reference voltage source to generate an alternating current (AC) reference voltage having a reference frequency, the common mode reference voltage source being electrically coupled to the common input terminal;
detecting, via detection circuitry of the electrical parameter measurement device, a first signal present at the voltage test input terminal;
detecting, via the detection circuitry, a second signal present at the common input terminal;
processing, via processing circuitry of the electrical parameter measurement device, the first and second signals; and
determining, via the processing circuitry, at least one electrical characteristic of a device under test that is electrically coupled to the voltage test input terminal and the common input terminal based at least in part on the processing of the first and second signals.

17. The method of claim 16 , further comprising:
displaying, on a display of the electrical parameter measurement device, the determined at least one electrical characteristic.

18. The method of claim 16 wherein processing the first and second signals comprises comparing a phase of the first signal to a phase of the second signal to determine a measure of impedance of the device under test.

19. The method of claim 16 wherein determining at least one electrical characteristic comprises determining the presence or absence of a ghost voltage in the device under test based at least in part on the processing of the first and second signals.

20. The method of claim 16 wherein determining at least one electrical characteristic comprises determining at least one of an inductance value or a capacitance value of the device under test based at least in part on the processing of the first and second signals.

21. The method of claim 16 wherein determining at least one electrical characteristic comprises determining whether the device under test is electrically coupled to each of the voltage test input terminal and the common input terminal based at least in part on the processing of the first and second si

Assignees

• Fluke Corp

Inventors

• Steuer Ronald

Classifications

• G01R1/025

  concerning dedicated user interfaces, e.g. GUI, or dedicated keyboards (G01R31/31912 takes precedence) · CPC title

• H01R2201/20

  for testing or measuring purposes · CPC title

• G01R19/0023

  Measuring currents or voltages from sources with high internal resistance by means of measuring circuits with high input impedance, e.g. OP-amplifiers (electrostatic instruments G01R5/28; measuring electrostatic potential G01R15/165; measuring electrostatic fields G01R29/12; amplifiers per se H03F) · CPC title

• G01R27/14 Primary

  Measuring resistance by measuring current or voltage obtained from a reference source (G01R27/16, G01R27/20, G01R27/22 take precedence) · CPC title

• G01R15/04

  Voltage dividers · CPC title