Abstract:
In a radio transceiver having a transceiver unit and a remote control unit, a remote control system in which the operation of the transceiver unit is controlled by control signals coupled synchronously from the remote control unit. The remote control unit has a volume control, a squelch level control, a transmit/receive control switch, a channel select code converter etc., and analog and digital switches for synchronously coupling the above signals. The transceiver unit is capable of transmitting/receiving a plurality of radio signals at preselected frequencies and the operation is controlled by signals regenerated synchronously from the control signals received from the remote control unit.

Description:
BACKGROUND OF THE INVENTION 
     This invention generally relates to radio transceivers and, more particularly, to a remote control system in which a transceiver unit is controlled by control signals received from the remote control unit, using only a few electrical wires or cables between the remote control unit and the transceiver unit. 
     In a conventional remote control type transceiver, the remote control unit includes a microphone, a volume control means, a squelch control means, a transmit/receive switch means, a channel selection (up or down) switch, and a channel indicator. Therein, the remote control unit is coupled to the transceiver unit by a multi-conductor cable which conducts the respective signals or control signals. 
     While the above-described remote control type transceivers have been put to practical use for some applications, they have some disadvantages. One disadvantage is that many conductors are needed to couple the remote control unit to the transceiver unit. Therefore, the multi-conductor cable must be very thick and very heavy. It is inconvenient to operate such a remote control unit. Another disadvantage is that many connectors are needed to electrically connect the remote control unit or the transceiver unit to the multi-conductor cable, resulting in inefficiency in mass production of such systems and also resulting in poor reliability for such systems. 
     SUMMARY OF THE INVENTION 
     It is an object of this invention to provide a new and improved radio transceiver. 
     It is another object of this invention to provide such a transceiver which has a small and light remote control unit that is convenient to operate. 
     It is a further object of this invention to provide such a transceiver which is suitable for mass production and has good reliability. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects and features and advantages of this invention will be apparent from considering the following description with the accompanying drawings, in which: 
     FIG. 1 is a basic schematic diagram of a remote control unit in a conventional remote control type radio transceiver; 
     FIG. 2 is a basic schematic diagram of a transceiver unit in a conventional remote control type radio transceiver; 
     FIG. 3 is a circuit diagram of a basic circuit of a remote control unit in a radio transceiver according to this invention; 
     FIG. 4 is a circuit diagram of a basic circuit of a transceiver unit in a radio transceiver according to this invention; 
     FIG. 5 is another circuit diagram of a basic circuit of a remote control unit according to this invention; and 
     FIG. 6 is another circuit diagram of a basic circuit of a transceiver unit according to this invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to FIG. 1, there is shown a basic schematic diagram of a remote control unit 1 of a conventional remote control type radio transceiver. The remote control unit 1 is supplied with a power source 3 by a wire 15 from the transceiver unit, and provides, to the transceiver unit: a power ON/OFF control signal 2 from a power switch 102; an output signal 4 of a microphone 104; a control voltage 5 from a volume control potentiometer 105; a control voltage 6 from a squelch level control potentiometer 106; a transmit/receive control signal 7 from a switch 107; and output signals of a code converter 10 for controlling a phase locked loop (PLL) circuit 37 of the transceiver unit (FIG. 2). These signals are conducted by wires 14, 16, 17, 18, 19 and 20 respectively. The transceiver unit is controlled by these signals or control signals. 
     An up/down signal 8 from a channel select switch 108 is provided to an up/down counter 9 which is changed to a greater number or a lower number, step by step, in response to the up/down signal 8. The output of the up/down counter 9 is provided to a code converter 10 and is converted thereby to a preselected channel code for controlling the PLL circuit 37 of the transceiver unit (FIG. 2). The output of the up/down counter 9 is also used to drive a channel indicator 13 via a decoder 11 and a driver 12. 
     With respect to FIG. 2, there is shown a schematic circuit diagram for a transceiver unit 21 of a conventional remote control type radio transceiver type, in which the same reference numerals designate the same components as those of FIG. 1. A relay 22 is activated by the power ON/OFF control signal conducted by the wire 14 for turning on a power switch 22A. The power switch 22A supplies current from a power source 23 to all circuits of the transceiver unit 21. The microphone output signal 4 is conducted to a transmit/receive control switch 29 by the wire 16, and is amplified by an audio amplifier 30. A variable gain controlled amplifier 28 is controlled by the voltage from the wire 17. The operating level of a squelch circuit 27 is controlled by the voltage from the wire 18. A transmit/receive control circuit 35 is controlled by the transmit/receive control signal 7 conducted by the wire 19. The phase locked loop (PLL) circuit 37 which determines the transmit/receive channel frequencies is controlled by output signals of the code converter 10 conducted by the wire 20. 
     In FIG. 2, all of the circuits except the above-described circuitry may be the conventional and well known circuitry ordinarily employed in a transceiver. The elements of such conventional circuitry are an antenna 24, the transmit/receive control switches 25, 29, 31 controlled by the control circuit 35, a receiver unit 26, a speaker 32, an AM modulator 33, a power amplifier 34, a voltage controlled oscillator 36 controlled by the PLL circuit 37. The circuits are therefore not described in greater detail. 
     As mentioned above with reference to FIG. 1 and FIG. 2, each function of the transceiver unit is controlled by a signal conducted from the remote control unit 1 via the multi-conductor cable according to the prior art. Therefore, the multi-conductor cable is very thick, heavy and inflexible. Moreover, many connectors are needed to electrically connect the remote control unit 1 or the transceiver unit 21 to the multi-conductor cable, resulting in inefficient mass production of the systems and poor reliability for each system. 
     This invention which will be described in detail below can make it possible to decrease the number conductors required in the multi-conductor cable and to eliminate many of the disadvantages mentioned above, improving the function and characteristics of a transceiver. Circuits according to one embodiment of this invention are shown in FIG. 3 and FIG. 4. A remote control unit 40 is shown in FIG. 3 and a transceiver unit 60 is shown in FIG. 4, in which the same reference numerals designate the same components as those of FIGS. 1 and 2, respectively. 
     In FIG. 3, a power source 3 of the remote control unit 40 is controlled by a power switch 102. The current increase which is generated at wire 47 by turning on the power switch 102 is detected by a current detector 61 in FIG. 4. A power switch 63 is activated by the current detector 61 and supplies current from a power source 23 to all circuits of the transceiver unit 60. The ground point of the remote control unit 40 is connected to the ground point of the transceiver unit 60 by a wire 48. 
     The output signal 4 of a microphone 104 is conducted to a transmit/receive switch 29 via a wire 49. A volume control voltage 5 and a squelch control voltage 6 are provided to an analog switch 42 which generates a linear output in proportion to an input thereof. A transmit/receive control signal 7 and the output signals of code converter 10 are provided to a digital switch 43 which generates a digital output in response to an input logic level. The outputs of the analog switch 42 and the digital switch 43 are added by an adder 44, and are conducted to an analog switch 64 and a digital switch 66 of the transceiver unit 60 via a wire 50. A counter 46 is driven by a synchronous pulse via a cable 51. This pulse is generated by a synchronous pulse generator 77. A synchronous switch control circuit 45 is driven by the counter 46 and controls the analog switch 42 and the digital switch 43. 
     In the transceiver unit 60, a counter76 and a synchronous switch control circuit 75 operate synchronously with a synchronous pulse from the synchronous pulse generator 77, similarly to the counter 46 and the synchronous switch control circuit 45. That is, each switch (a. . .i) constituting the analog switch 64 and the digital switch 66 is made conductive synchronously when the corresponding switch (A. . .I) constituting the analog switch 42 and digital switch 43 is made conductive. Therefore, the control signals from the remote control unit 40 are conducted, in turn, to the transceiver unit 60, and thereby the output signals 68, 69 of the analog switch 64, and the output signals 70, 71 of the digital switch 66 are regenerated. These output signals 68 and 69 are stored in a hold circuit 65 and are used as a volume control voltage 72 and a squelch control voltage 73, respectively. Output signals 70 and 71 are provided to a latch circuit 67, and used as a transmit/receive control signal 74 and a PLL control signal 71A, respectively. 
     Although, in FIG. 3, the up/down counter 9, the code converter 10 and the decoder 11 are included in the remote control unit 40, these three elements may be included in the transceiver unit. This will be illustrated as follows. Thus, circuits according to another embodiment of this invention are shown in FIGS. 5 and 6. In FIG. 5, a remote control unit 80 is shown, and in FIG. 6, a transceiver unit 85 is shown, in which similar reference numerals designate similar components to those of the foregoing drawings. 
     A transmit/receive control signal 7 and an up/down signal 8 are provided to a digital switch 82, and are conducted to a digital switch 86 (FIG. 6) via an adder 44 and a wire 50, and are regenerated as output signals 74 and 8A from a latch circuit 87. The up/down signal 8A is provided to an up/down counter 9 connected to code converter 10. In addition, the output of the up/down counter 9 is decoded by a decoder 11. The outputs of the decoder 11 are switched by a digital switch 88 and are coupled synchronously in phase with the pulse of a synchronous pulse generator 77 to a digital switch 84 of the remote control unit 40 via the wire 50. The outputs of the digital switch 84 are memorized by a latch circuit 84A and are provided to a display driver 12. A channel indicator 13 (for example, 2 digits of 7 segment LED numeral display) is driven by the driver 12 and displays the channel number of the signal which the transceiver unit is transmitting or receiving. Just as in FIG. 3 and FIG. 4, the analog switches 42, 64 and the digital switches 82, 84, 86, 88 are controlled synchronously by the pulse of the synchronous pulse generator 77. 
     The advantage of this invention as illustrated in FIG. 5 and FIG. 6 is that the remote control unit can be made to be more compact because it requires fewer electrical components. Although specific preferred embodiments of this invention have been described and shown, it will be readily understood that modifications of this invention, in its various aspects, will be apparent to those skilled in the art, some being apparent only after study, and others being merely matters of routine design. As such, the scope of this invention should not be limited by the particular embodiments and specific constructions herein described, but should be defined only by the appended claims, and equivalents thereof.