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US4077004A
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Fault location system for a repeatered PCM transmission system
Assignee: NEC Corp
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Filing: 1976-03-11
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Granted: 1978-02-28
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Expires: 1996-03-11
Abstract
Abstract A PCM fault location system for repeaters and a code generator used therefor employ fault location codes generated on the basis of pseudo-random codes. The PCM fault location system transmits the codes through a repeatered transmission line, and the fault location codes including repeater transmission errors are received by the repeaters. A component of the repeater-designation frequency signal is extracted from the received fault location codes by means of a particular repeater-built-in fault locating circuit, and the thus extracted repeater-designation frequency component is received at a transmitting point of the fault location codes. The code generator employed at the transmitting point includes first means for obtaining codes which have an appropriate and sufficient difference in an average number of occurrences of digits "1" and "0" and are constructed using at least one series of pseudo-random codes, second means for controlling the state of the codes obtained by the first means in accordance with a repeater-designation frequency signal, and third means for performing differential code-conversion of the codes obtained by the second means.
Inventors
- 👤 Yoshiki Higo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 06:38
CPC Classifications
H; H04; H04B; H04B17/00; H04B17/40; H04B17/401; H04B17/406
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
289 words
A fault location system for a repeatered PCM transmission system comprising: a first means for transmitting through a repeatered transmission line fault location codes based on pseudo-random codes, said fault location codes being capable of code conversion into codes having their two states controllable in response to a repeater-designation frequency signal, one of said two states having the occurrence probability of the digit "1" equal to k sufficiently greater or smaller than 0.5 while the other of the two states has the occurrence probability of the digit "1" equal to (1-k), said first means including a first pseudo-random code generator having a frame repetition period T.sub.1 = (2.sup.m.sbsp.1 - 1).sup.-1 × f.sub.o .sup.-1 where m 1 is the number of stages of said first generator and f o is a clock frequency, a second code generator having a frame repetition rate which differs from T 1 , gate means for logically combining the outputs of said first and second code generators, complementing means for selectively controlling the change of the digits of the combined codes from said gate means to their complementary digits in response to the repeater-designation frequency signal, and conversion means for performing differential code-conversion of the codes obtained from said complementing means; a second means disposed at a designated repeater for receiving the fault location codes including repeater transmission errors; a third means for extracting a component of the repeater-designation frequency signal from the received fault location codes by means of a fault locating circuit built into the repeater and including an additional code-converter; and a fourth means for receiving said extracted repeater-designation frequency signal component at a transmitting point of the fault location codes, whereby the fault location for the repeatered transmission line is achieved.
Claim 2
Dependent Claim
289 words
A fault location system for a repeatered PCM transmission system comprising: a first means for transmitting through a repeatered transmission line fault location codes based on pseudo-random codes, said fault location codes being capable of code conversion into codes having their two states controllable in response to a repeater-designation frequency signal, one of said two states having the occurrence probability of the digit "1" equal to k sufficiently greater or smaller than 0.5 while the other of the two states has the occurrence probability of the digit "1" equal to (1-k), said first means including a first pseudo-random code generator having a frame repetition period T.sub.1 = (2.sup.m.sbsp.1 - 1).sup.-1 × f.sub.o .sup.-1 where m 1 is the number of stages of said first generator and f o is a clock frequency, a second code generator having a frame repetition rate which differs from T 1 , gate means for logically combining the outputs of said first and second code generators, complementing means for selectively controlling the change of the digits of the combined codes from said gate means to their complementary digits in response to the repeater-designation frequency signal, and conversion means for performing differential code-conversion of the codes obtained from said complementing means; a second means disposed at a designated repeater for receiving the fault location codes including repeater transmission errors; a third means for extracting a component of the repeater-designation frequency signal from the received fault location codes by means of a fault locating circuit built into the repeater and including an additional code-converter; and a fourth means for receiving said extracted repeater-designation frequency signal component at a transmitting point of the fault location codes, whereby the fault location for the repeatered transmission line is achieved.
Claim 3
Dependent Claim
49 words
A fault location system as recited in claim 1 wherein said second code generator is a pseudo-random code generator having a frame repetition period T.sub.2 = (2.sup.m.sbsp.2 -1).sup.-1 × f.sub.o.sup.-1 where m 2 is the number of stages of said second generator and m 1 ≠ m 2 .
Claim 4
Dependent Claim
24 words
A fault location system as recited in claim 1, wherein said second code generator is a clock generator having a frequency f o /2.
Claim 5
Dependent Claim
17 words
A fault location system as recited in claim 1, wherein said gate means is an AND gate.
Claim 6
Dependent Claim
17 words
A fault location system as recited in claim 1, wherein said gate means is an OR gate.
Claim 7
Dependent Claim
39 words
A fault location system as recited in claim 1, wherein said complementing means is an exclusive OR circuit connected to receive as one input the output of said gate means and as the other input said repeater-designation frequency signal.
Claim 8
Dependent Claim
53 words
A fault location system as recited in claim 1, wherein said conversion means comprises: a 1-bit delay connected to the output of said complementing means; and an exclusive OR circuit connected to receive as one input the output of said complementing means and as the other input the output of said 1-bit delay.
Claim 9
Dependent Claim
58 words
A fault location system as recited in claim 1, wherein said additional code converter in said third means comprises: a 1-bit delay connected to the output of said second means; and an exclusive OR circuit connected to receive as one input the output of said second means and as the other input the output of said 1-bit delay.
Claim 10
Dependent Claim
249 words
In a fault location system for a repeatered PCM transmission system including a first means for transmitting through a repeatered transmission line fault location codes, said fault location codes being capable of code conversion into codes having their two states controllable in response to a repeater-designation frequency, a second means disposed at a designated repeater for receiving the fault location codes including repeater transmission errors, a third means for extracting a component of the repeater-designation frequency signal from the received fault location codes by means of a fault locating circuit built into the repeater and including an additional code-converter, and a fourth means for receiving said extracted repeater-designation frequency signal component at a transmitting point of the fault location codes, the improvement wherein the fault location codes are based on pseudo-random codes and one of said two states of said codes having the occurrence probability of the digit "1" equal to k sufficiently greater or smaller than 0.5 while the other of the two states has the occurrence probability of the digit "1" equal to (1-k), said first means being a code generator comprising: fifth means for generating the codes having the occurrence probability of the digit "1" equal to k by means of at least one series of pseudo-random codes; sixth means for controlling the change of the digits of said codes to their complementary digits in response to the repeater-designation frequency signal; and seventh means for performing differential code-conversion of the codes obtained by the second means.
Claim 11
Dependent Claim
249 words
In a fault location system for a repeatered PCM transmission system including a first means for transmitting through a repeatered transmission line fault location codes, said fault location codes being capable of code conversion into codes having their two states controllable in response to a repeater-designation frequency, a second means disposed at a designated repeater for receiving the fault location codes including repeater transmission errors, a third means for extracting a component of the repeater-designation frequency signal from the received fault location codes by means of a fault locating circuit built into the repeater and including an additional code-converter, and a fourth means for receiving said extracted repeater-designation frequency signal component at a transmitting point of the fault location codes, the improvement wherein the fault location codes are based on pseudo-random codes and one of said two states of said codes having the occurrence probability of the digit "1" equal to k sufficiently greater or smaller than 0.5 while the other of the two states has the occurrence probability of the digit "1" equal to (1-k), said first means being a code generator comprising: fifth means for generating the codes having the occurrence probability of the digit "1" equal to k by means of at least one series of pseudo-random codes; sixth means for controlling the change of the digits of said codes to their complementary digits in response to the repeater-designation frequency signal; and seventh means for performing differential code-conversion of the codes obtained by the second means.
Claim 12
Dependent Claim
38 words
A code generator as recited in claim 9, wherein said sixth means is an exclusive OR circuit connected to receive as one input the output of said fifth means and as the other input said repeater-designation frequency signal.
Claim 13
Dependent Claim
52 words
A code generator as recited in claim 9, wherein said seventh means comprises: a 1-bit delay connected to the output of said sixth means; and an exclusive OR circuit connected to receive as one input the output of said sixth means and as the other input the output of said 1-bit delay.
Claim 14
Dependent Claim
79 words
A code generator as recited in claim 9, wherein said fifth means comprises: a first pseudo-random code generator having a frame repetition period T.sub.1 = (2.sup.m.sbsp.1 - 1).sup.-1 × f.sub.o.sup.-1 where m 1 is the number of stages of said first generator and f o is a clock frequency; a second code generator having a frame repetition rate which differs from T 1 ; and gate means for logically combining the outputs of said first and second code generators.
Claim 15
Dependent Claim
49 words
A code generator as recited in claim 12, wherein said second code generator is a pseudo-random code generator having a frame repetition period T.sub.2 = (2.sup.m.sbsp.2 - 1).sup.-1 × f.sub.o.sup.-1 where m 2 is the number of stages of said second generator and m 1 ≠ m 2 .
Claim 16
Dependent Claim
23 words
A code generator as recited in claim 12, wherein said second code generator is a clock generator having a frequency f o /2.
Claim 17
Dependent Claim
16 words
A code generator as recited in claim 12, wherein said gate means is an AND gate.
Claim 18
Dependent Claim
16 words
A code generator as recited in claim 12, wherein said gate means is an OR gate.
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) | 1981-02-27 | 1981-08-29 | 1982-02-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-02-27 | 1985-08-29 | 1986-02-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-02-27 | 1989-08-29 | 1990-02-28 | $7700.00 | Window Closed / Lapsed |