This class covers electrical communication systems with propagation paths employing light (optical communication), infra-red, ultrasonic, sonic, or infrasonic waves.
This subclass covers 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.
circuits or apparatus for combining or dividing signals for the purpose of transmitting them simultaneously or sequentially over the same transmission path;
In this subclass, the following expression is used with the meaning indicated:
"secret communication" includes secret line and radiation transmission systems, i.e. those in which apparatus at the transmitting station modifies the signal in such a way that the information cannot be intelligibly received without corresponding modifying apparatus at the receiving station.
This subclass covers transmission of signals having been supplied in digital form and includes data transmission, telegraphic communication, or methods or arrangements for monitoring.
transmission of pictures or their transient or permanent reproduction either locally or remotely, by methods involving both the following steps:
step (a): the scanning of a picture, i.e. resolving the whole picture-containing area into individual picture-elements and the derivation of picture-representative electric signals related thereto, simultaneously or in sequence;
step (b): the reproduction of the whole picture-containing area by the reproduction of individual picture-elements into which the picture is resolved by means of picture-representative electric signals derived therefrom, simultaneously or in sequence;
(in group Fulltext... Hierarchy... Expanded...H04N 1/00) systems for the transmission or the reproduction of arbitrarily composed pictures or patterns in which the local light variations composing a picture are not subject to variation with time, e.g. documents (both written and printed), maps, charts, photographs (other than cinematograph films);
circuits specially designed for dealing with pictorial communication signals, e.g. television signals, as distinct from merely signals of a particular frequency range.
systems in which legible alphanumeric or like character forms are analysed according to step (a) of Note (1) to derive an electric signal from which the character is recognised by comparison with stored information, which are covered by subclass Fulltext... Hierarchy... Expanded...G06K;
systems for the direct photographic copying of an original picture in which an electric signal representative of the picture is derived according to the said step (a) and employed to modify the operation of the system, e.g. to control exposure, which are covered by class Fulltext... Hierarchy... Expanded...G03;
systems for the reproduction according to step (b) of Note (1) of pictures comprising alphanumeric or like character forms but involving the production of the equivalent of a signal which would be derived according to the above-mentioned step (a), e.g. by cams, punched card or tape, coded control signal, or other means, which are covered by the subclass for the application, e.g. Fulltext... Hierarchy... Expanded...G01D, Fulltext... Hierarchy... Expanded...G06F, Fulltext... Hierarchy... Expanded...H04L;
systems for the reproduction according to the above-mentioned step (b) of pictures comprising alphanumeric or like character forms and involving the generation according to the above-mentioned step (a) of picture-representative electric signals from a pre-arranged assembly of such characters, or records thereof, forming an integral part of the systems, which are covered by the subclass for the application, e.g. Fulltext... Hierarchy... Expanded...B41B, Fulltext... Hierarchy... Expanded...G06K, subject to those applications which are covered by this subclass;
In this subclass, the following expression is used with the meaning indicated:
"television systems" means those systems for the transmission and reproduction of arbitrarily composed pictures in which the local light variations composing a picture may change with time, e.g. natural "live" scenes, recordings of such scenes such as cinematograph films.
methods, circuits, or apparatus for establishing selectively a connection between a desired number of stations (normally two), or between a main station and a desired number of substations (normally one) for the purpose of transferring information via this connection after it has been established;
selective calling arrangements over connections already established. In either case, the connection may be by means of electric conductors or electromagnetic waves.
In this subclass, the following terms or expressions are used with the meanings indicated:
"subscriber" is ageneral term for terminal equipment, e.g. telephone for public use;
"substation" means a subscriber or monitoring equipment which may connect a single subscriber to a line without choice as to subscriber;
"satellite" is a kind of exchange the operation of which depends upon control signals received from a supervisory exchange;
"switching centres" includes exchanges and satellites.
instruments capable of converting sonic, ultrasonic, or infrasonic waves, or other mechanical vibrations into variations of electric current or voltage or vice versa;
instruments actuated by variations of electric current or voltage for cutting grooves in records;
circuits for the above-mentioned instruments;
deaf-aid sets;
public address systems;
monitoring or testing the above-mentioned equipment.