A facsimile system capable of automatically transmitting or receiving the image through a telephone channel is disclosed in which each facsimile set may automatically reset its facsimile recorder and reader when the intercommunication with the other subscriber's facsimile set is interrupted by an accident during the transmission and reception mode. The facsimile set includes means for disconnecting it from the telephone circuit and means for giving an operator suitable alarm or warning signals so that the transmission or reception may be started again from the beginning.
In a data transmission system comprising, for example, a facsimile transmitter connected to a facsimile receiver through a public telephone network, failure or malfunction sensors are provided at the transmitter and receiver which generate failure signals having the same frequency as the telephone network busy signal upon detection of a malfunction. Both the transmitter and receiver reset at high speed to an initial ready-for-transmission status upon reception of a failure signal from either sensor and automatically disconnect from the telephone network. The failure sensor at the receiver preferably comprises means for generating a failure signal when the failure rate of parity or other digital checks exceeds a predetermined value.
In a communication apparatus, if an operator manually operates the apparatus immediately before a designated time preset in the communication apparatus for automatic communication, an alarm is issued and the designated time communication is effected after the manual operation.
A communication system for communicating data such as image data has a transmitter and a receiver connected through a communication line. Each transmitter or receiver has an NCU, a modem, a control unit, a reader, a recorder, and a console unit. A sound output unit for producing a sound representing the state of a received image (the number of errors in the received image data) can be included in the transmitter or the receiver. After an operator at the transmitter sends data, the operator is called and can hear a sound message representing the state of the data received by the receiver.
An abnormality indication system of a facsimile apparatus comprises a pattern generator, disposed in the facsimile apparatus on the reception side, which is capable of producing image element information indicating the abnormality of the facsimile apparatus when the facsimile apparatus is hung up and which applies the abnormality indicating information to a plotter of the facsimile apparatus, instead of an original image information so far applied to the plotter. The abnormality indicating information is written on a recording sheet by the plotter and the recording sheet is then discharged from the plotter.
A sensor circuit for telephone line includes a line current detecting circuit (52, 54) which generates a detection signal in response to a line current flowing in a telephone line (20, 22). The detection signal is applied to a first amplifier (56), and the detection signal as amplified is not only further amplified by a second amplifier (57) but also applied to a tone deriving circuit (60) and a CI detecting circuit (61) via a coupling capacitor (59). The detection signal as amplified twice is applied to a comparing circuit (58) which compares the detection signal from the second amplifier with a first reference voltage (V1) and a second reference voltage (V2), so that a line current supervisory signal is outputted from the comparing circuit. The tone deriving circuit includes a band-pass filter and derives a tone signal from the detection signal from the first amplifier. The CI detecting circuit detects a CI (calling tone) on the basis of the detection signal from the first amplifier.
