US 4,247,951 AGranted

Frequency synthesizer with unauthorized frequency inhibiting means

AssigneeMicro Power Systems, Inc.

InventorsKeisuke Hattori, Alexander R. Sabo

Life of this patent

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Abstract

A radio which has assigned frequencies or channels for operation is prevented from operating on other channels. The frequency synthesizer in the radio is a large scale integrated circuit in a single semiconductor chip which is controlled by input codes from channel select switches. The synthesizer includes circuitry which responds to input codes for illegal channels and produces an inhibit signal thereby preventing generation of unauthorized frequencies. The circuitry may include a read only memory which is addressed by the input code. Alternatively, logic circuitry may be provided which responds to codes for illegal channels. Due to the circuitry being in integrated form, the method of inhibiting unauthorized signal generation cannot be easily circumvented.

Claims4

Dependent claims

A frequency synthesizer for generating authorized signals and inhibiting unauthorized signals comprising:

a reference frequency source,
a voltage controlled oscillator,
a phase detector,
means connecting said reference frequency source to an input to said phase detector,
means including a programmable counter connecting said voltage controlled oscillator to an input to said phase detector,
means connecting an output signal from said phase detector to a control terminal of said voltage controlled oscillator,
frequency selector means operably connected to said programmable counter for controlling the oscillation frequency of said voltage controlled oscillator,
output gate means connected to said voltage controlled oscillator;
and
means for inhibiting said output gate means when said frequency selector means selects an unauthorized frequency, said means comprising a read only memory which provides a first inhibit signal when said frequency selector means indicates an unauthorized frequency.

7 more elements

Dependencies are inferred from the claim text.

Facts

Application: 05/956,279Filed 31 Oct 1978
Granted: 27 Jan 1981
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

H03J 5/0281
The digital values being used to preset a counter or a frequency divider in a phase locked loop, e.g. frequency synthesizer: the digital values…
H03J 5/029
Discontinuous tuning using an electrical variable impedance element, e.g. a voltage variable reactive diode, in which no corresponding analogue…:…
H04B 1/40
Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of…: circuits
H03J
Tuning resonant circuits