Telephonic communications – Audio message storage – retrieval – or synthesis
Patent
1989-01-13
1992-03-17
Brown, Thomas W.
Telephonic communications
Audio message storage, retrieval, or synthesis
379 63, 455 54, H04M 1100
Patent
active
050975005
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to radio telephone systems and, more particularly, to a radio telephone system which allows the easy modification of identification code (ID code).
BACKGROUND ART
A prior art system of the type referred to is arranged as shown in FIG. 11.
A base unit 1, which is coupled through a radio communication circuit to a wireless set 2, is also connected to a wire telephone line 3.
The outline of the operation of the base unit 1 will be explained in the following.
A signal transmitted from the wire telephone line 3 is applied through a line relay 33 and a hybrid circuit 4 to a transmitter 5 to be modulated thereat and to obtain modulated radio waves. The modulated radio waves are sent through an antenna duplexer 6 to an antenna 7 to be transmitted from the antenna to the radio telephone set 2.
Radio waves transmitted from the radio telephone set 2, on the other hand, are received at the antenna 7 and then sent through the antenna duplexer 6 to a receiver 8 to be demodulated therein and to obtain a demodulated signal. The demodulated signal is sent onto the wire telephone line 3 through the hybrid circuit 4 and the line relay 33.
A synthesizer 9 outputs a frequency corresponding to a radio channel to the transmitter 5 and the receiver 8.
One output of the receiver 8 is applied to a received-electric-field detecting circuit 10 to determine the intensity of the received electric field. This circuit 10 is usually called a carrier squelch circuit or a noise squelch circuit.
The other output of the receiver 8 is output as a data signal included in the received demodulated waves, that is, it is applied to an identification signal detecting circuit 11 to be compared with an identification signal that is determined by a combination of the base unit 1 and the radio telephone set 2. This identification signal is generally called an ID code.
An output of the detection circuit 11 and the demodulated output of the data signal of the receiver 8 are input to a control circuit 12 to be used for control of interconnection. The control circuit 12 in turn controls the synthesizer 9 for control of the radio channel, and also controls to cause the supply of a transmission data signal to the transmitter as a modulation input.
Similarly to the base unit 1, the radio telephone set 2 also has an antenna 13, an antenna duplexer 18 and a receiver 14, in which a demodulated output of the receiver 14 is sent to a telephone receiver 15. A voice input signal from a telephone transmitter 16 is applied to a transmitter 17 to be modulated and then sent through the antenna duplexer 18 to the antenna 13, from which the voice signal is radiated in the form of radio waves.
A synthesizer 19, a received-electric-field detecting circuit 20 and an identification signal detecting circuit 21 are the same as those in the base unit 1, and a control circuit 22 performs control over the radio telephone set 2. A loudspeaker 23 is a sounder which emits a calling voice indicative of a receiving call.
With respect to the power of these circuits, the base unit 1 is connected through an AC plug 24 to a commercial AC 100V plug receptacle so that outputs of a rectifier and stabilizer circuit 25 are distributed to the respective circuits of the base unit. One of the outputs of the circuit 25 is also supplied through a current control resistor 26, charging terminals 27 and 28 to a chargeable battery 29 to use the output of the battery 29 as the power of the radio telephone set 2.
The control of the above prior art example in a signal reception mode will be schematically shown in FIG. 12.
More specifically, when the base unit 1 detects a ringing signal from the wire telephone line 3 at a ringing-signal detector 30 in an await mode (step 34), the unit 1 sets the synthesizer 9 for the control channel and turns ON the transmitter 5 to transmit the received signal (step 35). The received signal includes a signal specifying a speech channel (S-CH).
The radio telephone set 2, on the other hand, turns ON the synthesizer 19 for a pe
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patent: 4650928 (1987-03-01), Numata
patent: 4682351 (1987-06-01), Makino
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patent: 4748655 (1988-05-01), Thrower et al.
patent: 4776001 (1988-10-01), Murata et al.
patent: 4794636 (1988-12-01), Sanglier et al.
Patent Abstracts of Japan, vol. 9, No. 270, Japanese Application, No. 60-114044, Oct. 26, 1985.
Bost Dwayne D.
Brown Thomas W.
Kabushiki Kaisha Toshiba
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