|  | H |
SECTION H — ELECTRICITY

|  | H |
Note(s) These Notes cover the basic principles and general instructions for use of section H. Section H covers: basic electric elements, which cover all electric units and the general mechanical structure of apparatus and circuits, including the assembly of various basic elements into what are called printed circuits and also cover to a certain extent the manufacture of these elements (when not covered elsewhere); generation of electricity, which covers the generation, conversion and distribution of electricity together with the controlling of the corresponding gear; applied electricity, which covers: general utilisation techniques, viz. those of electric heating and electric lighting circuits; some special utilisation techniques, either electric or electronic in the strict sense, which are not covered by other sections of the Classification, including: electric light sources, including lasers; electric X-ray technique; electric plasma technique and the generation and acceleration of electrically charged particles or neutrons; basic electronic circuits and their control; radio or electric communication technique; the use of a specified material for the manufacture of the article or element described. In this connection, paragraphs 88 to 90 of the Guide should be referred to. In this section, the following general rules apply: Subject to the exceptions stated in I(c), above, any electric aspect or part peculiar to a particular operation, process, apparatus, object or article, classified in one of the sections of the Classification other than section H, is always classified in the subclass for that operation, process, apparatus, object or article. Where common characteristics concerning technical subjects of similar nature have been brought out at class level, the electric aspect or part is classified, in conjunction with the operation, process, apparatus, object or article, in a subclass which covers entirely the general electrical applications for the technical subject in question; The electrical applications referred to under (a), above, either general or particular, include: the therapeutic processes and apparatus, in class Fulltext... Hierarchy... Expanded...A61; the electric processes and apparatus used in various laboratory or industrial operations, in classes Fulltext... Hierarchy... Expanded...B01 and Fulltext... Hierarchy... Expanded...B03 and in subclass Fulltext... Hierarchy... Expanded...B23K; the electricity supply, electric propulsion and electric lighting of vehicles in general and of particular vehicles, in the subsection "Transporting" of section B; the electric ignition systems of internal-combustion engines, in subclass Fulltext... Hierarchy... Expanded...F02P, and of combustion apparatus in general, in subclass Fulltext... Hierarchy... Expanded...F23Q; the whole electrical part of section G, i.e. measuring devices including apparatus for measuring electric variables, checking, signalling and calculating. Electricity in that section is generally dealt with as a means and not as an end in itself; All electrical applications, both general and particular, presuppose that the "basic electricity" aspect appears in section H (see I(a) above) as regards the electric "basic elements" which they comprise. This rule is also valid for applied electricity, referred to in I(c), above, which appears in section H itself. In this section, the following special cases occur: Among the general applications covered by sections other than section H, it is worth noting that electric heating in general is covered by subclasses Fulltext... Hierarchy... Expanded...F24D or Fulltext... Hierarchy... Expanded...F24H or class Fulltext... Hierarchy... Expanded...F27, and that electric lighting in general is partly covered by class Fulltext... Hierarchy... Expanded...F21, since in section H (see I(c), above) there are places in Fulltext... Hierarchy... Expanded...H05B which cover the same technical subjects; In the two cases referred to under (a), above, the subclasses of section F, which deal with the respective subjects, essentially cover in the first place the whole mechanical aspect of the apparatus or devices, whereas the electrical aspect, as such, is covered by subclass Fulltext... Hierarchy... Expanded...H05B; In the case of lighting, this mechanical aspect should be taken to cover the material arrangement of the various electric elements, i.e., their geometrical or physical position in relation to one another; this aspect is covered by subclass Fulltext... Hierarchy... Expanded...F21V, the elements themselves and the primary circuits remaining in section H. The same applies to electric light sources, when combined with light sources of a different kind. These are covered by subclass Fulltext... Hierarchy... Expanded...H05B, whereas the physical arrangement which their combination constitutes is covered by the various subclasses of class Fulltext... Hierarchy... Expanded...F21; As regards heating, not only the electric elements and circuitry designs, as such, are covered by subclass Fulltext... Hierarchy... Expanded...H05B, but also the electric aspects of their arrangement, where these concern cases of general application; electric furnaces being considered as such. The physical disposition of the electric elements in furnaces is covered by section F. If a comparison is made with electric welding circuits, which are covered by subclass Fulltext... Hierarchy... Expanded...B23K in connection with welding, it can be seen that electric heating is not covered by the general rule stated in II, above.

|  | H04 |
ELECTRIC COMMUNICATION TECHNIQUE

|  | H04 |
Note(s) This class covers electrical communication systems with propagation paths employing beams of corpuscular radiation, acoustic waves or electromagnetic waves, e.g. radio or optical communication. [4]

|  | H04L |
TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (typewriters Fulltext... Hierarchy... Expanded...B41J; order telegraphs, fire or police telegraphs Fulltext... Hierarchy... Expanded...G08B; visual telegraphy Fulltext... Hierarchy... Expanded...G08B, Fulltext... Hierarchy... Expanded...G08C; teleautographic systems Fulltext... Hierarchy... Expanded...G08C; ciphering or deciphering apparatus per se Fulltext... Hierarchy... Expanded...G09C; coding, decoding or code conversion, in general Fulltext... Hierarchy... Expanded...H03M; arrangements common to telegraphic and telephonic communication Fulltext... Hierarchy... Expanded...H04M; selecting Fulltext... Hierarchy... Expanded...H04Q) [4]

|  | H04L |
Note(s) This subclass covers transmission of signals having been supplied in digital form and includes data transmission, telegraphic communication, or methods or arrangements for monitoring.

|  | H04L |
Subclass index
SYSTEMS CHARACTERISED BY: |
The code used: Morse; Baudot; details | 15/00; 17/00; 13/00
Otherwise: step by step; mosaic printers; other systems | 19/00; 21/00; 23/00
BASEBAND SYSTEMS | 25/00
MODULATED-CARRIER SYSTEMS | 27/00
DATA SWITCHING NETWORKS | 12/00
ARRANGEMENTS OF GENERAL APPLICATION |
Security: errors; secret | 1/00; 9/00
Multiple communications; synchronising | 5/00; 7/00
OTHER ARRANGEMENTS, APPARATUS OR SYSTEMS | 29/00

P:20 |  | H04L 1/00 |
Arrangements for detecting or preventing errors in the information received (correcting synchronisation Fulltext... Hierarchy... Expanded...H04L 7/00; arrangements in the transmission path Fulltext... Hierarchy... Expanded...H04B)

|  | H04L 1/02 |
· | by diversity reception (in general Fulltext... Hierarchy... Expanded...H04B 7/02)

|  | H04L 1/04 |
· · | using frequency diversity

|  | H04L 1/06 |
· · | using space diversity

|  | H04L 1/08 |
· | by repeating transmission, e.g. Verdan system

|  | H04L 1/12 |
· | by using return channel

|  | H04L 1/14 |
· · | in which the signals are sent back to the transmitter to be checked

|  | H04L 1/16 |
· · | in which the return channel carries supervisory signals, e.g. repetition request signals

|  | H04L 1/18 |
· · · | Automatic repetition systems, e.g. van Duuren system

|  | H04L 1/20 |
· | using signal-quality detector [3]

|  | H04L 1/22 |
· | using redundant apparatus to increase reliability [3]

|  | H04L 1/24 |
· | Testing correct operation [3]

P:110 |  | H04L 5/00 |
Arrangements affording multiple use of the transmission path (multiplex communication in general Fulltext... Hierarchy... Expanded...H04J)

|  | H04L 5/02 |
· | Channels characterised by the type of signal

|  | H04L 5/04 |
· · | the signals being represented by different amplitudes or polarities, e.g. quadriplex

|  | H04L 5/06 |
· · | the signals being represented by different frequencies (combined with time-division multiplexing Fulltext... Hierarchy... Expanded...H04L 5/26)

|  | H04L 5/08 |
· · · | each combination of signals in different channels being represented by a fixed frequency

|  | H04L 5/10 |
· · · | with dynamo-electric generation of carriers; with mechanical filters or demodulators

|  | H04L 5/12 |
· · | the signals being represented by different phase modulations of a single carrier

|  | H04L 5/14 |
· | Two-way operation using the same type of signal, i.e. duplex (conditioning for two-way transmission in general Fulltext... Hierarchy... Expanded...H04B 3/20)

|  | H04L 5/16 |
· · | Half-duplex systems; Simplex/duplex switching; Transmission of break signals

|  | H04L 5/18 |
· · | Automatic changing of the traffic direction

|  | H04L 5/20 |
· | using different combinations of lines, e.g. phantom working

|  | H04L 5/22 |
· | using time-division multiplexing

|  | H04L 5/24 |
· · | with start-stop synchronous converters

|  | H04L 5/26 |
· · | combined with the use of different frequencies

P:130 |  | H04L 7/00 |
Arrangements for synchronising receiver with transmitter

|  | H04L 7/02 |
· | Speed or phase control by the received code signals, the signals containing no special synchronisation information

|  | H04L 7/027 |
· · | extracting the synchronising or clock signal from the received signal spectrum, e.g. by using a resonant or bandpass circuit [5]

|  | H04L 7/033 |
· · | using the transitions of the received signal to control the phase of the synchronising-signal- generating means, e.g. using a phase-locked loop [5]

|  | H04L 7/04 |
· | Speed or phase control by synchronisation signals

|  | H04L 7/06 |
· · | the synchronisation signals differing from the information signals in amplitude, polarity, or frequency

|  | H04L 7/08 |
· · | the synchronisation signals recurring cyclically

|  | H04L 7/10 |
· · | Arrangements for initial synchronisation

P:10 |  | H04L 9/00 |
Arrangements for secret or secure communication (spread spectrum techniques in general Fulltext... Hierarchy... Expanded...H04B 1/69)

|  | H04L 9/06 - H04L 9/32 |
Note(s) In group Fulltext... Hierarchy... Expanded...Fulltext... Hierarchy... Expanded...H04L 9/06-H04L 9/32, in the absence of an indication to the contrary, classification is made in the last appropriate place. [5]

|  | H04L 9/06 |
· | the encryption apparatus using shift registers or memories for blockwise coding, e.g. D.E.S. systems [5]

|  | H04L 9/08 |
· · | Key distribution [5]

|  | H04L 9/10 |
· | with particular housing, physical features or manual controls [5]

|  | H04L 9/12 |
· | Transmitting and receiving encryption devices synchronised or initially set up in a particular manner [5]

|  | H04L 9/14 |
· | using a plurality of keys or algorithms [5]

|  | H04L 9/16 |
· · | the keys or algorithms being changed during operation [5]

|  | H04L 9/18 |
· | Encryption by serially and continuously modifying data stream elements, e.g. stream cipher systems [5]

|  | H04L 9/20 |
· · | Pseudorandom key sequence combined element-for-element with data sequence [5]

|  | H04L 9/22 |
· · · | with particular pseudorandom sequence generator [5]

|  | H04L 9/24 |
· · · · | sequence produced by more than one generator [5]

|  | H04L 9/26 |
· · · · | producing a nonlinear pseudorandom sequence [5]

|  | H04L 9/28 |
· | using particular encryption algorithm [5]

|  | H04L 9/30 |
· · | Public key, i.e. encryption algorithm being computationally infeasible to invert and users' encryption keys not requiring secrecy [5]

|  | H04L 9/32 |
· | including means for verifying the identity or authority of a user of the system (computer systems Fulltext... Hierarchy... Expanded...G06F; coin-freed or like apparatus with coded identity card or credit card Fulltext... Hierarchy... Expanded...G07F 7/08) [5]

|  | H04L 9/34 |
· | Bits, or blocks of bits, of the telegraphic message being interchanged in time [5]

|  | H04L 9/36 |
· | with means for detecting characters not meant for transmission [5]

|  | H04L 9/38 |
· | Encryption being effected by mechanical apparatus, e.g. rotating cams, switches, keytape punchers [5]

P:120 |  | H04L 12/00 |
Data switching networks (interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units Fulltext... Hierarchy... Expanded...G06F 13/00) [5]

|  | H04L 12/02 |
· | Details [5]

|  | H04L 12/04 |
· · | Switchboards [5]

|  | H04L 12/06 |
· · | Answer-back mechanisms or circuits [5]

|  | H04L 12/08 |
· · | Allotting numbers to messages; Counting characters, words or messages [5]

|  | H04L 12/10 |
· · | Current supply arrangements [5]

|  | H04L 12/12 |
· · | Arrangements for remote connection or disconnection of substations or of equipment thereof [5]

|  | H04L 12/14 |
· · | Charging arrangements [5]

|  | H04L 12/16 |
· · | Arrangements for providing special services to substations [5]

|  | H04L 12/18 |
· · · | for broadcast or conference [5]

|  | H04L 12/20 |
· · · | for converting transmission speed from the inherent speed of a substation to the inherent speed of other substations [5]

|  | H04L 12/22 |
· · | Arrangements for preventing the taking of data from a data transmission channel without authorisation (means for verifying the identity or the authority of a user of a secure or secret communication system Fulltext... Hierarchy... Expanded...H04L 9/32) [5]

|  | H04L 12/24 |
· · | Arrangements for maintenance or administration [5]

|  | H04L 12/26 |
· · | Monitoring arrangements; Testing arrangements [5]

|  | H04L 12/28 |
· | characterised by path configuration, e.g. local area networks (LAN), wide area networks (WAN) [5,6]

|  | H04L 12/40 |
· · | Bus networks [5,6]

|  | H04L 12/403 |
· · · | with centralised control, e.g. polling [6]

|  | H04L 12/407 |
· · · | with decentralised control [6]

|  | H04L 12/413 |
· · · · | with random access, e.g. carrier-sense multiple-access with collision detection (CSMA-CD) [6]

|  | H04L 12/417 |
· · · · | with deterministic access, e.g. token passing [6]

|  | H04L 12/42 |
· · | Loop networks [5,6]

|  | H04L 12/423 |
· · · | with centralised control, e.g. polling [6]

|  | H04L 12/427 |
· · · | with decentralised control [6]

|  | H04L 12/43 |
· · · · | with synchronous transmission, e.g. time division multiplex (TDM), slotted rings [6]

|  | H04L 12/433 |
· · · · | with asynchronous transmission, e.g. token ring, register insertion [6]

|  | H04L 12/437 |
· · · | Ring fault isolation or reconfiguration [6]

|  | H04L 12/44 |
· · | Star or tree networks [5,6]

|  | H04L 12/46 |
· · | Interconnection of networks [5,6]

|  | H04L 12/50 |
· | Circuit switching systems, i.e. systems in which the path is physically permanent during the communication [5,6]

|  | H04L 12/52 |
· · | using time division techniques (in digital transmission systems Fulltext... Hierarchy... Expanded...H04L 5/22) [5,6]

|  | H04L 12/54 |
· | Stored and forward switching systems [5,6]

|  | H04L 12/56 |
· · | Packet switching systems [5,6]

|  | H04L 12/58 |
· · | Message switching systems (permutation- code selecting Fulltext... Hierarchy... Expanded...H04Q 3/02) [5,6]

|  | H04L 12/60 |
· · · | Manual relay systems, e.g. push-button switching [5,6]

|  | H04L 12/62 |
· · · · | with perforated tape storage [5,6]

|  | H04L 12/64 |
· | Hybrid switching systems [5,6]

|  | H04L 12/66 |
· | Arrangements for connecting between networks having differing types of switching systems, e.g. gateways [5,6]

P:50 |  | H04L 13/00 |
Details of the apparatus or circuits covered by groups Fulltext... Hierarchy... Expanded...H04L 15/00 or Fulltext... Hierarchy... Expanded...H04L 17/00

|  | H04L 13/02 |
· | Details not particular to receiver or transmitter

|  | H04L 13/04 |
· · | Driving mechanisms; Clutches (in general Fulltext... Hierarchy... Expanded...F16)

|  | H04L 13/06 |
· · | Tape or page guiding or feeding devices

|  | H04L 13/08 |
· · | Intermediate storage means

|  | H04L 13/10 |
· · | Distributors

|  | H04L 13/12 |
· · · | Non-mechanical distributors, e.g. relay distributors

|  | H04L 13/14 |
· · · · | Electronic distributors (in general Fulltext... Hierarchy... Expanded...H03K 17/00)

|  | H04L 13/16 |
· | of transmitters, e.g. code-bars, code-discs

|  | H04L 13/18 |
· | of receivers

P:40 |  | H04L 15/00 |
Apparatus or local circuits for transmitting or receiving dot-and-dash codes, e.g. Morse code (teaching apparatus therefor Fulltext... Hierarchy... Expanded...G09B; keyboard switches in general Fulltext... Hierarchy... Expanded...H01H 13/70, Fulltext... Hierarchy... Expanded...H03K 17/94; telegraph tapping keys Fulltext... Hierarchy... Expanded...H01H 21/86; coding in connection with keyboards or like devices, in general Fulltext... Hierarchy... Expanded...H03M 11/00)

|  | H04L 15/03 |
· | Keys structurally combined with sound generators [2]

|  | H04L 15/04 |
· | Apparatus or circuits at the transmitting end

|  | H04L 15/06 |
· · | with a restricted number of keys, e.g. separate key for each type of code element

|  | H04L 15/08 |
· · · | with a single key which transmits dots in one position and dashes in a second position

|  | H04L 15/10 |
· · · | combined with perforating apparatus

|  | H04L 15/12 |
· · | with keyboard co-operating with code-bars

|  | H04L 15/14 |
· · · | combined with perforating apparatus

|  | H04L 15/16 |
· · | with keyboard co-operating with code discs

|  | H04L 15/18 |
· · | Automatic transmitters, e.g. controlled by perforated tape

|  | H04L 15/20 |
· · · | with optical sensing means

|  | H04L 15/22 |
· · | Apparatus or circuits for sending one or a restricted number of signals, e.g. distress signals

|  | H04L 15/24 |
· | Apparatus or circuits at the receiving end

|  | H04L 15/26 |
· · | operating only on reception of predetermined code signals, e.g. distress signals, party-line call signals

|  | H04L 15/28 |
· · | Code reproducing apparatus

|  | H04L 15/30 |
· · · | Writing recorders

|  | H04L 15/32 |
· · · | Perforating recorders

|  | H04L 15/34 |
· · | Apparatus for recording received coded signals after translation, e.g. as type-characters

P:30 |  | H04L 17/00 |
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 Fulltext... Hierarchy... Expanded...H01H 13/70, Fulltext... Hierarchy... Expanded...H03K 17/94; coding in connection with keyboards or like devices, in general Fulltext... Hierarchy... Expanded...H03M 11/00)

|  | H04L 17/02 |
· | Apparatus or circuits at the transmitting end

|  | H04L 17/04 |
· · | with keyboard co-operating with code-bars

|  | H04L 17/06 |
· · · | Contact operating means

|  | H04L 17/08 |
· · · | combined with perforating apparatus

|  | H04L 17/10 |
· · | with keyboard co-operating with code-discs

|  | H04L 17/12 |
· · | Automatic transmitters, e.g. controlled by perforated tape

|  | H04L 17/14 |
· · · | with optical sensing means

|  | H04L 17/16 |
· | Apparatus or circuits at the receiving end

|  | H04L 17/18 |
· · | Code selection mechanisms

|  | H04L 17/20 |
· · | using perforating recorders

|  | H04L 17/22 |
· · | using mechanical translation and type-bar printing

|  | H04L 17/24 |
· · | using mechanical translation and type-head printing, e.g. type-wheel, type-cylinder

|  | H04L 17/26 |
· · | using aggregate motion translation

|  | H04L 17/28 |
· · | using pneumatic or hydraulic translation

|  | H04L 17/30 |
· · | using electric or electronic translation

P:70 |  | H04L 19/00 |
Apparatus or local circuits for step-by-step systems

P:60 |  | H04L 21/00 |
Apparatus or local circuits for mosaic printer telegraph systems

|  | H04L 21/02 |
· | at the transmitting end

|  | H04L 21/04 |
· | at the receiving end

P:80 |  | H04L 23/00 |
Apparatus or local circuits for systems other than those covered by groups Fulltext... Hierarchy... Expanded...Fulltext... Hierarchy... Expanded...H04L 15/00-H04L 21/00

|  | H04L 23/02 |
· | adapted for orthogonal signalling [2]

P:90 |  | H04L 25/00 |
Baseband systems

|  | H04L 25/02 |
· | Details (circuits in general for handling pulses Fulltext... Hierarchy... Expanded...H03K; in line transmission systems in general Fulltext... Hierarchy... Expanded...H04B 3/02)

|  | H04L 25/03 |
· · | Shaping networks in transmitter or receiver, e.g. adaptive shaping networks (impedance networks per se Fulltext... Hierarchy... Expanded...H03H) [2]

|  | H04L 25/04 |
· · · | Passive shaping networks [2]

|  | H04L 25/05 |
· · | Electric or magnetic storage of signals before transmitting or retransmitting for changing the transmission rate [7]

|  | H04L 25/06 |
· · | Dc level restoring means; Bias distortion correction

|  | H04L 25/08 |
· · | Modifications for reducing interference; Modifications for reducing effects due to line faults

|  | H04L 25/10 |
· · | Compensating for variations in line balance

|  | H04L 25/12 |
· · | Compensating for variations in line impedance

|  | H04L 25/14 |
· · | Channel dividing arrangements

|  | H04L 25/17 |
· · | Interpolating arrangements [4]

|  | H04L 25/18 |
· · | Arrangements for inductively generating telegraphic signals (induction coil interrupters Fulltext... Hierarchy... Expanded...H01H 51/34; dynamo-electric generators Fulltext... Hierarchy... Expanded...H02K)

|  | H04L 25/20 |
· · | Repeater circuits; Relay circuits

|  | H04L 25/22 |
· · · | Repeaters for converting two wires to four wires (in general Fulltext... Hierarchy... Expanded...H04B); Repeaters for converting single current to double current

|  | H04L 25/24 |
· · · | Relay circuits using discharge tubes or semiconductor devices

|  | H04L 25/26 |
· · · | Circuits with optical sensing means

|  | H04L 25/28 |
· · · | Repeaters using modulation and subsequent demodulation

|  | H04L 25/30 |
· | Non-synchronous systems

|  | H04L 25/32 |
· · | characterised by the code employed

|  | H04L 25/34 |
· · · | using three or more different amplitudes, e.g. cable code

|  | H04L 25/38 |
· | Synchronous or start-stop systems, e.g. for Baudot code

|  | H04L 25/40 |
· · | Transmitting circuits; Receiving circuits (repeater circuits, relay circuits Fulltext... Hierarchy... Expanded...H04L 25/52)

|  | H04L 25/42 |
· · · | using mechanical distributors

|  | H04L 25/44 |
· · · | using relay distributors

|  | H04L 25/45 |
· · · | using electronic distributors (electronic distributors in general Fulltext... Hierarchy... Expanded...H03K 17/00) [2]

|  | H04L 25/46 |
· · · | using tuning forks or vibrating reeds

|  | H04L 25/48 |
· · · | characterised by the code employed (Fulltext... Hierarchy... Expanded...H04L 25/49 takes precedence) [2]

|  | H04L 25/49 |
· · · | 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]

|  | H04L 25/493 |
· · · · | by transition coding, i.e. the time-position or direction of a transition being encoded before transmission [3]

|  | H04L 25/497 |
· · · · | by correlative coding, e.g. partial response coding or echo modulation coding [3]

|  | H04L 25/52 |
· · | Repeater circuits; Relay circuits

|  | H04L 25/54 |
· · · | using mechanical distributors

|  | H04L 25/56 |
· · · | Non-electrical regenerative repeaters

|  | H04L 25/58 |
· · · | using relay distributors

|  | H04L 25/60 |
· · · | Regenerative repeaters with electromagnetic switches

|  | H04L 25/62 |
· · · | using tuning forks or vibrating reeds

|  | H04L 25/64 |
· · · | Start-stop regenerative repeaters using discharge tubes or semiconductor devices

|  | H04L 25/66 |
· · · | Synchronous repeaters using discharge tubes or semiconductor devices

P:100 |  | H04L 27/00 |
Modulated-carrier systems

|  | H04L 27/01 |
· | Equalisers [5]

|  | H04L 27/02 |
· | Amplitude-modulated carrier systems, e.g. using on/off keying; Single sideband or vestigial sideband modulation (Fulltext... Hierarchy... Expanded...H04L 27/32 takes precedence) [2,5]

|  | H04L 27/04 |
· · | Modulator circuits (in general Fulltext... Hierarchy... Expanded...H03C); Transmitter circuits

|  | H04L 27/06 |
· · | Demodulator circuits (in general Fulltext... Hierarchy... Expanded...H03D); Receiver circuits

|  | H04L 27/08 |
· · | Amplitude regulation arrangements

|  | H04L 27/10 |
· | Frequency-modulated carrier systems, i.e. using frequency-shift keying (Fulltext... Hierarchy... Expanded...H04L 27/32 takes precedence) [5]

|  | H04L 27/12 |
· · | Modulator circuits (in general Fulltext... Hierarchy... Expanded...H03C); Transmitter circuits

|  | H04L 27/14 |
· · | Demodulator circuits (in general Fulltext... Hierarchy... Expanded...H03D); Receiver circuits

|  | H04L 27/144 |
· · · | with demodulation using spectral properties of the received signal, e.g. by using frequency selective- or frequency sensitive elements [6]

|  | H04L 27/148 |
· · · · | using filters, including PLL-type filters [6]

|  | H04L 27/152 |
· · · · | using controlled oscillators, e.g. PLL arrangements [6]

|  | H04L 27/156 |
· · · | with demodulation using temporal properties of the received signal, e.g. detecting pulse width [6]

|  | H04L 27/16 |
· · | Frequency regulation arrangements

|  | H04L 27/18 |
· | Phase-modulated carrier systems, i.e. using phase-shift keying (Fulltext... Hierarchy... Expanded...H04L 27/32 takes precedence) [5]

|  | H04L 27/20 |
· · | Modulator circuits (in general Fulltext... Hierarchy... Expanded...H03C); Transmitter circuits

|  | H04L 27/22 |
· · | Demodulator circuits (in general Fulltext... Hierarchy... Expanded...H03D); Receiver circuits

|  | H04L 27/227 |
· · · | using coherent demodulation [6]

|  | H04L 27/233 |
· · · | using non-coherent demodulation [6]

|  | H04L 27/24 |
· · | Half-wave signalling systems

|  | H04L 27/26 |
· | Systems using multi-frequency codes (Fulltext... Hierarchy... Expanded...H04L 27/32 takes precedence) [5]

|  | H04L 27/28 |
· · | with simultaneous transmission of different frequencies each representing one code element

|  | H04L 27/30 |
· · | wherein each code element is represented by a combination of frequencies

|  | H04L 27/32 |
· | Carrier systems characterised by combinations of two or more of the types covered by groups Fulltext... Hierarchy... Expanded...H04L 27/02, Fulltext... Hierarchy... Expanded...H04L 27/10, Fulltext... Hierarchy... Expanded...H04L 27/18, or Fulltext... Hierarchy... Expanded...H04L 27/26 [5]

|  | H04L 27/34 |
· · | Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems [5]

|  | H04L 27/36 |
· · · | Modulator circuits; Transmitter circuits [5]

|  | H04L 27/38 |
· · · | Demodulator circuits; Receiver circuits [5]

P:0 |  | H04L 29/00 |
Arrangements, apparatus, circuits or systems, not covered by a single one of groups Fulltext... Hierarchy... Expanded...Fulltext... Hierarchy... Expanded...H04L 1/00-H04L 27/00 (interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units Fulltext... Hierarchy... Expanded...G06F 13/00) [5]

|  | H04L 29/02 |
· | Communication control; Communication processing (Fulltext... Hierarchy... Expanded...H04L 29/12, Fulltext... Hierarchy... Expanded...H04L 29/14 take precedence) [5]

|  | H04L 29/04 |
· · | for plural communication lines [5]

|  | H04L 29/06 |
· · | characterised by a protocol [5]

|  | H04L 29/08 |
· · · | Transmission control procedure, e.g. data link level control procedure [5]

|  | H04L 29/10 |
· · | characterised by an interface, e.g. the interface between the data link level and the physical level [5]

|  | H04L 29/12 |
· | characterised by the data terminal [5]

|  | H04L 29/14 |
· | Counter-measures to a fault [5]