CCIR 476 is a character encoding used in radio data protocols such as SITOR, AMTOR and Navtex. It is a recasting of the ITA2 character encoding, known as Baudot code, from a five-bit code to a seven-bit code. In each character, exactly four of the seven bits are mark bits, and the other three are space bits. This allows for the detection of single-bit errors.
Technical detailsedit
The number of possible valid binary code values in CCIR 476 is the number of ways to choose 4 marks for 7 bit positions, and the number can be calculated using the binomial coefficient: Thus CCIR 476 has 3 additional code points available over ITA2's 32 code points.
The SITOR protocol uses the additional three code points (denoted as SIA, SIB and RPT below) for idle, phasing, and repeat requests.[1] In addition, some of the ordinary characters are reused as control signals.[2]
Character setedit
In these tables, the hexadecimal code values are converted from a binary representation, with 1 being mark, 0 being space, and the most significant bit given first. The international version of ITA2 is used here; note also the added non-ITA2 codes SIA, SIB and RPT, used by SITOR.
^ ab(PDF). 2013. Archived from the original (PDF) on 2022-02-11.
Schetgen, Robert, ed. (1995), The ARRL Handbook for Radio Amateurs (Seventy-Third (1996) ed.), Newington, CT: The American Radio Relay League, ISBN0-87259-173-5
January 01, 1970
ccir, character, encoding, used, radio, data, protocols, such, sitor, amtor, navtex, recasting, ita2, character, encoding, known, baudot, code, from, five, code, seven, code, each, character, exactly, four, seven, bits, mark, bits, other, three, space, bits, t. CCIR 476 is a character encoding used in radio data protocols such as SITOR AMTOR and Navtex It is a recasting of the ITA2 character encoding known as Baudot code from a five bit code to a seven bit code In each character exactly four of the seven bits are mark bits and the other three are space bits This allows for the detection of single bit errors Technical details editThe number of possible valid binary code values in CCIR 476 is the number of ways to choose 4 marks for 7 bit positions and the number can be calculated using the binomial coefficient 7 3 7 4 35 displaystyle textstyle binom 7 3 binom 7 4 35 nbsp Thus CCIR 476 has 3 additional code points available over ITA2 s 32 code points The SITOR protocol uses the additional three code points denoted as SIA SIB and RPT below for idle phasing and repeat requests 1 In addition some of the ordinary characters are reused as control signals 2 Character set editIn these tables the hexadecimal code values are converted from a binary representation with 1 being mark 0 being space and the most significant bit given first The international version of ITA2 is used here note also the added non ITA2 codes SIA SIB and RPT used by SITOR CCIR 476 Letter set 3 0 1 2 3 4 5 6 7 8 9 A B C D E F 0x SIA 1x J F C K 2x W Y P Q 3x SIB G FIGS M X V 4x A S I U 5x D R E N LTRS SP 6x Z L RPT H BLK LF 7x O B T CR CCIR 476 Figure set 3 0 1 2 3 4 5 6 7 8 9 A B C D E F 0x SIA 1x BEL 2x 2 6 0 1 3x SIB amp FIGS 4x 8 7 5x ENQ 4 3 LTRS SP 6x RPT BLK LF 7x 9 5 CRReferences edit Schetgen 1995 p 12 21 CCIR Rec 625 Service Information Signals a b ARRL 2013 Handbook Chapter 16 ITA2 Baudot and AMTOR Codes PDF 2013 Archived from the original PDF on 2022 02 11 Schetgen Robert ed 1995 The ARRL Handbook for Radio Amateurs Seventy Third 1996 ed Newington CT The American Radio Relay League ISBN 0 87259 173 5 Retrieved from https en wikipedia org w index php title CCIR 476 amp oldid 1142449286, wikipedia, wiki, book, books, library,
