IPC 6 English version H04B 7/00-H04B 17/02

H04B00700-H04B01702

SECTION H– ELECTRICITY

H 04

ELECTRIC COMMUNICATION TECHNIQUE

H 04 B

TRANSMISSION (transmission systems for measured values, control or similar signals G 08 C; coding, decoding or code conversion, in general H 03 M; broadcast communication H 04 H; multiplex systems H 04 J; secret communication H 04 K; transmission of digital information H 04 L) [4]

Radio transmission systems, i.e. using radiation field (H 04 B 10/00, H 04 B 15/00 take precedence)

005

Control of transmission; Equalising [3]

Reducing phase shift [3]

015

Reducing echo effects [3]

Diversity systems (for direction finding G 01 S 3/72; aerial arrays or systems H 01 Q)

using a plurality of spaced independent aerials

at transmitting station

at receiving station

using a single aerial system characterised by its polarisation or directive properties, e.g. polarisation diversity, direction diversity

Frequency-diversity systems

Relay systems (interrogator-responder radar systems G 01 S 13/74) [2]

145

Passive relay systems [2]

Active relay systems [2]

155

Ground-based stations (H 04 B 7/204 takes precedence) [2,5]

165

employing angle modulation [2]

employing pulse modulation, e.g. pulse code modulation [2]

185

Space-based or airborne stations (H 04 B 7/204 takes precedence) [2,5]

Earth-synchronous stations [2]

195

Non-synchronous stations [2]

204

Multiple access [5]

208

Frequency-division multiple access [5]

212

Time-division multiple access [5]

216

Code-division or spread-spectrum multiple access (spread spectrum techniques in general H 04 B 1/69) [5]

Scatter propagation systems

for communication between two or more posts (for selecting H 04 Q 7/00) [2]

at least one of which is mobile [2]

10/

Transmission systems employing electromagnetic waves other than radio waves, e.g. light, infra-red (optical coupling, mixing or splitting G 02 B; light guides G 02 B 6/00; switching, modulation, demodulation of light beams G 02 B, G 02 F; devices or arrangements for the control, e.g. modulation, of light beams G 02 F 1/00; devices or arrangements for demodulating light, transferring the modulation or changing the frequency of light G 02 F 2/00; optical multiplex systems H 04 J 14/00) [5]

10/

Details [5]

10/

Transmitters [5]

10/

Receivers [5]

10/

Equipment for monitoring, testing or fault measuring [5]

10/

Transmission through free space, e.g. through the atmosphere (H 04 B 10/22, H 04 B 10/24 take precedence) [5]

10/

105

specially adapted for satellite links [6]

10/

Transmission through light guides, e.g. optical fibres (H 04 B 10/22, H 04 B 10/24 take precedence) [5]

10/

using multimodal transmission [6]

10/

135

using single mode transmission [6]

10/

Terminal stations [5]

10/

142

Coherent homodyne or heterodyne systems [6]

10/

145

Transmitters [6]

10/

148

Receivers [6]

10/

152

Non-coherent direct-detection systems [6]

10/

155

Transmitters [6]

10/

158

Receivers [6]

10/

Repeaters [5]

10/

in which processing or amplification is carried out without conversion of the signal from optical form [6]

10/

Arrangements for reducing or eliminating distortion or dispersion, e.g. equalisers [5]

10/

Arrangements for networking, e.g. bus or star coupling [5]

10/

207

using a star-type coupler [6]

10/

213

using a T-type coupler [6]

10/

Transmission between two stations which are mobile relative to each other [5]

10/

Bidirectional transmission (H 04 B 10/22 takes precedence) [5]

10/

using a single light source for both stations involved [6]

10/

using a single device as a light source or a light receiver [6]

11/

Transmission systems employing ultranosic, sonic or infrasonic waves

13/

Transmission systems characterised by the medium used for transmission, not provided for in groups H 04 B 3/00 to H 04 B 11/00

13/

Transmission systems in which the medium consists of the earth or a large mass of water thereon, e.g. earth telegraphy (line transmission systems with earth or water return H 04 B 3/00)

14/

Transmission systems not characterised by the medium used for transmission (details thereof H 04 B 1/00) [4]

14/

characterised by the use of pulse modulation (in radio transmission relays H 04 B 7/17) [4]

14/

using pulse code modulation (analogue/digital or digital/analogue conversion H 03 M 1/00) [4]

14/

using differential modulation, e.g. delta modulation (conversion of analogue values to or from differential modulation H 03 M 3/00) [4]

14/

characterised by the use of a sub-carrier [4]

15/

Suppression or limitation of noise or interference (by means associated with receiver H 04 B 1/10)

15/

Reducing interference from electric apparatus by means located at or near the interfering apparatus (structural association with dynamo-electric machines H 02 K 11/00)

15/

the interference being caused by substantially sinusoidal oscillations, e.g. in a receiver, in a tape-recorder (reducing parasitic oscillations H 03 B, H 03 F; screening H 05 K 9/00)

15/

by local oscillators of receivers

17/

Monitoring; Testing [2]

17/

of relay systems [2]

H04 - H04B 5/06