US4674087A
Expired / Lapsed
US
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Asynchronous signaling for digital communication channel
Assignee: British Columbia Telephone Co
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Filing: 1985-07-30
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Granted: 1987-06-16
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Expires: 2005-07-30
Abstract
Abstract A selected one of a plurality of unique N-bit digital code words that corresponds to an associated signaling message is continuously transmitted until it is desired to transmit a different signaling message. Decoder logic in the receiver looks at a new group of N-signaling bits during each signaling bit interval, without reference to the start of a transmitted code word, and makes a decision during each signaling bit interval as to what signaling message was transmitted. In this manner a keep-alive signal is virtually continuously provided in the receiver. Latch circuitry repeats the previous decision from the decoder logic when the current group of N-signaling bits does not correspond to one of the unique code words or an ordered permutation thereof. In an alternate embodiment a memory circuit requires that the decoder logic repeat the same decision as to what signaling message was transmitted for P consecutive groups of N-signaling bits (i.e., for P consecutive signaling bit intervals) before the latch circuit will indicate that a different signaling message is being transmitted.
Inventors
- 👤 Michael J. Green
- 👤 James B. McKay
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 12:26
CPC Classifications
H; H04; H04J; H04J3/00; H04J3/02; H04J3/12; H04J3/06
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
320 words
An asynchronous signaling method in a digital communication system including transmitting and receiving equipment for multiplexing and demultiplexing digital traffic information signals and digital signaling information signals comprising the steps of: defining a plurality of signaling states S1-SM first selecting a plurality of M unique N-bit primary digital code words Sm1 each defining a different one of the signal states S1-SM and each having N-1 additional ordered permutations of the order of the bits thereof, said additional ordered permutations being designated secondary code words; second selecting a particular state Ss for transmission; serially producing bits B1-BN of one of the primary and secondary code words for the selected signaling state Ss at a signaling clock rate; multiplexing signaling bits with traffic information bits at signaling time slots in a bit stream, said signaling time slots occurring at the signaling clock rate; transmitting the multiplexed bit stream to receiver equipment; extracting a signaling clock signal from the multiplexed bit stream in the receiver equipment; demultiplexing the multiplexed bit stream in the receiver equipment for producing a stream of serial signaling bits; determining whether the most recently received N signaling bits in the serial signaling bit stream match with one of the N-bit patterns of the primary and secondary code words during each signaling bit interval; producing during each signaling bit interval a first indication that the selected and transmitted signaling state is a prescribed signaling state Sp when there is a match between the most recently received N signaling bits of the serial signaling bit stream and one of the N-bit primary and secondary code words associated with the prescribed signaling state Sp; and producing during each signaling bit interval a second indication that is the same as the preceding first indication when there is not a match between the most recently received N signaling bits of the serial signaling bit stream and any of the primary and secondary code words.
Claim 2
Dependent Claim
320 words
An asynchronous signaling method in a digital communication system including transmitting and receiving equipment for multiplexing and demultiplexing digital traffic information signals and digital signaling information signals comprising the steps of: defining a plurality of signaling states S1-SM first selecting a plurality of M unique N-bit primary digital code words Sm1 each defining a different one of the signal states S1-SM and each having N-1 additional ordered permutations of the order of the bits thereof, said additional ordered permutations being designated secondary code words; second selecting a particular state Ss for transmission; serially producing bits B1-BN of one of the primary and secondary code words for the selected signaling state Ss at a signaling clock rate; multiplexing signaling bits with traffic information bits at signaling time slots in a bit stream, said signaling time slots occurring at the signaling clock rate; transmitting the multiplexed bit stream to receiver equipment; extracting a signaling clock signal from the multiplexed bit stream in the receiver equipment; demultiplexing the multiplexed bit stream in the receiver equipment for producing a stream of serial signaling bits; determining whether the most recently received N signaling bits in the serial signaling bit stream match with one of the N-bit patterns of the primary and secondary code words during each signaling bit interval; producing during each signaling bit interval a first indication that the selected and transmitted signaling state is a prescribed signaling state Sp when there is a match between the most recently received N signaling bits of the serial signaling bit stream and one of the N-bit primary and secondary code words associated with the prescribed signaling state Sp; and producing during each signaling bit interval a second indication that is the same as the preceding first indication when there is not a match between the most recently received N signaling bits of the serial signaling bit stream and any of the primary and secondary code words.
Claim 3
Dependent Claim
33 words
The method according to claim 1 wherein said serial producing step comprises serially producing the N-bits B1-BN of the primary code word Ss1 for the selected state Ss at the signaling clock rate.
Claim 4
Dependent Claim
33 words
The method according to claim 2 further comprising the step of passing one of a first and second indication during each signaling bit interval as the receivers designation of the transmitted signaling state.
Claim 5
Dependent Claim
45 words
The method according to claim 3 wherein said second named producing step comprises first latching said passing step to the most recent first or second indication of a match between N consecutive signaling bits of the serial bit stream and any of said code words.
Claim 6
Dependent Claim
34 words
The method according to claim 4 further comprising unlatching said passing step whenever there is a match between the most recent N signaling bits of the stream thereof and any of the code words.
Claim 7
Dependent Claim
61 words
The method according to claim 5 further comprising the step of second latching said passing step to the most recent first indication for at least P consecutive signaling time intervals whenever there is a match between the most recent N signaling bits and a code word corresponding to a different signaling state than is designated by the most recent first indication.
Claim 8
Dependent Claim
48 words
The method according to claim 6 further comprising first changing the signaling state designated by the first indication so as to designate a different signaling state only after there is a match between P consecutive groups of N signaling bits and code words designating the same signaling state.
Claim 9
Dependent Claim
30 words
The method according to claim 7 wherein said second latching step also occurs whenever there is not a match between the most recent N signaling bits and any code word.
Claim 10
Dependent Claim
66 words
The method according to claim 7 wherein said serially producing step comprises the additional step of second changing from producing the ordered N bits of the one primary code word for one selected signaling state to producing the ordered N-bits of another primary code word for a different selected signaling state only after completion of producing all of the N-bits for the one primary code word.
Claim 11
Dependent Claim
62 words
The method according to claim 7 wherein said serially producing step comprises the additional step of second changing from producing the ordered N bits of the one primary code word for one selected signaling state to producing the ordered N-bits of another primary code word for a different selected signaling state during any signaling bit interval for only some specified signaling states.
Claim 12
Dependent Claim
60 words
The method according to claim 7 wherein said serially producing step comprises the additional step of second changing from producing the ordered N bits of the one primary code word for one selected signaling state to producing the ordered N-bits of another primary code word for a different selected signaling state during any signaling bit interval for any signaling state.
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) | 1990-06-15 | 1990-12-15 | 1991-06-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-06-15 | 1994-12-15 | 1995-06-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-06-15 | 1998-12-15 | 1999-06-16 | $7700.00 | Window Closed / Lapsed |