JPS6349930B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention is designed to automatically receive radio waves from other broadcasting stations broadcasting the same content with a stronger electric field level when the reception level decreases when driving long distances. This relates to a car radio that can be switched to

Conventionally, when receiving radio broadcasts on a car radio while driving long distances, if the car leaves the reception area of the broadcast station the car is receiving, the reception level will drop, so in such cases, the reception level will drop. In order to listen to the same content being broadcast from a station, the driver had to perform a tuning operation each time. In addition, in order to eliminate such trouble, the frequencies of multiple broadcasting stations, especially those broadcasting the same content, are checked in advance and stored in the radio, and as the reception level decreases, A system has also been proposed in which the receiving frequency is sequentially switched so as to receive broadcasts from the broadcasting station with the highest reception level.

However, even in such a system, it is necessary to check in advance the frequencies of broadcasting stations that broadcast the same content and store them in the radio, which is troublesome.

The present invention has been made in order to eliminate the above-mentioned conventional drawbacks, and the present invention has been made in order to eliminate the above-mentioned drawbacks of the conventional broadcasting station. If it continues,
By determining that both broadcasts have the same broadcast content, when the reception level of the broadcasting station being received is lower than the level of another broadcasting station with the same broadcast content, the reception frequency of the other broadcasting station is automatically switched. The aim is to provide a car radio with

The drawing shows a block circuit of a car radio according to an embodiment of the present invention, in which 1 indicates an antenna;
2 is a tuner that tunes the received radio waves from this antenna 1; 3 is a tuner that detects and quantizes the reception level of the received signal of the broadcasting station tuned by this tuner 2 using a plurality of predetermined threshold values; , a level determination circuit that outputs this as a digital reception level value, 4 a demodulation output detection circuit that detects the presence or absence of the demodulation output of the tuner 2, and 6 a broadcast frequency of the broadcasting station currently being received (hereinafter referred to as the current station). and the current station data area 6a for storing the reception level, and the broadcasting frequency and reception level of other broadcasting stations to be inspected (hereinafter referred to as inspection stations) to see if they are broadcasting the same content as the current station. 7 is a tuning voltage generation circuit composed of a PLL (Phase Locked Loop) frequency synthesizer and the like that generates a tuning voltage and applies it to the tuner 2; 8 is a demodulator of the tuner 2; A muting circuit 5 for attenuating the output obtains the outputs of the reception frequency detection circuit 11, the level determination circuit 3, the demodulation output detection circuit 4, and the data in the data memory 6, processes them, and operates the tuning voltage generation circuit. 7 and mutating circuit 8
It is a control means for giving appropriate commands to the controller or storing data in the data memory 6, and can be configured by a dedicated LSI, a microcomputer, etc. 9 is a low frequency amplifier, and 10 is a speaker.

Next, the operation will be explained.

The data of the station currently being received (current station) is stored in the current data area 6a of the current data memory 6, and this data is stored in the tuning voltage generation circuit 7.
The tuner 2 is tuned based on the output of the tuning voltage generating circuit 7 and receives the broadcast program of the current station. The received signal of the current station received by the tuner 2 is sent to the level judgment circuit 3.
Furthermore, the demodulated outputs are respectively given to demodulated output detection circuits 4. The output of this level determination circuit 3 is accumulated and averaged by the control unit 5, and is determined as the reception level of the current station by the current station data area 6 of the current data memory 6.
It is stored in a.

Then, the demodulation output detection circuit 4
When a cessation of audio is detected for a certain period of about s, the control section 5 performs the following series of operations.

First, in order to prevent the generation of noise, the control section 5 gives a command to the muting circuit 8 to
This attenuates the demodulated output signal and interrupts the audio output.

Next, the control section 5 increases the reception frequency of the current station in the current station data area 6a by the minimum inter-station space, sets this as the reception frequency of the inspection station, and stores it in the inspection station data area 6b. Then, the control unit 5 replaces the frequency data stored in the current station data area 6a and the inspection station data area 6b of the current data memory 6, and uses the frequency data stored in the original inspection station data area 6b. Then, the tuner 2 receives the inspection station, and once the reception level of the inspection station is obtained, this is compared with the current station reception level. If the reception level of the current station exceeds the reception level of the inspection station, the control unit 5 immediately returns the frequency data of the current station data area 6a of the current data memory 6 and the inspection station data area 6b.
The mutating signal to the mutating circuit 8 is turned off to cancel the audio interruption, and the receiving frequency of the inspection station data area 6b is increased by the minimum inter-station space. . The above operation is performed within several to several tens of milliseconds at the moment when the demodulated output is not detected, so that it does not interfere with the broadcast reception of the current station. Then, when there is a moment when the demodulated output stops again, a new inspection station is inspected in the same manner as described above. In this way, it is checked whether the broadcast contents of other broadcast stations are the same as the broadcast contents of the current station, and when the reception frequency of the inspection station reaches one band edge of the reception band, it is turned to the other band edge. By decreasing the reception frequency by the minimum inter-station space, all broadcast stations within the reception band can be tested without exception.

Now, in the above-described operation, if the reception level of the inspection station exceeds the reception level of the current station, the control section 5 performs the following two operations.

First, the control section 5 takes in the output of the demodulation output detection circuit 4 and detects whether or not the audio has stopped. If the sound does not stop, the control unit 5
determines that the broadcast contents of the two broadcasts are different, returns to reception of the current station, and continues checking other broadcast stations in the same way as above.

Next, if the demodulation output of the inspection station also stops at the moment the demodulation output of the current station stops, the broadcast contents of both stations may be the same, so even after returning to reception of the current station, the inspection station data area 6b The frequency data of the station will not change and the inspection of that inspection station will continue.

In other words, at the moment when the demodulation output of the current station stops, there is a possibility that the demodulation output of a testing station with a different broadcast content also stops, so the probability that the demodulation output of both stations stops at the same time is 1/2. Then, the probability of erroneously determining that the broadcast contents of the current station and the inspection station are the same becomes 1/2 ⁿ when the demodulated outputs of both stations stop n times in a row. Therefore, when n=10, it is about 0.1% or less,
By continuously performing the above test 10 times, it can be determined with 99.9% probability that the broadcast content of both stations is the same.

In this way, when a broadcasting station that broadcasts the same content as the current station is detected with a predetermined probability, the control unit 5 selects the current station data area 6 of the current data memory 6.
While exchanging the frequency data of a and the inspection station data area 6b, muting is canceled and switching to inspection station reception is performed. By doing this, when the reception level of the current station is lower than that of the inspection station, the station is automatically switched to a station with the same broadcast content and a higher reception level. Thereafter, by repeating exactly the same operation using this switched station as the current station, it is possible to always catch up with and receive stations with the same broadcast content and good reception conditions.

In this way, with the car radio of this embodiment, even when the car travels long distances beyond the reception area of each broadcast station, it is possible to automatically switch to a station broadcasting the same content and listen to the broadcast. , the trouble of selecting channels is eliminated.

As described above, according to the car radio according to the present invention, a station that is broadcasting the same content while the current station is being received is automatically searched for, and the reception level of the current station is lower than the reception level of the relevant station. Since the system automatically switches to receive broadcasts from the station in question, you can always receive broadcasts from stations with good reception level among stations broadcasting the same content, and you can easily switch to a station with a good reception level. This has the effect of eliminating the hassle of operation.

[Brief explanation of the drawing]

The drawing is a block diagram of a car radio according to an embodiment of the present invention. 2...Tuner, 8...Tuning voltage generation circuit, 3...Level judgment circuit, 4...Demodulation output detection circuit, 6...Data memory, 6a...Current station data area, 6b...Inspection station data area, 5...
...control means.

Claims (1)

[Scope of Claims] 1. A reception system comprising a tuner and a tuning voltage generation circuit that changes the tuning frequency of the tuner, a level determination circuit that determines the reception level of a signal received by the tuner, and a demodulation output of the tuner. It comprises a demodulation output detection circuit for detecting the presence or absence of the demodulation output, and a control means for supplying reception frequency data to the tuning voltage generation circuit, and the control means instantaneously controls the reception system itself every time the demodulation output is not detected by the current station. When the reception frequency is switched to the test station and the reception level of the test station is higher than the reception level of the current station, the program broadcasts the same content as the current station by repeating the operation of detecting the presence or absence of demodulated output of the test station a predetermined number of times. A car radio is characterized in that it determines which station is currently being broadcast and switches reception to a test station with the same broadcast content as the current station. 2. The car radio according to claim 1, wherein the demodulated output is muted when switching to the inspection station.