US3733585A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Systems for detecting errors in a digital transmission channel
Assignee: Post Office
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Filing: 1971-06-07
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Granted: 1973-05-15
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Expires: 1991-06-07
Abstract
Abstract A system for detecting transmission errors arising in a digital transmission channel in which digits of a predetermined multidigit check signal not related to the information digits, are inserted successively after respective groups of information digits before transmission. After transmission the digits of the check signal are extracted and compared with the predetermined check signal, errors extracted indicating malfunctioning of the channel and loss of alignment of the check signal extraction. If the extraction of the check signal digits is out of alignment with the structure of the digital information after transmission, the rate of occurence of errors will be very high, and the detection of a very high error rate can be used to effect alignment of the check signal extraction with the structure of the digital information after transmission. A lower error rate indicates malfunctioning of the channel.
Inventors
- 👤 D Merlo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 18:53
CPC Classifications
H; H04; H04L; H04L25/00; H04L25/02; H04L25/05; H04L1/00; H04L1/004
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
258 words
A system for detecting malfunctioning of a digital transmission channel having a sending terminal and a receiving terminal, the sending terminal including an input circuit for receiving information digits of an original signal at a first pulse repetition frequency to be transmitted through the channel, first storage means connected to the input circuit for storing successive groups of the information digits, means for reading each stored group of information digits from the first storage means at a second pulse repetition frequency higher than the first so as to have gaps between the successive groups of information digits read from the first storage means, and means for inserting the digits of a predetermined multidigit check signal into the gaps so as to produce a digital signal of said second pulse repetition frequency for transmission through the channel, and the receiving terminal including means for separating the digits of the check signal from the information digits in the digital signal after transmission through the channel, second storage means for storing successive groups of the separated information digits, the groups having equal numbers of digits to the groups stored by the first storage means, means for reading the digits from the second storage means at the first pulse, repetition frequency to regenerate the original signal, means for comparing a representation of the predetermined check signal with the digits of the check signal derived from the digital signal by the separating means, and indicating means responsive to errors detected by the comparing means to indicate the occurrence of malfunctioning of the channel.
Claim 2
Independent Claim
258 words
A system for detecting malfunctioning of a digital transmission channel having a sending terminal and a receiving terminal, the sending terminal including an input circuit for receiving information digits of an original signal at a first pulse repetition frequency to be transmitted through the channel, first storage means connected to the input circuit for storing successive groups of the information digits, means for reading each stored group of information digits from the first storage means at a second pulse repetition frequency higher than the first so as to have gaps between the successive groups of information digits read from the first storage means, and means for inserting the digits of a predetermined multidigit check signal into the gaps so as to produce a digital signal of said second pulse repetition frequency for transmission through the channel, and the receiving terminal including means for separating the digits of the check signal from the information digits in the digital signal after transmission through the channel, second storage means for storing successive groups of the separated information digits, the groups having equal numbers of digits to the groups stored by the first storage means, means for reading the digits from the second storage means at the first pulse, repetition frequency to regenerate the original signal, means for comparing a representation of the predetermined check signal with the digits of the check signal derived from the digital signal by the separating means, and indicating means responsive to errors detected by the comparing means to indicate the occurrence of malfunctioning of the channel.
Claim 3
Dependent Claim
21 words
A system according to claim 1, in which the groups of information digits all consist of the same number of digits.
Claim 4
Dependent Claim
122 words
A system according to claim 2, in which the means for comparing the check signal derived from the digital signal after transmission through the channel with a representation of the predetermined check signals can produce a first signal if the rate of occurrence of errors detected exceeds a first threshold value and a second signal if the rate of occurrence of errors detected is below the first threshold value and above the second threshold value smaller than the first, the indicating means responding to the second signal, and the separating means responds to the first signal to alter the timing of its operation relative to the digital signal after transmission through the channel so as to tend to bring them into alignment.
Claim 5
Dependent Claim
91 words
A system according to claim 3, in which the first storage means includes two shifting registers, each having one more stage that there are digits in a group of information digits, means for entering groups of information digits into the registers alternately at the first pulse repetition frequency, and means for reading the digits from the registers in sequence at the second pulse repetition frequency, the inserting means entering the digits of the check signal in cyclic succession respectively at the ends of successive groups of information digits in the registers.
Claim 6
Dependent Claim
79 words
A system according to Claim 4, in which the second storage means includes two shifting registers having the same number of stages as there are digits in a group of information digits, means for applying groups of information digits from the separating means for storage in the registers alternatively at the second pulse repetition frequency, and means for reading out the contents of the shifting registers serially at the first pulse repetition frequency, alternately to reproduce the original signal.
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) | 1976-05-14 | 1976-11-13 | 1977-05-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-14 | 1980-11-13 | 1981-05-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-14 | 1984-11-13 | 1985-05-15 | $7700.00 | Window Closed / Lapsed |