WO1996025825B1 - Method and structure for detecting a customer premises equipment alerting signal - Google Patents
Method and structure for detecting a customer premises equipment alerting signalInfo
- Publication number
- WO1996025825B1 WO1996025825B1 PCT/US1996/001526 US9601526W WO9625825B1 WO 1996025825 B1 WO1996025825 B1 WO 1996025825B1 US 9601526 W US9601526 W US 9601526W WO 9625825 B1 WO9625825 B1 WO 9625825B1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- frequency
- signal
- count
- detected signal
- frequency range
- Prior art date
Links
- 238000005070 sampling Methods 0.000 claims 11
- 238000001914 filtration Methods 0.000 claims 2
Abstract
A method and device for detecting a customer premises equipment alerting signal (CAS) tone in a telephone system which has both caller identification and call waiting. The present invention distinguishes between valid CAS tones transmitted by the telephone company central office and invalid CAS tones which are caused by music or a human voice. The present invention samples detected tone during a plurality of sample periods. The change of frequency, as well as the direction of frequency change, between successive sample periods is calculated. The number of transitions in the direction of frequency change are counted and used to determine whether the detected tone corresponds to a valid CAS tone or an invalid CAS tone.
Claims
AMENDED CLAIMS
[received by the International Bureau on 11 September 1996 (11.09.96); original claims 9 and 24 cancelled; original claims 7, 10, 11, 14, 22, 25 and 26 amended; new claims 29-34 added; remaining claims unchanged (15 pages)] maintaining a count of the pairs of successive valid sample periods; dividing the sum by the count to obtain an average change of frequency; using the average change of frequency to select a frequency tolerance which the detected signal must meet to find correspondence with the , predetermined signal.
5. The method of Claim 4, wherein the predetermined signal represents one frequency of a customer premises equipment alerting signal (CAS) tone.
6. The method of Claim 4, further comprising the step of providing a narrow frequency tolerance for a high average change of frequency, and a broad frequency tolerance for a low average change of frequency.
7. A method of determining whether a detected signal corresponds to a predetermined signal having first and second nominal frequencies, the method comprising the steps of: sampling the detected signal during a plurality of sample periods; during each sample period, determining whether the detected signal has a first frequency component within a first frequency range which includes the first nominal frequency; during each sample period, determining whether the detected signal has a second frequency component within a second frequency range which includes the second nominal frequency; maintaining a first count of the number of sample periods during which the first frequency component is within the first frequency range; maintaining a second count of the number of sample periods during which the second frequency
48
component is within the second frequency range; using the first and second counts to determine whether the detected signal corresponds to the predetermined signal; during each sample period, determining whether the first frequency component does not have a frequency within the first frequency range; during each sample period, determining whether the second frequency component does not have a frequency within the second frequency range; maintaining a third count of the number of sample periods during which the first frequency component is not within the first frequency range; maintaining a fourth count of the number of sample periods during which the second frequency component is not within the second frequency range; and using the third and fourth counts to determine whether the detected signal corresponds to the predetermined signal.
8. The method of Claim 7, further comprising the step of determining that the detected signal corresponds to the predetermined signal if the total of the first and second counts exceeds a preselected number.
10. The method of Claim 7, further comprising the step of determining that the detected signal corresponds to the predetermined signal if the total of the first and second counts exceeds a first preselected number and either the third count or the fourth count exceeds a second preselected number.
49
11. A method of determining whether a detected signal corresponds to a predetermined signal having first and second nominal frequencies, the method comprising the steps of: sampling the detected signal during a plurality of sample periods; during each sample period, determining whether the detected signal has a first frequency component within a first frequency range which includes the first nominal frequency; during each sample period, determining whether the detected signal has a second frequency component within a second frequency range which includes the second nominal frequency; maintaining a first count of the number of sample periods during which the first frequency component is within the first frequency range; maintaining a second count of the number of sample periods during which the second frequency component is within the second frequency range; using the first and second counts to determine whether the detected signal corresponds to the predetermined signal; for each sample period, determining whether the first frequency component falls within a third frequency range which is wider than the first frequency range; maintaining a third count of the number of times the first frequency component falls within the third frequency range; for each sample period, determining whether the second frequency component falls within a fourth frequency range which is wider than the second frequency range;
50
maintaining a fourth count of the number of times the second frequency component falls within the fourth frequency range; and determining that the detected signal does not correspond to the predetermined signal if either the third count or the fourth count exceeds a preselected count.
12. A method of determining whether a detected signal corresponds to a predetermined signal having first and second nominal frequencies, the method comprising the steps of: sampling a first frequency component of the detected signal to determine the time required for the first frequency component to complete a first number of cycles; sampling a second frequency component of the detected signal to determine the time required for the second frequency component to complete a second number of cycles; selecting the first number of cycles and the second number of cycles such that the time required for the first frequency component to complete the first number of cycles is approximately equal to the time required for the second frequency component to complete the second number of cycles when the detected signal corresponds to the predetermined signal.
13. The method of Claim 12, wherein the first frequency component has a frequency of approximately 2130 hz and the second frequency component has a frequency of approximately 2750 hz.
14. A circuit for determining when a detected analog tone corresponds to a predetermined analog tone
51
*»■»>SHEET ARTICLE*
having a first nominal frequency and a second nominal frequency, the circuit comprising: a first bandpass filter having an input terminal connected to receive the detected tone, wherein the first bandpass filter passes a first analog signal at frequencies approximately equal to the first nominal frequency; a second bandpass filter having an input terminal connected to receive the detected tone, wherein the second bandpass filter passes a second analog signal at frequencies approximately equal to the second nominal frequency; a first threshold limiter circuit having an input terminal connected to an output terminal of the first bandpass filter, wherein the first threshold limiter circuit generates a first digital signal in response to the first analog signal, the first digital signal having a frequency equal to the frequency of the first analog signal; a second threshold limiter circuit having an input terminal connected to an output terminal of the second bandpass filter, wherein the second threshold limiter circuit generates a second digital signal in response to the second analog signal, the second digital signal having a frequency equal to the frequency of the second analog signal; a microprocessor having input terminals connected to the first and second threshold limiter circuits, wherein the microprocessor monitors the first and second digital signals to determine a first period required for the first digital signal to complete a first predetermined number of cycles, and a second period required for the second digital signal to complete a second
52
*«»© SHEET (ARTICLE 19)
predetermined number of cycles, and wherein the microprocessor further determines from the first and second periods whether the detected signal corresponds to the predetermined signal.
15. The circuit of Claim 14, further comprising a dual tone multi-frequency (DTMF) generator connected to the microprocessor, wherein the microprocessor causes the DTMF generator to generate an acknowledge signal when the microprocessor determines that the detected signal corresponds to the predetermined signal.
16. A circuit for determining whether a detected signal corresponds to a predetermined signal, the circuit comprising: means for sampling the frequency of the detected signal during a plurality of sample periods; means for calculating the change of frequency between successive sample periods; means for determining a direction of frequency change between successive sample periods; means for counting the number of transitions in the direction of frequency change; and means for using the number of transitions to determine whether the detected signal corresponds to the predetermined signal.
17. The circuit of Claim 16, wherein the predetermined signal represents one frequency of a customer premises equipment alerting signal (CAS) tone.
18. The circuit of Claim 16, further comprising means for determining that the detected signal
53
AMENDEDSHSET(AKnCL£19)
corresponds to the predetermined signal if the number of transitions exceeds a preselected number.
19. A circuit for determining whether a detected signal corresponds to a predetermined signal, the circuit comprising: means for sampling the frequency of the detected signal during a plurality of sample periods; means for determining whether the sampled frequency represents a valid sample period; means for calculating the change of frequency between successive valid sample periods; means for maintaining a sum of each calculated change of frequency; means for maintaining a count of the pairs of successive valid sample periods; means for dividing the sum by the count to obtain an average change of frequency; and means for using the average change of frequency to select a frequency tolerance which the detected signal must meet to find correspondence with the predetermined signal.
20. The circuit of Claim 19, wherein the predetermined signal represents one frequency of a customer premises equipment alerting signal (CAS) tone.
21. The circuit of Claim 19, further comprising means for providing a narrow frequency tolerance for a high average change of frequency, and a broad frequency tolerance for a low average change of frequency.
22. A circuit for determining whether a detected signal corresponds to a predetermined signal having
54
first and second nominal frequencies, the circuit comprising: means for sampling the detected signal during a plurality of sample periods; means for determining during each sample period whether the detected signal has a first frequency component within a first frequency range which includes the first nominal frequency; means for determining during each sample period whether the detected signal has a second frequency component within a second frequency range which includes the second nominal frequency; means for maintaining a first count of the number of sample periods during which the first frequency component is within the first frequency range; means for maintaining a second count of the number of sample periods during which the second frequency component is within the second frequency range; means for using the first and second counts to determine whether the detected signal corresponds to the predetermined signal; means for determining during each sample period whether the first frequency component does not have a frequency within the first frequency range; means for determining during each sample period whether the second frequency component does not have a frequency within the second frequency range; means for maintaining a third count of the number of sample periods during which the first frequency component is not within the first frequency range;
55
means for maintaining a fourth count of the number of sample periods during which the second frequency component is not within the second frequency range; and means for using the third and fourth counts to determine whether the detected signal corresponds to the predetermined signal.
23. The circuit of Claim 22, further comprising means for determining that the detected signal corresponds to the predetermined signal if the total of the first and second counts exceeds a preselected number.
25. The circuit of Claim 22, further comprising means for determining that the detected signal corresponds to the predetermined signal if the total of the first and second counts exceeds a first preselected number and either the third count or the fourth count exceeds a second preselected number.
26. A circuit for determining whether a detected signal corresponds to a predetermined signal having first and second nominal frequencies, the circuit comprising: means for sampling the detected signal during a plurality of sample periods; means for determining during each sample period whether the detected signal has a first frequency component within a first frequency range which includes the first nominal frequency; means for determining during each sample period whether the detected signal has a second frequency component within a second frequency range which includes the second nominal frequency;
56
means for maintaining a first count of the number of sample periods during which the first frequency component is within the first frequency range; means for maintaining a second count of the number of sample periods during which the second frequency component is within the second frequency range; means for using the first and second counts to determine whether the detected signal corresponds to the predetermined signal; means for determining for each sample period whether the first frequency component falls within a third frequency range which is wider than the first frequency range; means for maintaining a third count of the number of times the first frequency component falls within the third frequency range; means for determining for each sample period whether the second frequency component falls within a fourth frequency range which is wider than the second frequency range; means for maintaining a fourth count of the number of times the second frequency component falls within the fourth frequency range; and means for determining that the detected signal does not correspond to the predetermined signal if either the third count or the fourth count exceeds a preselected count.
27. A circuit for determining whether a detected signal corresponds to a predetermined signal having first and second nominal frequencies, the circuit comprising: means for sampling a first frequency component of the detected signal to determine the
57
time required for the first frequency component to complete a first number of cycles; means for sampling a second frequency component of the detected signal to determine the time required for the second frequency component to complete a second number of cycles; and means for selecting the first number of cycles and the second number of cycles such that the time required for the first frequency component to complete the first number of cycles is approximately equal to the time required for the second frequency component to complete the second number of cycles when the detected signal corresponds to the predetermined signal.
28. The circuit of Claim 27, wherein the first frequency component has a frequency of approximately 2130 hz and the second frequency component has a frequency of approximately 2750 hz.
29. A method of determining whether a detected signal corresponds to a predetermined signal having first and second nominal frequencies, the method comprising the steps of: filtering the detected signal with a first bandpass filter which passes a first analog component of the detected signal having a frequency approximately equal to the first nominal frequency; filtering the detected signal with a second bandpass filter which passes a second analog component of the detected signal having a frequency approximately equal to the second nominal frequency; converting the first analog component into a first digital signal; converting the second analog component into a second digital signal;
58
monitoring the first digital signal to determine a first period required for the first digital signal to complete a first predetermined number of cycles; monitoring the second digital signal to determine a second period required for the second digital signal to complete a second predetermined number of cycles; determining whether the first period is representative of a signal with a frequency within a first frequency range which includes the first nominal frequency; determining whether the second period is representative of a signal with a frequency within a second frequency range which includes the second nominal frequency; maintaining a first count of the number of times that the first period is representative of a signal with a frequency within the first frequency range; maintaining a second count of the number of times that the second period is representative of a signal with a frequency within the second frequency range; and using the first and second counts to determine whether the detected signal corresponds to the predetermined signal.
30. The method of Claim 29, further comprising the step of determining that the detected signal corresponds to the predetermined signal if the total of the first and second counts exceeds a preselected number.
31. The method of Claim 29, further comprising the steps of: determining whether the first period is not representative of a signal having a frequency within the first frequency range;
59
determining whether the second period is not representative of a signal having a frequency within the second frequency range; maintaining a third count of the number of times which the first period is not representative of a signal having a frequency within the first frequency range; maintaining a fourth count of the number of times which the second period is not representative of a signal having a frequency within the second frequency range; and using the third and fourth counts to determine whether the detected signal corresponds to the predetermined signal.
32. The method of Claim 31, further comprising the step of determining that the detected signal corresponds to the predetermined signal if the total of the first and second counts exceeds a first preselected number and either the third count or the fourth count exceeds a second preselected number.
33. The method of Claim 29, further comprising the steps of: determining whether the first period is representative of a signal having a frequency which falls within a third frequency range which is wider than the first frequency range; maintaining a third count of the number of times the first period is representative of a signal having a frequency which falls within the third frequency range; determining whether the second period is representative of a signal having a frequency
60
which falls within a fourth frequency range which is wider than the second frequency range; maintaining a fourth count of the number of times the second period is representative of a signal having a frequency which falls within the fourth frequency range; determining that the detected signal does not correspond to the predetermined signal if either the third count or the fourth count exceeds a preselected count.
34. A circuit for determining whether a detected signal corresponds to a predetermined signal having first and second nominal frequencies, the circuit comprising: a first bandpass filter which passes a first analog component of the detected signal having a frequency approximately equal to the first nominal frequency; a second bandpass filter which passes a second analog component of the detected signal having a frequency approximately equal to the second nominal frequency; means for converting the first analog component into a first digital signal; means for converting the second analog component into a second digital signal; means for monitoring the first digital signal to determine a first period required for the first digital signal to complete a first predetermined number of cycles; means for monitoring the second digital signal to determine a second period required for the second digital signal to complete a second predetermined number of cycles;
61
means for determining whether the first period is representative of a signal with a frequency within a first frequency range which includes the first nominal frequency; means for determining whether the second period is representative of a signal with a frequency within a second frequency range which includes the second nominal frequency; means for maintaining a first count of the number of times that the first period is representative of a signal with a frequency within the first frequency range; means for maintaining a second count of the number of times that the second period is representative of a signal with a frequency within the second frequency range; and means for determining whether the detected signal corresponds to the predetermined signal in response to the first and second counts.
62
AMEN0E&SHEET(ARTICLE $
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP96906285A EP0809914A1 (en) | 1995-02-13 | 1996-02-13 | Method and structure for detecting a customer premises equipment alerting signal |
| JP8524988A JPH11504170A (en) | 1995-02-13 | 1996-02-13 | Apparatus and structure for detecting in-home apparatus notification signal |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US38766695A | 1995-02-13 | 1995-02-13 | |
| US387,666 | 1995-02-13 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| WO1996025825A1 WO1996025825A1 (en) | 1996-08-22 |
| WO1996025825B1 true WO1996025825B1 (en) | 1996-10-24 |
Family
ID=23530875
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/US1996/001526 WO1996025825A1 (en) | 1995-02-13 | 1996-02-13 | Method and structure for detecting a customer premises equipment alerting signal |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US5862212A (en) |
| EP (1) | EP0809914A1 (en) |
| JP (1) | JPH11504170A (en) |
| WO (1) | WO1996025825A1 (en) |
Families Citing this family (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5844977A (en) * | 1997-03-27 | 1998-12-01 | Northern Telecom Limited | On-hook customer premise equipment alerting signal detection |
| US6101252A (en) * | 1997-03-31 | 2000-08-08 | Nortel Networks Corporation | CAS tone disguising method and apparatus |
| US6393124B1 (en) * | 1997-04-15 | 2002-05-21 | Virata Corporation | CPE alert signal tone detector |
| FR2775145B1 (en) * | 1998-02-13 | 2000-04-28 | Matra Communication | METHOD AND DEVICE FOR DETECTING AN ALERT SIGNAL ON A TELEPHONE LINE |
| GB2335823B (en) * | 1998-03-26 | 2003-03-12 | Inventec Corp | method of improving the cas tone signal detection of a telephone, and the apparatus therefor |
| US6269160B1 (en) * | 1998-04-20 | 2001-07-31 | Advanced Micro Devices, Inc. | Communications device including an improved CPE alerting signal (CAS) detection system |
| US6480589B1 (en) | 1998-07-14 | 2002-11-12 | Samsung Electronics Co., Ltd. | CPE alert signal detector and caller identification detector using peak detection |
| CN1085457C (en) * | 1998-07-16 | 2002-05-22 | 英业达股份有限公司 | Improved audio alarm signal detection method and device for front-end user equipment |
| US6665350B1 (en) * | 1998-09-25 | 2003-12-16 | Legerity, Inc. | Method and system for improved analog signal detection |
| US6295347B1 (en) * | 1999-04-30 | 2001-09-25 | Fanstel Systems, Llc | Apparatus and method for subscriber loop powered calling identity delivery on call waiting |
| US20060121938A1 (en) * | 1999-08-12 | 2006-06-08 | Hawkins Jeffrey C | Integrated handheld computing and telephony device |
| US7558824B2 (en) * | 2000-06-15 | 2009-07-07 | At&T Intellectual Property I, L.P. | Electronic mail (Email) Internet appliance methods and systems |
| US6850610B1 (en) | 2001-04-17 | 2005-02-01 | Bellsouth Intellectual Property Corporation | Telecommunications device and method for providing information during a call waiting condition |
| US7023981B2 (en) * | 2002-01-08 | 2006-04-04 | Freescale Semiconductor, Inc. | Method and apparatus for signal detection |
| EP1339241B1 (en) * | 2002-02-21 | 2005-11-16 | Winbond Electronics Corporation | Dual hysteresis signal detection circuit |
| US7020448B2 (en) * | 2003-03-07 | 2006-03-28 | Conwise Technology Corporation Ltd. | Method for detecting a tone signal through digital signal processing |
| US7088985B2 (en) * | 2003-11-18 | 2006-08-08 | Skyworks Solutions, Inc. | Low-noise filter for a wireless receiver |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4395595A (en) * | 1980-04-23 | 1983-07-26 | Nippon Electric Co., Ltd. | Digital pushbutton signalling receiver |
| CA1216380A (en) * | 1984-11-09 | 1987-01-06 | Gordon J. Reesor | Digital tone detector |
| US5109409A (en) * | 1989-12-15 | 1992-04-28 | Alcatel Na, Inc. | Apparatus and method to detect telephony signaling states |
| JP2547891B2 (en) * | 1990-06-28 | 1996-10-23 | シャープ株式会社 | Signal detector |
| US5251256A (en) * | 1991-07-15 | 1993-10-05 | Rolm Company | Independent hysteresis apparatus for tone detection |
| EP0566928A3 (en) * | 1992-04-24 | 1994-08-10 | Alcatel Australia | Tone detection method for telephone subset |
| US5353342A (en) * | 1992-12-08 | 1994-10-04 | Bell Communications Research, Inc. | Adaptive multitone signaling method |
-
1996
- 1996-02-13 JP JP8524988A patent/JPH11504170A/en active Pending
- 1996-02-13 WO PCT/US1996/001526 patent/WO1996025825A1/en not_active Application Discontinuation
- 1996-02-13 EP EP96906285A patent/EP0809914A1/en not_active Withdrawn
- 1996-08-29 US US08/705,911 patent/US5862212A/en not_active Expired - Lifetime
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| WO1996025825B1 (en) | Method and structure for detecting a customer premises equipment alerting signal | |
| US5442694A (en) | Ring tone detection for a telephone system | |
| US4540855A (en) | Detecting signals within a passband on a telephone line | |
| CA1289281C (en) | Digital dtmf tone detector | |
| US5319702A (en) | Method and apparatus for detecting and responding to hook flash events occurring on a remote telephone | |
| EP0622964B1 (en) | Voice activity detection method and apparatus using the same | |
| EP0153125A2 (en) | Tone detection apparatus for use in a telephone system | |
| US5862212A (en) | Method and structure for detecting a customer premises equipment alerting signal | |
| US5479501A (en) | Far-end disconnect detector for telephony systems | |
| US5450485A (en) | Detecting whether a telephone line has been disconnected | |
| US6067353A (en) | Method and apparatus for detecting a call waiting signal on a telephone line connected to a modem | |
| JP2851974B2 (en) | DTMF signal judgment circuit | |
| CA1238128A (en) | Digital multifrequency signal receiver | |
| US5426693A (en) | Apparatus and method for automatically blocking the transmission of identifying information concerning a telephone calling party | |
| US6229889B1 (en) | Robust signaling tone frequency measurement | |
| US5995557A (en) | Tone detection with aliasing bandpass filters | |
| US4276447A (en) | Signal processing apparatus for subscriber circuits | |
| EP0373887B1 (en) | Telephone ringing detector | |
| US5343420A (en) | Signal discrimination circuit | |
| US6836181B2 (en) | FSK demodulation system | |
| US4022989A (en) | Telephone receiver-off-hook-and-in-use detector | |
| US6665350B1 (en) | Method and system for improved analog signal detection | |
| US5533092A (en) | Order wire in telephone communication system | |
| US3993875A (en) | Tone receiver | |
| JP2859024B2 (en) | DTMF receiver with malfunction prevention circuit |