Table of Contents
Advertisement
USER'S GUIDE
MYTHS AND MISUNDERSTANDINGS
1.
'RTTY' Means 'Baudot' – Not True!
'RTTY' does not mean 'Baudot'. 'RTTY' is a simple abbreviation for 'RadioTeleTypewriter.' Baudot,
ASCII, AMTOR and packet radio are not exactly different modes. They are different languages and
methods within the same mode – RTTY. Think of them this way:
MODE:
CODES:
2.
'Baudot Code is Obsolete' – Not True!
The largest record communications network in the world today (record communications systems
leave a permanent record of the traffic passed) is the International Telex Network. Worldwide,
there are over one-and-one-half million regular telex subscribers connected to their domestic net-
works, and, in turn, to the International Telex Network through gateway switching systems in each
country.
Telex is, by definition, a Baudot code system, operating at 50 bauds- (66 WPM) in CCITT Interna-
tional Alphabet Number 2, the same code specified for the amateur radio service in Part 97.69 of
the Commission's rules.
Although telex was invented in 1932 and the first automatic telex network established in 1933, un-
til the recent advent of packet network transmission and switching standards, the telex networks
of the world had been growing world-wide at an annual rate of about 22 % per year. This does
not indicate obsolescence.
Here in the U.S.A. many of the commercial carriers are still enlarging their networks. Instead of
abandoning the Baudot code in favor of anything else, they are changing from the traditional 50-
baud operating speed to 200- and 300-baud telex, still using Baudot, and generally working into
stored program control computer-based telex switching exchanges. In many of these cases, the
Baudot code is being retained in those applications where line and circuit noise is greater than the
optimal design goals, and not easily improved.
Many manufacturers are still producing Baudot telex and teleprinter systems. What has disap-
peared is the electromechanical teleprinter. The older teleprinters are being replaced with all-elec-
tronic systems using microprocessor-based terminals with video displays and various types of disk
and tape storage. Internally, many of these terminals work with the ASCII and EBCDIC codes.
By means of code- and speed-conversion firmware, these terminals send the Baudot code to the
telex and telephone lines for integration into the telex and gentex networks and leased-line serv-
ices.
At times, the Baudot code has certain advantages over other standardized codes. These advan-
tages are discussed in detail later in these Appendices.
PK232UG Rev. E 9/87
APPENDIX G – DATA TRANSMISSION CODES
Human Speech
English
French
Spanish
Italian
RTTY
Baudot
ASCII
AMTOR
Packet
G-1
DATA TRANSMISSION CODES
189
Advertisement
Table of Contents
