BS 6403:1983

Foreword
Committees responsible
Specification
1 Scope
2 Abbreviations and definitions
3 General requirements
4 Physical signal characteristics
5 Technical signal characteristics
6 Reliability
7 Marking
8 Instructions for use
9 Information to be provided by the supplier for
    testing purposes
Appendices
A The international telegraph alphabet No. 2 with UK
    options
B General conditions for tests
C Measurement of physical signal characteristics
D Measurement of technical signal characteristics
E Repeat calling
F Reliability tests
Tables
1 Allocation of plug pins
2 Spectral power limits
3 Tolerances of components and physical quantities
4 Repeat call rates
Figures
1 Power spectral density limits at frequencies above
    3.4 kHz
2 Measurement of longitudinal output
3 Longitudinal output power limits as a function of
    frequency
4 Derivation of d.c. wetting current
5 Test circuit for measuring transmit frequency and
    output signal power
6 Test circuit for measuring spectral power up to
    8.9 kHz
7 Relative positioning of equipment for spectral power
    measurements
8 Measurement of transmit distortion
9 Test circuit for spectral power measurements above
    8.9 kHz
10 Measurement of receiver margin
11 Measurement of effect of hits
12 Hit profile (type 1)
13 Hit profile (type 2)
14 Measurement of return loss
15 Measurement of longitudinal conversion loss
16 Transverse conversion loss
17 Telegraph character measurement
18 Measurement of technical signal characteristics

Gives requirements for simple telex terminals (STT) for direct connection to the British Telecommunications (BT) telex network which aims to minimize the risk of interference to other subscribers and provide compatibility with BT telex network and other telex terminals connected to the network. Lists characteristics of suitable apparatus. Covers both an STT capable of working to an electromechanical exchange or a stored programme control SPC exchange. Includes the international telegraph alphabet No. 2 with UK options, general conditions for tests, measurement of physical and technical characteristics, repeat calling and reliability tests.