Parallel handset on-hook/off-hook detection by software-based signal power measurement

• US 6,687,344 B1
• Filed: 09/07/2001
• Issued: 02/03/2004
• Est. Priority Date: 09/07/2001
• Status: Expired due to Fees

• Current Assignee: Silicon Laboratories Incorporated
• Original Assignee: Inx. Pctel
• Inventors: Tung, Chien-Cheng, Mazzarini, Anthony L., Luo, XiaoHua
• Primary Examiner(s): CHAN, WING F
• Application Number:
  US09/949,342
• Time in Patent Office: 879 Days
• Field of Search: 379/93-5-, 379/93.09, 379/93.11, 379/93.37, 379/106.08, 379/100.15, 379/399.01, 379/377
• US Class Current: 379/93.09
• CPC Class Codes: H04M 1/82 Line monitoring circuits for call progress or status discrimination for detecting caller identity H04M1/573

Abstract

A computer having a modem is programmed with software (also called a “on-hook/off-hook detector”) that detects a change in status (e.g., on-hook or off-hook) of a device (e.g., a telephone having a handset) by measuring a change in the signal power of a signal flowing through a telephone line connecting the modem and the device. In particular, the computer programmed with the on-hook/off-hook detector detects a status of a telephone handset by measuring power of a reference signal and measuring power of an instantaneous signal on the connection and comparing these two measurements. The reference signal is a constant signal whose power does not change. Then, the computer programmed with the on-hook/off-hook detector is able to detect whether there has been a change in status of the telephone handset by comparing the detected status with a previous status of the telephone handset. The on-hook/off-hook detector may be executed in a central processing unit (CPU) of a computer or in a digital signal processor (DSP) of a modem.

Claims

1. A process for operating a first communication device, comprising:

obtaining a measure of a reference signal power of a communication medium;

obtaining a measure of an instantaneous signal power of the communication medium;

comparing the measure of the instantaneous signal power to a range that is determined based on the measure of the reference signal power; and

detecting the status of a second communication device connected to the communication medium based on the comparison.

2. The process of claim 1, wherein the first communication device comprises a modem.

3. The process of claim 1, wherein the second communication device comprises a telephone handset.

4. The process of claim 1, wherein the status reflects whether the second communication device connected to the communication medium is on-hook or off-hook.

5. The process of claim 1, wherein the instantaneous signal power and the reference signal power are determined based on an alternating current.

6. The process of claim 1, further comprising:

comparing the detected status to a previous status of the second communication device; and

determining whether there has been a chance of status for the second communication device based on the comparison.

7. The process of claim 1, further comprising;

generating an echo signal, wherein the measure of the reference signal power is obtained based on the echo signal.

8. A method of detecting a change of status for a device connected to a telephone line, comprising:

obtaining a measure of a reference signal power of the telephone line;

obtaining a measure of an instantaneous signal power of the telephone line;

comparing the measures of the reference signal power and the instantaneous signal power, and

detecting that there has been a change in status of the device connected to the telephone line based on the comparison.

9. The method of claim 8, wherein the status reflects whether the device connected to the telephone line is on-book or off-hook.

10. The method of claim 8, wherein the signal power is determined based on an alternating current.

11. The method of claim 8, further comprising generating an echo signal and wherein the measure of the reference signal power is obtained based on the echo signal.

12. A method of detecting a change of status for a device connected to a telephone line, comprising:

generating an echo signal;

obtaining a measure of an echo signal power of the echo signal;

obtaining a measure of an instantaneous signal power of the telephone line; and

detecting the status of the device connected to the telephone line based on whether the measured instantaneous signal power falls within a range that is set based on a value of the echo signal power.

13. The method of claim 12, wherein the status reflects whether the device connected to the telephone line is on-hook or off-hook.

14. The method of claim 12, wherein the instantaneous signal power is determined based on an alternating current.

15. A process for communicating over a communication medium, comprising:

monitoring a change in a signal power of the communication medium connecting a first communication device to a second communication device as compared to a reference signal power;

determining that there is a change in the signal power; and

detecting that the second communication device has changed status.

16. The process of claim 15, wherein the change in status results in the second communication device being off-hook.

17. The process of claim 15, wherein change in status results in the second communication device being on-hook.

18. A communication system, comprising:

a communication medium;

a first communication device coupled to the communication medium;

a second communication device coupled to the communication medium; and

a digital signal processor with an on-hook/off-hook detector in the first communication device, wherein the on-hook/off-hook detector includes a means for detecting a status of the second communication device by comparing a measure of an instantaneous power of the communication medium to a range that is based on a measure of a reference signal power of the communication medium.

19. The system of claim 18, wherein the status reflects whether the second communication device is on-hook or off-hook.

20. The system of claim 18, wherein the first communication device comprises a modem and the second communication device comprises a telephone handset.

21. The system of claim 18, further comprising:

an alternating current signal traveling on the communication medium.

22. A communication system, comprising:

a communication medium;

a first communication device coupled to the communication medium;

a second communication device coupled to the communication medium; and

a detector for detecting a change in status of the second communication device, wherein the change in status of the second communication includes a comparison of a measure of an instantaneous power of the communication medium to a range that is based on a measure of a reference signal power of the communication medium and reflects whether the second communication device is on-hook or off-hook.

23. A computer-readable storage medium storing a computer program executable by one or more computers, the computer program comprising computer instructions for:

obtaining a measure of a reference signal power;

obtaining a measure of an instantaneous signal power of the telephone line;

comparing the measured signal power and reference signal power; and

detecting a status of the device connected to the telephone line based on the comparison.

24. The computer-readable storage medium of claim 23, further comprising generating all echo signal and wherein the reference signal power is determined based on the echo signal.

25. A system, comprising:

a first communication device coupled to a communication medium;

a second communication device coupled to the communication medium;

a computer having a processor and coupled to the first communication device; and

a memory coupled to said processor and encoded with a first group of storage elements containing one or more samples of a reference signal of the communication medium, a second group of storage elements containing one or more samples of an instantaneous signal of the communication medium, and instructions for determining a status of the second communication device by comparing a second value from the second group of storage elements to a range that is based on a fit value from the first group of storage elements.

26. The system of claim 25, wherein the memory further comprises an operating system and an application.

27. The system of claim 25, wherein the processor is a central processing unit.

28. The system of claim 25, wherein the processor is a digital signal processor.

29. A computer-readable storage medium storing a computer program executable by one or more computers, the computer program comprising computer instructions for:

obtaining a measure of a reference signal power of a communication line;

monitoring a change in a measure of an instantaneous signal power as compared to the reference signal power; and

when it is determined that there is a change in the measure of the instantaneous signal power relative to an instantaneous status of a device, detecting that the device connected to the communication line has moved to a new status.

30. The computer-readable storage medium of claim 29, wherein the status reflects whether the device connected to the communication line is on-hook or off-hook.

31. The computer-readable storage medium of claim 29, wherein the signal power is determined as a function of an amplitude of an alternating current.