Timestamping signal monitor device
View Patent ↗A signal monitor device that detects a signal propagating on a signal line and that generates a timestamp when the signal is detected. The timestamp may be used in a variety of applications including measuring the propagation delays on signal lines and determining the timing in a system.
1. A signal monitor device, comprising:
a signal detector that detects a signal propagating on a signal line and that generates a timestamp when the signal is detected; and
a device controller that corrects the timestamp by subtracting delays introduced by the signal monitor device.
2. The signal monitor device of claim 1 , wherein the timestamp is derived from a clock in the signal monitor device that is synchronized to a system time.
3. The signal monitor device of claim 1 , comprising a pair of connectors that enable the signal monitor device to be inserted into the signal line.
4. The signal monitor device of claim 1 , wherein the signal detector presents a high impedance to the signal line.
5. The signal monitor device of claim 1 , comprising circuitry that injects a timed signal onto the signal line.
6. The signal monitor device of claim 1 , wherein the device controller transfers a message carrying the timestamp over a network.
7. The signal monitor device of claim 1 , further comprising:
an input circuit that decodes a signal received via the signal line for detection by the signal detector; and
an output circuit that encodes the decoded signal and outputs the signal back onto the signal line.
8. A method for signal monitoring, comprising:
detecting a signal propagating on a signal line;
generating a timestamp when the signal is detected; and
correcting the timestamp by subtracting delays introduced by the signal monitoring.
9. The method of claim 8 , further comprising determining a propagation delay of the signal on the signal line in response to the timestamp.
10. The method of claim 8 , further comprising determining a time of an event in a system in response to the timestamp.
11. The method of claim 8 , wherein generating a timestamp includes obtaining the timestamp from a clock that is synchronized to a system time.
12. The method of claim 8 , wherein detecting a signal comprises physically connecting to the signal line.
13. The method of claim 8 , wherein detecting a signal comprises sensing electromagnetic energy emitted from the signal line.
14. The method of claim 8 , wherein detecting a signal comprises sensing light emitted from the signal line.
15. The method of claim 8 , further comprising injecting a timed signal onto the signal line.
16. A system, comprising:
a set of two or more signal monitor devices that generate a set of timestamps in response to a set of signals propagating on a set of signal lines; and
a device that obtains the timestamps from the signal monitor devices via a network, the device having a clock that provides a time base for evaluating the timestamps.
17. The system of claim 16 , wherein the device determines a propagation delay of the signal lines in response to the timestamps.
18. The system of claim 16 , wherein the device determines a timing of the signal in response to the timestamps.
19. The system of claim 16 , wherein each device includes a local clock such that the local clocks are synchronized to the clock in the device.
20. The system of claim 16 , wherein the signal monitor devices inject a set of timed signals onto the corresponding signal lines in response to a message from the device.