Systems and methods for synchronizing multiple test and measurement instruments

Patent metadata

Field	Value
Publication number	US-11002764-B2
Application number	US-202016788176-A
Country	US
Kind code	B2
Filing date	Feb 11, 2020
Priority date	Feb 12, 2019
Publication date	May 11, 2021
Grant date	May 11, 2021

Abstract

A system includes a plurality of oscilloscopes, each oscilloscope having an output port and an input port, a cable connecting the output port of an initial oscilloscope of the plurality of oscilloscopes to the input port of a second oscilloscope of the plurality of oscilloscopes, the initial oscilloscope having a processing element to generate a master run clock, the second oscilloscope having a processing element including a phase-locked loop to lock a slave run clock to the master run clock, wherein the processing element of one of the oscilloscopes executes code to cause the processing element to manipulate one of the run clocks to pass trigger information to another of the plurality of oscilloscopes. A method of synchronizing at least two oscilloscopes including a master oscilloscope and at least one slave oscilloscope includes connecting the at least two oscilloscopes together using output ports and input ports of the at least two oscilloscopes and at least one cable; sending a master run clock from the master oscilloscope to at least one slave oscilloscope; synchronizing a run clock of the at least one slave oscilloscope to the master run clock; recognizing a trigger event at a first oscilloscope of the at least two oscilloscopes; altering the run clock at the first oscilloscope to encode a trigger indication; and receiving the altered run clock at a second oscilloscope of the at least two oscilloscopes, wherein the trigger indication causes the second oscilloscope to recognize the trigger event.

First claim

What is claimed is:

1. A system, comprising:
a plurality of oscilloscopes, each oscilloscope having an output port and an input port;
a cable connecting the output port of an initial oscilloscope of the plurality of oscilloscopes to the input port of a second oscilloscope of the plurality of oscilloscopes;
the initial oscilloscope having a processing element to generate a master run clock;
the second oscilloscope having a processing element including a phase-locked loop to lock a slave run clock to the master run clock, wherein
the processing element of one of the oscilloscopes executes code to cause the processing element to manipulate one of the run clocks to pass trigger information to another of the plurality of oscilloscopes.

2. The system as claimed in claim 1 , wherein the plurality of oscilloscopes further comprises one or more additional oscilloscopes connected in a series with the initial oscilloscope and the second oscilloscope, each additional oscilloscope having a cable connecting the output port of a previous oscilloscope in the series to the input port of a current oscilloscope in the series, wherein the second oscilloscope is a previous oscilloscope in the series.

3. The system as claimed in claim 1 , wherein the plurality of oscilloscopes comprises a final oscilloscope having a cable connecting the output port of the final oscilloscope and the input port of the initial oscilloscope to form a closed loop through the plurality of oscilloscopes.

4. The system as claimed in claim 1 , wherein the system is implemented using legacy hardware.

5. The system as claimed in claim 1 , wherein the cable connecting the output port of the initial oscilloscope to the input port of one other of the plurality of oscilloscopes connects to the input port of the other oscilloscope through a hub.

6. The system as claimed in claim 5 , wherein the hub has one input port and multiple output ports to connect to the input ports of multiple oscilloscopes.

7. The system as claimed in claim 5 , wherein the hub is connected to multiple oscilloscopes and at least one of the multiple oscilloscopes has a cable connected to an output port and connected to an input port of one other oscilloscopes that is not connected to the hub or any other oscilloscopes.

8. The system as claimed in claim 1 , wherein each oscilloscope other than the initial oscilloscope has a phase-locked loop with symmetric paths.

9. The system as claimed in claim 1 , wherein the phase-locked loop is implemented in the processing element.

10. A method of synchronizing at least two oscilloscopes including a master oscilloscope and at least one slave oscilloscope, comprising:
connecting the at least two oscilloscopes together using output ports and input ports of the at least two oscilloscopes and at least one cable;
sending a master run clock from the master oscilloscope to at least one slave oscilloscope;
synchronizing a run clock of the at least one slave oscilloscope to the master run clock;
recognizing a trigger event at a first oscilloscope of the at least two oscilloscopes;
altering the run clock at the first oscilloscope to encode a trigger indication; and
receiving the altered run clock at a second oscilloscope of the at least two oscilloscopes, wherein the trigger indication causes the second oscilloscope to recognize the trigger event.

11. The method as claimed in claim 10 , wherein altering the run clock comprises encoding information to be sent between the at least two oscilloscopes by altering the intervals between a first edge polarity of the run clock and a second edge polarity of the run clock.

12. The method as claimed in claim 11 , wherein the encoding information comprises encoding at least one of a time stamp of the trigger event and an acquisition control message.

13. The method as claimed in claim 11 , wherein the encoding information comprises encoding device addresses.

14. The method as claimed in claim 10 , further comprising connecting the output port of one of a final of the at least two oscilloscopes to the input port of the master oscilloscope to form a closed series of oscilloscopes.

15. The method as claimed in claim 14 , further comprising sending encoded acquisition control queries to at least one other oscilloscope.

16. The method as claimed in claim 10 , wherein synchronizing comprises using a phase-locked loop on the at least one slave oscilloscope.

17. The method as claimed in claim 16 , where the encoding minimizes energy within the phase-locked loop bandwidth.

18. The method as claimed in claim 16 , further comprising setting a bandwidth of the phase-locked loop to minimize jitter between the oscilloscopes.

19. The method as claimed in claim 10 , further comprising performing calibration of a designated oscilloscope of the at least two oscilloscopes, by:
connecting a cable from an output port of the designated oscilloscope to an input port of the designated oscilloscope;
comparing an edge on a signal on the output port to an edge on the input port; and
measuring a delay for the cable.

20. The method as claimed in claim 19 , further comprising
using the measured cable delay to adjust signals when the designated oscilloscope is connected in series with at least one other oscilloscope of the at least two oscilloscopes.

Assignees

• Tektronix Inc

Inventors

• Knierim Daniel G
• Hickman Barton T
• O'Brien Joshua J

Classifications

• G01R31/319

  Tester hardware, i.e. output processing circuits · CPC title

• G01R13/0263

  for non-recurrent functions, e.g. transients · CPC title

• G01R13/0254 Primary

  for triggering, synchronisation · CPC title

• H03L7/08

  Details of the phase-locked loop · CPC title

• H03K2005/00019

  Variable delay · CPC title