EP0088564A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Improvements relating to communication over noisy lines
Assignee: QED Intellectual Property Ltd
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Filing: 1983-02-25
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Granted: —
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Expires: 2003-02-25
Abstract
Abstract A line network communication system (Figure 3) transmits coded data signals on a base band carrier signal and includes a receiver capable of recovering the coded data signals from transmitted signals. The receiver operates in a search mode initially, in which a series of data signals received at (13) is compared, at different relative phases, with a series of coded reference signals using an arrangement of shift registers (12,15) and an exclusive OR gate (11). The reference signals are generated by a coder (1) under the command of a central control unit (3). The control unit monitors the results of comparisons and varies, by means of a shifter circuit (6), the relative phase of compared signals until at least one comparison indicates a degree of correlation exceeding a threshold value. The control unit then operates, in a tracking mode, to verify that said degree of correlation is maintained for a preset number of subsequent comparisons and in dependence on a successful verification enters a locking mode. The control unit maintains a selected phase difference between compared series while the degree of correlation exceeding said threshold value exists.
Inventors
- 👤 Duncan George Derwent Clark
- 👤 Ian David Kimber
- 👤 Roderick Gerald May
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-25 09:17
CPC Classifications
H; H04; H04L; H04L23/00; H04L23/02; H04B; H04B1/00; H04B1/69; H04B1/707; H04B1/7073; H04B1/7075; H04B1/70755; H04B2001/70706
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
142 words
A line network communication system including a transmitter means capable of transmitting a series of coded data signals on a baseband carrier signal and receiver means capable of receiving a transmitted signal and recovering therefrom said coded data signals, the receiver being arranged to operate in a search mode to compare a series of received data signal with a series of coded reference signals at different relative phases until at least one comparison signal generated as a result of said comparisons indicates a degree of correlation exceiding a threshold value, a tracking mode to verify that said degree of correlation exists for a preset time interval and, in dependence on a successful verification in the tracking mode, a locking mode to maintain a selected phase difference between the compared series while said degree of correlation exists permitting recovery of the coded signals.
Claim 2
Dependent Claim
142 words
A line network communication system including a transmitter means capable of transmitting a series of coded data signals on a baseband carrier signal and receiver means capable of receiving a transmitted signal and recovering therefrom said coded data signals, the receiver being arranged to operate in a search mode to compare a series of received data signal with a series of coded reference signals at different relative phases until at least one comparison signal generated as a result of said comparisons indicates a degree of correlation exceiding a threshold value, a tracking mode to verify that said degree of correlation exists for a preset time interval and, in dependence on a successful verification in the tracking mode, a locking mode to maintain a selected phase difference between the compared series while said degree of correlation exists permitting recovery of the coded signals.
Claim 3
Dependent Claim
194 words
A line network communication system according to Claim 1 wherein said receiver means comprises comparison means for comparing, in said search mode, a series of received data signals with a series of coded reference signals at a number of different relative phases thereby to generate a corresponding number of comparison signals forming a set, means (6) capable of varying the relative phases of compared signals until at least one comparison signal in a set indicates a degree of correlation exceeding said threshold value, means capable of verifying, in said tracking mode, that having so varied the relative phases of compared signals at least one comparison signal in each of a plurality of different sets, generated by comparing a corresponding plurality of series of successively received signals with said series of coded reference signals, represents a degree of correlation exceeding said threshold value, and means (3) for further varying, in a locking mode and in dependence on a successful verification in the tracking mode, the relative phases of the compared series so that the comparison signal in successive sets representing the maximum degree of correlation, occurs when the compared series have said selected phase difference.
Claim 4
Dependent Claim
104 words
3-. A line network communication system according to Claim 2 wherein said comparison means comprises means (1) for generating, at a fixed rate, successive signals in said series of coded reference signals, means (7) for advancing, at said fixed rate, received data signals through a first storage means (15), second storage means (12) for receiving selected ones of signals prevailing in the first storage means, means (11) for comparing, in turn, the signals in said second storage means, with a respective coded reference signal and means (17) for combining the results of said comparisons so as to generate said corresponding number of comparison signals.
Claim 5
Dependent Claim
46 words
A line network communication system according to Claim 2 or Claim 3 including means (6) capable of influencing generation of said series of coded reference signals to change by an adjustable amount, the relative phases of said series of coded reference signals and received data signals.
Claim 6
Dependent Claim
104 words
A line network communication system according to Claim 2 wherein the comparison means comprises storage means (48, 49) arranged to receive at respective storage locations a number, equal to said corresponding number, of reference signals, means (42) for varying periodically, in accordance with a cyclical operation, the positions of said reference signals in the storage means, means (41) for comparing each reference signal, in turn, as the positions of the reference signals are varied, with a data signal, and means (43) for generating each said comparison signal in dependence on comparisons of a respective reference signal with successively received data signals forming said series.
Claim 7
Dependent Claim
67 words
A line network communication system according to any one of Claims 1 to 5 including means capable of monitoring, in the locking mode, the number of times within a preset time interval the comparison signal indicates a degree of correlation exceeding said threshold value, and means for causing said receiver means to operate in the search mode if said number of times is below a predetermined value.
Claim 8
Dependent Claim
29 words
A line network communication system according to any preceding claim arranged to retransmit received data in dependence on the presence of a repeat instruction in the recovered data signals.
Claim 9
Dependent Claim
25 words
A line network communication receiver comprising receiver means as used in a line network communication system according to any one of Claims 1 to 7.
References Cited (Backward Citations)
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