Front-end architecture for a measurement instrument

• US 5,930,745 A
• Filed: 04/09/1997
• Issued: 07/27/1999
• Est. Priority Date: 04/09/1997
• Status: Expired due to Fees

• Current Assignee: Fluke Corporation (Fortive Corp.)
• Original Assignee: Fluke Corporation (Fortive Corp.)
• Inventors: Swift, Steven D.
• Primary Examiner(s): ASSOUAD, PATRICK J
• Application Number:
  US08/840,086
• Time in Patent Office: 839 Days
• Field of Search: 702/190, 702/189, 702/198, 702/57, 324/76.11, 324/99 D, 327/100, 341/126, 341/137, 341/155, 340/870.21, 364/724.011, 364/724.013, 364/724.1
• US Class Current: 702/190
• CPC Class Codes: G01R 19/2503 for measuring voltage only, e.g. digital volt meters (DVM's) G01R19/2506 - G01R19/257 take precedence
• CPC Class Codes: G01R 19/2509 Details concerning sampling, digitizing or waveform capturing

Abstract

A front-end architecture is provided for a measurement instrument having a single path for the input signal for conversion into digital samples. A signal conditioner may be coupled via a pair of test leads across a voltage source, current source, or component to develop an input signal. The input signal is provided to a sampling system, which comprises a sigma-delta converter followed by a decimation filter, which over-samples the input signal to produce a continuous stream of digital samples. The digital samples are provided to a set of digital extraction filters, each digital extraction filter having a structure and transfer function adapted for extracting a measurement parameter from the stream of digital samples. Parameter extraction is performed on a continuous basis so that the digital samples and the resulting digital measurement values arrive in a continuous stream. Extracted parameters include the d.c. value of the input signal, the rms value of the input signal, the waveform parameters of the input signal, and the peak min/max values of the input signal.

Claims

1. A measurement front-end for a measurement instrument comprising:

(a) a signal conditioner for receiving a signal voltage and producing an input voltage from said signal voltage;

(b) a sampling system coupled to said signal conditioner for receiving said input voltage and producing digital samples of said input signal; and

(c) a plurality of digital extraction filters connected in parallel and directly coupled to said sampling system to receive simultaneously said digital samples and simultaneously extract a plurality of measurement parameters of said input signal from said digital samples.

2. A measurement front-end for a measurement instrument according to claim 1, wherein said sampling system includes a digital interface coupled to said set of digital extraction filters to receive said simultaneously extracted measurement parameters and provide digital measurement values corresponding to said simultaneously extracted measurement parameters to said measurement instrument.

3. A measurement front-end for a measurement instrument according to claim 1, said sampling system further comprising:

(a) a sigma-delta converter for receiving said input voltage and producing raw digital samples; and

(b) a decimation filter coupled to said sigma-delta converter for receiving said raw digital sample and producing said digital samples.

4. A measurement front-end for a measurement instrument according to claim 1, said sampling system further comprising an analog to digital converter for receiving said input voltage and producing said digital samples.

5. A measurement front-end for a measurement instrument according to claim 1, wherein said plurality of digital extraction filters further comprises a d.c. extraction filter, an rms extraction filter, a waveform extraction filter, and a peak min/max extraction filter.

6. A measurement front-end for a measurement instrument according to claim 1, wherein said measurement parameters include d.c., rms, waveform, and peak min/max parameters.

7. A measurement front-end for a measurement instrument according to claim 1 wherein said plurality of digital extraction filters extract said plurality of measurement parameters continuously.

8. In a measurement instrument, a method for obtaining a plurality of measurement parameters from a signal voltage, comprising:

(a) conditioning said signal voltage to obtain an input signal;

(b) sampling said input signal in a sampling system to obtain digital samples; and

(c) extracting simultaneously said plurality of measurement parameters from said digital samples using a plurality of parallel-connected digital extraction filters.

9. In a measurement instrument, a method for obtaining a plurality of measurement parameters from a signal voltage according to claim 8 further comprising selectively providing said plurality of measurement parameters to said measurement instrument as digital measurement values.

10. In a measurement instrument, a method for obtaining a plurality of measurement parameters from a signal voltage according to claim 8, said plurality of digital extraction filters further comprising a d.c. extraction filter, an rms extraction filter, a waveform extraction filter, and a peak min/max extraction filter.

11. In a measurement instrument, a method for obtaining a plurality of measurement parameters from a signal voltage according to claim 10, said plurality of measurement parameters further comprising d.c., rms, waveform, and peak min/max.

12. In a measurement instrument, a method for obtaining a plurality of measurement parameters from a signal voltage according to claim 8, further comprising continously extracting said plurality of measurement parameters from said digital samples using said plurality of digital extraction filters.