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Thursday, March 21, 2013

Recommendation ITU-R M.2034
















Recommendation  ITU-R  M.2034
(02/2013)

Telegraphic alphabet for data communication by phase shift
keying at 31 Bd in the amateur
and amateur-satellite services


M Series
Mobile, radiodetermination, amateur
and related satellite services







Foreword
The role of the Radiocommunication Sector is to ensure the rational, equitable, efficient and economical use of the radio-frequency spectrum by all radiocommunication services, including satellite services, and carry out studies without limit of frequency range on the basis of which Recommendations are adopted.
The regulatory and policy functions of the Radiocommunication Sector are performed by World and Regional Radiocommunication Conferences and Radiocommunication Assemblies supported by Study Groups.

Policy on Intellectual Property Right (IPR)

ITU-R policy on IPR is described in the Common Patent Policy for ITU-T/ITU-R/ISO/IEC referenced in Annex 1 of Resolution ITU-R 1. Forms to be used for the submission of patent statements and licensing declarations by patent holders are available from http://www.itu.int/ITU-R/go/patents/en where the Guidelines for Implementation of the Common Patent Policy for ITU‑T/ITU‑R/ISO/IEC and the ITU-R patent information database can also be found.


Series of ITU-R Recommendations
(Also available online at http://www.itu.int/publ/R-REC/en)
Series
Title
BO
Satellite delivery
BR
Recording for production, archival and play-out; film for television
BS
Broadcasting service (sound)
BT
Broadcasting service (television)
F
Fixed service
M
Mobile, radiodetermination, amateur and related satellite services
P
Radiowave propagation
RA
Radio astronomy
RS
Remote sensing systems
S
Fixed-satellite service
SA
Space applications and meteorology
SF
Frequency sharing and coordination between fixed-satellite and fixed service systems
SM
Spectrum management
SNG
Satellite news gathering
TF
Time signals and frequency standards emissions
V
Vocabulary and related subjects



Note: This ITU-R Recommendation was approved in English under the procedure detailed in Resolution ITU-R 1.


Electronic Publication
Geneva, 2013

ã ITU 2013
All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without written permission of ITU.

RECOMMENDATION  ITU-R  M.2034
Telegraphic alphabet for data communication by phase shift keying
at 31 Bd in the amateur and amateur-satellite services
(Question ITU-R 48-6/5)
(2013)
Scope
This Recommendation establishes a telegraphic alphabet and transmission protocols for phase shift keying at 31 Bd in the amateur and amateur-satellite services.
The ITU Radiocommunication Assembly,
considering
a)          that phase shift keying at a data rate of 31 Bd has become a predominant transmission mode in the amateur and amateur-satellite services;
b)          that phase shift keying at 31 Bd utilizes a telegraphic alphabet, commonly called “Varicode”, optimized for the English language, in which more frequently used characters occupy fewer bits;
c)          that telegraphic alphabets should be documented and updated from time to time to meet the needs of radiocommunication services,
recommends
1           that the Annex should be used to define Varicode characters and their applications in the amateur and amateur-satellite services.


Annex

1           Introduction

PSK‑31 is a digital communication mode which is intended for live keyboard-to-keyboard conversations, similar to radioteletype. Its data rate is 31.25 Bd (about 50 words per minute), and its narrow bandwidth (approximately 60 Hz at –26 dB) reduces its susceptibility to noise. PSK‑31’s ITU emission designator is 60H0J2B. It uses either BPSK modulation without error correction or QPSK modulation with error correction (convolutional encoding and Viterbi decoding). In order to minimize occupied bandwidth, the output is cosine-filtered before reaching the transmitter audio input. PSK‑31 is readily monitored and the most popular implementations use DSP software running on a computer soundcard.
Each transmission has a preamble, an idle signal of continuous zeroes corresponding to continuous phase reversals at the symbol rate of 31.25 reversals/second, and a postamble, continuous unmodulated carrier representing a series of logical ones. The absence of phase reversals squelches the decoder.
While a symbol rate of 31.25 Bd is typical of most amateur service use, the symbol rate can be varied in direct proportion to the frequency of phase reversals. Transmissions at symbol rates as high as 125 Bd have been achieved.

2           Varicode characters

Different characters are represented by a variable-length combination of bits called Varicode. Because shorter bit-lengths are used for the more common letters in the English language, Varicode improves efficiency in terms of the average character duration. Varicode is also self-synchronizing. No separate process is needed to define where one character ends and the next begins since the pattern used to represent a gap between two characters (at least two consecutive zeroes) never occurs in a character. Because no Varicode characters can begin or end with a zero (0), the shortest character is a single one (1) by itself. The next is 11, then 101, 111, 1011, and 1101, but not 10, 100, or 1000 (because they end with zeroes), and not 1001 (since it contains two consecutive zeros). This scheme generates the 128-character ASCII set with ten bits. The encoding philosophy, however, accommodates longer bit sequences which allow for additional characters, e.g. accented characters.
The Varicode character set is shown below. The codes are transmitted left bit first, with 0 representing a phase reversal on BPSK and 1 representing a steady carrier. A minimum of two zeros is inserted between characters. Some implementations may not handle all the codes below 32. Note that the lower case letters have the shortest patterns and so are the fastest to transmit.
The varicode character set control characters

Varicode
Abbreviation
Description
1010101011
NUL
Null character
1011011011
SOH
Start of Header
1011101101
STX
Start of Text
1101110111
ETX
End of Text
1011101011
EOT
End of Transmission
1101011111
ENQ
Enquiry
1011101111
ACK
Acknowledgment
1011111101
BEL
Bell
1011111111
BS
Backspace
11101111
HT
Horizontal Tab
11101
LF
Line feed
1101101111
VT
Vertical Tab
1011011101
FF
Form feed
11111
CR
Carriage return
1101110101
SO
Shift Out
1110101011
SI
Shift In
1011110111
DLE
Data Link Escape
1011110101
DC1
Device Control 1 (XON)
1110101101
DC2
Device Control 2
1110101111
DC3
Device Control 3 (XOFF)
1101011011
DC4
Device Control 4
1101101011
NAK
Negative Acknowledgement
1101101101
SYN
Synchronous Idle
1101010111
ETB
End of Trans. Block
1101111011
CAN
Cancel
1101111101
EM
End of Medium
1110110111
SUB
Substitute
1101010101
ESC
Escape
1101011101
FS
File Separator
1110111011
GS
Group Separator
1011111011
RS
Record Separator
1101111111
US
Unit Separator
1110110101
DEL
Delete
Printable characters

Varicode
Glyph

Varicode
Glyph

Varicode
Glyph
1
SP

1010111101
@

1011011111
`
111111111
!

1111101
A

1011
a
101011111
"

11101011
B

1011111
b
111110101
#

10101101
C

101111
c
111011011
$

10110101
D

101101
d
1011010101
%

1110111
E

11
e
1010111011
&

11011011
F

111101
f
101111111
'

11111101
G

1011011
g
11111011
(

101010101
H

101011
h
11110111
)

1111111
I

1101
i
101101111
*

111111101
J

111101011
j
111011111
+

101111101
K

10111111
k
1110101
,

11010111
L

11011
l
110101
-

10111011
M

111011
m
1010111
.

11011101
N

1111
n
110101111
/

10101011
O

111
o
10110111
0

11010101
P

111111
p
10111101
1

111011101
Q

110111111
q
11101101
2

10101111
R

10101
r
11111111
3

1101111
S

10111
s
101110111
4

1101101
T

101
t
101011011
5

101010111
U

110111
u
101101011
6

110110101
V

1111011
v
110101101
7

101011101
W

1101011
w
110101011
8

101110101
X

11011111
x
110110111
9

101111011
Y

1011101
y
11110101
:

1010101101
Z

111010101
z
110111101
;

111110111
[

1010110111
{
111101101

111101111
\

110111011
|
1010101
=

111111011
]

1010110101
}
111010111

1010111111
^

1011010111
~
1010101111
?

101101101
_