|  | G |
SECTION G — PHYSICS

|  | G |
Note(s) In this section, the following term is used with the meaning indicated: "variable" (as a noun) means a feature or property (e.g., a dimension, a physical condition such as temperature, a quality such as density or colour) which, in respect of a particular entity (e.g., an object, a quantity of a substance, a beam of light) and at a particular instant, is capable of being measured; the variable may change, so that its numerical expression may assume different values at different times, in different conditions or in individual cases, but may be constant in respect of a particular entity in certain conditions or for practical purposes (e.g., the length of a bar may be regarded as constant for many purposes). Attention is drawn to the definitions of terms or expressions used, appearing in the notes of several of the classes in this section, in particular those of "measuring" in class Fulltext... Hierarchy... Expanded...G01 and "control" and "regulation" in class Fulltext... Hierarchy... Expanded...G05. Classification in this section may present more difficulty than in other sections, because the distinction between different fields of use rests to a considerable extent on differences in the intention of the user rather than on any constructional differences or differences in the manner of use, and because the subjects dealt with are often in effect systems or combinations, which have features or parts in common, rather than "things", which are readily distinguishable as a whole. For example, information (e.g., a set of figures) may be displayed for the purpose of education or advertising (Fulltext... Hierarchy... Expanded...G09), for enabling the result of a measurement to be known (Fulltext... Hierarchy... Expanded...G01), for signalling the information to a distant point or for giving information which has been signalled from a distant point (Fulltext... Hierarchy... Expanded...G08). The words used to describe the purpose depend on features that may be irrelevant to the form of the apparatus concerned, for example, such features as the desired effect on the person who sees the display, or whether the display is controlled from a remote point. Again, a device which responds to some change in a condition, e.g., in the pressure of a fluid, may be used, without modification of the device itself, to give information about the pressure (Fulltext... Hierarchy... Expanded...G01L) or about some other condition linked to the pressure (another subclass of class Fulltext... Hierarchy... Expanded...G01, e.g., Fulltext... Hierarchy... Expanded...G01K for temperature), to make a record of the pressure or of its occurrence (Fulltext... Hierarchy... Expanded...G07C), to give an alarm (Fulltext... Hierarchy... Expanded...G08B), or to control another apparatus (Fulltext... Hierarchy... Expanded...G05). The classification scheme is intended to enable things of a similar nature (as indicated above) to be classified together. It is therefore particularly necessary for the real nature of any technical subject to be decided before it can be properly classified.

INSTRUMENTS

|  | G08 |
SIGNALLING (indicating or display devices per se Fulltext... Hierarchy... Expanded...G09F; transmission of pictures Fulltext... Hierarchy... Expanded...H04N)

|  | G08B |
SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS (signalling arrangements on vehicles Fulltext... Hierarchy... Expanded...B60Q, Fulltext... Hierarchy... Expanded...B62D 41/00; railway signalling systems or devices Fulltext... Hierarchy... Expanded...B61L; on cycles Fulltext... Hierarchy... Expanded...B62J 3/00, Fulltext... Hierarchy... Expanded...B62J 6/00; safes or strong-rooms with alarm devices Fulltext... Hierarchy... Expanded...E05G; signalling or alarm devices in mines Fulltext... Hierarchy... Expanded...E21F 17/18; lamps or shutters therefor Fulltext... Hierarchy... Expanded...F21; sensitive measuring elements, see the appropriate subclasses of Fulltext... Hierarchy... Expanded...G01; traffic control systems Fulltext... Hierarchy... Expanded...G08G; visual indicating means Fulltext... Hierarchy... Expanded...G09; sound-producing devices Fulltext... Hierarchy... Expanded...G10; radio or near-field calling systems Fulltext... Hierarchy... Expanded...H04B 5/00, Fulltext... Hierarchy... Expanded...H04B 7/00; selecting arrangements Fulltext... Hierarchy... Expanded...H04Q 7/00, Fulltext... Hierarchy... Expanded...H04Q 9/00; loudspeakers, microphones, gramohpone pick-ups or like acoustic electromechanical transducers Fulltext... Hierarchy... Expanded...H04R)

|  | G08B |
Note(s) This subclass covers also means for identifying or incapacitating burglars or the like. This subclass does not cover: the mere provision of an audible or visible signalling device on measuring or switching apparatus; alarm systems for indicating that a specific variable has exceeded, or fallen below, a predetermined value, which are covered by the relevant subclasses of class Fulltext... Hierarchy... Expanded...G01 for the measurement of that variable. alarms for specific processes or types of machines or apparatus, which are covered by the relevant subclasses for the processes, machines, or apparatus. In this subclass, the following term is used with the meaning indicated: "systems" may cover also devices peculiar thereto.

|  | G08B |
Subclass index
SIGNALLING OR CALLING SYSTEMS |
Characterised by the transmission of the signal | 1/00
Characterised by the nature of the indication: audible; visible; tactile; combined | 3/00; 5/00; 6/00; 7/00
ORDER TELEGRAPHS | 9/00
ALARM SYSTEMS |
Responsive to an unspecified condition | 23/00
Responsive to two or more different conditions | 19/00
Responsive to one specified condition: intrusion; fire; other | 13/00, 15/00; 17/00; 21/00
With transmission from or to a central station | 25/00, 26/00, 27/00
Predictive alarm systems | 31/00
CHECKING, MONITORING | 29/00

|  | G08C |
TRANSMISSION SYSTEMS FOR MEASURED VALUES, CONTROL OR SIMILAR SIGNALS (fluid pressure transmission systems Fulltext... Hierarchy... Expanded...F15B; sensing members for specific physical variables, see the relevant subclasses, e.g. of Fulltext... Hierarchy... Expanded...G01, of Fulltext... Hierarchy... Expanded...H01; indicators or recorders, see the relevant subclasses, e.g. Fulltext... Hierarchy... Expanded...G01D, Fulltext... Hierarchy... Expanded...G09F; mechanical means for transferring the output of a sensing member into a different variable Fulltext... Hierarchy... Expanded...G01D 5/00; self-balancing bridges Fulltext... Hierarchy... Expanded...G01R; position control in general Fulltext... Hierarchy... Expanded...G05D 3/00; mechanical control systems Fulltext... Hierarchy... Expanded...G05G; systems for transmitting "on/off" signals only, systems for transmitting alarm conditions Fulltext... Hierarchy... Expanded...G08B; order telegraph systems Fulltext... Hierarchy... Expanded...G08B 9/00; generating electric pulses Fulltext... Hierarchy... Expanded...H03K; coding, decoding or code conversion, in general Fulltext... Hierarchy... Expanded...H03M; transmission of digital information Fulltext... Hierarchy... Expanded...H04L; selective calling from one station to another Fulltext... Hierarchy... Expanded...H04Q 9/00) [4]

|  | G08C |
Subclass index
TRANSMISSION SYSTEMS IN GENERAL |
Electric; non-electric | 19/00; 23/00
SYSTEMS FOR TRANSMITTING THE POSITION OF AN OBJECT | 21/00
ARRANGEMENTS CHARACTERISED BY THE METHOD OF TRANSMISSION |
Multiplex; use of a wireless electrical link | 15/00; 17/00
PROCESSING SIGNALS |
Differentiating, delaying | 13/00
MONITORING, PREVENTING OR CORRECTING ERRORS | 25/00

|  | G08G |
TRAFFIC CONTROL SYSTEMS (guiding railway traffic, ensuring the safety of railway traffic Fulltext... Hierarchy... Expanded...B61L; arrangement of road signs or traffic signals Fulltext... Hierarchy... Expanded...E01F 9/00; radar systems or analogous systems, designed for traffic control Fulltext... Hierarchy... Expanded...G01S 13/91; sonar or lidar systems specially designed for traffic control Fulltext... Hierarchy... Expanded...G01S 15/88, Fulltext... Hierarchy... Expanded...G01S 17/88) [2]

|  | G08G |
Note(s) This subclass covers: identification of traffic offenders; indication of the position of vehicles; indication of free spaces in parking areas.