JPH09200102A - Diversity device for mobile television receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To select an antenna offering a best sound electric field strength level not subjected to the effect of multi-path distortion even when the electric field strength is fluctuated during movement. SOLUTION: In the diversity device for a mobile television receiver placing emphasis on a sound signal, a sound diversity antenna selection circuit 8 provides an output of an antenna switching signal to an antenna changeover switch 2 so as to select an antenna providing a highest level of an electric field strength of a sound signal that is received by a high frequency tuner 3 through the antenna changeover switch 2 from a space diversity antenna 1 and demodulated by a sound detection circuit 5. Even when the electric field strength level of the sound signal is strong and the selected antenna receives multi-path interference, the selected antenna is rejected and another antenna with less multi-path distortion is selected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile television diversity device used in a car, a bus, or the like.

[0002]

2. Description of the Related Art A conventional mobile television diversity apparatus will be described with reference to FIG.

In FIG. 2, 1 is a space diversity antenna, 2 is an antenna changeover switch of the space diversity antenna 1, 3 is a high frequency tuner connected to the space diversity antenna 1 through the antenna changeover switch 2, and 4 is a high frequency tuner 3. Phase locked loop, 5
Is a video detection circuit for detecting the video intermediate frequency signal from the high frequency tuner 3 to demodulate the video signal, 6 is an audio detection circuit for separating and demodulating the audio signal from the video intermediate frequency signal, and 7 is a diversity antenna selection circuit, The antenna switching signal is output to the antenna switching switch 2 so that the space diversity antenna 1 switches to the antenna having the highest electric field level of the video signal.

Next, the operation of the conventional diversity device configured as described above will be described.

The high frequency signal received by the space diversity antenna 1 is input to the high frequency tuner 3 via the antenna changeover switch 2, and the video intermediate frequency signal obtained by the frequency conversion in this high frequency tuner 3 is detected by the video detection circuit 5. Demodulated. The audio detection circuit 6 separates and demodulates the audio signal from the video intermediate frequency signal.

On the other hand, the demodulated video signal is input to the diversity antenna selection circuit 7. In the diversity antenna selection circuit 7, by outputting the antenna changeover signal to the antenna changeover switch 2 during the vertical retrace period of the video signal, the antenna changeover switch 2 is sequentially changed over to each antenna of the space diversity antenna 1 and the changed antenna is used. The electric field level of the received video signal is sequentially compared with the previous electric field level, and the antenna changeover signal is output to the antenna changeover switch 2 so as to switch to the antenna with the highest electric field level.

[0007]

However, in the conventional diversity device as described above, since the antenna is switched to the antenna having the highest electric field level of the video signal, the antenna can be switched regardless of the strength. As a result, the variation in the electric field level of the video signal does not match the variation in the electric field level of the audio signal, and the antenna with the best audio level is not always selected.

[0008] Further, if the vehicle is affected by multipath while traveling, a large noise is generated. Here, when comparing the disturbance of the image while running and the generation of the sound distortion sound, since the synchronization stabilization circuit etc. for the image have been developed for in-vehicle use, it is possible to stabilize the image while running, For voice, there is a problem that the effects of multipath distortion remain.

The present invention is intended to solve the above-mentioned problems, and it is possible to select an antenna having the best voice electric field level that is not affected by multipath distortion even if electric field fluctuations occur during movement. An object of the present invention is to provide a television diversity device.

[0010]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention is directed to a mobile television diversity apparatus which emphasizes sound, receives from a space diversity antenna through a high frequency tuner through an antenna changeover switch and is demodulated by a sound detection circuit. Outputs the antenna changeover signal to the antenna changeover switch so as to switch to the antenna with the highest electric field level of the voice signal, and receives the multipath when the selected antenna is receiving multipath even if the electric field level of the voice signal is strong. It is provided with a voice diversity antenna selection circuit that eliminates the antenna and selectively connects to the antenna with less multipath distortion.

Thus, it is possible to select the antenna having the best voice electric field level which is not affected by the multipath distortion even if the electric field changes during the movement.

[0012]

The invention according to claim 1 is a space diversity antenna having a plurality of antennas, an antenna changeover switch for sequentially switching the space diversity antenna, and a high-frequency signal received by the antenna through the antenna changeover switch. Is tuned to the selected channel and is converted to an intermediate frequency, a video detection circuit for demodulating a video signal from the intermediate frequency signal of the high frequency tuner, and an audio signal is demodulated from the intermediate frequency signal of the high frequency tuner. A diversity device for a mobile television having an audio detection circuit,
The high frequency tuner receives from the space diversity antenna through the antenna changeover switch, and outputs the antenna changeover signal to the antenna changeover switch so that the electric field level of the voice signal demodulated by the voice detection circuit is switched to the largest antenna. Even if the electric field level of the voice signal is strong, when the selected antenna is receiving multipath, it is equipped with a voice diversity antenna selection circuit that eliminates the multipath receiving antenna and selectively connects to the antenna with less multipath distortion. It is a thing.

According to a second aspect of the present invention, in the audio diversity antenna selection circuit, the antenna changeover signal is output to the antenna changeover switch during the vertical blanking period of the video signal, and the antenna changeover switch is used for each of the space diversity antennas. Switching to the antenna in order, comparing the electric field level of the audio signal received by this switched antenna with the previous electric field level in sequence, and outputting the antenna switching signal to the antenna switching switch so that the antenna with the highest electric field level is switched. From the comparing unit and the multipath receiving antenna excluding unit that excludes the multipath receiving antenna when the selected antenna receives multipath even if the electric field level is strong and selectively connects to the antenna with less multipath distortion It is composed.

Therefore, the antenna having the best voice electric field level can always be selected, and accordingly, the antenna having the best voice electric field level which is not affected by the multipath distortion even if the electric field varies during the movement. Select to enable voice-focused reception.

The embodiment of the present invention will be described below with reference to FIG.
This will be described with reference to FIG. FIG. 1 is a block diagram showing the configuration of a mobile television diversity device according to an embodiment of the present invention.

In FIG. 1, the same components as those in FIG. 2 are designated by the same reference numerals, 1 is a space diversity antenna, 2 is an antenna changeover switch of the space diversity antenna 1, and 3 is an antenna changeover switch 2. High-frequency tuner connected to the space diversity antenna 1, 4 is a phase-locked loop for tuning and selecting the high-frequency tuner 3 to the selected channel, and 5 is for detecting the video intermediate frequency signal from the high-frequency tuner 3 to demodulate the video signal. An image detection circuit 6 is an audio detection circuit for separating and demodulating an audio signal from an image intermediate frequency signal.

Reference numeral 8 denotes a voice diversity antenna selection circuit for achieving the above-mentioned object. This voice diversity antenna selection circuit 8 has an electric field strength comparison unit 81 similar to the FM tuner diversity, and a multi-channel even if the electric field strength is strong. The multipath reception antenna excluding unit 82 that excludes the reception antenna affected by the path distortion is provided.

Next, the operation of the present embodiment configured as described above will be described. The high frequency signal received by the space diversity antenna 1 is the antenna switch 2
Is input to the high frequency tuner 3 via. The phase locked loop 4 tunes and selects the high frequency tuner 3 to the selected channel.

The high frequency tuner 3 converts the high frequency signal selected for tuning into an intermediate frequency, and inputs this intermediate frequency signal to the video detection circuit 5 and the audio detection circuit 6. The video detection circuit 5 detects the video intermediate frequency signal, demodulates it into a video signal, and outputs it to the video amplification stage. The audio detection circuit 6 separates the audio signal from the video intermediate frequency signal, demodulates it, and outputs it to the audio amplification stage.

On the other hand, the demodulated voice signal is input to the voice diversity antenna selection circuit 8. In the audio diversity antenna selection circuit 8, the antenna changeover switch 2 is sequentially changed over to each antenna of the space diversity antenna 1 by outputting the antenna changeover signal to the antenna changeover switch 2 during the vertical blanking period of the video signal, and this changeover is performed. The electric field level of the audio signal received by the antenna and the previous electric field level are sequentially compared by the electric field strength comparison unit 81,
An antenna switching signal is output to the antenna switching switch 2 so as to switch to the antenna having the highest electric field level.
Further, even when the electric field strength is strong, if the selected antenna is subjected to multipath, it is eliminated by the multipath reception antenna excluding unit 82, and the antenna switching signal with less multipath distortion is vertically retraced to the video signal. It outputs to the antenna changeover switch 2 during the period, and the space diversity antenna 1 is selectively connected to the antenna with less multipath distortion.

According to the present embodiment as described above, it is possible to always select the antenna having the best voice electric field level without multipath distortion.

[0022]

As described above, according to the present invention, it is possible to always select the antenna having the best audio electric field level,
As a result, even if the electric field fluctuates during the movement, it is possible to select the antenna having the best audio electric field level that is not affected by the multipath distortion and perform the audio-oriented reception.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a mobile television diversity device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a conventional mobile television diversity device.

[Explanation of symbols]

 1 Diversity antenna 2 Antenna selector switch 3 High frequency tuner 4 Phase locked loop 5 Video detection circuit 6 Audio detection circuit 8 Audio diversity antenna selection circuit 81 Electric field strength comparison unit 82 Multipath reception antenna rejection unit

Claims (2)

[Claims] 1. A space diversity antenna having a plurality of antennas, an antenna changeover switch for sequentially switching the space diversity antenna, a high frequency signal received by the antenna through the antenna changeover switch is tuned to a selected channel, and an intermediate signal is selected. Diversity of a mobile television having a high frequency tuner for converting a frequency, a video detection circuit for demodulating a video signal from an intermediate frequency signal of the high frequency tuner, and an audio detection circuit for demodulating an audio signal from the intermediate frequency signal of the high frequency tuner. In the device, the antenna switching signal is received from the space diversity antenna through the antenna changeover switch through the high frequency tuner and is switched to the antenna in which the electric field level of the voice signal demodulated by the voice detection circuit is the largest. Even if the selected antenna receives multipath even when the electric field level of the audio signal is strong while outputting to the antenna changeover switch, the multipath receiving antenna is excluded and the multipath distortion is selectively connected to the antenna with less distortion. A mobile television diversity device including an audio diversity antenna selection circuit. 2. The voice diversity antenna selection circuit comprises:
During the vertical blanking period of the video signal, the antenna changeover signal is output to the antenna changeover switch and the antenna changeover switch is sequentially changed over to each antenna of the space diversity antenna, and the electric field level of the audio signal received by this changed antenna and the previous The electric field level is compared sequentially and the electric field strength comparison unit that outputs the antenna switching signal to the antenna changeover switch so as to switch to the antenna with the highest electric field level and the selected antenna receives multipath even if the electric field level is strong. 2. The diversity apparatus for a mobile television according to claim 1, further comprising: a multipath receiving antenna excluding section that selectively removes the multipath receiving antenna when it is present and selectively connects to an antenna with less multipath distortion. .