US 4,399,438 AGranted

Coded signal radio transmitter for remote control mechanisms

OwnerEdgar L. Bonnerinventor

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Abstract

A radio transmitter is operatively arranged to develop and broadcast a coded signal which may be used to effect remote control functions, for example, to control door opening mechanism. The transmitter includes a radio frequency oscillator having a coil which constitutes the radiating element. The radio frequency oscillator is modulated by a first low frequency oscillator, which is frequency modulated by output from a second low frequency oscillator, both low frequency oscillators being controlled by a timer which turns the low frequency oscillators ON for about one second and holds them OFF for about thirty seconds. The low frequency oscillators and the timer are realized by a commercially available, integrated CMOS circuit.

Claims13

Dependent claims

A radio transmitter for transmitting a coded signal, the transmitter comprising timer means for supplying a timing signal;

first low frequency oscillator means and second low frequency oscillator means coupled to said timer means and responsive to its output for generating respectively a first low frequency signal and a second low frequency signal, the second low frequency signal being of a lower frequency than the first low frequency signal;
means for frequency modulating said first low frequency oscillator means with the second low frequency signal;
and radio frequency signal means coupled to said first low frequency oscillator means and responsive to its frequency modulated output signal for producing an intermittant radio frequency output modulated by the frequency modulated output signal wherein said first and second low frequency oscillator means comprise respective first and second NAND circuits, each having a respective first input terminal coupled to said timer means and responsive to its output so as to be intermittently enabled thereby;
a first RC circuit means for establishing frequency at which said first low frequency oscillator means is to operate in the absence of modulation being supplied thereto, said first RC circuit means being in circuit between a second input terminal and an output terminal of said first NAND circuit;
a second RC circuit means for establishing a second frequency at which said second low frequency oscillator is to operate, said second RC circuit means being in circuit between a second input terminal and an output of said second NAND circuit;
and wherein said modulating means includes a diode connected in series with a capacitor between a point of reference potential and said second input terminal of said first NAND circuit and a switching means connected in series between said diode and a source of potential.

3 more elements

An oscillator arrangement comprising timer means;

first and second low frequency oscillator means including respective first and second NAND circuits, each having a respective first input terminal coupled to said timer means and responsive to its output so as to be intermittently enabled thereby;
a first RC circuit means for establishing a frequency at wich said first oscillator means is to operate in the absence of modulation being supplied thereto, said first RC circuit means being in circuit between a second input terminal and an output terminal of said first NAND circuit;
a second RC circuit means for establishing a second frequency at which said second oscillator is to operate, said second RC circuit means being in circuit between a second input terminal and an output of said terminal second NAND circuit;
and modulating means including a diode connected in series with a capacitor between a point of reference potential and said second input terminal of said first NAND circuit and a switching means connected in series between said diode and a source of potential.

1 more element

Dependencies are inferred from the claim text.