Communications: electrical – Systems – Selsyn type
Patent
1983-07-21
1985-03-26
Groody, James J.
Communications: electrical
Systems
Selsyn type
340310CP, 455 41, 455270, 343905, H04M 1104
Patent
active
045076464
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a radio communication system, including a method and a device for radio communication in at least one direction.
The invention is based on a desire for a paging system, which can be used in a limited area with very simple means, especially within a large building, such as an office or a factory building, a hotel, a public building or the like. In such a system it is a primary object to achieve good cooperation between the antennas of a transmitter a the receiver. Another object is to enable the use of an existing electrical network for the power supply of the transmitter or the receiver.
SUMMARY OF THE INVENTION
According to the invention, one uses an existing electrical supply network, e.g. a phase wire of an electrical supply system, as an antenna of one of the units, the electrical supply network being coupled capacitively, e.g. by means of a capacitor, to the signal connection of the unit. In principle, the antenna of either the transmitter or the receiver may consist of such an existing wiring.
In case of a paging system, a central transmitter is preferably connected to the electrical network, which in this case serves partly as a power source for the electronic and indication equipment of the transmitter, partly as an antenna in that the signal amplifier output of the transmitter is capacitively coupled to a phase or neutral wire. A certain damping of the signals along the wire will of course take place, but if the power output is of the magnitude of 50 W, sufficient electromagnetic radiation from the corresponding wire or wires can be obtained in the entire building or the like so that the transmitted radiation can be detected by means of portable, battery powered receiver units provided with ordinary ferrite antennas.
Other possible applications are data communication, data collection and alarm systems. In the latter case, a number of different transmitters can emit radio signals which are detected by an electrical supply network, which serves as a receiver antenna and is capacitively coupled to an alarm center. The transmitters as well as the central receiver may in this case be powered either by the network or by batteries.
The invention will be explained further below with reference to the appended drawings which schematically illustrate an embodiment in the form of a paging system.
DESCRIPTION OF THE FIGURES
FIG. 1 shows a simplified block diagram of a transmitter which is coupled to an electrical network, and a separate receiver;
FIG. 2 shows an oscillator included in the transmitter;
FIG. 3 shows an amplifier included in the transmitter; and
FIG. 4 shows a power unit included in the transmitter.
The upper part of FIG. 1 shows a transmitter and the lower part shows a receiver 2. According to the invention, the transmitter is coupled to an existing wiring network, namely an ordinary electrical supply system 3 having a group of wires comprising a protective earth 4, a neutral wire 5 and a phase wire 6 of a 220 V alternating voltage.
In the illustrated example, the transmitter 1 constitutes the central unit of a paging system and comprises a control device 7 with a microphone 8, a FM-modulator 9, an oscillator 10, an amplifier 11, a power device 12 and a match device 13, the latter being coupled to the amplifier output via a capacitor 14. The control device 7 is connected to the remaining transmitter portions 9-14 by means of a 7-wire cable 15, which partly secures the current supply from the power device 12, partly transmits coded information for addressing a receiver 2 paging device, which information is transmitted via the devices 9-13 to be described further below. For this purpose, the control device is provided with the following means (not shown): an on-off switch, a set of keys for dialling a five-digit code number e.g. in a 5-tone-CCIR-code, a display for indicating the dialled code numer, a transmitter key for emitting the coded information via the devices 9-13, a red light emitting diode or the like for indicating that such information transmission is bei
REFERENCES:
patent: 2922598 (1960-01-01), Heijnis
patent: 2925598 (1960-02-01), Williams
patent: 3603881 (1971-09-01), Thornton
patent: 3978469 (1976-08-01), Schaad
patent: 3993989 (1976-11-01), Held
patent: 4097801 (1978-06-01), Freeman
patent: 4097808 (1978-06-01), Parke
patent: 4409590 (1983-10-01), Baker
Beudat Andre
Hamlin Inge
Groody James J.
Heim Michael F.
P.S. Paging System, A.B.
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