JPH0153527B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a vehicle-mounted radio receiver that tracks the same broadcast content station and automatically switches between them.

Frequency data for several stations with the same broadcast content can be stored in the same channel selection button, and when you move out of the receiving station's service area, you can automatically switch to a station broadcasting the same broadcast on another frequency. Several vehicle radio receivers are known. However, in this type of in-vehicle radio receiver, storing frequency data is a manual operation, which is extremely troublesome. For this reason,
The present invention relates to an improvement of an automatic switching vehicle radio receiver that searches for the same content station and automatically switches without the need for memory operations. In other words, once a station has been switched, it is necessary to remember that it previously had the same content, and for this station, it is only necessary to determine whether it is a local broadcast or not. If the criteria for determining whether the content is the same is relaxed, or if local broadcasting ends, it is expected that the content will be the same, so checking the content can be omitted and switching between stations will be smooth. It was made to be carried out in In the case of the present invention, a method is proposed in which it is determined that the content is the same when the synchronization of the presence or absence of the demodulated output is detected several times in succession. When lags for a certain period of time,
The demodulated output is When a certain period of time has elapsed, the second search means synchronizes the searched stations and checks whether the demodulated output has stopped, but the time required for this determination may vary depending on the broadcast content. This time is variable and can be quite long, especially in the case of relatively loud music with few pauses. Therefore, as in the present invention, it is remembered that the station once switched was broadcasting the same content.
By relaxing the criteria or omitting the content check, the time required for this determination can be significantly shortened, especially in mountainous areas, where communication between stations whose service areas intersect in a complex manner due to the line of sight of the transmitting antenna is possible. It has the effect of smoothing the transition. By the way, if this happens to be the time of a local broadcast, it will only take a short time to check the content, so you can avoid constantly switching to stations with different content. However, during local broadcasting, the reception level of the station being received deteriorated too much.
Although there may be cases where it becomes impossible to check the contents,
In this case, if you stop checking the content depending on the reception level, you can switch smoothly.

A detailed description will be given below with reference to the drawings. The figure shows one embodiment of the invention.

Antenna 1 is connected to tuner 2 and a received signal is supplied to tuner 2. A part of the signal tuned by the tuner 2 is given to the level determination circuit 3.
This level determination circuit 3 detects the reception level of the reception signal of the broadcasting station tuned by the tuner 2 at a plurality of predetermined levels, and supplies this level to the control section 5. Further, a part of the demodulated output of tuner 2 is given to demodulation level detection circuit 4 . The demodulation output detection circuit 4 detects the cessation of demodulated audio,
For example, if the broadcast content is speech, the pause period is detected and a signal for detecting this period is supplied to the control unit 5. Further, the tuner 2 is applied to a low frequency amplifier 9 via a muting circuit 8, amplified, and applied to a speaker 10.

Now, the data of the station currently being received is stored in the current station data area 6a of the current data memory area 6, and this data is given to the tuning voltage generation circuit 7, and the tuner 2 outputs the output of this tuning voltage generation circuit 7. is tuned based on.
This tuning voltage generation circuit 7 is, for example,
It consists of a PLL frequency synthesizer, etc.
In operation, first, the tuning voltage generation circuit 7 generates a tuning voltage based on the frequency data of the data area 6a. Then, the tuner 2 tunes to the current station based on the tuning voltage supplied from the tuning voltage generating circuit 7 and receives the broadcast program. 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 a demodulated output detection circuit 4. The output of the level determination circuit 3 is accumulated and averaged by the control section 5, and is stored as the reception level of the current station. The output of the demodulation output detection circuit 4 remains constant for a certain period of time, for example, this period ranges from several ms to several hundred
When it detects this voice and pause, which lasts for about ms, it performs the following series of actions. First, the control unit 5 applies a muting signal to the muting circuit 8, and the audio level is attenuated to interrupt the audio in order to prevent the generation of noise. Next, the frequency data stored in the current station data area 6a and the inspection station data area 6b of the current data memory 6 are exchanged, and the frequency data stored in the inspection station data area 6b is changed to the tuning voltage generation circuit. 7 to tuner 2. The tuner 2 tunes to that frequency and receives the corresponding station. Then, the reception level of the inspection station received by the tuner 2 is given to the level determination circuit 3, and the level is determined. The level signal determined by the level determination circuit 3 is provided to the control section 5. If this level is above a predetermined level, the control unit 5 stores the frequency data and reception level data of this station in the data area 11a of the memory device 11, and stores them again in the current station data area 6a of the current data memory 6. The frequency data stored in the inspection station data area 6b is replaced with the frequency data stored in the inspection station data area 6b. Then, the control section 5 turns off the muting signal applied to the muting circuit 8 to cancel the audio interruption.
Next, the frequency data in the inspection station data area 6b is incremented (or decremented) by the minimum inter-station space. These operations take several ms to several tens of ms
However, since it occurs at the moment when the audio is interrupted, it will not interfere with the broadcast reception of the current station. Then, when there is a moment when the audio is interrupted again, the muting circuit 8
A mutating signal is applied to the station, the audio is interrupted, a station corresponding to the frequency data in the data area 6b of the test station is received, and its reception level is determined. If this reception level does not reach a predetermined level, the current station is immediately returned and this station is not stored. Every time these operations are performed several times, the frequency data in the inspection station data area 6b of the current data memory area 6 is temporarily saved in the control unit 5, and the frequency data stored in the memory device 11 is saved in the inspection station data area 6b.
, and check the reception level in the same way.The reception level is changed to a new value, but at this time, if there is a station whose reception level exceeds the reception level of the station currently being received,
The broadcast program for this station is determined as follows. That is, at the same time as switching to this station and taking in the reception level from the reception level determination circuit 3 to the control section 5, the demodulation level detection circuit 4
There is a slight time delay when checking the output of the station, but based on the expected value regarding audio interruptions described later, if the audio is interrupted in the same way as the current station, it is determined that there is a possibility that the broadcast content is the same, and this station is is left in the inspection station data area 6b. Now, I'll test this station again the next time the audio breaks. In addition, it would be even more effective if you added a method of detecting the audio interruption, returning to the current station, detecting the start of the sound of the current station, and checking whether the sound of the testing station is starting in synchronization. It is true. If the synchronicity of the sounds is confirmed several to more than ten times, it is determined that the content is the same. In this way, when a station with the same content as the current station is found in the data memories 11a to 11h, the station is switched to, and the frequency data of the station that was originally being received is transferred to the data memory of the station to which it was switched. , so that the original broadcast of the same broadcast will remain.
For example, set up the allocated memory bits. Then, when this station becomes an inspection station next time, the control unit 5 determines this bit and relaxes the criteria for determining the content. In this way, when the reception level check for the frequency data in the memory device 11 is completed, the control section 5
The frequency data that had been saved in the test station data area 6b is returned to the inspection station data area 6b, and the search for a newly received station is continued while sequentially changing the data. Now, when the data area of the memory device 11 becomes full in this way, the lowest reception level of the data areas 11a to 11h in the memory device 11 and the received data of the newly discovered station are If the received level of the newly found station is higher than that of the newly found station, it is rewritten with new data, and in the end, only the recently found station with good received level remains in the memory device 11. become. Then, when the current station becomes weak, memory device 1
1, stations with the same broadcast content are discovered using the method described above, and the stations are switched one after another. Therefore, it is possible to always track the same broadcast content station in good condition without performing a channel selection operation. By the way, in this method, when moving into the service area of a new broadcasting station, it is important to quickly capture this broadcasting station in memory and not to interfere with the broadcast reception of the current station. As a result of statistical measurements of audio interruptions, the following was found. In other words, from the time when audio interruptions for a certain period of time are detected,
Concerning the length of time that the audio continues to be interrupted, the longer the period of audio interruption that is detected first, the longer the expected value of the amount of time that the audio will continue to be interrupted. For example, to give an example of experimental values, when an 85 ms audio interruption is detected, the time for which there is a 90% chance that it will continue after that is about 10 ms, and
When a 200ms audio interruption is detected, it is approximately
It was 35ms. Judgments about broadcast content are made based on such probabilistic facts.
Even if the time when there is audio output in a broadcast is equal to the time when there is no audio output, if it is detected that audio interruptions occur at the same time n times in a row, the probability that it is different broadcast content is (1/2) ⁿ . , when n=10, it is less than 0.1%. Also, even if you interrupt the audio by that much at a point where you can expect more than 90% of the audio interruptions to continue,
It has been confirmed that if these interruptions are not frequent, they have little effect on broadcast reception and are not a problem. In other words, if you check the inspection station only when both a certain interval, for example one second interval, and a certain period of audio interruption are satisfied, you will be able to receive most of the current station's broadcasts. This means that it is possible to check the level of other stations without affecting them. In addition, as mentioned above, if a long interruption time is detected, the expected value of the continuing interruption time will be longer, so if audio interruptions continue at a certain interval, inspection should be performed according to the interruption time. It is also possible to increase the number of stations. However, depending on the program, there may be few audio interruptions, and until it is determined that the content is the same,
It may take a considerable amount of time, but once the station has been switched, unless the reception level drops completely, remember that it was the same station and relax the standards for content judgment to ensure a smooth switch. This is extremely effective, especially when driving in areas where electric fields intersect.

As described above, according to the present invention, it is possible to realize an in-vehicle radio receiver that, once a certain broadcasting station is selected, automatically selects a station with the same content and a good reception level and automatically switches to it. It can provide a very powerful tool when it comes to moving forward.

[Brief explanation of drawings]

The figure is a block diagram showing an embodiment of the in-vehicle radio receiver of the present invention. In the figure, 1 is an antenna, 2 is a tuner, 3
is a level judgment circuit, 4 is a demodulation level detection circuit, and 5 is a level judgment circuit.
is a control section, 6 is a current data memory area, 6a is a current station data area, 6b is an inspection station data area, 7 is a tuning voltage generation circuit, 8
is a mutating circuit, 9 is a low frequency amplifier, 10
is a speaker, 11 is a memory device, 11a to 11
h is a data area.

Claims (1)

[Claims] 1 A tuner that tunes to a desired station from among multiple stations and receives the transmitted signal from that station, and a tuner that searches for stations other than the desired station in the reception band and obtains the tuning data and reception level of the searched station. a first search means for storing in a memory a station searched for by the first search means when the memory becomes full; and a station with the lowest reception level among the stations stored in the memory; storage means for comparing the reception level of the station with the higher reception level and storing the tuning data and reception level of the station with the higher reception level in the memory; a second search means for searching for a station with a high reception level, and then searching whether a station whose reception level is higher than the station currently being received has the same program content as the station being received; a tuning means for tuning the tuner to a station searched by the tuning means; and when the tuned station of the tuner is switched by the tuning means, the same program information is added to the tuning data or reception level of the station to which it has been tuned so far. and information adding means for storing the information in the memory.