US-12620978-B2 - Use of pulse width modulation to generate excitation pulses offset from sampling pulses

Abstract

A system and method for time domain reflectometry (TDR) using fine edge placement pulse width modulation (PWM) is disclosed. The system may include a first pulse width modulation (PWM) circuit. The first PWM circuit may be to generate an excitation pulse and output the excitation pulse to a node of a transmission medium. The system may also include a second PWM circuit. The second PWM circuit may be to generate a sampling pulse and output the sampling pulse a sampling circuit to cause to the sampling circuit to record a signal. The sampling pulse may be offset from the excitation pulse by a time interval. The signal may be indicative of a reflection of the excitation pulse at the node of the transmission medium.

Inventors

• Stefan Weiers

Assignees

• MICROCHIP TECHNOLOGY INCORPORATED

Dates

Publication Date

20260505

Application Date

20240809

Claims (20)

1. 1 . An apparatus, comprising: a first pulse width modulation (PWM) circuit to: generate an excitation pulse; and output the excitation pulse to a driver to cause the driver to generate a voltage pulse and communicate the voltage pulse to a node of a transmission medium; and a second PWM circuit to: generate a sampling pulse, the sampling pulse is offset from the excitation pulse by a time interval, the time interval based on an expected time a reflection of the excitation pulse is to be received at the node; and output the sampling pulse to a sampling circuit to cause the sampling circuit to record a signal, the signal is indicative of the reflection of the excitation pulse at the node of the transmission medium.
2. 2 . The apparatus of claim 1 , wherein the sampling circuit is a sample and hold circuit.
3. 3 . The apparatus of claim 1 , comprising an analog-to-digital converter to receive the signal from the sampling circuit.
4. 4 . The apparatus of claim 1 , wherein the time interval is based on a resolution of the first PWM circuit or a resolution of the second PWM circuit.
5. 5 . The apparatus of claim 1 , wherein the time interval is based on a resolution of a measurement signal.
6. 6 . The apparatus of claim 1 , wherein the time interval is equal to one cycle of the first PWM circuit.
7. 7 . An apparatus, comprising: a sampling circuit to record a signal after receiving a sampling pulse, the signal is indicative of a reflection of an excitation pulse at a node of a transmission medium; and a pulse width modulation (PWM) circuit to: generate the excitation pulse; output the excitation pulse to a driver to cause the driver to generate a voltage pulse and communicate the voltage pulse to the node of the transmission medium; generate the sampling pulse, the sampling pulse is offset from the excitation pulse by a time interval, the time interval based on an expected time the reflection of the excitation pulse is to be received at the node; and output the sampling pulse to the sampling circuit.
8. 8 . The apparatus of claim 7 , wherein the sampling circuit is a track and hold circuit.
9. 9 . The apparatus of claim 7 , wherein the time interval is based on a resolution of the PWM circuit.
10. 10 . The apparatus of claim 7 , comprising an analog-to-digital converter to receive the signal from the sampling circuit.
11. 11 . The apparatus of claim 7 , wherein the time interval is based on a resolution of a measurement signal.
12. 12 . The apparatus of claim 7 , wherein the time interval is equal to one cycle of the PWM circuit.
13. 13 . A method, comprising: generating an excitation pulse; outputting the excitation pulse to a driver to cause the driver to generate a voltage pulse and communicate the voltage pulse to a node of a transmission medium; generating a sampling pulse, the sampling pulse is offset from the excitation pulse by a time interval, the time interval based on an expected time a reflection of the excitation pulse is to be received at the node; and outputting the sampling pulse to a sampling circuit to cause the sampling circuit to record a signal after receiving the sampling pulse, the signal is indicative of the reflection of the excitation pulse at the node of the transmission medium.
14. 14 . The method of claim 13 , comprising receiving the signal from the sampling circuit.
15. 15 . The method of claim 14 , comprising diagnosing the transmission medium based on the signal.
16. 16 . The method of claim 15 , wherein diagnosing the transmission medium uses time domain reflectometry.
17. 17 . The method of claim 13 , wherein the sampling pulse is generated before a second excitation pulse.
18. 18 . The method of claim 13 , wherein the excitation pulse is generated before the sampling pulse.
19. 19 . The method of claim 13 , wherein the time interval is based on a resolution of a PWM circuit.
20. 20 . The method of claim 13 , wherein the time interval is based on a resolution of a measurement signal.

Description

PRIORITY This application claims priority to U.S. Provisional Patent Application No. 63/652,897 filed May 29, 2024, the contents of which are hereby incorporated in their entirety. TECHNICAL FIELD The present disclosure relates generally to data communication networks, and more specifically, to differentiating nodes with identical hardware on a shared bus within a local area network. BACKGROUND Time domain reflectometry (TDR) is a technique used to analyze electrical lines by sending a short voltage pulse and examining its reflections. Time-domain reflectometers measure reflections along a conductor by transmitting an incident signal onto the conductor and listening for its reflections. A conductor having uniform impedance, and which is properly terminated will produce no reflections and the incident signal will be absorbed by the termination at the far-end. Reflections in a TDR measurement occur when the pulse encounters a change in the electrical properties of the transmission medium, such as a cable break or a faulty connection. By measuring the time it takes for the reflected pulse to return and considering the propagation speed of the pulse within the transmission medium, a TDR can pinpoint the exact location of the electrical discontinuity. This makes TDR a tool for, for example, troubleshooting and maintaining cables used in telecommunications, data networks, and various electronic systems. TDR may also be used to differentiate notes with identical hardware in 10Base-T1S systems for automotive and industrial applications. However, TDR implementations are often too complex, expensive, or both to be used for node differentiation due to the high sampling rates and memory transfer speeds used for this application. For example, TDR may use very fast sampling, but may be used to identify conditions on in the transmission medium such as identification of a short core to core, a parallel resistance core to core, an interrupt, or a serial resistance. Pulse width modulation (PWM) is a technique for controlling analog-like behavior with digital signals. PWM rapidly switches a signal on and off, but by changing the duration of the “on” pulses relative to the “off” periods, PWM creates an average voltage output that can be controlled. SUMMARY OF THE INVENTION Aspects provide systems and methods for time domain reflectometry (TDR) using fine edge placement pulse width modulation (PWM). Examples of the present disclosure may include an apparatus. The apparatus may include a first pulse width modulation (PWM) circuit. The first PWM circuit may be to generate an excitation pulse and output the excitation pulse to a node of a transmission medium. The apparatus may also include a second PWM circuit. The second PWM circuit may be to generate a sampling pulse and output the sampling pulse a sampling circuit to cause to the sampling circuit to record a signal. The sampling pulse may be offset from the excitation pulse by a time interval. The signal may be indicative of a reflection of the excitation pulse at the node of the transmission medium. In combination with any of the above examples, the sampling circuit may be a sample and hold circuit. In combination with any of the above examples, the apparatus may include an analog-to-digital converter to receive the signal from the sampling circuit. In combination with any of the above examples, the time interval may be based on a resolution of the first PWM circuit or a resolution of the second PWM circuit. In combination with any of the above examples, the time interval may be based on a resolution of a measurement signal. In combination with any of the above examples, the time interval may be equal to one cycle of the first PWM circuit. Alone or in combination with any of the above examples, examples of the present disclosure may include an apparatus with a sampling circuit to record a signal after receiving a sampling pulse. The signal may be indicative of a reflection of an excitation pulse at a node of a transmission medium. The apparatus may include a pulse width modulation (PWM) circuit. The PWM circuit may be to generate the excitation pulse. The PWM circuit may also be to output the excitation pulse to the node of the transmission medium. The PWM circuit may additionally be to generate the sampling pulse, the sampling pulse is offset from the excitation pulse by a time interval and output the sampling pulse the sampling circuit. In combination with any of the above examples, the sampling circuit may be a track and hold circuit. In combination with any of the above examples, the time interval may be based on a resolution of the PWM circuit. In combination with any of the above examples, the apparatus may include an analog-to-digital converter to receive the signal from the sampling circuit. In combination with any of the above examples, the time interval may be based on a resolution of a measurement signal. In combination with any of the above examples, the time inter