APPARATUS AND METHOD FOR PERFORMING BURST TRIGGERING IN A TEST AND MEASUREMENT INSTRUMENT

• US 20100228508A1
• Filed: 03/05/2010
• Published: 09/09/2010
• Est. Priority Date: 03/09/2009
• Status: Active Grant

• Current Assignee: Tektronix Incorporated (Fortive Corp.)
• Original Assignee: Tektronix Incorporated (Fortive Corp.)
• Inventors: HAZZARD, Shane A., SMITH, Patrick A., TRAN, Que Thuy, KELLY, David L.
• Granted Patent: US 9,075,696 B2
• Time in Patent Office: Days
• US Class Current: 702/68
• CPC Class Codes: G01R 13/02 for displaying measured electric variables in digital form
• CPC Class Codes: G01R 13/0254 for triggering, synchronisation
• CPC Class Codes: G01R 31/50 Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections testing of sparking plugs H01T13/58
• CPC Class Codes: G16Z 99/00 Subject matter not provided for in other main groups of this subclass

Abstract

A test and measurement apparatus, system, and method for synchronizing an acquisition or triggering system to a specific burst of interest. The subject apparatus and method triggers on varying energy content of a signal qualified by time in the presence of high-frequency input signal bursts, by using an adjustable pulse width envelope detector, disposed in the signal path of the trigger circuitry, as a digital rectifier or to otherwise process and extract an envelope signal. An RF envelope probe having an analog envelope detector among other suitable components is disclosed. A method is implemented for isolating an interval of interest in a signal under test. An envelope detector circuit produces an envelope signal from the signal. Trigger circuitry receives the envelope signal from the envelope detector, and isolates the interval of interesting in the signal under test using the envelope signal.

Claims

1. A test and measurement instrument, comprising:

an input terminal to receive a signal under test;

an envelope detector circuit coupled to the input terminal and structured to receive the signal under test and produce an envelope signal from the signal under test; and

trigger circuitry coupled to the envelope detector circuit, the trigger circuitry structured to isolate a burst in the signal under test using the envelope signal.

2. The test and measurement instrument of claim 1, wherein the envelope detector circuit includes a digital envelope detector.

3. The test and measurement instrument of claim 2, wherein the digital envelope detector comprises:

a delay circuit to receive the signal under test; and

a logic gate to receive the signal under test and a delayed signal from the delay circuit,

wherein the logic gate is structured to produce the envelope signal using the signal under test and the delayed signal.

4. The test and measurement instrument of claim 1, wherein the envelope detector circuit comprises an analog envelope detector.

5. The test and measurement instrument of claim 1, wherein the trigger circuitry is structured to isolate a gap in the signal under test using the envelope signal.

6. The test and measurement instrument of claim 1, wherein the trigger circuitry is structured to receive the envelope signal and to isolate the burst in the signal under test having a defined width corresponding to a pulse in the envelope signal.

7. The test and measurement instrument of claim 6, wherein the defined width corresponds to one of (a) a range of widths within predetermined bounds and (b) a range of widths outside of predetermined bounds.

8. The test and measurement instrument of claim 1, wherein the trigger circuitry is structured to receive the envelope signal and to isolate a gap in the signal under test having a defined width corresponding to a pulse in the envelope signal.

9. The test and measurement instrument of claim 8, wherein the defined width corresponds to one of (a) a range of widths within predetermined bounds and (b) a range of widths outside of predetermined bounds.

10. The test and measurement instrument of claim 1, wherein the trigger circuitry is structured to receive the envelope signal and to count a plurality of bursts in the signal under test corresponding to a plurality of pulses in the envelope signal.

11. The test and measurement instrument of claim 10, wherein the trigger circuitry is structured to isolate one of the plurality of bursts when the count exceeds a threshold.

12. The test and measurement instrument of claim 1, wherein the trigger circuitry is structured to receive the envelope signal and to isolate a burst glitch in the signal under test using the envelope signal.

13. The test and measurement instrument of claim 1, wherein the trigger circuitry is structured to receive the envelope signal and to isolate a burst runt in the signal under test using the envelope signal.

14. The test and measurement instrument of claim 1, wherein the trigger circuitry is structured to receive the envelope signal and to timeout after a period of time during which no burst is detected using the envelope signal.

15. The test and measurement instrument of claim 1, wherein the trigger circuitry is structured to receive the envelope signal and to isolate a fall time in the envelope signal, wherein the fall time is one of (a) within predetermined bounds and (b) outside of predetermined bounds.

16. The test and measurement instrument of claim 1, wherein the trigger circuitry is structured to receive the envelope signal and to isolate a rise time in the envelope signal, wherein the rise time is one of (a) within predetermined bounds and (b) outside of predetermined bounds.

17. The test and measurement instrument of claim 1, wherein the trigger circuitry is structured to receive the envelope signal and to cause a trigger event in association with the burst based on a trigger level set in relation to the envelope signal.

18. A test and measurement system, comprising:

an oscilloscope including trigger circuitry; and

an envelope probe attachable to an input terminal of the oscilloscope, wherein the envelope probe comprises;

a power splitter to divide a signal under test into first and second signals; and

an envelope detector to receive the first signal and to produce an envelope signal from the first signal,

wherein the oscilloscope is structured to receive and process the envelope signal and the second signal, and the trigger circuitry is structured to receive and process the envelope signal.

19. The test and measurement system of claim 18, wherein the envelope probe further comprises:

a microcontroller to operate with a probe communication section of the oscilloscope; and

a variable gain amplifier to receive the envelope signal from the envelope detector,

wherein the microcontroller is structured to control an amount of gain in the variable gain amplifier.

20. The test and measurement system of claim 19, wherein the microcontroller is structured to control a time constant of the envelope detector.

21. The test and measurement system of claim 18, wherein the envelope probe further comprises a Radio Frequency (RF) amplifier to receive and amplify the second signal before transmitting the second signal to the oscilloscope.

22. A test and measurement instrument, comprising:

an input terminal to receive a signal under test;

an envelope detector to produce an envelope signal from the signal under test,

trigger circuitry to receive the envelope signal and to isolate an interval of interest within the signal under test using the envelope signal.

23. The test and measurement instrument of claim 22, wherein the envelope detector comprises a digital envelope detector.

24. The test and measurement instrument of claim 23, further comprising a comparator to receive the signal under test and to reference the signal under test to a threshold voltage.

25. The test and measurement instrument of claim 23, further comprising timer circuitry coupled to the digital envelope detector to process time intervals between transitions of the envelope signal.

26. The test and measurement instrument of claim 23, further comprising a counter coupled to the digital envelope detector to extend a pulse of the envelope signal.

27. The test and measurement instrument of claim 23, further comprising:

a preamplifier to receive and amplify the signal under test;

a comparator coupled to the preamplifier and structured to reference the amplified signal to a threshold voltage;

an oversampler coupled to an output of the comparator, wherein the oversampler is structured to produce an output signal having replicated digital values; and

a counter coupled to an output of the digital envelope detector,

wherein the digital envelope detector is coupled to the oversampler and structured to receive the output signal having the replicated digital values, and to produce a logical high signal for each transition of the output signal of the oversampler; and

wherein the counter is structured to extend a digital value received from the output of the digital envelope detector.

28. The test and measurement instrument of claim 22, wherein the envelope detector comprises an analog envelope detector.

29. The test and measurement instrument of claim 28, further comprising:

a preamplifier to receive and amplify the signal under test;

acquisition circuitry coupled to the preamplifier and structured to receive and process the signal under test;

a comparator coupled to the preamplifier and structured to receive the signal under test and to remove a DC offset from the signal under test,

wherein an output of the comparator is coupled to an input of the analog envelope detector, and an output of the analog envelope detector is coupled to the trigger circuitry.

30. The test and measurement instrument of claim 29, wherein the analog envelope detector is coupled to the acquisition circuitry so that the envelope signal can be displayed to a user of the oscilloscope.

31. The test and measurement instrument of claim 28, further comprising:

a preamplifier to receive and amplify the signal under test;

acquisition circuitry coupled to the preamplifier and structured to receive and process the signal under test;

a variable gain amplifier coupled to an output of the analog envelope detector to accommodate output gain variations;

a comparator coupled to an output of the variable gain amplifier and structured to reference the signal under test to a threshold voltage,

wherein an output of the comparator is coupled to the trigger circuitry.

32. The test and measurement instrument of claim 31, wherein the analog envelope detector is coupled to the acquisition circuitry so that the envelope signal can be displayed to a user of the oscilloscope.

33. The test and measurement instrument of claim 22, further comprising:

a graphical user interface including a trigger type selection option having selections for at least one of (a) trigger RF burst width, (b) trigger RF gap width, (c) trigger RF envelope rise time, (d) trigger RF envelope fall time, (e) trigger RF glitch, (f) trigger RF timeout, and (g) trigger RF level.

34. The test and measurement instrument of claim 22, further comprising:

a graphical user interface including a trigger type selection option having selections for at least one of (a) trigger serial burst width, (b) trigger serial gap width, (c) trigger serial envelope rise time, (d) trigger serial envelope fall time, (e) trigger serial glitch, (f) trigger serial timeout, and (g) trigger serial level.

35. The test and measurement instrument of claim 22, further comprising a calibration unit to convert the type of units for which a signal is displayed according to a user selection.

36. The test and measurement instrument of claim 35, wherein the signal is displayed in units of at least one of decibel units (dBm), decibel micro volts (dBμ

V), and watts (W).

37. A method for isolating an interval of interest in a signal under test in a test and measurement device, the test and measurement device including trigger circuitry and an envelope detector, the method comprising:

receiving the signal under test at a terminal of the test and measurement device;

the envelope detector circuit producing an envelope signal from the signal under test;

the trigger circuitry receiving the envelope signal from the envelope detector; and

the trigger circuitry isolating the interval of interesting in the signal under test using the envelope signal.

38. The method of claim 37, further comprising:

applying a plurality of trigger types to the envelope signal; and

isolating and displaying a plurality of intervals of interest in the signal under test for each trigger type.

39. An article drawn from the set including floppy disks, optical disks, fixed disks, random access memory, read-only memory, or flash memory, comprising a machine-accessible medium having associated instructions that, when executed in a test and measurement device, results in a machine performing the steps of claim 37.