JP3119806B2 - Diversity receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diversity receiving apparatus which has a plurality of antennas and selects an antenna having an optimum receiving condition.

[0002]

2. Description of the Related Art Conventionally, there has been known a TV receiver mounted on a mobile body such as an automobile for receiving TV broadcasts. In such a TV receiver, when receiving a TV broadcast, multiple interference fading may occur due to the influence of the terrain and buildings around the moving object. by this,
The image receiving state in the TV receiver is significantly deteriorated.

In order to solve this drawback, a diversity receiver has been proposed in which a plurality of antennas are installed on a moving body and the best antenna is selected by switching the antennas. In such a device, each antenna is switched every vertical blanking period, and the electric field strength of the video signal received by each antenna, that is, the electric field level is compared.
Then, the antenna having the highest electric field level is selected, and the selected antenna is connected to the antenna input of the TV receiver.

However, such a diversity receiver performs a so-called video diversity operation that focuses only on the electric field level of a received video signal when selecting an antenna, and does not control an audio signal received together with a video signal. Was not taken into account. Therefore,
Even if the best antenna is selected for the video signal, it is not always the best antenna for the audio signal. This is because the best antenna may differ between video and audio depending on the modulation method, frequency, and the like. For this reason, when a TV broadcast is received, the received video may be prevented from deteriorating, but the sound may be degraded.

[0005] In order to solve such a problem, there has been proposed a diversity receiving apparatus adopting a system combining a video diversity operation and an audio diversity operation for selecting the best antenna for an audio signal. The following is a specific example.

FIG. 13 is a block diagram showing an example of the diversity receiving apparatus described in Japanese Patent Application No. 6-281381. In the figure, 1 is, for example, four (1a to 1)
d), 2 is four antennas 1a
A changeover switch for arbitrarily changing .about.1d. Reference numeral 3 denotes a front end, which selects a desired station from a signal received from an arbitrary antenna via the changeover switch 2 and converts it to an intermediate frequency (IF). Reference numeral 4 denotes a video IF circuit which takes out a video IF signal from the output of the front end 3 and amplifies it. Reference numeral 5 denotes a video detection circuit, which reproduces a video signal from the output of the video IF circuit 4. 6 is a voice IF
A circuit for extracting an audio IF signal from the output of the front end 3, amplifying the signal, and displaying an S level indicating a reception electric field level.
Outputs meter signal. Reference numeral 7 denotes an audio detection circuit which reproduces an audio signal from the output of the audio IF circuit 6. Reference numeral 8 denotes a multipath detection circuit, which outputs S from the audio IF circuit 6.
A multipath signal is detected from the meter signal. Furthermore, 10
Is a timing controller which extracts a vertical synchronization signal from the output of the video detection circuit 5 and generates a timing signal (video diversity signal) for antenna switching. 1
1 is an antenna switching controller, based on a video diversity signal from the timing controller 10,
A switching signal is output to the switch 2 during the vertical blanking period. Reference numeral 12 denotes a maximum receiving antenna selection circuit, which selects the maximum image electric field level from the output of the image detection circuit 5. Reference numeral 9 denotes an audio diversity controller, which receives a multipath signal from the multipath detection circuit 8 and a video diversity signal from the timing controller 10. Then, when a multipath signal is input, it outputs a voice diversity signal (antenna switching signal) to the antenna switching controller 11.
This voice diversity signal has a constant wait time T
1, a signal for switching a plurality of antennas during a period other than the vertical blanking period.

In such a configuration, based on the vertical synchronizing signal of the video signal, the timing controller 10
Video diversity signal is transmitted to antenna switching controller 1
Output to 1. As a result, the antenna switching controller 11 outputs a switching signal to the switching switch 2 to sequentially switch the four antennas 1a to 1d within the vertical blanking period. Then, the maximum receiving antenna selection circuit 12
Compares the electric field levels of the four antennas 1a to 1d, selects the antenna having the highest electric field level, and outputs the result to the antenna switching controller 11. The antenna switching controller 11 outputs a switching signal to the changeover switch 2 under the control of the timing controller 10 based on the above result. As a result, the changeover switch 2
Connect the selected antenna. Thereafter, video reception by this antenna is continued until the next vertical blanking period. On the other hand, when a multipath signal is detected by the multipath detection circuit 8 during such video reception, the audio diversity controller 9 outputs an audio diversity signal to the antenna switching controller 11.
Then, the antenna switching controller 11 outputs a switching signal to the changeover switch 2 so that the currently receiving antenna is switched to another antenna. Then, when the antenna is switched, the multipath is determined by the switched antenna. When a multipath signal is detected, switching to the next antenna is similarly performed, and thereafter, the switching operation is repeated until no multipath signal is detected. Such a switching operation does not affect the video diversity operation, as described above,
This is performed during a period other than the vertical blanking period.

[0008]

However, the above-mentioned diversity receiver has the following problems. That is, when a multipath signal is detected, antenna switching is performed sequentially, and this switching operation is repeated until the multipath signal is no longer detected. Therefore, unless the multipath is improved, the antenna switching is repeated endlessly, so that the number of antenna switching becomes very large, and conversely, there is a problem that the switching noise increases.

The multipath signal in the audio signal includes multipath noise (hereinafter referred to as MP noise) and multipath beat noise (hereinafter referred to as MB noise).
Are included. MP noise is
This is a skip noise generated mainly due to a sudden change in the electric field, and is a multipath signal having a short electric field fluctuation period generated in a relatively short time. The MB noise is a beat noise including frequency modulation, and is a multipath signal generated for a relatively long time and having a long electric field fluctuation cycle. These have different characteristics in terms of space, and the MP noise is concentrated in a very narrow space, whereas the MB noise is more spatially spread than the MP noise. However, in the diversity receiving apparatus described above, antenna switching is performed using these noises as the same multipath signal. Therefore, there is a problem that appropriate antenna switching control is not performed for noises having different characteristics. .

[0010] The present invention has been proposed to solve the problems of the prior art as described above.
Provided is a diversity receiving apparatus that suppresses unnecessary antenna switching, reduces the number of times of antenna switching, and performs effective antenna switching for each component of a multipath signal in a voice signal, thereby improving voice diversity performance. It is in.

[0011]

In order to achieve the above object, a diversity receiving apparatus according to the present invention comprises a plurality of antennas for receiving a voice signal and one of the plurality of antennas. A multipath signal detection circuit for detecting a multipath signal from the received audio signal, separately detecting multipath noise and multipath beat noise from the multipath signal, and outputting each of the multipath noise and the multipath beat noise; A multipath noise control circuit that outputs an antenna switching signal when multipath noise is input from a signal detection circuit, and an antenna switching signal when multipath beat noise is input from the multipath signal detection circuit. A multipath beat noise control circuit for outputting the signal;
And the multipath beat noise control circuit.
Input the antenna switching signal, and
Signal and select another receiving antenna from the antenna.
An antenna switching control circuit that performs switching control for switching to an antenna
And a road .

According to the first aspect of the present invention, the following effects can be obtained. When a multipath signal is detected from the audio signal received by the antenna, the multipath signal detection circuit detects multipath noise and multipath beat noise from the multipath signal.
When multipath noise is detected by the multipath signal detection circuit, it is input to the multipath noise control circuit, and when multipath beat noise is detected, it is input to the multipath beat noise control circuit. Is done. The multipath noise control circuit and the multipath beat noise control circuit output an antenna switching signal when each noise is input. This allows the antenna switching control circuit to appropriately switch one of the switching signals.
The selected antenna is switched from the antenna to another antenna.

As described above, by decomposing the multipath signal into different noise components of multipath noise and multipath beat noise, it is possible to perform antenna switching control corresponding to the nature of each noise.

That is, for each noise component, the antenna can be switched according to the characteristics such as the generation period or the spatial spread. For example, the multipath noise is skip noise mainly due to a sudden change in the electric field, and has a property that the electric field fluctuation cycle is relatively short and is concentrated in a narrow space. In this case, when a part of the plurality of antennas is affected by the multipath noise, the reception state can be improved by switching to another antenna separated by a certain distance or more. Therefore, it is required that such switching control of the antenna by the multipath noise be performed immediately upon detection of the occurrence of the noise.

On the other hand, multipath beat noise is beat noise having a long electric field fluctuation period including frequency modulation, and has the property of having a spatial spread. For this reason, when the receiving antenna is affected by the multipath beat noise, there is a high possibility that the switched antenna is also affected by the multipath beat noise. In addition, multipath beat noise is easily affected by switching noise due to antenna switching. Therefore, unlike multipath noise in which the reception state is likely to be improved by switching, when multipath beat noise is detected, the number of times of performing antenna switching control needs to be minimized.

According to a second aspect of the present invention, in the diversity receiving apparatus according to the first aspect of the present invention, the multi-path noise control circuit outputs a timing signal of a fixed cycle a predetermined number of times. And each time the timing signal is output from the first timer
A multipath noise determination circuit that determines whether or not the multipath noise is input, and when the multipath noise determination circuit determines that multipath noise is input, A second switching signal output circuit for outputting an antenna switching signal, wherein the multipath beat noise control circuit outputs a timing signal having a constant period a predetermined number of times, a second timer;
The timing signal is output from the second timer
Each time, the multi-pass beat noise determining circuit that determines whether or not the multi-path beat noise is input and the multi-pass beat noise determining circuit determine that the multi-path beat noise is detected. A second switching signal output circuit that outputs an antenna switching signal when the switching is performed.

According to the second aspect of the invention, the following operation is obtained. Each of the multipath noise control circuit and the multipath beat noise control circuit determines whether or not each noise is input at the timing when the timing signal is generated. Therefore, after a certain wait time has elapsed after the timing signal is generated and the antenna switching signal is output, the reception state of the switched antenna is detected. Therefore, even if the reception state is not improved immediately after the antenna switching, the reception state can be detected without being affected by the noise before the antenna switching.

Further, even if the antenna is switched by the number of times of generation of the timing signal, if noise is detected and the reception state is not improved, after switching the predetermined number of times, the antenna is fixed to the antenna selected at that time. Is done. Therefore, it is possible to prevent the antenna from being uselessly switched despite no improvement effect.

According to a third aspect of the present invention, in the diversity receiving apparatus according to the second aspect, the multipath noise control circuit detects an edge of the input multipath noise. And wherein the first switching signal output circuit is configured to output the antenna switching signal even when the rising edge of the multipath noise is detected by the edge detection circuit. .

According to the third aspect of the present invention, the following effects can be obtained. As described above, since the characteristics of the multipath noise and the multipath beat noise are different, it is necessary to control the switching of the antenna by each noise in accordance with the characteristics. That is, due to the nature of multipath noise, it is necessary to perform antenna switching control immediately after the occurrence of noise is detected. On the other hand, with respect to multipath beat noise, unlike the multipath noise in which the reception state is likely to be improved by the switching, it is required that the minimum required antenna switching control be performed.

Therefore, in the multipath noise control circuit, when the multipath noise is input, the rising edge is detected by the edge detection circuit. At this time, the antenna switching signal is output from the first switching signal output circuit. Is done. That is, for multipath noise, antenna switching is performed each time noise is detected. On the other hand, for multipath beat noise, antenna switching is not performed every time noise is detected.

According to a fourth aspect of the present invention, in the diversity receiving apparatus of the second aspect, the diversity receiving apparatus is interposed between the multipath signal detection circuit, the multipath noise control circuit, and the multipath beat noise control circuit. , The multipath output from the multipath signal detection circuit.
Noise and multi-path beat noise to the multi-path noise control circuit and the multi-path beat noise control circuit, and when the respective noises are output simultaneously from the multi-path signal detection circuit, the multi-path beat A noise selection circuit that preferentially selects and outputs noise, a first reset circuit that stops the operation of the multipath noise control circuit while the multipath beat noise control circuit is operating, A second reset circuit for stopping the operation of the multipath beat noise control circuit during the operation of the noise control circuit;
The first reset circuit outputs the antenna switching signal from the multipath beat noise control circuit and switches the antenna, so that the multipath beat noise is no longer detected, or After the antenna switching signal has been output by the number of times the timing signal is generated in the beat noise control circuit, the operation of the multipath noise control circuit is stopped for a certain period.

According to the fourth aspect of the present invention, the operation of the multipath beat noise control circuit is stopped while the multipath noise is detected and the antenna switching signal is output by the multipath noise control circuit. And multi-pass
While the beat noise is detected and the antenna switching signal is output by the multipath beat noise control circuit,
The operation of the multipath noise control circuit stops.

By the way, the beat sound generated by the multipath beat noise is much more annoying than the skip noise sound generated by the multipath noise. Therefore, after the optimum antenna is selected by the multipath beat noise control circuit, the multipath beat noise
If the antenna is switched to another antenna due to noise, a beat sound may be generated again at that antenna. That is, not only the number of unnecessary antenna switching times increases, but also the effect of improving the sound decreases.

Therefore, antenna switching due to multipath beat noise needs to be performed preferentially over antenna switching due to multipath noise. Therefore, when multipath noise and multipath beat noise are simultaneously output from the multipath signal detection circuit, the multipath beat noise is preferentially selected by the noise selection circuit.

After the antenna switching signal is output from the multipath beat noise control circuit, the antenna is switched by the antenna switching control circuit, and after the multipath beat noise is no longer detected, the first reset circuit Stops the operation of the multipath noise control circuit. As a result, the fixed period is fixed to the antenna selected by antenna switching due to multipath beat noise.

According to a fifth aspect of the present invention, in the diversity receiving apparatus, the multipath signal detection circuit detects a drop of an S meter signal indicating a reception electric field level of the audio signal as multipath noise. And a multi-path beat noise detection circuit for extracting a predetermined frequency component from the S-meter signal and detecting multi-path beat noise.

According to the fifth aspect of the present invention, the drop of the S meter signal of the audio signal is detected as multipath noise, and a predetermined frequency component of the S meter signal is detected as multipath beat noise. This predetermined frequency component is, for example, in the case of a TV diver system, a frequency component that is twice the horizontal synchronization signal of the video signal. In this way, by separately detecting each noise component, the effects according to the first to fourth aspects of the present invention can be obtained.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the diversity receiving apparatus according to the present invention will be specifically described below with reference to the drawings. In the present embodiment, a TV diver system employed in a TV receiver will be described as an example.

(1) Configuration FIG. 1 is a block diagram showing a circuit configuration of audio diversity in the TV diver system according to the present embodiment. In the figure, parts corresponding to those in FIG. 13 are denoted by the same reference numerals, and description thereof is omitted.

In FIG. 1, reference numeral 20 denotes an antenna switching circuit including the changeover switch 2 and the front end 3 shown in FIG. Reference numeral 200 denotes an audio diversity control circuit that performs an audio diver operation based on the S-meter signal output from the audio IF 6;
1, antenna switching control circuit 22, MP noise control circuit 2
3 and an MB noise control circuit 24.

The multi-path signal detection circuit 21 has a voice IF
A multipath signal is detected from the output of the circuit 6, and the multipath signal is divided into an MP noise component and an MB noise component.
Output as MP signal and MB signal. The antenna switching control circuit 22 outputs an antenna switching signal to the antenna switching circuit 20 outside the vertical blanking period. The antenna switching control circuit 22 includes a multipath signal detection circuit 21
Output to the MP noise control block 23 and the MB noise control block 24. The antenna switching control circuit 22 operates based on an audio diver control signal supplied from a timing controller (not shown) outside the vertical blanking period.
P noise control circuit 23 or MB noise control circuit 24
Switching circuit 20 according to the antenna switching signal from
To output a switching signal.

When the MP signal is input from the antenna switching control circuit 22, the MP noise control circuit 23 outputs an antenna switching signal based on the MP signal. When receiving the MB signal from the antenna switching control circuit 22, the MB noise control circuit 24 outputs an antenna switching signal based on the MB signal.

<Multipath Signal Detection Circuit 21> Next, the configuration of the multipath signal detection circuit 21 will be described. FIG. 2 shows a circuit configuration of the multipath signal detection circuit 21.

As shown in the figure, the multipath signal detection circuit 21 includes an MP noise detection circuit 21A and an MB noise detection circuit 21B. The MP noise detection circuit 21A detects a drop in the S-meter signal as an MP signal, and the MB noise detection circuit 21B extracts a predetermined frequency component from the S-meter signal and detects it as an MB signal. Hereinafter, the detailed configuration will be described.

The MP noise detection circuit 21A is provided with a comparator OP1.
The meter signal a is input via the resistor R3 (signal b). The S-meter signal a is divided and integrated by the resistors R4 and R5 and the capacitor C2 at the-input terminal of the operational amplifier OP1 to set an offset level and an integration constant. Input (signal c). And
An MP signal indicating detection of a multipath noise component is output from the output terminal of the comparator OP1.

FIG. 3A shows an S meter signal a, a signal b,
3 shows response characteristics and signal levels of c and MP signals. As shown in this figure, a relatively long period drop of the S meter signal a is detected as MP noise by the comparator OP1.

When it is difficult to separate the low-frequency signal component due to the noise of the high-frequency component contained in the S-meter signal, a capacitor is provided between the resistor R3 and the comparator OP1 and grounded. As a result, the high-frequency component of the signal b can be suppressed, and a malfunction in the detection of the MP signal can be prevented.

On the other hand, the MB noise detection circuit 21B is provided with a band-pass filter BPF including a coil L1, a capacitor C1, resistors R1, R2, and an amplifier OP2. This bandpass filter BPF has only a signal component (signal d) of a specific frequency included in the S-meter signal a, that is, a subcarrier frequency of 31.468 kHz (twice the horizontal synchronization frequency of 15.7334 KHz) during audio multiplex broadcasting. And amplify.

The MB noise detection circuit 21B is provided with a detection circuit including capacitors C3 and C4 and diodes D1 and D2, and a comparator OP3. The signal d selected and amplified by the bandpass filter BPF is detected by a detection circuit,
The level of the DC signal corresponds to the intensity of the P noise (signal e). The comparator OP3 calculates the level of the signal e
An MB signal indicating detection of a multipath beat noise component is detected by comparing with a preset setting level.

FIG. 3B shows the response characteristics and signal levels of the signals d, e and the MB signal. As shown in this figure,
An MB signal based on the frequency modulation component is detected. In FIG. 2, a voltage doubler detection circuit is used as the detection circuit, but this is not necessarily required, and another detection circuit may be used.

As described above, the multipath detection circuit 21
By using the same S-meter signal to classify the frequency components of the signal with a filter, a multipath signal of each component is detected. These detected multipath signals are M
It is output as a P signal and an MB signal.

<Antenna Switching Control Circuit 22> Next, the configuration of the antenna switching control circuit 22 will be described. FIG. 4 shows a circuit configuration of the antenna switching control circuit 22. As shown in the figure, the antenna switching control circuit 22
MB priority selection circuit 71 which is the above-described noise selection circuit
And a reset circuit including NOT circuits 72 and 74, a flip-flop 75, and AND circuits 73 and 76 to 78, and an OR circuit 79.

When either the MP signal or the MB signal is input from the multipath signal detecting circuit 21, the MB priority selecting circuit 71 outputs the MP signal or the MB signal as it is. When the MP signal and the MB signal are input simultaneously, the MB priority selection circuit 71 selects and outputs the MB signal preferentially.

MP output from MB priority selection circuit 71
The signal is input to the MP noise control circuit 23. The MP noise control circuit 23 outputs the MP antenna switching signal MP_AT
N and an MP operation control signal MPWIN. The MP operation control signal MPWIN is output from the NOT circuit 7
2 and input to the AND circuit 73.

MB output from MB priority selection circuit 71
The signal is input to the MB noise control circuit 24. The MB noise control circuit 24 outputs the MB antenna switching signal MB_AT
N and an MB operation control signal MBWIN. The MB operation control signal MBWIN is output from the NOT circuit 7
4 and input to a flip-flop (D-type flip-flop) 75 as a clock input. The audio diver period signal SDV_TM output from the AND circuit 76 is input to the flip-flop 75 as a clear input. Then, the flip-flop 75 outputs the output signal FFS based on these inputs.
Is output.

The AND circuit 76 has an audio diver control signal SDV from a timing controller (not shown).
And the system reset signal res are input, and when they are ON, the audio diver period signal SDV_TM output to the flip-flop 75 is turned ON.

Output signal FF from flip-flop 75
S and the output signal SDV_TM of the AND circuit 76 are input to the AND circuit 77. The output signal CRST from the AND circuit 77 is input to AND circuits 78 and 73. The AND circuit 78 outputs a reset release signal RST1 to the MP noise control circuit 23 based on the output signal from the NOT circuit 74 and the output signal CRST from the AND circuit 77. The MP noise control circuit 23 turns on the reset release signal RST1 from the AND circuit 78.
, The reset state is released, and when the reset release signal RST1 is OFF, the reset state is maintained. In this reset state, the MP noise control circuit 23
Does not operate even when the MP signal is input.

The output signal from the NOT circuit 72 and the output signal CRST from the AND circuit 77 are input to the AND circuit 73. The AND circuit 73 outputs a reset release signal RST2 to the MB noise control circuit 24 based on these signals. MB noise control circuit 2
4 is a reset release signal RS from the AND circuit 73.
When T2 is ON, the reset state is released, and when the reset release signal RST2 is OFF, the reset state is maintained. In the reset state, the MB noise control circuit 24 does not operate even when the MB signal is input.

The OR circuit 79 has an MP antenna control signal MP_ATN or an MB antenna control signal MB_AT
N is input. As a result, the antenna control signal ATN is output from the OR circuit 79.

<MP Noise Control Circuit 23> Next, the configuration of the MP noise control circuit 23 will be described. FIG. 5 shows a circuit configuration diagram of the MP noise control circuit 23.

In FIG. 5, when an MP signal is input from the antenna switching control circuit 22, an edge detection circuit 31 detects a rising edge of the MP signal and outputs an edge detection signal EDG corresponding to the rising edge of the MP signal. The edge detection signal EDG is input to an OR circuit 32, a flip-flop (D-type flip-flop) 33, and a NOT circuit. In the flip-flop 33, the edge detection signal E
DG becomes a clock input, and AND circuits 35, 36, 3
7 and the MP operation control signal MPWIN to the NOT circuit 72 shown in FIG.

The AND circuit 36 includes an MPWIN timer 38
Outputs a reset release signal RST1. MPW
When the reset release signal RST1 is turned ON, the IN timer 38 releases the reset of the timer, and performs a 12H cycle (1H
Outputs an MPWIN timer signal MPWIN_TM in one cycle time of the horizontal synchronizing signal of the video signal. This MPWIN timer signal MPWIN_TM is N
The signal is inverted by the OT circuit 39 and input to the AND circuit 40.

The AND circuit 40 outputs a signal to be a clear input to the flip-flop 33 based on the signal from the NOT circuit 39 and the system reset signal res. This signal is turned ON when the signal from the NOT circuit 39 and the system reset signal res are both ON, and the reset of the flip-flop 33 is released at that time.

The edge detection signal EDG from the edge detection circuit 31 is inverted by the NOT circuit 34,
The signal is input to the ND circuit 37. The AND circuit 37 outputs a reset release signal RST2 to the MP cycle timer 41. When the reset release signal RST2 from the AND circuit 37 is turned on, the MP cycle timer 41 releases the reset of the timer and outputs the MP cycle signal MP_TM with a 4H cycle. That is, the MP operation control signal MPWIN is turned on.
During the state, the MP cycle signal MP_TM is output in a 4H cycle in synchronization with the rise of the edge detection signal EDG. This MP cycle timer 41 constitutes the first timer described above.

The MP cycle signal MP_TM is input to an AND circuit 35, inverted by a NOT circuit 42, and input to an AND circuit 37. Further, the AND circuit 35 outputs the MP signal and the MP signal from the flip-
By inputting the operation control signal MPWIN and the MP cycle signal MP_TM from the MP cycle timer 41,
A signal is output to the R circuit 32. The OR circuit 32 receives the edge detection signal EDG from the edge detection circuit 31 and the NOT.
At least one of the output signals from the circuit 35 is ON
, An MP antenna switching signal MP_ATN is output. The AND circuit 35 and the OR circuit 32 constitute the above-described multipath noise determination circuit, and the OR circuit 32 constitutes a first switching signal output circuit.

<MB Noise Control Circuit 24> Next, the configuration of the MB noise control circuit 24 will be described. FIG. 6 shows a circuit configuration diagram of the MB noise control circuit 24.

In the figure, an edge detection circuit 51 receives a system reset signal res, receives an MB signal from the antenna switching control circuit 22, and outputs an edge detection signal EDG. This edge detection signal EDG
Is input to the flip-flop 52 as a clock input. In the flip-flop 52, based on the edge detection signal EDG, the MB operation control signal MBWIN is sent from one of the two output terminals to the AND circuits 53, 54, 55, 56 and the NOT circuit 74 shown in FIG.
Is output. The flip-flop 52 outputs a signal for detecting the rising of the MP operation control signal MBWIN to the flip-flop 57 from the other output terminal.

The AND circuit 54 has an MBWIN timer 58
Outputs a reset release signal RST1. MBW
When the reset release signal RST1 is turned on, the IN timer 58 releases the reset of the timer, and the MBW
An IN timer signal MBWIN_TM is output. This MB
The WIN timer signal MBWIN_TM is supplied to the NOT circuit 59.
And is input to the AND circuit 60.

The AND circuit 60 outputs a signal to be a clear input to the flip-flop 52 when both the signal from the NOT circuit 59 and the system reset signal res are ON. The AND circuit 55 outputs a reset release signal RST2 to the MB cycle timer 61.
When the reset release signal RST2 from the AND circuit 55 is turned on, the MB cycle timer 61 releases the reset of the timer and outputs the MB cycle signal MB_TM at a 4H cycle. This MB cycle timer 61 constitutes the second timer described above.

The MB periodic signal MB_TM is input to an AND circuit 53, inverted by a NOT circuit 62, and input to an AND circuit 55.

On the other hand, the flip-flop 57 receives the system reset signal res and the output signal from the flip-flop 52, so that the AND circuit 56
To output a signal. When both the MB operation control signal MBWIN and the output signal from the flip-flop 57 are ON, the AND circuit 56 outputs the output signal MB.
The WIN detection signal STAT is turned ON.

The OR circuit 63 outputs an output signal from the AND circuit 53 and an output signal from the AND circuit 56, that is, M
The BWIN detection signal STAT is input. OR circuit 63
Indicates that at least one of these signals is O
When N, an MB antenna switching signal MB_ATN is output. The AND circuit 53 and the OR circuit 63 constitute the above-described multipath beat noise determination circuit.
The R circuit 63 forms a second switching signal output circuit.

(2) Operation Next, the operation of the TV diver system according to the present embodiment will be described with reference to the flowcharts and timing charts of FIGS.

In the TV diver system according to the present embodiment, a video diver operation is performed within a vertical blanking period based on a vertical synchronization signal of a video signal, and an antenna having the highest electric field level is selected, as in the related art. . Then, during the vertical blanking period, that is, during a period other than the video diver operation period, audio diversity control is performed.

FIGS. 7 and 8 are a flowchart and a timing chart showing the operation of the antenna switching control circuit 22. First, in the antenna switching control circuit 22 shown in FIG. 4, when the video diver operation period ends and the audio diver control signal SDV turns on, the audio diver period signal SDV_TM turns on (time T in FIG. 7).
1). Thereby, the output signal CRST of the AND circuit 77 is
Is turned ON, and the reset release signals RST1 and RST2 from the AND circuits 78 and 73 are turned ON, respectively, so that the MP noise control circuit 23 and the MB noise control circuit 2
Reference numeral 4 denotes an input signal waiting state for the MP signal and the MB signal.

When a multipath signal is detected by the multipath signal detection circuit 21 shown in FIG. 1 in such a state, the multipath signal is converted into an MP noise component and an MB noise component by the multipath signal detection circuit 21. Divided. When both the MP noise component and the MB noise component are included, both are input to the antenna switching control circuit 22 as an MP signal or an MB signal when only one is included. You.

The MB of the antenna switching control circuit 22
When a multipath signal is input to the priority selection circuit 71 (step SA1), it is determined whether or not the time is within the operation period of the audio diver (step SA2). If it is not during the operation period of the audio diver, that is, if it is during the video diver operation period, the detected MP signal or M
If the B signal is ignored and it is within the operation period of the voice diver, it is determined whether the signal is an MP signal or an MB signal (step SA3).

If the input signal is an MP signal, it is determined whether the MB noise control circuit 24 is operating (step SA4). If the signal is operating, the MP signal is ignored and the MB noise control circuit 24 is operating. If not, the MP noise control circuit 2
Then, an MP signal is input to the device 3 (step SA5). As a result, the MP noise control circuit 23 performs an MP noise control operation described later, and outputs an MP antenna switching signal MP_ATN.

During this time, the MP operation control signal MPWIN is output from the MP noise control circuit 23, and the reset release signal RST2 output from the AND circuit 73 is turned off.
Becomes Therefore, the MB noise control circuit 24 is held in the reset state (time T2 to time T3). Therefore, during this time, the MB noise control circuit 24 does not perform the MB noise control operation even if the MB signal is input.

Then, the MP noise control circuit 23
When the P noise control operation is completed, the MB noise control circuit 2
4, the reset release signal RST2 is turned on, the reset state is released, and the input signal waits for the MB signal (time T3). Similarly, the antenna switching control circuit 22
Is again in a multipath signal input standby state.

Here, since the reset release signal RST1 for the MP noise control circuit 23 is held in the ON state, the MP noise control circuit 23 holds the MP signal input standby state. Therefore, when the MP noise is input again to the MB priority selection circuit 76, the MP signal is input to the MP noise control circuit 23, and the MP antenna switching signal MP_ATN is output.

On the other hand, if the input signal is an MB signal, the MB signal is input to the MB noise control circuit 24 (step SA6). Thereby, the MB noise control circuit 24
Performs an MB noise control operation described later, and outputs an MB antenna switching signal MB_ATN. Then, the antenna switching signal ATN is output from the OR circuit 79.

During this time, the MB noise control circuit 24 outputs the MB operation control signal MBWIN.
The reset release signal RST1 output from the D circuit 78 is turned off. Therefore, the MP noise control circuit 23 is kept in the reset state (time T4 to T5). Therefore,
During this time, the MP noise control circuit 23 does not perform the MP noise control operation even if the MP signal is input.

Then, the MB noise control circuit 24
When the B noise control operation is completed, the MB operation control signal MB
Since WIN is turned off, the input signal to the AND circuit 78 is turned on. However, the MB operation control signal MB
As WIN changes from ON to OFF, the clock input of the flip-flop 75 changes from OFF to ON, so that the output signal FFS of the flip-flop turns OFF. Thus, the output signal CRST of the AND circuit 77 and the reset release signal RST1 of each of the AND circuits 78 and 73 are output.
, RST2 are similarly turned off (time T5). Therefore, during this time, the MP noise control circuit 23 and the MB noise control circuit 24 are in the reset state, and do not perform the control operation even if the MP signal and the MB signal are input.

That is, the antenna switching control circuit 22
It waits until the operation period of the voice diver ends (step SA7), and holds the last selected antenna. Then, the output signal FFS of the flip-flop is kept OFF until the audio diver control signal SDV changes from ON to OFF and the flip-flop 75 is reset (time T5 to T6). Thereafter, when the audio diver control signal SDV changes from OFF to ON, AND
Output signal CRST of circuit 77, AND circuits 78 and 73
Reset release signals RST1 and RST2
N (time T7). Then, when the operation period of the audio diver ends, the antenna switching control circuit 22 enters the MP signal or MB signal detection standby state again.

As described above, when the MB noise control operation is performed, the selected antenna is held after the output of the antenna control signal ATN ends once during the voice diver operation period. That is, the MP signal is detected and the
After the noise control operation is performed, if the MP noise or the MB noise is detected again within the operation period of the audio diver, the above operation is repeated. On the other hand, when the MB signal is detected and the MB noise control operation is executed, during the operation period of the audio diver, the MP noise or the MB noise is not detected and the antenna selected by the MB noise control operation is held. I do.

<Operation of MP Noise Control Circuit 23> Next, the above-described MP noise control operation by the MP noise control circuit 23 will be described. 9 and FIG.
6 is a flowchart and a timing chart showing an operation of the noise control circuit 23.

When the MP signal is input to the MP noise control circuit 23, the MPWIN timer 38 and the MP cycle timer 4
1 is released (steps SB1 and SB1).
2), MPWIN timer 38 and MP cycle timer 41
Starts counting (time T1 in FIG. 10).
1).

At this time, the edge detection signal EDG from the edge detection circuit 31 is supplied to the MP
It is output to antenna switching control circuit 22 as antenna switching signal MP_ATN. As a result, the antenna control signal ATN is output from the antenna switching control circuit 22 to the antenna switching circuit 2, and the antenna is switched (step SB3).

Until the MP cycle signal MP_TM is output from the MP cycle timer 41 (from time T11 to T12), it is determined whether the reception state has been recovered by the selected antenna (step SB4). SB
5). If the reception state is not recovered, the time until the MPWIN timer signal MPWIN_TM is output (time T1
Step SB6) up to 7, and the above processing is repeated. That is, when the edge detection signal EDG is output, or when the MP signal, the MP operation control signal MPWIN, and M
When all the P periodic signals MP_TM are turned ON, A
The output of the ND circuit 35 is turned on, and an MP antenna switching signal MP_ATN is output. Thereby, antenna switching is performed.

When the reception state is recovered by switching the antenna (step SB5, time T13),
The MP noise control operation ends. When the MP signal is input again after the reception state is recovered, the MP cycle timer 41 is reset again (time T14 and time T15). At this time, when the MP signal is input, an MP antenna switching signal MP_ATN is output, and the antenna is switched.

Further, the MPWIN timer 38 outputs the MPWI
When the N timer signal MPWIN_TM is output, the flip-flop 33 is cleared at that time, and the MP operation control signal MPWIN is turned off (time T17). As a result, the MPWIN timer 38 and the MP cycle timer 41 are both reset, and enter a standby state until the MP signal is input again.

<Operation of MB Noise Control Circuit 24> Next, the above-described MB noise control operation by the MB noise control circuit 24 will be described. FIG. 11 and FIG.
6 is a flowchart and a timing chart showing the operation of the B noise control circuit 24.

When the MB signal is input to the MP noise control circuit 24, as in the case of the MP noise control circuit 23, M
The BWIN timer 58 and the MB cycle timer 61 are reset (steps SC1 and SC2), and the MPWIN timer 5
8 and the MB cycle timer 61 start counting (time T21 in FIG. 12).

At this time, the rising of the MB operation control signal MBWIN output from the flip-flop 52 is detected by the flip-flop 57 and the AND circuit 56, and the MBWIN detection signal STAT is turned on. Therefore, the MB antenna switching signal MB_ATN is turned ON,
Switching of the antenna is performed (step SC3).

Until the MB cycle signal MB_TM is output from the MB cycle timer 61 (from time T21 to T22), it is determined whether or not the reception state has been recovered by the selected antenna (step SC4). SC
5). If the reception state does not recover, the time until the MBWIN timer signal MBWIN_TM is output (time T2
Up to 5), the antenna switching is repeated.

Here, unlike the MP noise control circuit 23, when the edge detection circuit EDG is output before the MB cycle signal MB_TM is output from the MB cycle timer 61, the MB cycle timer 61 is not reset. (Time T23). Therefore, the antenna switching after the second time
Only when all of the MB signal, the MB operation control signal MBWIN, and the MB cycle signal MB_TM are turned on, M
This is performed by outputting the B antenna switching signal MB_ATN (time T22).

Then, the MBWIN timer 58 sends the MBW
When the IN timer signal MBWIN_TM is output, the flip-flop 52 is cleared at that time, and the MB operation control signal MBWIN is turned off (time T25). Thereby, the MBWIN timer 58 and the MB cycle timer 61
Are reset, and enter a standby state until the MB signal is input again.

(3) Effect As described above, according to the present embodiment, the multi-path noise outputs an antenna switching signal every time its rising edge is detected, and thus immediately after the noise detection. Switching can be performed. On the other hand, with respect to multipath beat noise, an antenna switching signal is not output each time its rising edge is detected, so that erroneous determination due to the influence of antenna switching noise can be prevented.

After the antenna switching control by the multipath beat noise is completed, the antenna switching is not performed during the voice diver operation period.
Useless switching of the antenna can be prevented.

(4) Other Embodiments The present invention is not limited to the above-described embodiment, and the embodiment can be freely changed. Is also included. For example,
Since the MP noise control circuit 23 and the MB noise control circuit 24 are separately provided, the MPWIN timer 3
8, the MP cycle timer 41, the MBWIN timer 58, and the MB cycle timer 61 are provided with four timer circuits, but the MPWIN timer 38 and the MBWIN timer 5
8 may be used.

Further, in this embodiment, the description has been given of the TV diver system. However, the present invention is not limited to this.

[0094]

As described above, according to the present invention, unnecessary antenna switching is suppressed, the number of antenna switching is reduced, and effective antenna switching is performed for each component of the multipath signal in the voice signal. As a result, the performance of voice diversity can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a diversity receiving apparatus according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a configuration of a multipath signal detection circuit 21 according to the embodiment.

FIG. 3 is a waveform chart showing an internal signal of a multipath signal detection circuit 21 according to the embodiment.

FIG. 4 is an antenna switching control circuit 2 according to the embodiment;
Schematic circuit diagram showing the configuration of FIG.

FIG. 5 is an MP noise control circuit 23 according to the embodiment.
Schematic circuit diagram showing the configuration of

FIG. 6 shows an MB noise control circuit 24 according to the embodiment.
Schematic circuit diagram showing the configuration of

FIG. 7 is a block diagram showing an operation of the antenna switching control circuit 22 according to the embodiment of the present invention.

FIG. 8 is an antenna switching control circuit 2 according to the embodiment;
2 is a timing chart showing the operation

FIG. 9 is an MP noise control circuit 23 according to the embodiment.
Flow chart showing the operation of

FIG. 10 is an MP noise control circuit 2 according to the embodiment.
Timing chart showing the operation of 3

FIG. 11 is a diagram illustrating an MB noise control circuit 2 according to the embodiment;
4 is a flowchart showing the operation.

FIG. 12 is an MB noise control circuit 2 according to the embodiment;
4 is a timing chart showing the operation of FIG.

FIG. 13 is a block diagram showing a configuration of a conventional diversity receiving apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Antenna 20 ... Antenna switching circuit 21 ... Multipath signal detection circuit 22 ... Antenna switching control circuit 23 ... MP noise control circuit 24 ... MB noise control circuit 31, 51 ... Edge detection circuit 41 ... MP cycle timer 61 ... MB cycle timer 71: MB priority selection circuit 200: Voice diversity control circuit

Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04B 7/00 H04B ⁷ /02-7/12 H04L 1/02-1/06

Claims (5)

(57) [Claims] A plurality of antennas for receiving an audio signal; detecting a multipath signal from the audio signal received by any one of the plurality of antennas; and detecting a multipath noise from the multipath signal. A multipath signal detection circuit that separately detects the multipath and beat noise and outputs each of them; and a multipath that outputs an antenna switching signal when multipath noise is input from the multipath signal detection circuit. - a noise control circuit, when the multipath signal multipath beat noise from the detection circuit is input, and multipath beat noise control circuit for outputting an antenna switching signal, the multipath noise control circuit and multipath beat
Input antenna switching signal output from noise control circuit
To select one of the switching signals as appropriate and
Switching the antenna from the antenna to another antenna
An antenna switching control circuit for performing control. 2. The multipath noise control circuit, comprising: a first timer for outputting a timing signal having a fixed period a predetermined number of times; and the timing signal being output from the first timer.
A multipath noise determination circuit for determining whether or not the multipath noise is input each time; and a multipath noise determination circuit
A first switching signal output circuit that outputs an antenna switching signal when it is determined that noise has been input, wherein the multipath beat noise control circuit is configured to set a predetermined period of timing signal in advance. A second timer that outputs a number of times, and the timing signal is output from the second timer
Each time, a multipath beat noise determination circuit that determines whether or not the multipath beat noise has been input, and the multipath beat noise determination circuit determines that multipath beat noise has been detected. 2. The diversity receiver according to claim 1, further comprising a second switching signal output circuit that outputs an antenna switching signal when the switching is performed. 3. The multipath noise control circuit has an edge detection circuit that detects a rise of the input multipath noise, and the first switching signal output circuit is configured by the edge detection circuit 3. The diversity receiving apparatus according to claim 2, wherein said antenna switching signal is output even when a rising of multipath noise is detected. 4. The multipath noise output between the multipath signal detection circuit and the multipath noise control circuit and the multipath beat noise control circuit and output from the multipath signal detection circuit. And the multi-path beat noise is output to the multi-path noise control circuit and the multi-path beat noise control circuit. A noise selection circuit that preferentially selects and outputs a signal; and a first circuit that stops operation of the multipath noise control circuit during operation of the multipath beat noise control circuit.
And a second circuit for stopping the operation of the multipath beat noise control circuit during the operation of the multipath noise control circuit.
Wherein the first reset circuit outputs the antenna switching signal from the multipath beat noise control circuit and switches the antenna,
After the multipath beat noise is no longer detected, or after the antenna switching signal is output as many times as the timing signal is generated in the multipath beat noise control circuit, the multipath beat control circuit 3. The diversity receiver according to claim 2, wherein the operation is stopped for a certain period. 5. A multipath noise detection circuit for detecting a drop of an S meter signal indicating a reception electric field level of the audio signal as multipath noise, wherein the multipath signal detection circuit detects a predetermined level from the S meter signal. The diversity receiver according to any one of claims 1 to 4, further comprising a multipath beat noise detection circuit that extracts a frequency component and detects multipath beat noise.