JPH07212192A - Radio receiver - Google Patents

Abstract

PURPOSE:To drastically reduce the time required for a frequency scan in a simple circuitry by changing a received frequency according to a frequency difference between the IF station of radio wave of a broadcasting and the reference IF. CONSTITUTION:When an automatic selection station is started in a microcomputer part 6A, it is judged that a broadcasting''station radio wave which is possible to be received exists if an SD port is seen five times for every 4ms after about 30ms, for instance, is waited after a PLL lock 8 and the port of this SD detection is in high grade more than three times. The IF count for 8 ms or the frequency difference of the IF of received radio wave and a reference IF is counted. If the frequency difference is within + or -3.5KHz, the IF count, 450KHz and a difference KHz are extracted for 8ms. If this n is within + or -3. 5, a reception frequency is shifted by + or -n, the IF count is performed for 8ms, and whether the frequency difference with the reference IF is within 500 Hz or not is discriminated. As a result, if the difference is within 500Hz, the automatic selection station is completed, and if it is not within 500Hz, the TIF count is performed again for 8ms.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio receiver for automatically selecting and receiving radio waves from broadcasting stations.

[0002]

2. Description of the Related Art As a radio receiver having such an automatic channel selection function (hereinafter referred to simply as "receiver"), Japanese Patent Laid-Open No. 3-10
There is one disclosed in Japanese Patent No. 6110. FIG. 3 shows a block diagram of the AM receiver described in this publication.

In FIG. 3, reference numeral 1 is a receiving antenna that receives an incoming radio wave from an AM broadcasting station, and reference numeral 2 is an AM tuner unit that matches a tuning frequency with the radio wave from the antenna 1 and extracts a desired high-frequency reception signal. 3 converts the high frequency reception signal from the AM tuner unit 2 into an intermediate frequency (IF) and detects it,
An AM-IF detection unit that sends a low frequency (AF) signal, 4 is an AM amplifier unit that amplifies this low frequency signal, and 5 is a speaker that receives the low frequency signal and outputs a sound. 6A is a microcomputer section for controlling this receiver, 6B is this microcomputer section 6A
It is a scanning speed variable unit provided inside. Reference numeral 7 is a switch portion, and 8 is a PLL portion for electronic tuning.

Next, the operation of the configuration shown in FIG. 3 will be described.
First, in the audible frequency band, frequency scanning is performed in steps of a certain wide bandwidth (10 kHz), and only when the presence of a receivable station is detected, only within a predetermined band centered on the relevant frequency. It is described that the time required for frequency scanning for channel selection can be significantly reduced by performing frequency scanning in steps of narrow bandwidth (1 kHz).

[0005]

However, in the above-mentioned conventional receiver, the first frequency scanning is performed in a wide band width first, the presence of a receivable station is detected, and then the second frequency scanning is performed in a narrower band width. Therefore, there is a problem in that the effect of greatly reducing the time required for frequency scanning cannot be obtained in practice.

There is also a problem that it is necessary to switch the bandwidth of automatic channel selection, which complicates the circuit configuration of the receiver.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to significantly reduce the time required for frequency scanning and to provide a receiver having an excellent simple circuit configuration.

[0008]

In order to achieve the above object, the present invention detects a receivable broadcasting station radio wave while updating the reception frequency for each predetermined frequency bandwidth, and detects the receivable broadcasting station radio wave. It has a receiving station search means for calculating a frequency difference between the intermediate frequency and the reference intermediate frequency and changing the received frequency according to the frequency difference.

[0009]

Therefore, according to the present invention, the broadcasting station radio wave can be received by one frequency scanning, and the time required for frequency scanning can be greatly reduced with a simple circuit configuration.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of a receiver of the present invention. In FIG. 1, the same components as those of the conventional example shown in FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted. The characteristic configuration of this embodiment is the IF counting unit of 6C provided in the microcomputer unit 6A. This I
The F counting unit 6C has a frequency between the intermediate frequency (digital value) of the radio wave being received and the reference intermediate frequency (digital value; 450 kHz in this case) that would be obtained if the center frequency of the broadcast station radio wave was received. It is a means for counting and calculating the difference.

FIG. 2 is a flowchart of the automatic channel selection operation executed by the microcomputer section 6A. When automatic tuning starts, after locking the PLL, wait about 30 ms and then look at the SD port 5 times every 4 ms. If this SD detection port is high level 3 times or more, there is a receivable broadcasting station radio wave. Then, it is determined (step S1). And 8m
During s, the IF count, that is, the frequency difference between the intermediate frequency of the received radio wave and the reference intermediate frequency is counted (step S2). It is determined whether or not the frequency difference is within ± 3.5 kHz (step S3), and if it is within ± 3.5 kHz, IF counting is performed for 8 ms (step S4), and the difference n (kHz) from 450 kHz is determined. It is detected (step S5).

It is determined whether or not the value of n is within ± 3.5 (step S6), and if it is within 3.5, the reception frequency is shifted by ± n (step S7). For example, when the determination result is +3, the reception frequency is shifted by -3, and when the determination result is -3, the reception frequency is shifted by +3. Then, IF counting is performed for 8 ms (step S8), and it is determined whether the frequency difference from the reference intermediate frequency is within 500 Hz (step S9). Frequency difference is 50
If it is within 0 Hz, IF counting is further performed for 8 ms (step S10), and it is determined whether the frequency difference from the reference intermediate frequency is within 500 Hz (step S1).
1). When the frequency difference is within 500 Hz, it is determined that the automatic tuning is completed and the tuning is stopped.

In step S9, the frequency difference is 500
If it is not within Hz, the IF is again counted for 8 ms (step S12), and it is determined whether the frequency difference is within 500 Hz (step S13). Frequency difference is 500
If it is within Hz, the IF count is further performed for 8 ms (step S14), and it is determined whether or not the frequency difference is within 500 Hz (step S15). Frequency difference is 500H
If it is within z, tuning is stopped.

In step S11, the frequency difference is 50
If it is not 0 Hz, the process proceeds to step S14 again. In steps S13 and S15, if the frequency difference is not within 500 Hz, it is determined whether or not it is the first time (step S16). Also,
If the SD detection is not performed in step S1, the frequency difference is ± in steps S3 and S6.
When the frequency difference is not within 3.5 kHz, and the frequency difference is 50 in the second and subsequent steps S13 and S15.
If it is not within 0 Hz, the process proceeds to the next step (step S17).

[0016]

As is apparent from the above embodiment, the present invention changes the reception frequency according to the frequency difference between the receivable intermediate frequency of the radio wave of the broadcasting station and the reference intermediate frequency, thereby performing one frequency scanning. As a result, it is possible to receive broadcasting station radio waves, and it is possible to greatly reduce the time required for frequency scanning with a simple circuit configuration.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a radio receiver of the present invention.

FIG. 2 is a flowchart of an automatic channel selection operation executed by a microcomputer unit of FIG.

FIG. 3 is a block diagram of a conventional radio receiver having an automatic channel selection function.

[Explanation of symbols]

 1 Receiving Antenna 2 AM Tuner Section 3 AM-IF Detection Section 4 AF Amplifier Section 5 Speaker 6A Microcomputer Section 6C IF Count Section 7 Switch Section 8 PLL Section

Claims (1)

[Claims] 1. A receivable broadcasting station radio wave is detected while updating a reception frequency for each predetermined frequency bandwidth, a frequency difference between an intermediate frequency of the receivable broadcasting station radio wave and a reference intermediate frequency is calculated, and A radio receiver having a receiving station search means for changing the reception frequency according to a frequency difference.