JPH0774686A - Diversity antenna system receiver - Google Patents

Abstract

PURPOSE:To eliminate disturbance of reproduction due to antenna changeover by selecting and fixing an antenna in the best reception state in a standstill state of a mobile body whose position and direction are unchanged. CONSTITUTION:An antenna changeover circuit 21 selects one antenna among antennas A, B, C and connects the selected antenna to a reception circuit 22. The antenna selection among the antennas A, B, C by the antenna changeover circuit 21 is executed by communication through lines A, B, C, D from a control circuit 23. That is, when the line A is set, the antenna A is selected, and when the line B is set, the antenna B is selected. The line D is used to communicate distinguishment of continuity/stop of the diversity operation to the antenna changeover circuit 21, and when the line D is set, the connection is fixed to the first antenna at the set of the line independently of the signal state of the lines A, B, C. In this case, when the vehicle speed is zero, it is identified that an automobile is at a standstill and the selective operation of the diversity antenna is fixed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diversity antenna type receiver which automatically selects an antenna in the best receiving state from a plurality of antennas and receives radio waves.

[0002]

2. Description of the Related Art Diversity antenna type receivers are sometimes used for television receivers, FM broadcast receivers, analog radios, portable transceivers, etc., which are mounted on mobile bodies such as automobiles. The diversity antenna type receiver automatically selects the antenna having the best reception state (for example, the maximum reception intensity of radio waves) from the plurality of antennas provided on the moving body, and connects to the receiver.

[0003] For example, in a diversity antenna type vehicle-mounted television receiver, a plurality of antennas having different mounting heights and directivities are provided on a vehicle body, and the reception intensity of radio waves by different antennas is periodically measured in order. Then, if the reception strength is higher than that of the original antenna connected at that time, the connection is switched to a new antenna having a high reception strength. By repeating this operation and sequentially selecting antennas with high reception strength, it is possible to always receive the television broadcast using the antenna with the final maximum reception strength.

That is, in a television receiver for home use, the height and directivity of the antenna can be fixed according to the best reception state at the time of initial installation, but in a car, the position, direction and height of the antenna can be fixed while driving. However, since a single antenna fixed to the vehicle body changes the reception state of the radio wave continuously, it is impossible to maintain a good reception state.

Therefore, from the plurality of antennas, the antenna in the best reception state that suits the position, direction, and height of the automobile is selected, and if the reception state deteriorates, another antenna in a good reception state is selected. Switch to one after another.

FIG. 4 is an explanatory view of a conventional vehicle-mounted television receiver. In the figure, (a) shows a circuit configuration and (b) shows a control program. Here, the antenna with the maximum reception strength is selected from the three antennas.

In FIG. 4A, the antenna switching circuit 41
Selects one of the antennas A, B and C and connects it to the receiving circuit 42. The high frequency signal received by the selected antenna is input to the receiving circuit 42 and processed by the receiving circuit 42. The selection of the antennas A, B, C in the antenna switching circuit 41 is executed by a designation signal from the control circuit 43. That is, when the line A is turned on, the antenna A is selected, and when the line B is turned on, the antenna B is selected.

The receiving circuit 42 band-selects the high-frequency signal input from the antenna switching circuit 41 to convert it into an intermediate-frequency signal, further selects the band and performs a detection operation to take out a baseband signal. From the baseband signal, the image signal and the audio signal are further separated, and from the image signal,
The luminance signal and the color signal (difference signal) are reproduced.

From the luminance signal and the color signal, R,
The G and B image signals are assembled and sent to the liquid crystal monitor 44. On the other hand, the audio signal is reproduced as audio from an amplifier circuit attached to the liquid crystal monitor 44 through a small speaker.

The receiving circuit 42 also sends to the control circuit 43 a signal corresponding to the intensity of the received radio wave. This signal is the signal strength at a certain phase position of the image signal,
For example, it corresponds to the intensity of the black level signal of the pedestal portion of the specific scanning line extracted from the image signal in the vertical blanking period of the television reproduction screen.

The control circuit 43 is composed of an arithmetic circuit having a plurality of input ports and executes a program for diversity operation. That is, the analog signal sent from the receiving circuit 42 is sampled and A / D converted at a specific timing synchronized with the image signal to form radio wave intensity data.

The control circuit 43 uses this radio field intensity data to select the antenna with the maximum reception intensity, turns on the signal of the line corresponding to this antenna, and sets this antenna in the antenna switching circuit.

In FIG. 4B, when the antenna A is first selected, the antenna B is selected for a very short time at the timing of a certain phase position of the image signal, and the antenna B is selected.
The radio wave intensity data is taken in by the antenna A
Connection back to.

If the antenna A has a higher reception strength than the antenna B, the connection of the antenna A is maintained as it is, and the reception strength of the antenna C is compared with that of the antenna C at the next timing.

However, if the reception strength of the antenna B is higher than that of the antenna A, the antenna A is switched to the antenna B at a phase position that does not affect the image signal displayed on the screen, and the reception by the antenna B is started. It At the next timing, the reception intensity of the antenna C is compared with the reception intensity of the antenna B.

By repeating such operations, the antenna having the optimum directivity and height is selected according to the momentary position and height of the automobile and the surrounding environment, and stable reception and reproduction of television broadcasting becomes possible. .

[0017]

In the vehicle-mounted television receiver shown in FIG. 4, the antenna is switched at a phase position that does not affect the image signal displayed on the screen. Therefore, for the image displayed on the liquid crystal monitor 44, the antenna is switched. It is not necessary to generate image distortion or noise due to. However, as for the voice, since the analog voice signal is continuously output irrespective of the scanning of the television screen, noise is added to the voice signal when the antenna is switched.

Therefore, when the antenna is switched, the voice is muted so that the noise due to the antenna switching is not reproduced in the voice. However, when the voice is muted, the original sound is lost at the mute portion, the voice is interrupted, and a jarring noise such as lumpy noise is generated.

Particularly, when the vehicle is traveling in a place where the radio field intensity is strong or when it is traveling in a place where the radio field intensity is very weak, the difference in the reception intensity between the plurality of antennas is small, and even if there is a difference. It does not affect the quality of the reproduced image.

When the difference between the reception strengths of the plurality of antennas is small, a kind of chattering occurs and the switching of the antennas is frequently executed, and the interruption of the reproduced voice exceeds the allowable range. become.

In many cases, the on-vehicle television receiver shares the monitor screen with the navigation device, and while driving, the television broadcast may be blocked from being reproduced and the television broadcast may not be received. Therefore, the reception of TV broadcasting is started only after the driver guides the car to a safe place and stops it, but the in-vehicle TV receiver in the stopped state is exactly the same as the home TV receiver. Therefore, the direction and height of the directivity of each antenna do not change at all.

In such a case, if there is no difference in the reception intensities of the plurality of antennas, the switching of the antennas is frequently repeated although it is not necessary, and the disturbance or interruption of the reproduced voice exceeds the allowable range. Become. Especially, when watching a television broadcast in a quiet car with the engine stopped, the noise caused by the mute becomes unbearable.

An object of the present invention is to provide a diversity antenna type receiver in which unnecessary antenna switching does not occur when a mobile unit is stopped and receiving is performed, and reproduction disorder due to antenna switching does not occur.

[0024]

FIG. 1 is an explanatory view of the basic constitution of the present invention. In FIG. 1, the diversity antenna type receiver according to claim 1 is an antenna switching unit 11 capable of selecting one from a plurality of antennas and receiving radio waves.
Based on the received radio wave signal, the detecting means 12 for detecting the reception state of the radio wave and the detection state of the plurality of antennas are repeatedly compared with each other at almost constant intervals, and the antenna with the best reception state is selected. In the diversity antenna receiver having the control means 13 for setting the antenna switching means, the identification means 14 for identifying the moving state and the stopped state of the moving body provided with the plurality of antennas, and the stopped state. After shifting to (1), the fixing means 15 for searching for the antenna in the best receiving state, selecting the antenna in the best receiving state, and fixing it to the antenna switching means.
And ,.

A diversity antenna type receiver according to a second aspect is the diversity antenna type receiver according to the first aspect, wherein a plurality of antennas are cyclically and sequentially arranged for a certain period of time after the fixing means shifts to the stop state. By switching, the level of the reference signal arranged at a specific phase position in the received signal is obtained for each of the plurality of antennas,
The program is configured to repeat the operation of selecting an antenna having the maximum level obtained by switching for one cycle and fixing it to the antenna switching means until the beginning of the next cycle.

[0026]

In the diversity antenna type receiver according to the first aspect of the present invention, the contents of the diversity function are made different when moving and when stopped. That is, during the movement in which the direction and the position of the moving body may change every moment, the reception states of the respective antennas are frequently compared with each other, the antenna in the best reception state is selected, and the antennas are switched one after another as before.

However, at the time of stoppage in which the direction or position of the moving body does not change, in the first stage, the receiving states of the respective antennas are compared, the antenna in the best receiving state is selected and fixed, and thereafter, For example, it is assumed that only the antenna is used and the antenna is not switched at all until the movement is started again.

The fixing means 15 is preferably the control means 1
3 as part of the program executed. The procedure for selecting and fixing the antenna in the best reception state when the vehicle is stopped can be modified in various ways, but a method that is not much different from the diversity operation during traveling is desirable.

In the case of an automobile, the fixing means 14 is, for example,
ON-OFF of engine, ON-OF of side brake
The moving state and the stopped state of the automobile are identified by a combination of F and the output of the vehicle speed sensor. As the antenna, a combination of a glass antenna and a pole antenna having different directivity, height, position, etc. can be used.

In the diversity antenna type receiver of the second aspect, the procedure for selecting and fixing the antenna in the best receiving state when stopped is limited. That is, the level of the reference signal is measured through multiple antennas in a very short time, the antenna with the highest level detected is maintained until the next measurement is started, and the same operation is repeated in the next measurement. The operation is executed only for a certain period of time after shifting to the stop state.

As the reference signal, a synchronizing signal or a reference level signal inserted in the received signal can be used.

[0032]

FIG. 2 is an explanatory diagram of a vehicle-mounted television receiver of the embodiment, and FIG. 3 is a control program of the embodiment. In FIG.
(a) shows the circuit configuration and (b) shows the antenna arrangement. Here, when the wheel speed is 0, the vehicle is identified as being in a stopped state, and the diversity antenna selection operation is fixed.

In FIG. 2A, the antenna switching circuit 21
Selects one of the antennas A, B, and C and connects it to the receiving circuit 22. The selection of the antennas A, B and C by the antenna switching circuit 21 is performed by the line A from the control circuit 23,
It is executed by communication through B, C and D.

That is, when the line A is turned on, the antenna A is selected, and when the line B is turned on, the antenna B is selected. The line D is for communicating to the antenna switching circuit 21 whether the diversity operation is continued or stopped,
When the line D is turned on, the connection is fixed to the original antenna that was turned on regardless of the signal states of the lines A, B, and C.

The receiving circuit 22 band-selects the high-frequency signal input from the antenna switching circuit 21 to convert it into an intermediate-frequency signal, further selects the band and performs a detection operation to take out a baseband signal. From the baseband signal, the image signal and the audio signal are further separated, and from the image signal,
The luminance signal and the color signal (difference signal) are reproduced.

From the luminance signal and the color signal, R,
The G and B image signals are assembled and sent to the liquid crystal monitor 24. On the other hand, the audio signal is reproduced by an amplifier circuit attached to the liquid crystal monitor 24 through a small speaker.

The receiving circuit 22 also sends a signal corresponding to the intensity of the received radio wave to the control circuit 23. This signal is the signal strength at a certain phase position of the image signal,
This corresponds to the intensity of the luminance signal at the specific phase position in the scanning line during the vertical blanking period that does not appear on the reproduction screen.

The control circuit 23 is composed of an arithmetic circuit having a plurality of input ports for analog signals and digital signals,
It has a built-in memory for storing and comparing input data. The control circuit 23 samples the analog signal of the radio field intensity sent from the receiving circuit 22 at a specific phase position of the image signal and performs A-D conversion to form radio field intensity data.

The control circuit 23 uses this radio field intensity data to execute a program for selecting the antenna with the maximum reception intensity regardless of whether the vehicle is running or stopped. However, at the time of stop, the program that selects the antenna is executed for a maximum of 10 seconds, and thereafter, the connection of the antenna is fixed.

Two digital signals are input to the control circuit 23. One is to express the distinction between when the vehicle is running and when it is stopped. The ECU (Elec
tricControl Unit) 25. ECU 25
Outputs this input signal when the wheel speed is zero.
F

The other one is an antenna fixing switch 26 for manually stopping the diversity operation. The driver can stop the diversity operation by turning on the antenna fixing switch 26.

In FIG. 2B, antennas A, B, C
Are fixed to the rear glass of the car at different heights. The directivities of the antennas A, B, and C are not so different from each other, and the difference in height is not so large,
An effective diversity effect can be realized.

In FIG. 3, in the control circuit 23 of FIG. 2A, first, at step 31, the distinction between running and stopping of the automobile is identified. Then, when traveling, the normal diversity operation is selected, and when stopped, the stop program 32 is selected.

After the program 32 at the time of stop, the program 32 at the time of stop is spent for 1 to 10 seconds to switch the antennas one after another, and 15 pieces of effective radio wave intensity data of the antennas A, B, and C are accumulated. Then, after the accumulation is completed, the average reception strengths of the antennas A, B, and C are calculated and compared with each other, and the identified antenna having the maximum average reception strength is selected and the antenna switching circuit 21 is selected. Fixed.

On the other hand, at the time of traveling, in step 33, as shown in FIG.
The ON / OFF distinction of the antenna fixing switch 26 in (a) is identified. At this time, if the antenna fixing switch 26 is OFF, the normal diversity operation program is executed, but if it is ON, the reception state is fixed by the antenna at that time. That is, the normal diversity operation is not executed and the antenna fixed switch 26 is turned on.
The antenna that was connected at that time will continue to be used.

Therefore, when the driving vehicle is traveling in a place where the radio field intensity is strong or in a place where the radio field intensity is very weak, the antenna fixing switch 26 is turned on to display the reproduction screen. It is possible to prevent useless switching of antennas irrelevant to the quality of, and to eliminate noise and interruption of voice due to switching of antennas.

In the above embodiment, the antenna in the best receiving state is obtained by averaging (averaging) the accumulated radio field intensity data, but various methods can be adopted in addition to this. For example, compare the reception status of the receiving antenna to the reception status of another antenna, and if the reception status of another antenna is better, repeat the procedure to connect another antenna instead of the receiving antenna. Alternatively, the method of selecting the antenna with the final best reception state after a certain period of time may be used.

Also, the reference signal level inserted in the vertical blanking period of the luminance signal of the television broadcast is detected, the antennas A, B and C are cyclically switched, and the magnitude of the equivalent pulse of 5 μsec that appears every 30 μsec. The pedestal level is calculated for the antennas A, B, and C in order and compared, and the antenna with the maximum value is compared with the vertical retrace period of 60
You may reselect every msec.

That is, the pedestal level of the horizontal synchronizing signal of the portion of the luminance signal that does not appear on the screen (avoid teletext portion) is detected by different antennas for the three adjacent scanning lines, and the maximum level is detected. Connected antenna. The connection state of the antenna is maintained until the same three scanning lines on the next screen. This operation is repeated for each screen, and the reception / reproduction of the next screen is executed using the antenna with the maximum reception intensity on the previous screen.

This operation is repeated only for 1 to 10 seconds after the vehicle is stopped, and the antenna in the final and best receiving state is selected and fixed.

[0051]

According to the diversity antenna type receiver of the first aspect, unnecessary antenna switching does not occur when a mobile unit is stopped and receiving, and there is no disturbance of reproduction due to antenna switching.

For example, in a vehicle-mounted television receiver, noise (diver noise) associated with antenna switching does not mix with reproduced sound, and there is no continuous interruption of sound due to mute, resulting in an uncomfortable state.

Therefore, even in a quiet car where the engine is stopped, it is possible to watch a television broadcast with a stable screen and high-quality audio. Then, even in a place where the radio wave intensity is strong or a very weak place, or even when there is no difference in the reception intensity of the plurality of antennas, it is not necessary to perform unnecessary antenna switching unrelated to the quality of the reproduction screen.

According to the diversity antenna type receiver of the second aspect, the diversity operation during movement is such that the plurality of antennas are cyclically switched in sequence and the level of the reference signal arranged at a specific phase position in the received signal is changed. Is calculated for each of a plurality of antennas, the antenna having the maximum level obtained through the switching of one cycle is selected, and the program is fixed to the antenna switching means until the beginning of the next cycle. You can configure the program at stop by simply inserting.

Therefore, the program of the control means is simplified, the processing speed is improved, the spare capacity of the arithmetic elements of the control means is increased, and it is possible to allocate the functions to other functions.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a basic configuration of the present invention.

FIG. 2 is an explanatory diagram of a vehicle-mounted television receiver according to an embodiment.

FIG. 3 is an explanatory diagram of a control program according to the embodiment.

FIG. 4 is an explanatory diagram of a conventional vehicle-mounted television receiver.

[Explanation of symbols]

 11 Antenna Switching Means 12 Detecting Means 13 Control Means 14 Identifying Means 15 Fixing Means

Claims (2)

[Claims] 1. An antenna switching means (11) capable of receiving a radio wave by selecting one from a plurality of antennas, and a detection means (12) for detecting a reception state of the radio wave based on a received radio wave signal. And a control means (13) for repeating the reception states of the plurality of antennas and comparing the reception states of the plurality of antennas with each other, selecting the antenna in the best reception state and setting the antenna switching means. In the type receiver, an identification means (14) for identifying a moving state and a stopped state of a moving body provided with the plurality of antennas; and, after shifting to the stopped state, searching for an antenna in the best receiving state, Fixing means (15) for selecting an antenna in a receiving state and fixing it to the antenna switching means (11)
And a diversity antenna type receiver. 2. The diversity antenna type receiver according to claim 1, wherein the fixing means cyclically switches a plurality of antennas sequentially for a certain period of time after the shift to the stopped state, and selects a specific one in a received signal. The level of the reference signal arranged at the phase position is obtained for each of the plurality of antennas, and the antenna having the maximum level obtained through one cycle switching is selected and fixed to the antenna switching means until the beginning of the next cycle. A diversity antenna type receiver characterized by comprising a repeating program.