US5982874A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Transmission system with improved tone detection
Assignee: US Philips Corp
•
Filing: 1997-01-23
•
Granted: 1999-11-09
•
Expires: 2017-01-23
Abstract
Abstract In a transmission system a pair of signalling tone signals is transmitted by a transmitter (2) to a receiver (6) via a transmission channel (4). In the terminal (6) a tone detector is used to detect the presence of the pair of signalling tone signals. In order to improve the reliability of the tone detector in the case of differing strength of both tone signals, the decision on the presence of the pair of signalling tone signals is based on a combined strength measure which is determined by an adder (23). The combined strength measure is compared with a reference level TH 2 . In a further embodiment, also a check on the level of the individual tone signals is done with comparators (11) and (9), in order to specify the maximum strength difference tolerated.
Inventors
- 👤 Harm Braams
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 07:29
CPC Classifications
H; H04; H04Q; H04Q1/00; H04Q1/18; H04Q1/30; H04Q1/44; H04Q1/444; H04Q1/45; H04Q1/453
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
106 words
A transmission system comprising a terminal and a transmitter for transmitting simultaneously a plurality of tone signals via a transmission medium to the terminal, said terminal comprising: strength measuring means for deriving tone strength measures for said plurality of tone signals; and decision means for deciding on the presence of a plurality of tone signals if a combined strength measure of the plurality of tone signals exceeds a first threshold value, and individual strength measures of the tone signals involved exceed a second threshold value, said first threshold value being greater than the product of the number of tones in said plurality times the second threshold.
Claim 2
Dependent Claim
106 words
A transmission system comprising a terminal and a transmitter for transmitting simultaneously a plurality of tone signals via a transmission medium to the terminal, said terminal comprising: strength measuring means for deriving tone strength measures for said plurality of tone signals; and decision means for deciding on the presence of a plurality of tone signals if a combined strength measure of the plurality of tone signals exceeds a first threshold value, and individual strength measures of the tone signals involved exceed a second threshold value, said first threshold value being greater than the product of the number of tones in said plurality times the second threshold.
Claim 3
Dependent Claim
93 words
A terminal for receiving a simultaneously transmitted plurality of tone signals, said terminal comprising: strength measuring means for deriving tone strength measures for said plurality of tone signals; and decision means for deciding on the presence of a plurality of tone signals if a combined strength measure of the plurality of tone signals exceeds a first threshold value, and individual strength measures of the tone signals involved exceed a second threshold value, said first threshold value being greater than the product of the number of tones in said plurality times the second threshold.
Claim 4
Dependent Claim
93 words
A terminal for receiving a simultaneously transmitted plurality of tone signals, said terminal comprising: strength measuring means for deriving tone strength measures for said plurality of tone signals; and decision means for deciding on the presence of a plurality of tone signals if a combined strength measure of the plurality of tone signals exceeds a first threshold value, and individual strength measures of the tone signals involved exceed a second threshold value, said first threshold value being greater than the product of the number of tones in said plurality times the second threshold.
Claim 5
Dependent Claim
100 words
A tone detector for detecting the presence of a plurality of tone signals in an input signal, said tone detector comprising: strength measuring means for deriving tone strength measures for said plurality of tone signals; and decision means for deciding on the presence of a plurality of tone signals if a combined strength measure of the plurality of tone signals exceeds a first threshold value, and individual strength measures of the tone signals involved exceed a second threshold value, said first threshold value being greater than the product of the number of tones in said plurality times the second threshold.
Claim 6
Dependent Claim
100 words
A tone detector for detecting the presence of a plurality of tone signals in an input signal, said tone detector comprising: strength measuring means for deriving tone strength measures for said plurality of tone signals; and decision means for deciding on the presence of a plurality of tone signals if a combined strength measure of the plurality of tone signals exceeds a first threshold value, and individual strength measures of the tone signals involved exceed a second threshold value, said first threshold value being greater than the product of the number of tones in said plurality times the second threshold.
Claim 7
Independent Claim
90 words
A method for receiving a simultaneously transmitted plurality of tone signals, said method comprising: deriving a tone strength measure for each one of said plurality of tone signals; and deciding on the presence of a plurality of tone signals if a combined strength measure of the plurality of tone signals exceeds a first threshold value, and individual strength measures of the tone signals involved exceed a second threshold value, said first threshold value being greater than the product of the number of tones in said plurality times the second threshold.
Claim 8
Independent Claim
90 words
A method for receiving a simultaneously transmitted plurality of tone signals, said method comprising: deriving a tone strength measure for each one of said plurality of tone signals; and deciding on the presence of a plurality of tone signals if a combined strength measure of the plurality of tone signals exceeds a first threshold value, and individual strength measures of the tone signals involved exceed a second threshold value, said first threshold value being greater than the product of the number of tones in said plurality times the second threshold.
References Cited (Backward Citations)
US3882283A
Cited
US4085295A
Cited
US4395595A
Cited
US4868872A
Cited
US5119322A
Cited
US5214693A
Cited
EP0689366A1
Cited
US5649002A
Cited
US5619564A
Cited
US5694466A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2002-11-08 | 2003-05-10 | 2003-11-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-11-08 | 2007-05-10 | 2007-11-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-11-08 | 2011-05-10 | 2011-11-09 | $7700.00 | Window Closed / Lapsed |