|  | H |
SECTION H — ELECTRICITY

|  | H04 |
ELECTRIC COMMUNICATION TECHNIQUE

|  | H04B |
TRANSMISSION (broadcast communication Fulltext... Hierarchy... Expanded...H04H; multiplex systems Fulltext... Hierarchy... Expanded...H04J; secret communication Fulltext... Hierarchy... Expanded...H04K)

|  | H04B |
Note(s) This sub-class deals with the transmission of information-carrying signals, the transmission being independent of the nature of the information, and includes monitoring and testing arrangements and the suppression and limitation of noise and interference.

|  | H04B 1/00 |
Details of systems covered by groups Fulltext... Hierarchy... Expanded...Fulltext... Hierarchy... Expanded...H04B 3/00-H04B 13/00 (tuning resonant circuits Fulltext... Hierarchy... Expanded...H03J)

|  | H04B 1/02 |
· | Transmitters (spatial arrangements of component circuits in radio pills for living beings Fulltext... Hierarchy... Expanded...A61B 5/07)

|  | H04B 1/03 |
· · | Constructional details, e.g. casings, housings [2]

|  | H04B 1/034 |
· · · | Portable transmitters [2]

|  | H04B 1/036 |
· · · | Cooling arrangements (cooling transformers Fulltext... Hierarchy... Expanded...H01F 27/08; cooling discharge tubes Fulltext... Hierarchy... Expanded...H01J 7/24, Fulltext... Hierarchy... Expanded...H01J 19/74) [2]

|  | H04B 1/04 |
· · | Circuits (of television transmitters Fulltext... Hierarchy... Expanded...H04N 5/38)

|  | H04B 1/06 |
· | Receivers (control of amplification Fulltext... Hierarchy... Expanded...H03G; television receivers Fulltext... Hierarchy... Expanded...H04N 5/44, Fulltext... Hierarchy... Expanded...H04N 5/64)

|  | H04B 1/08 |
· · | Constructional details, e.g. cabinet

|  | H04B 1/10 |
· · | Means associated with receiver for limiting or suppressing noise or interference

|  | H04B 1/12 |
· · · | Neutralising, balancing, or compensation arrangements

|  | H04B 1/14 |
· · · | Automatic detuning arrangements

|  | H04B 1/16 |
· · | Circuits

|  | H04B 1/18 |
· · · | Input circuits, e.g. for coupling to an aerial or a transmission line (input circuits for amplifiers in general Fulltext... Hierarchy... Expanded...H03F; coupling networks between aerials or lines and receivers independent of the nature of the receiver Fulltext... Hierarchy... Expanded...H03H)

|  | H04B 1/20 |
· · · | for coupling gramophone pick-up, recorder output, or microphone to receiver

|  | H04B 1/22 |
· · · | for receivers in which no local oscillation is generated

|  | H04B 1/24 |
· · · · | the receiver comprising at least one semiconductor device having three or more electrodes

|  | H04B 1/26 |
· · · | for superheterodyne receivers (multiple frequency-changing Fulltext... Hierarchy... Expanded...H03D 7/16)

|  | H04B 1/28 |
· · · · | the receiver comprising at least one semiconductor device having three or more electrodes

|  | H04B 1/30 |
· · · | for homodyne or synchrodyne receivers (demodulator circuits Fulltext... Hierarchy... Expanded...H03D 1/22)

|  | H04B 1/32 |
( transferred to Fulltext... Hierarchy... Expanded...H03J 7/18 )

|  | H04B 1/34 |
( transferred to Fulltext... Hierarchy... Expanded...H03J 7/22, Fulltext... Hierarchy... Expanded...H03J 7/26 )

|  | H04B 1/36 |
( transferred to Fulltext... Hierarchy... Expanded...H03J 7/32 )

|  | H04B 1/38 |
· | Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving

|  | H04B 1/40 |
· · | Circuits

|  | H04B 1/44 |
· · · | Transmit/receive switching (tubes therefor Fulltext... Hierarchy... Expanded...H01J 17/64; waveguide switches per se Fulltext... Hierarchy... Expanded...H01P 1/10) [2]

|  | H04B 1/46 |
· · · · | by voice-frequency signals; by pilot signals

|  | H04B 1/48 |
· · · · | in circuit for connecting transmitter and receiver to a common transmission path, e.g. by energy of transmitter (in radar systems Fulltext... Hierarchy... Expanded...G01S)

|  | H04B 1/50 |
· · · | using different frequencies for the two directions of communication

|  | H04B 1/52 |
· · · · | Hybrid arrangements, i.e. for transition from single-path two-way transmission to single transmission on each of two paths, or vice versa

|  | H04B 1/54 |
· · · | using the same frequency for both directions of communication (Fulltext... Hierarchy... Expanded...H04B 1/44 takes precedence)

|  | H04B 1/56 |
· · · · | with provision for simultaneous communication in both directions

|  | H04B 1/58 |
· · · · | Hybrid arrangements, i.e. for transition from single-path two-way transmission to single transmission on each of two paths, or vice versa

|  | H04B 1/59 |
· | Responders; Transponders (relay systems Fulltext... Hierarchy... Expanded...H04B 7/14)

|  | H04B 1/60 |
· | Supervising unattended repeaters

|  | H04B 1/62 |
· | Modifications of systems to provide a predistortion of the signal in the transmitter and corresponding correction in the receiver, e.g. to improve the signal/noise ratio

|  | H04B 1/64 |
· · | Volume compression or expansion arrangements

|  | H04B 1/66 |
· | Modifications of systems to reduce bandwidth of signals (in pictorial communication or television systems Fulltext... Hierarchy... Expanded...H04N); Modifications of systems to improve efficiency of transmission

|  | H04B 1/68 |
· · | by wholly or partially suppressing the carrier or one side band

|  | H04B 1/70 |
· | using a sub-carrier

|  | H04B 1/72 |
· | Circuits or components for simulating aerials, e.g. dummy aerial (dissipative waveguide terminations Fulltext... Hierarchy... Expanded...H01P 1/26)

|  | H04B 1/74 |
· | Modifications of systems to increase reliability, e.g. using redundant or spare channels or apparatus [3]

|  | H04B 1/76 |
· | Pilot transmitters or receivers for control of transmission or for equalising [3]

|  | H04B 3/00 |
Line transmission systems (combined with near-field transmission systems Fulltext... Hierarchy... Expanded...H04B 5/00; constructional features of cables Fulltext... Hierarchy... Expanded...H01B 11/00)

|  | H04B 3/02 |
· | Details

|  | H04B 3/03 |
· · | Hybrid circuits (for transceivers Fulltext... Hierarchy... Expanded...H04B 1/52, Fulltext... Hierarchy... Expanded...H04B 1/58; hybrid junctions of the waveguide type Fulltext... Hierarchy... Expanded...H01P 5/16) [3]

|  | H04B 3/04 |
· · | Control of transmission; Equalising (control of amplification in general Fulltext... Hierarchy... Expanded...H03G)

|  | H04B 3/06 |
· · · | by the transmitted signal

|  | H04B 3/08 |
· · · · | in negative-feedback path of line amplifier

|  | H04B 3/10 |
· · · | by pilot signal

|  | H04B 3/11 |
· · · · | using pilot wire (Fulltext... Hierarchy... Expanded...H04B 3/12 take precedence) [3]

|  | H04B 3/12 |
· · · · | in negative-feedback path of line amplifier

|  | H04B 3/14 |
· · · | characterised by the equalising network used

|  | H04B 3/16 |
· · · | characterised by the negative-impedance network used

|  | H04B 3/18 |
· · · · | wherein the network comprises semiconductor devices

|  | H04B 3/20 |
· · | Reducing echo effects or singing; Opening or closing transmitting path; Conditioning for transmission in one direction or the other

|  | H04B 3/21 |
· · · | using a set of bandfilters [3]

|  | H04B 3/22 |
( transferred to Fulltext... Hierarchy... Expanded...H04B 3/21, Fulltext... Hierarchy... Expanded...H04B 3/23, covered by Fulltext... Hierarchy... Expanded...H04B 3/20 )

|  | H04B 3/23 |
· · · | using a replica of transmitted signal in the time domain, e.g. echo cancellers [3]

|  | H04B 3/24 |
( transferred to Fulltext... Hierarchy... Expanded...H04B 3/21, Fulltext... Hierarchy... Expanded...H04B 3/23, covered by Fulltext... Hierarchy... Expanded...H04B 3/20 )

|  | H04B 3/26 |
· · | Improving frequency characteristic by the use of loading coils (loading coils per se Fulltext... Hierarchy... Expanded...H01F 17/08)

|  | H04B 3/28 |
· · | Reducing interference caused by currents induced in cable sheathing or armouring

|  | H04B 3/30 |
· · | Reducing interference caused by unbalance current in a normally balanced line

|  | H04B 3/32 |
· · | Reducing cross-talk, e.g. by compensating

|  | H04B 3/34 |
· · · | by systematic interconnection of lengths of cable during laying; by addition of balancing components to cable during laying

|  | H04B 3/36 |
· · | Repeater circuits (Fulltext... Hierarchy... Expanded...H04B 3/58 takes precedence; amplifiers therefor Fulltext... Hierarchy... Expanded...H03F)

|  | H04B 3/38 |
· · · | for signals in two different frequency ranges transmitted in opposite directions over the same transmission path

|  | H04B 3/40 |
· · | Artificial lines; Networks simulating a line of certain length

|  | H04B 3/42 |
· · | Circuits for by-passing of ringing signals

|  | H04B 3/44 |
· · | Arrangements for feeding power to a repeater along the transmission line

|  | H04B 3/46 |
· · | Monitoring; Testing

|  | H04B 3/48 |
· · · | Testing attenuation

|  | H04B 3/50 |
· | Systems for transmission between fixed stations via two-conductor transmission lines (Fulltext... Hierarchy... Expanded...H04B 3/54 takes precedence)

|  | H04B 3/52 |
· | Systems for transmission between fixed stations via waveguides

|  | H04B 3/54 |
· | Systems for transmission via power distribution lines (remote indication of power network conditions, remote control of switching means in a power distribution network Fulltext... Hierarchy... Expanded...H02J 13/00)

|  | H04B 3/56 |
· · | Circuits for coupling, blocking, or by-passing of signals

|  | H04B 3/58 |
· · | Repeater circuits (amplifiers therefor Fulltext... Hierarchy... Expanded...H03F)

|  | H04B 3/60 |
· | Systems for communication between relatively movable stations, e.g. for communication with lift (Fulltext... Hierarchy... Expanded...H04B 3/54 takes precedence)

|  | H04B 5/00 |
Near-field transmission systems, e.g. inductive loop type

|  | H04B 5/02 |
· | using transceiver

|  | H04B 5/04 |
· | Calling systems, e.g. paging system

|  | H04B 5/06 |
· | using a portable transmitter associated with a microphone

|  | H04B 7/00 |
Radio transmission systems, i.e. using radiation field (Fulltext... Hierarchy... Expanded...H04B 9/00, Fulltext... Hierarchy... Expanded...H04B 15/00 take precedence)

|  | H04B 7/005 |
· | Control of transmission; Equalising [3]

|  | H04B 7/01 |
· | Reducing phase shift [3]

|  | H04B 7/015 |
· | Reducing echo effects [3]

|  | H04B 7/02 |
· | Diversity systems (for direction finding Fulltext... Hierarchy... Expanded...G01S 3/72; aerial arrays or systems Fulltext... Hierarchy... Expanded...H01Q)

|  | H04B 7/04 |
· · | using a plurality of spaced independent aerials

|  | H04B 7/06 |
· · · | at transmitting station, e.g. time diversity

|  | H04B 7/08 |
· · · | at receiving station, e.g. space diversity

|  | H04B 7/10 |
· · | using a single aerial system characterised by its polarisation or directive properties, e.g. polarisation diversity, direction diversity

|  | H04B 7/12 |
· · | Frequency-diversity systems

|  | H04B 7/14 |
· | Relay systems (interrogator-responder radar systems Fulltext... Hierarchy... Expanded...G01S 13/74) [2]

|  | H04B 7/145 |
· · | Passive relay systems [2]

|  | H04B 7/15 |
· · | Active relay systems [2]

|  | H04B 7/155 |
· · · | Ground-based stations [2]

|  | H04B 7/165 |
· · · · | employing angle modulation [2]

|  | H04B 7/17 |
· · · · | employing pulse modulation, e.g. pulse code modulation [2]

|  | H04B 7/185 |
· · · | Space-based or airborne stations [2]

|  | H04B 7/19 |
· · · · | Earth-synchronous stations [2]

|  | H04B 7/195 |
· · · · | Non-synchronous stations [2]

|  | H04B 7/22 |
· | Scatter propagation systems

|  | H04B 7/24 |
· | for communication between two or more posts [2]

|  | H04B 7/26 |
· · | at least one of which is mobile [2]

|  | H04B 9/00 |
Transmission systems employing electromagnetic waves other than radio waves, e.g. light, infra-red (controlling, e.g. modulating, of light beams Fulltext... Hierarchy... Expanded...G02F 1/00; demodulating, transferring the modulation, or frequency changing, of light Fulltext... Hierarchy... Expanded...G02F 2/00)

|  | H04B 11/00 |
Transmission systems employing sonic, ultrasonic or infrasonic waves

|  | H04B 12/00 |
Transmission systems characterised by the use of pulse modulation (in radio transmission relays Fulltext... Hierarchy... Expanded...H04B 7/17) [3]

|  | H04B 12/02 |
· | using pulse code modulation (pulse code modulation per se Fulltext... Hierarchy... Expanded...H03K 13/01) [3]

|  | H04B 12/04 |
· | using delta or differential modulation [3]

|  | H04B 13/00 |
Transmission systems not provided for in the preceding groups

|  | H04B 13/02 |
· | 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 Fulltext... Hierarchy... Expanded...H04B 3/00)

|  | H04B 15/00 |
Suppression or limitation of noise or interference (by means associated with receiver Fulltext... Hierarchy... Expanded...H04B 1/10)

|  | H04B 15/02 |
· | Reducing interference from electric apparatus by means located at or near the interfering apparatus (structural association with dynamo-electric machines Fulltext... Hierarchy... Expanded...H02K 11/00)

|  | H04B 15/04 |
· · | the interference being caused by substantially sinusoidal oscillations, e.g. in a receiver, in a tape-recorder (reducing parasitic oscillations Fulltext... Hierarchy... Expanded...H03B, Fulltext... Hierarchy... Expanded...H03F; screening Fulltext... Hierarchy... Expanded...H05K 9/00)

|  | H04B 15/06 |
· · · | by local oscillators of receivers

|  | H04B 17/00 |
Monitoring; Testing [2]

|  | H04B 17/02 |
· | of relay systems [2]