GB1495935A - Telephone dialling and signal transmission apparatus - Google Patents

Abstract

1495935 Automatic alarm systems ALPHALAMBDA Ltd 18 March 1975 [21 Dec 1973] 59392/73 Heading H4K In an alarm system wherein the detection of an alarm condition causes a first relay to loop a telephone line and connect an automatic dialling and message sending apparatus to the line, the apparatus comprises a magnetic tape having the dialling information and message information recorded on the same channel, there being recorded on the tape between the dialling information and the message a control signal of different duration from the dialling information and which is used to effect a changeover from a dialling mode to a message mode. The dialling information is stored as a series of 10 ms. bursts of 1 kHz tone which are used to operate an impulsing relay to transmit the digits over a telephone line, and a 500 ms. burst of 1kHz tone is recorded at the end of the dialling information to cause a relay to connect the telephone line to the tape replay head. At the end of the message, which is played without waiting for the called subscriber to answer, a 15-60 second continuous tone is used to cause the telephone line to be disconnected. A plurality of different messages preceded by corresponding dialling information may be recorded on the tape to enable a sequence of messages to be transmitted to different numbers. The tape loop has a stop foil at the end of the loop to cause the apparatus to be shut down, and may be arranged as a cartridge. A detailed description of the circuitry is given (Figs. 1-4, not shown). Figure 4 illustrates a delay circuit for setting off the apparatus after a delay of 2-20 minutes has elapsed from the initiation of an alarm condition. In the event that the apparatus is not in position to make an alarm call, a local alarm may be immediately set off.