US 5,335,348 AGranted

Radio receiver having frequency sweep control apparatus

AssigneeNEC Corporation

InventorShinichi Kono

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Abstract

A frequency sweep control apparatus includes a variable frequency oscillator, a demodulator, a unique word signal detector, a sweep range controller, and a frequency controller. The variable frequency oscillator is capable of controlling an oscillation frequency. The demodulator demodulates a reception intermediate frequency signal by using an output from the variable frequency oscillator. The unique word signal detector detects a unique word signal in the reception signal from a demodulated output from the demodulator 102 and outputs a detection signal indicating a unique word signal detected state in which the unique word signal is detected or a unique word signal non-detected state in which the unique word signal is not detected. The sweep range controller controls a sweep range on the basis of an output from the unique word signal detector. The frequency controller controls the oscillation frequency of the variable frequency oscillator on the basis of an output from the sweep range controller.

Claims12

Dependent claims

A frequency sweep control apparatus comprising:

variable frequency oscillation means for generating an oscillation frequency;
demodulation means for demodulating a reception intermediate frequency signal by using an output from said variable frequency oscillation means;
unique word signal detection means for detecting a unique word signal in the reception signal from a demodulated output from said demodulation means and outputting a detection signal indicating a unique word signal detected state in which the unique word signal is detected or a unique word signal non-detected state in which the unique word signal is not detected;
sweep range control means for outputting a sweep range control information in accordance with the duration of the unique word signal detected state as detected by said unique word signal detection means;
frequency control means for causing said variable frequency oscillation means to oscillate within a sweep range of the oscillation frequency designated by the sweep range control information;
and
timer means for measuring a duration of the unique word signal non-detected state with respect to a time point where the unique word signal detected state change to the unique word signal non-detected state,
wherein said sweep range control means controls said frequency control means such that only a frequency range near a frequency set in an immediately preceding unique word signal detected state is set as said sweep range in order to shorten a time for detecting the unique word signal until a measuring result by said timer means comes to a predetermined period of time, and an entire frequency range is set as said sweep range after the measuring result by said timer means comes to the predetermined period of time.

5 more elements

A frequency sweep control apparatus comprising:

variable frequency oscillation means for generating an oscillation frequency;
demodulation means for demodulating a reception intermediate frequency signal by using an output from said variable frequency oscillation means;
unique word signal detection means for detecting a unique word signal in the reception signal from a demodulated output from said demodulation means and outputting a detection signal indicating a unique word signal detected state in which the unique word signal is detected or a unique word signal non-detected state in which the unique word signal is not detected;
sweep range control means for outputting a sweep range control information in accordance with the duration of the unique word signal detected state as detected by said unique word signal detection means;
frequency control means for causing said variable frequency oscillation means to oscillate within a sweep range of the oscillation frequency designated by the sweep range control information;
high-precision frequency oscillation means having an oscillation frequency closed to the oscillation frequency of said variable frequency oscillator means;
mixer means for mixing the oscillation output from said variable frequency oscillation means with an oscillation output from said high-precision frequency oscillation means and outputting a frequency difference signal;
low-pass filter means for extracting the frequency difference signal;
low-frequency, coarse frequency measurement means for measuring an output frequency from said low-pass filter means;
and
frequency determination means for determining whether a measurement value obtained by said frequency measurement means falls within said sweep range, and controlling said frequency control means to cause the measurement value to fall within the range if the measurement value falls outside the range.

8 more elements

Dependencies are inferred from the claim text.

Facts

Application: 07/998,397Filed 29 Dec 1992
Priority: JP 4-02193910 Jan 1992
Granted: 2 Aug 1994
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

H03J 1/0008
Details of adjusting, driving, indicating, or mechanical control arrangements for resonant circuits in general: using a central processing unit,…
H03J 7/26
Using varactors, i.e. voltage variable reactive diodes: in which an automatic frequency control circuit is brought into action after the scanning…
H04L 7/04
Arrangements for synchronising receiver with transmitter: speed or phase control by synchronisation signals
H03J
Tuning resonant circuits