GB1250924A - - Google Patents
Info
- Publication number
- GB1250924A GB1250924A GB1250924DA GB1250924A GB 1250924 A GB1250924 A GB 1250924A GB 1250924D A GB1250924D A GB 1250924DA GB 1250924 A GB1250924 A GB 1250924A
- Authority
- GB
- United Kingdom
- Prior art keywords
- disparity
- word
- words
- total
- digit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/38—Synchronous or start-stop systems, e.g. for Baudot code
- H04L25/40—Transmitting circuits; Receiving circuits
- H04L25/49—Transmitting circuits; Receiving circuits using code conversion at the transmitter; using predistortion; using insertion of idle bits for obtaining a desired frequency spectrum; using three or more amplitude levels ; Baseband coding techniques specific to data transmission systems
- H04L25/4917—Transmitting circuits; Receiving circuits using code conversion at the transmitter; using predistortion; using insertion of idle bits for obtaining a desired frequency spectrum; using three or more amplitude levels ; Baseband coding techniques specific to data transmission systems using multilevel codes
- H04L25/4923—Transmitting circuits; Receiving circuits using code conversion at the transmitter; using predistortion; using insertion of idle bits for obtaining a desired frequency spectrum; using three or more amplitude levels ; Baseband coding techniques specific to data transmission systems using multilevel codes using ternary codes
- H04L25/4925—Transmitting circuits; Receiving circuits using code conversion at the transmitter; using predistortion; using insertion of idle bits for obtaining a desired frequency spectrum; using three or more amplitude levels ; Baseband coding techniques specific to data transmission systems using multilevel codes using ternary codes using balanced bipolar ternary codes
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/24—Testing correct operation
- H04L1/245—Testing correct operation by using the properties of transmission codes
- H04L1/247—Testing correct operation by using the properties of transmission codes three-level transmission codes, e.g. ternary
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Synchronisation In Digital Transmission Systems (AREA)
- Dc Digital Transmission (AREA)
- Detection And Prevention Of Errors In Transmission (AREA)
Abstract
1,250,924. Digital transmission systems. STANDARD TELEPHONES & CABLES Ltd. 25 June, 1969, No. 32092/69. Heading H4P. Digital data words transmitted have disparity which varies in a predetermined manner. The receiver determines the variations in disparity expected and compares those with the variations actually received. Lack of identity indicates an error. As described 3-digit words comprising +, 0, and - digits are transmitted, each representing a 4-bit word. Each word has + or 0 disparity until the total disparity of all the transmitted digits reaches + 1 or more, whereupon the words are transmitted inverted, i.e. have - or 0 disparity until the total disparity reaches - 1 or more. This manner of variation of the disparity has the effect that when a word + 1 disparity is followed by a word of - 1 disparity (or vice versa), no words of other than 0 disparity lying between these words, the total disparity after reception of the second unit disparity word is the same as the disparity of that word. At the receiver, Fig. 2 (not shown), each 3- digit word is converted to parallel form to feed a unit generating a corresponding 4-bit signal which is serialized and passed to the output. A counter determines the disparity of each received word and another counter determines the total disparity. The occurrence of successive opposite unit disparity words is detected by monitoring the word disparity count and causes the outputs of the counters to be compared. If they differ, the total disparity counter is reset to the current word disparity count and an error is indicated. A further unit determines the rate at which errors occur. If this rate is excessive it is assumed that word synchronism has been lost and a control signal is then passed to a circuit which derives a word rate clock signal from a digit rate clock signal, the control signal causing the word rate clock signal to be shifted in phase by one digit period in an attempt to restore sync.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB3209269 | 1969-06-25 |
Publications (1)
Publication Number | Publication Date |
---|---|
GB1250924A true GB1250924A (en) | 1971-10-27 |
Family
ID=10333106
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB1250924D Expired GB1250924A (en) | 1969-06-25 | 1969-06-25 |
Country Status (6)
Country | Link |
---|---|
BE (1) | BE752490A (en) |
CH (1) | CH531816A (en) |
DE (1) | DE2030763C3 (en) |
ES (1) | ES381121A1 (en) |
FR (1) | FR2047924B1 (en) |
GB (1) | GB1250924A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2201567B (en) * | 1987-02-24 | 1991-09-25 | Codex Corp | Improvements in data signal encoders and decoders |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1423776A (en) * | 1973-02-08 | 1976-02-04 | Standard Telephones Cables Ltd | Error detection in pcm systems |
US5122688A (en) * | 1988-07-29 | 1992-06-16 | International Business Machines Corporation | Trinary check trit generator, latch, comparator and multiplexer |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
NL121569C (en) * | 1960-02-22 | |||
BE634332A (en) * | 1962-07-02 | |||
US3439330A (en) * | 1965-06-04 | 1969-04-15 | Bell Telephone Labor Inc | Error detection in paired selected ternary code trains |
-
1969
- 1969-06-25 GB GB1250924D patent/GB1250924A/en not_active Expired
-
1970
- 1970-06-23 FR FR7023106A patent/FR2047924B1/fr not_active Expired
- 1970-06-23 CH CH948770A patent/CH531816A/en not_active IP Right Cessation
- 1970-06-23 DE DE19702030763 patent/DE2030763C3/en not_active Expired
- 1970-06-24 ES ES381121A patent/ES381121A1/en not_active Expired
- 1970-06-25 BE BE752490D patent/BE752490A/en unknown
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2201567B (en) * | 1987-02-24 | 1991-09-25 | Codex Corp | Improvements in data signal encoders and decoders |
Also Published As
Publication number | Publication date |
---|---|
DE2030763C3 (en) | 1979-01-04 |
BE752490A (en) | 1970-12-28 |
DE2030763A1 (en) | 1971-01-14 |
CH531816A (en) | 1972-12-15 |
FR2047924A1 (en) | 1971-03-19 |
ES381121A1 (en) | 1972-11-16 |
DE2030763B2 (en) | 1978-05-11 |
FR2047924B1 (en) | 1975-04-18 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PS | Patent sealed | ||
435 | Patent endorsed 'licences of right' on the date specified (sect. 35/1949) | ||
PCNP | Patent ceased through non-payment of renewal fee |