IPC 6 English version H04L 13/00-H04L 29/14

H04L01300-H04L02914

SECTION H– ELECTRICITY

H 04

ELECTRIC COMMUNICATION TECHNIQUE

H 04 L

TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (typewriters B 41 J; order telegraphs, fire or police telegraphs G 08 B; visual telegraphy G 08 B, G 08 C; teleautographic systems G 08 C; ciphering or deciphering apparatus per se G 09 C; coding, decoding or code conversion, in general H 03 M; arrangements common to telegraphic and telephonic communication H 04 M; selecting H 04 Q) [4]

13/

Details of the apparatus or circuits covered by groups H 04 L 15/00 or H 04 L 17/00

13/

Details not particular to receiver or transmitter

13/

Driving mechanisms; Clutches (in general F 16)

13/

Tape or page guiding or feeding devices

13/

Intermediate storage means

13/

Distributors

13/

Non-mechanical distributors, e.g. relay distributors

13/

Electronic distributors (in general H 03 K 17/00)

13/

of transmitters, e.g. code-bars, code-discs

13/

of receivers

15/

Apparatus or local circuits for transmitting or receiving dot-and-dash codes, e.g. Morse code (teaching apparatus therefor G 09 B; keyboard switches in general H 01 H 13/70, H 03 K 17/94; telegraph tapping keys H 01 H 21/86; coding in connection with keyboards or like devices, in general H 03 M 11/00)

15/

Keys structurally combined with sound generators [2]

15/

Apparatus or circuits at the transmitting end

15/

with a restricted number of keys, e.g. separate key for each type of code element

15/

with a single key which transmits dots in one position and dashes in a second position

15/

combined with perforating apparatus

15/

with keyboard co-operating with code-bars

15/

combined with perforating apparatus

15/

with keyboard co-operating with code discs

15/

Automatic transmitters, e.g. controlled by perforated tape

15/

with optical sensing means

15/

Apparatus or circuits for sending one or a restricted number of signals, e.g. distress signals

15/

Apparatus or circuits at the receiving end

15/

operating only on reception of predetermined code signals, e.g. distress signals, party-line call signals

15/

Code reproducing apparatus

15/

Writing recorders

15/

Perforating recorders

15/

Apparatus for recording received coded signals after translation, e.g. as type-characters

17/

Apparatus or local circuits for transmitting or receiving codes wherein each character is represented by the same number of equal-length code elements, e.g. Baudot code (keyboard switches in general H 01 H 13/70, H 03 K 17/94; coding in connection with keyboards or like devices, in general H 03 M 11/00)

17/

Apparatus or circuits at the transmitting end

17/

with keyboard co-operating with code-bars

17/

Contact operating means

17/

combined with perforating apparatus

17/

with keyboard co-operating with code-discs

17/

Automatic transmitters, e.g. controlled by perforated tape

17/

with optical sensing means

17/

Apparatus or circuits at the receiving end

17/

Code selection mechanisms

17/

using perforating recorders

17/

using mechanical translation and type-bar printing

17/

using mechanical translation and type-head printing, e.g. type-wheel, type-cylinder

17/

using aggregate motion translation

17/

using pneumatic or hydraulic translation

17/

using electric or electronic translation

19/

Apparatus or local circuits for step-by-step systems

21/

Apparatus or local circuits for mosaic printer telegraph systems

21/

at the transmitting end

21/

at the receiving end

23/

Apparatus or local circuits for systems other than those covered by groups H 04 L 15/00 to H 04 L 21/00

23/

adapted for orthogonal signalling [2]

25/

Dc systems

25/

Details (circuits in general for handling pulses H 03 K; in line transmission systems in general H 04 B 3/02)

25/

Shaping networks in transmitter or receiver, e.g. adaptive shaping networks (impedance networks per se H 03 H) [2]

25/

Passive shaping networks [2]

25/

Dc level restoring means; Bias distortion correction

25/

Modifications for reducing interference; Modifications for reducing effects due to line faults

25/

Compensating for variations in line balance

25/

Compensating for variations in line impedance

25/

Channel dividing arrangements

25/

Interpolating arrangements [4]

25/

Arrangements for inductively generating telegraphic signals (induction coil interrupters H 01 H 51/34; dynamo-electric generators H 02 K)

25/

Repeater circuits; Relay circuits

25/

Repeaters for converting two wires to four wires (in general H 04 B); Repeaters for converting single current to double current

25/

Relay circuits using discharge tubes or semiconductor devices

25/

Circuits with optical sensing means

25/

Repeaters using modulation and subsequent demodulation

25/

Non-synchronous systems

25/

characterised by the code employed

25/

using three or more different amplitudes, e.g. cable code

25/

with electric or magnetic storage of the signals before transmitting or receiving to increase transmission speed

25/

Synchronous or start-stop systems, e.g. for Baudot code

25/

Transmitting circuits; Receiving circuits (repeater circuits, relay circuits H 04 L 25/52)

25/

using mechanical distributors

25/

using relay distributors

25/

using electronic distributors (electronic distributors in general H 03 K 17/00) [2]

25/

using tuning forks or vibrating reeds

25/

characterised by the code employed (H 04 L 25/49 takes precedence) [2]

25/

using code conversion at the transmitter; using predistortion; using insertion of idle bits for obtaining a desired frequency spectrum; using three or more amplitude levels [2]

25/

493

by transition coding, i.e. the time-position or direction of a transition being encoded before transmission [3]

25/

497

by correlative coding, e.g. partial response coding or echo modulation coding [3]

25/

with electric or magnetic storage of the signals before transmitting or receiving to increase transmission speed

25/

Repeater circuits; Relay circuits

25/

using mechanical distributors

25/

Non-electrical regenerative repeaters

25/

using relay distributors

25/

Regenerative repeaters with electromagnetic switches

25/

using tuning forks or vibrating reeds

25/

Start-stop regenerative repeaters using discharge tubes or semiconductor devices

25/

Synchronous repeaters using discharge tubes or semiconductor devices

27/

Ac systems

27/

Equalisers [5]

27/

Amplitude-modulated carrier systems, e.g. using on/off keying; Single sideband or vestigial sideband modulation (H 04 L 27/32 takes precedence) [2,5]

27/

Modulator circuits (in general H 03 C); Transmitter circuits

27/

Demodulator circuits (in general H 03 D); Receiver circuits

27/

Amplitude regulation arrangements

27/

Frequency-modulated carrier systems, i.e. using frequency-shift keying (H 04 L 27/32 takes precedence) [5]

27/

Modulator circuits (in general H 03 C); Transmitter circuits

27/

Demodulator circuits (in general H 03 D); Receiver circuits

27/

144

with demodulation using spectral properties of the received signal, e.g. by using frequency selective- or frequency sensitive elements [6]

27/

148

using filters, including PLL-type filters [6]

27/

152

using controlled oscillators, e.g. PLL arrangements [6]

27/

156

with demodulation using temporal properties of the received signal, e.g. detecting pulse width [6]

27/

Frequency regulation arrangements

27/

Phase-modulated carrier systems, i.e. using phase-shift keying (H 04 L 27/32 takes precedence) [5]

27/

Modulator circuits (in general H 03 C); Transmitter circuits

27/

Demodulator circuits (in general H 03 D); Receiver circuits

27/

227

using coherent demodulation [6]

27/

233

using non-coherent demodulation [6]

27/

Half-wave signalling systems

27/

Systems using multi-frequency codes (H 04 L 27/32 takes precedence) [5]

27/

with simultaneous transmission of different frequencies each representing one code element

27/

wherein each code element is represented by a combination of frequencies

27/

Carrier systems characterised by combinations of two or more of the types covered by groups H 04 L 27/02, H 04 L 27/10, H 04 L 27/18, or H 04 L 27/26 [5]

27/

Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems [5]

27/

Modulator circuits; Transmitter circuits [5]

27/

Demodulator circuits; Receiver circuits [5]

29/

Arrangements, apparatus, circuits or systems, not covered by a single one of groups H 04 L 1/00 to H 04 L 27/00 (interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units G 06 F 13/00) [5]

29/

Communication control; Communication processing (H 04 L 29/12, H 04 L 29/14 take precedence) [5]

29/

for plural communication lines [5]

29/

characterised by a protocol [5]

29/

Transmission control procedure, e.g. data link level control procedure [5]

29/

characterised by an interface, e.g. the interface between the data link level and the physical level [5]

29/

characterised by the data terminal [5]

29/

Counter-measures to a fault [5]

H04L - H04L 12/66