Index

Access time, 4, 9, 20, 136
Aerial installation,
	performance affected by, 54
Alphageometric displays, 7, 22
Alphanumeric characters
	display of, 48-49
	transmission of, 46
Alphaphotographic displays, 7,23
Alternative-frequency code (for RDS), 125, 126
ANTIOPE (French teletext), 5, 12
Arabic-language (editing) terminals, 28
ARI (Autofahrer Rundfunk Information), 108, 136
ASCII (American Standard Code for Information Interchange) code, 33, 47
Automatic (radio) station tuning, 123, 125-127, 128-129

Backup facilities, 40-42
BBC
	decoding margin meter, 97, 98
	RDS coder designed by, 116
	teletext service, 1, 136
BCD (binary coded decimal), 18
Bi-phase coding, 113, 136
	time function for, 114
Blanking signal, 50
B-MAC system, 83
BREMA (British Radio Equipment Manufacturers Association),
	working party on teletext, 1-2
Broadcast service data packet, 22, 59, 136
Buffer memory capacity, factors affecting, 50, 67

C-MAC system, 83
Calibrated distortion unit, 103, 105
	functional diagram of, 104
CEEFAX, 1, 136
Character code extension, 16
Character code look-up table, 17
Character codes, 15, 136
	extended set, 26-28
Character-generation ROM, operation of, 48
Character-rounding, 48-49
Clock cracker page, 95, 97
Clock frequency
	RDS, 113, 116
	teletext systems, 9,46
Clock time/date data, RDS broadcast of, 131
Closed captions, 72
Closed user groups, data transmission to, 65, 106, 107
Co-channel interference, meaning of term, 95
Conditional access system, 107
Control byte, 86
Control characters, 15, 137
Control codes, use in editing, 28
CRC (cyclic redundancy check) code, 86, 107, 137
Cut-and-paste technique, 28
Czechoslovakian-language displays, 26, 27

Data amplitude
	RDS, 111
	teletext, 10-11, 93, 137
Data asymmetry, meaning of term, 95
Data bridging, 62-65
	functional diagram for, 64
Data packets, 16
Data pulse amplitude, 10-11
Data pulse shape, 9, 10
Data rates
	RDS, 111
	teletext, 8-11, 20
	standards conversion for, 66, 67
Data reception, decoders for, 106-107
Data regeneration, 65-66
	subtitle regeneration and, 80
Data signal
	RDS, 111-118
	teletext, 8-23
Data waveform, 10
	measurement of, 90-97
Data words, 3
DBS (direct broadcasting by satellite) systems, 81-88
Decoders
	data reception, 106-107
	in-vision, 60-61
	measurements for, 99, 103-106
	teletext, 45-58
	see also In-vision systems; Teletext decoders
Decoding, duo-binary code, 83, 85, 86
Decoding margin, 54, 93, 106
	measurement of, 97-99
Decoding margin meter, 97, 98, 138
	functional diagram of, 100-101
Decoding threshold, meaning of term, 95
DELPHI (Defined Eye Loss with Precision Held Indication)
	technique, 103
Designation codes, 22
Digital compression techniques,
	satellite broadcasting, 81, 82
D-MAC system, 83
	data packets used by, 86
	D2-MAC system, 83
DRCS (dynamically redefinable character sets), 7, 22, 36
Dual-channel teletext system, 41, 42-43
Duo-binary coding system, 83
	data format of, 84
	decoding for, 83, 85, 86

Editing suites, 36-37
Editing terminals, 24-31
	commands by, 31-32
	communications for, 31-32
	displays on, 26, 29
	functional diagram of, 29-31
	keyboard layout for, 24-22
	see also Work stations
Enhancement levels, 5, 7
EPROMs
	RDS data held in, 117, 133
	teletext data management using, 40
	teletext decoding using, 50
	teletext editing using, 29


Error-correction circuits, 46
Error protection, 16-19
EUROM LSI circuit, 30
Extended character sets, 27
Eye display, 10
Eye displays
	arrangement to produce, 92, 93
	distorted, 96
	interpretation of, 94
Eyeheight
	display facility for, 92
	meaning of term, 93, 138

Fastext, 55
	data packets for, 21, 22
	tree page structure of, 56
FBI (field blanking interval)
	maximum number of lines used, 7
	meaning of term, 138
	separate line used for subtitles, 80
	transmission of information in, 1,2
Fixed-data format, 3,5
Fixed-format systems, 12-15
	teletext decoders for, 50, 52, 53
Floppy discs, subtitles stored on, 74,80
FM (frequency-modulated)
	transmissions, 138
	modulation bandwidth of, 108
Free-format systems, 11-12
	advantage of, 12
	error protection in, 18
	teletext decoders for, 50, 51
Full-Field Teletext Systems, 7

Ghost rows, 16, 138
	see also Data packets
Glossary, 136-141
Golay code, 87, 138
Graphics characters, 17, 139
Graphics digitizers, 32-36
	functional diagram of, 32-33, 34
Graphics-hold mode, 4, 139

Hamming codes, 3, 16, 18, 46, 53, 139
Header row, 3, 8, 13
	format for, 14
High-resolution graphics, digitizer used, 34-35

IBA, teletext service, 1, 140
Input circuits, teletext decoder, 45-46
Inserter equipment, performance
	requirements for, 89, 90
Interlaced displays, 49
In-vision systems, 60-61
	text legibility improved for, 61
 IRT (Institut für Rundfunktechnik),
	multi-page decoder technique, 55-58
Level-1 teletext, 5, 6, 18, 21
	data requirement for, 23
Level-2 teletext, 5, 21-22
	data requirement for, 23
Level-3 teletext, 6, 7, 22
	digitizer sampling for, 35-36
Level-4 teletext, 7, 22
Level-5 teletext, 7, 23
	data requirement for, 23
Lissajous figures, 91
	disadvantage of, 95
	display facility for, 92, 93
	see also Eye displays
Live programmes, subtitling of, 75-77
	shortforms used, 76
	shorthand used, 76-77

MAC (multiplexed analogue components) system, 81
	data packets used by, 86-87
	teletext data management in, 88
	transmitted frame format for, 82
Machine shorthand keyboard, 76-77
Macros, 41
Mail-box facility, editing terminals, 44
Measurements, teletext, 89-107
Mosaic graphics, 28-29
Mosaic graphics digitizers, 32-36
	functional diagram of, 32-33, 34
MPAG (magazine and packet address group), 21, 86
Multi-page decoders, 54-58

NABTS (North American Broadcast Teletext Specification), 12
Networking
	RDS, 133
	teletext, 62-69
Noise interference, meaning of term, 95
NRZ (Non-Return-to-Zero) coding, 9, 115, 139
Null modem, 135

Open captions, 72
ORACLE, 1, 140
Other-networks feature (for RDS), 125, 126-127
Output circuits, teletext decoder, 46-50

Packet header, satellite broadcasting, 87
Packets, 21
Page
	data contained in, 11
	format of, 2, 3, 8, 26
Page-exchange system (for regional services), 68-69
Page-header, 3, 8, 13, 140
	format for, 14
Paging service, 132
Parity bit check, 46
Personal computers, data decoded for, 106, 107
Prerecorded programmes, subtitling of, 72-75
Programme identification code (for RDS), 125, 126, 132
Programme-related data, RDS
	transmission of, 131-132
Programme service name (for RDS), 125
Pulse-and-bar waveform, 103

Radiotext, RDS transmission of, 132
RAM disc, subtitles stored in, 74
RDS (radio data system), 108-120, 140
	applications of, 123-133
	automatic station tuning by, 123, 125-127, 128-129
	traffic information service
	combined with, 127-131
	carrier frequency used, 109, 113
	clock time/date transmitted by, 131
	coding for, 112-118
	digital filter used, 116
	functional diagram of, 112
	principle behind, 113, 115-117
	data format for, 121-123
	data sub-carrier used, 109-111
	decoding for, 118-120
	principle behind, 119
	field trials for, 109
	message structure for, 123, 124
	networking by, 133
	paging by, 132
	programme-related data transmitted by, 131-132
	radiotext transmitted by, 132
	repetition rates for codes, 125
	specification for, 109, 121, 123, 125, 132
	traffic information broadcast by, 127-131

Reading list, 143
References listed, 141-143
Regenerators, data signal, 66
Regional services, 70-71
	page-exchange system for, 68-69
	subtitle recording system for, 77-80
Row, meaning of term, 140
Row-adaptive transmission, 15, 140
Row format, 14, 15
RS232 specification, 134-135, 140
	connections listed, 134
Run-in data sequence, 12, 13, 16, 21, 137

Satellite data broadcasting, 81-88
Shortform files, 76
Shorthand keyboards, subtitles
	prepared using, 76-77
Signal path distortion measurement of, 103
	teletext decoders affected by, 54
Single-channel teletext system, 39
SI (service identification) channel, 87-88
Sound buzz, 62,90
Spanish-language displays, 26, 27
Specifications, teletext, 3-4
Standards conversion, 66-67
	data rates for, 66, 67
Subtitles
	live programme, 75-77
	preparation of, 44, 72-77
	prerecorded programme, 72-75
	print-out of, 75 reading speed for, 72, 74
	recording for regional service, 78-79
	time taken to prepare, 72, 75-76
	transmission of, 15, 44, 77-80
Surface wave filters, 54

Telephone lines, data sent over, 135
Teleswitching, 108
Teletext
	cost of, 3
	development of, 1-7
	early trials, 2-3
	specification for, 3-4
Teletext adaptors, 58
Teletext data management, 38-44
Teletext data signal, 8-23
	bandwidth of, 8, 10
	data pulse amplitude for, 10, 11
	data pulse shape for, 10
	data rates for, 8-11
	degradation of, 99, 102
	fixed-format technique used, 12-15
	free-format technique used, 11-12
	measurement of, 90-97
	transmission of, 44
Teletext decoders, 45-58
	basic functions of, 45
	fixed-format system, 50, 52, 53
	free-format systems, 50, 51
	input circuits for, 45-46
	multi-page, 54-58
	output circuits for, 46-50
	control functions in, 50
	performance of, 53-54
	signal path distortion effects, 54
Teletext measurements, 89--107
Teletext transcoding, 67
TELIDON (Canadian teletext), 5, 12
TOPS multi-page decoding technique, 55-58
	data base structure for, 57
Traffic information, RDS broadcast of, 127-131
Transcoding
	satellite broadcast teletext signal, 82-83
	teletext, 67
Transparent data channel, 132
Two-phase phase-shift keying, 109

UTC (Co-ordinated Universal Time), 131

Variable-format data, 5
	see also Free-format systems
Video clamps, performance
	requirements for, 90
Video measurements, 89-90
Video Programming System, 59-60
Video recorders, control by teletext, 59-60

Work stations
	subtitles prepared on, 72-74
	see also Editing terminals
WST (World System Teletext), 5
	data amplitude for, 10, 137
	data formats used by, 12-15, 59
	data rate chosen for, 20
	decoders for, 50, 52, 53
	Fastext option for, 55, 56
	higher levels of, 16, 20-23

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