EP0232043A2
Expired / Lapsed
EP
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Scrambling data signals
Assignee: Nortel Networks Ltd
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Filing: 1987-01-19
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Granted: —
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Expires: 2007-01-19
Abstract
Abstract A word-interleaved tdm data signal including a synchronizing word in each tdm frame is scrambled for transmission via a high speed fiber optic transmission link (14) by exclusive-or gating (26) each data word (16) with a respective word from a pseudo-random sequence word generator (10). In response to each synchronizing word the pseudo-random sequence generator is reset (22) to produce an all-zeroes word which is gated with the synchronizing word which is unchanged thereby. This facilitates detection of the synchronizing word at a descrambler (12) which operates in a similar manner. The scrambled data is converted by a multiplexer into a serial bit stream, which at the descrambler is demultiplexed and word-aligned using a barrel shifter controlled from a frame find circuit (30) of the descrambler.
Inventors
- 👤 Stephen Charles Carlton
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-27 18:15
CPC Classifications
H; H04; H04L; H04L25/00; H04L25/02; H04L25/03; H04L25/03828; H04L25/03866; H04L25/03872
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
51 words
A method of processing word-interleaved time division multiplexed data including a periodically-occurring synchronizing word, comprising the steps of: generating words in a pseudo-random sequence; starting the pseudo-random sequence in response to each periodic occurrence of the synchronizing word; and scrambling data words in dependence upon the words in the pseudo-random sequence.
Claim 2
Independent Claim
51 words
A method of processing word-interleaved time division multiplexed data including a periodically-occurring synchronizing word, comprising the steps of: generating words in a pseudo-random sequence; starting the pseudo-random sequence in response to each periodic occurrence of the synchronizing word; and scrambling data words in dependence upon the words in the pseudo-random sequence.
Claim 3
Dependent Claim
20 words
A method as claimed in claim 1 and including the step of detecting each periodic occurrence of the synchronizing word.
Claim 4
Dependent Claim
64 words
A method as claimed in claim 1 or 2 wherein the pseudo-random sequence is started with a word of all zero bits and each data word is scrambled by an exclusive-or combination of the data with a respective word in the pseudo-random sequence, the synchronizing word thereby being combined in an exclusive-or operation with said word of all zero bits whereby it remains unscrambled.
Claim 5
Dependent Claim
35 words
A method of transmitting word-interleaved time division multiplexed data including a periodically-occurring synchronizing word, comprising the steps of: scrambling the data by the method of claim 1, 2 or 3; and transmitting the scrambled data.
Claim 6
Dependent Claim
113 words
A method of communicating word-interleaved time division multiplexed data including a periodically-occurring synchronizing word, comprising the steps of transmitting said data via a transmission link by the method of claim 4 and, at a receiving end of the transmission link: detecting the periodic occurrences of the synchronizing word in data received via the transmission link; generating words in the same pseudo-random sequence as at the transmitting end of the transmission link; starting the pseudo-random sequence in response to each detected periodic occurrence of the synchronizing word; and unscrambling the data received via the transmission link by combining each received data word with a respective word of the pseudo-random sequence in an exclusive-or operation.
Claim 7
Dependent Claim
20 words
A method as claimed in claim 5 wherein the scrambled data words are transmitted bit serially via the transmission link.
Claim 8
Dependent Claim
91 words
Apparatus for scrambling words of a time division multiplexed data signal which includes a periodically-occurring synchronizing word, comprising: first means for generating words in a pseudo-random sequence; second means for resetting the first means to produce a predetermined word in the pseudo-random sequence in response to each periodic occurrence of the synchronizing word in the data signal; and exclusive-or gating means for gating each word of the data signal with a respective word of the pseudo-random sequence, each periodically-occurring synchronizing word being gated with said predetermined word in the pseudo-random sequence.
Claim 9
Dependent Claim
91 words
Apparatus for scrambling words of a time division multiplexed data signal which includes a periodically-occurring synchronizing word, comprising: first means for generating words in a pseudo-random sequence; second means for resetting the first means to produce a predetermined word in the pseudo-random sequence in response to each periodic occurrence of the synchronizing word in the data signal; and exclusive-or gating means for gating each word of the data signal with a respective word of the pseudo-random sequence, each periodically-occurring synchronizing word being gated with said predetermined word in the pseudo-random sequence.
Claim 10
Dependent Claim
22 words
Apparatus as claimed in claim 7 wherein the second means comprises means for detecting the periodically-occurring synchronizing word in the data signal.
Claim 11
Dependent Claim
24 words
Apparatus as claimed in claim 7 or 8 and including means for converting the output of the gating means into a serial bit stream.
Claim 12
Dependent Claim
46 words
Apparatus as claimed in claim 7, 8, or 9 wherein the first means is responsive to the resetting by the second means to produce a word comprising only binary zero bits as said predetermined word, whereby the periodically-occurring synchronizing word is unchanged by the gating means.
Claim 13
Dependent Claim
89 words
Apparatus for descrambling words of a time division multiplexed data signal scrambled by the apparatus of claim 10, comprising: generating means for generating words in said pseudo-random sequence; detection means for detecting the periodically-occurring synchronizing word in the data signal and for resetting the generating means to produce said predetermined word in response to such detection; and exclusive-or gating means for gating each word of the scrambled data signal with a respective word of the pseudo-random sequence from the generating means to produce descrambled words of the data signal.
Claim 14
Dependent Claim
29 words
Apparatus as claimed in claim 11 wherein the detection means is arranged to detect the periodically-occurring synchronizing word in the descrambled data signal produced by the exclusive-or gating means.
Claim 15
Dependent Claim
75 words
Apparatus as claimed in claim 11 or 12 for descrambling words of a time division multiplexed data signal scrambled by the apparatus of claim 9, the apparatus further comprising means for converting a serial bit stream into the scrambled data signal words, the means for converting being responsive to the detection means failing to detect the periodically-occurring synchronizing word to effect realignment of bits of the serial bit stream into the scrambled data signal words.
References Cited (Backward Citations)
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