US3873774A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Equipment for the detection and extraction of a telegraph channel
Assignee: Alcatel CIT SA
•
Filing: 1973-06-27
•
Granted: 1975-03-25
•
Expires: 1993-06-27
Abstract
Abstract Equipment for detecting, on the basis of two consecutive tests, the existence of one or several telegraph channels on one or several telephone channels of a frequency multiplex system. The first test, which is relatively fast, is based on the presence of a predetermined frequency in the channel. The second test, which is slower in operation, is based on the amplitude identity of two moments, formed by alternate transitions in the transmission signal.
Inventors
- 👤 Alain Cabet
- 👤 Gaston Pinier
- 👤 Guy Eloy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 05:52
CPC Classifications
H; H04; H04L; H04L5/00; H04L5/02; H04L5/06; H04J; H04J1/00; H04J1/02; H04J1/14
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
182 words
A system for detecting and extracting a telegraph transmission from a frequency multiplex telephone transmission system including a plurality of telephone channels, comprising analyzer means for analyzing said telephone channels including scanning means for scanning said telephone channels and means for transposing the transmission on each telephone channel susceptible of carrying a telegraph transmission into a fixed channel Fo + OR - 30 Hz, first telegraphy detector means connected to the output of said analyzer means for generating a signal upon detecting one of the sidebands of said fixed channel, means for stopping said scanning means in response to said signal from said first telegraphy detector means, second telegraphy detector means for detecting a polarity characteristic of a transmission which identifies it as a telegraph transmission, and means responsive to said signal from said first telegraphy detector means for connecting said second telegraphy detector means to the output of said analyzer means, said second telegraphy detector means including means for overriding said stopping means upon failure to detect said polarity characteristic of the channel, thereby permitting said scanning means to resume operation.
Claim 2
Independent Claim
182 words
A system for detecting and extracting a telegraph transmission from a frequency multiplex telephone transmission system including a plurality of telephone channels, comprising analyzer means for analyzing said telephone channels including scanning means for scanning said telephone channels and means for transposing the transmission on each telephone channel susceptible of carrying a telegraph transmission into a fixed channel Fo + OR - 30 Hz, first telegraphy detector means connected to the output of said analyzer means for generating a signal upon detecting one of the sidebands of said fixed channel, means for stopping said scanning means in response to said signal from said first telegraphy detector means, second telegraphy detector means for detecting a polarity characteristic of a transmission which identifies it as a telegraph transmission, and means responsive to said signal from said first telegraphy detector means for connecting said second telegraphy detector means to the output of said analyzer means, said second telegraphy detector means including means for overriding said stopping means upon failure to detect said polarity characteristic of the channel, thereby permitting said scanning means to resume operation.
Claim 3
Dependent Claim
89 words
A system according to claim 1, characterized in that said first telegraphy detector means comprises a first branch receiving the output of said analyzer means and containing a bandpass filter centered on Fo + 30 Hz, a threshold detector and a peak limiter in series, a second branch receiving the output of said analyzer means and containing a band-pass filter centered on Fo-30 Hz, a threshold detector and a peak limiter in series, and an EXCLUSIVE OR circuit connected to receive the outputs of said first and second branches.
Claim 4
Dependent Claim
154 words
A system according to claim 1, characterized in that said second telegraphy detector means contains a frequency discriminator conNected to a telegraphic transition detector, a delay circuit connected to the output of said transition detector, a modulo 4 counter connected to the output of said delay circuit, a first analog memory selectively connected to the output of said frequency discriminator under the control of said counter at the time of a first counting state thereof, a second analog memory selectively connected to the output of said frequency discriminator under the control of the said counter at the time of a second counting state thereof, a comparator connected to the outputs of said first and second analog memories, and threshold detector means connected to the output of said comparator for applying the output signal of said frequency discriminator to a telegraphic operation member if the output of said comparator is lower than a reference value.
Claim 5
Dependent Claim
64 words
A system according to claim 3, characterized in that the second telegraphy detector means also contains timing means including a monostable flip-flop connected to the output of said transition detector for generating a signal for the end of the measuring operation, if said monostable flip-flop has remained set for a predetermined period of time without being reset by the output of the transition detector.
Claim 6
Dependent Claim
22 words
A system as defined in claim 4 wherein said first and second counting states of said counter are separated by two counts.
Claim 7
Dependent Claim
31 words
A system as defined in claim 5 wherein said first and second counting states of said counter are the first and third counts of the delay output of said transition detector.
Claim 8
Dependent Claim
89 words
A system according to claim 4, characterized in that said first telegraphy detector means comprises a first branch receiving the output of said analyzer means and containing a band-pass filter centered on Fo + 30 Hz, a threshold detector and a peak limiter in series, a second branch receiving the output of said analyzer means and containing a band-pass filter centered on Fo-30 Hz, a threshold detector and a peak limiter in series, and an EXCLUSIVE OR circuit connected to receive the outputs of said first and second branches.
Claim 9
Independent Claim
98 words
A method for detecting a telegraphic transmission formed of a series of signal transitions on one or more of a plurality of telephone channels in a frequency multiplex telephone system comprising: transposing the transmission on each channel susceptible of carrying a telegraphic transmission into a fixed channel of frequency Fo + or - 30 Hz, scanning said transposed channels in sequence, detecting one of the sidebands of said fixed channel of each channel scanned, and detecting in each channel where one of said sidebands is detected a repetition of the same polarity in alternate transitions in the transmission.
Claim 10
Independent Claim
98 words
A method for detecting a telegraphic transmission formed of a series of signal transitions on one or more of a plurality of telephone channels in a frequency multiplex telephone system comprising: transposing the transmission on each channel susceptible of carrying a telegraphic transmission into a fixed channel of frequency Fo + or - 30 Hz, scanning said transposed channels in sequence, detecting one of the sidebands of said fixed channel of each channel scanned, and detecting in each channel where one of said sidebands is detected a repetition of the same polarity in alternate transitions in the transmission.
Claim 11
Dependent Claim
46 words
A method as defined in claim 8, further including the steps of stopping said scanning in response to detecting one of said sidebands in the scanned channel and continuing to stop said scanning in response to detecting said repetition of the same polarity in alternate transitions.
Claim 12
Dependent Claim
30 words
A method as defined in claim 9, further including the step of resuming said scanning in response to failure to detect said repetition of the same polarity in alternate transitions.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-03-24 | 1978-09-23 | 1979-03-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-24 | 1982-09-23 | 1983-03-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-24 | 1986-09-23 | 1987-03-25 | $7700.00 | Window Closed / Lapsed |