JP2003174374A - Signal comparison detection switching device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a signal comparison detection switching device wherein detection error is little and detection time is short when delay difference, signal level difference, inversion of phase and noise mixing are present between input signals, in a signal comparison detection switching device which is to be built in a network follow type radio receiver or the like. <P>SOLUTION: In this signal comparison detection switching device, an adaptive filter 206 and a decision control unit are installed. In the adaptive filter 206, an FIR filter 303 for forming a selection signal 207 from a signal y204, an adaptive FIR filter 308 for forming a pseudo signal 208 from a signal x205, and a subtracter 312 for calculating a differential signal 211 of the selection signal 207 and the pseudo signal 208. The adaptive FIR filter 308 forms a filter coefficient 212 in such a manner that the differential signal 211 becomes minimum. The decision control unit decides whether contents of the selection signal 207 coincide with contents of the pseudo signal 208, on the basis of difference between the signal x205 and the differential signal 211, and the filter coefficient 212. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal comparison / detection switching device for detecting two signals having the same contents from a plurality of input signals and arbitrarily switching these signals, and more particularly to using an adaptive filter. The present invention relates to a signal comparison / detection switching device that determines whether or not two arbitrary signals have the same content.

[0002]

2. Description of the Related Art An on-vehicle radio receiver changes its receiving point as a vehicle moves. Therefore, if the broadcast from one broadcasting station is continuously received, the reception state may deteriorate as the automobile moves. On the other hand, broadcasting stations that broadcast terrestrial waves form a nationwide network and often broadcast the same contents simultaneously by a plurality of broadcasting stations belonging to the same network. Therefore, when receiving a radio broadcast in a car traveling a long distance, when the reception condition of the radio wave from the broadcasting station that has been receiving until then deteriorates,
By re-selecting to receive radio waves from another broadcasting station that has the same broadcast content and is in a better reception state, the same program can be continuously viewed in a good reception state.

The network follow type radio receiver is a radio receiver that automatically performs such a tuning operation. Such a network follow type radio receiver includes a signal comparison / detection device that compares a signal received up to that time with a signal broadcast from another broadcasting station and determines whether the contents match. Is built in.
The network follow type radio receiver selects and outputs a signal in a better condition when the contents of both signals match.

An example of a conventional signal comparison and detection device is Japanese Patent No. 2
No. 903334. FIG. 8 is a block diagram showing the configuration of this conventional signal comparison and detection apparatus. As shown in FIG. 8, in this conventional signal comparison and detection device,
Input signals 701 and 70 output from separate tuners
A silence detecting unit 703 and a coincidence detecting unit 704 to which both of the two are input are provided. The silence detector 703 receives the input signals 701 and 702 and determines whether or not they are silent, that is, whether or not the signal level is substantially zero. Further, the match detection unit 704 calculates the difference between the input signal 701 and the input signal 702, determines that the input signal 701 and the input signal 702 match if the difference is smaller than a predetermined reference value, and the difference is If the value is equal to or larger than the reference value, it is determined that the contents of both signals do not match.

Further, this signal comparison / detection device is provided with a judgment control circuit 705. The judgment control circuit 705
When the output signal of the silence detection unit 703 and the output signal of the coincidence detection unit 704 are input and both the input signals 701 and 702 are not silent and the input signals 701 and 702 match, the input signals 701 and 702 are A final determination that they match is made, and a match / mismatch determination output 706 is output. A network follow radio receiver (not shown) incorporating this signal comparison and detection device compares the input signal 701 with the input signal 702 when the content of the match / mismatch determination output 706 is “match”. Then, the input signal having a better reception state is selected and output.

[0006]

However, the above-mentioned conventional techniques have the following problems. In the conventional device shown in FIG. 8, if there is a delay difference, a signal level difference, phase inversion, or noise mixing between input signals to be compared, it is inaccurate to determine whether the input signals match or do not match. Therefore, even if the input signals have the same content, the input signals may be erroneously determined to have different content. That is, in the conventional device, it is judged from the difference signal between the two input signals whether or not they match with each other.
When there is a delay difference between two input signals, when there is a difference between the signal levels of the two input signals, and when the phases are inverted, the difference signal does not have the expected small value. As a result, even if the input signals have the same content, it is erroneously determined that the input signals have different contents, and the validity of the detection result deteriorates. Even if the signal comparison / detection device is provided with the silence detector 703 as shown in Japanese Patent No. 2903334, this problem cannot be solved. This is because this problem occurs when the signal level of the input signal is not zero.

Further, if an attempt is made to solve the above-described problem that the detection result becomes inaccurate by providing some adjustment means in the signal comparison and detection device, there arises a problem that the signal detection time increases. The reason is that it is necessary to monitor the determination result with a counter in order to improve the detection accuracy, and it takes time to obtain the detection result.

Further, the conventional apparatus has a problem that noise is generated when the output signal is switched from one signal to another signal.

The present invention has been made in view of the above problems, and in a signal comparison / detection switching device incorporated in a network follow type radio receiver or the like, a delay difference, a signal level difference, and a phase inversion between input signals. Also, it is an object of the present invention to provide a signal comparison / detection switching device in which detection error is small even when noise is mixed and the detection time is short. Another object of the present invention is to provide a signal comparison / detection switching device that generates less noise when switching signals.

[0010]

A signal comparison / detection switching device according to the present invention includes a first selector for selecting one input signal from a plurality of input signals and outputting the selected input signal as a first signal, and a plurality of inputs. A second selector that selects one input signal from the signals and outputs it as a second signal; and a first selector that selects the first signal from the second signal.
An adaptive FIR filter that generates a pseudo signal that minimizes the difference signal between the first signal and the differential signal, and the same contents of the first signal and the pseudo signal based on the difference between the first signal and the difference signal. A detector that determines whether or not the signal is a signal and outputs the determination result, a storage circuit that stores the determination result, and the determination result that is stored in the storage circuit when the switching control signal is input. The contents are based on the first
The next selection signal having the same content as that of the signal is selected from the plurality of input signals, and the first selector is caused to select the next selection signal, whereby the switching control signal is input to the first signal. And a control unit for switching the signal selected before the next selection signal to the next selection signal.

In the present invention, a pseudo signal is generated by the adaptive FIR filter, and whether the first signal and the pseudo signal have the same contents based on the difference signal between the first signal and the pseudo signal. Even if there is a delay difference, signal level difference, phase inversion, or noise mixing between input signals, it is canceled quantitatively by an adaptive FIR filter and the above judgment is made accurately because it is quantitatively judged. You can As a result, it is possible to reduce the occurrence of judgment errors. In addition, since the judgment can be made quantitatively,
This judgment can be made quickly.

Further, since the storage circuit stores the judgment result of the input signal which is a candidate for the next selection signal, it is optimal as the next selection signal when the switching control signal is input from the outside of the signal comparison detection switching device. Promptly select the appropriate signal,
The selection signal can be switched to the next selection signal.

Another signal comparison / detection switching device according to the present invention comprises first and second selectors for selecting one input signal from a plurality of input signals, and outputs of the first and second selectors. A switch circuit that selects one of the signals and outputs it as a first signal and the other as a second signal; an FIR filter that generates a selection signal from the first signal; and a second signal from the second signal. An adaptive FIR filter that generates a pseudo signal that minimizes a difference signal from the selection signal, a coefficient storage circuit that stores a filter coefficient of the adaptive FIR filter, and a difference between the selection signal and the difference signal. A detector that determines whether the selection signal and the pseudo signal have the same content and outputs the determination result, a storage circuit that stores the determination result, the selection signal and the pseudo signal. Signal is input to the selector signal, the pseudo signal, and a mixer switch that selects and outputs one signal of the mixed signal in which the select signal and the pseudo signal are mixed at an arbitrary ratio; A next selection signal, the content of which is the same as the content of the selection signal, is selected from the plurality of input signals based on the determination result stored in the storage circuit when input, and the first and second input signals are selected. After causing the selector outputting the second signal among the selectors to select the next selection signal and switching the output signal of the mixer detector from the selection signal to the pseudo signal stepwise, The switch circuit is caused to switch between the first signal and the second signal, and the filter coefficient of the next selection signal stored in the coefficient storage circuit is set to the F
A control unit for switching the output signal of the mixer detector from the selection signal to the next selection signal by inputting it to an IR filter and switching the output signal of the mixer detector from the pseudo signal to the selection signal. And are included.

In the present invention, a pseudo signal is generated by the adaptive FIR filter, and it is determined whether the selection signal and the pseudo signal have the same contents based on the difference signal between the selection signal and the pseudo signal. Therefore, even if there is a delay difference, a signal level difference, a phase inversion, or noise mixing between input signals, it is possible to make an accurate determination. As a result, it is possible to reduce the occurrence of judgment errors.

Further, since the storage circuit stores the judgment result of the input signal which is a candidate for the next selection signal, when the switching control signal is input, the optimum signal is promptly selected as the next selection signal, The selection signal can be switched to the next selection signal.

Furthermore, when the switching control signal is input, the mixer switcher switches its output signal from the selection signal to the pseudo signal in a stepwise manner, so that it is possible to suppress the generation of noise accompanying the switching process.

Still another signal comparison / detection switching device according to the present invention selects a first input signal from a plurality of input signals and outputs a first signal.
A first selector for outputting as a signal, a second selector for selecting one input signal from a plurality of input signals and outputting as a second signal, and a second signal for the first signal And an adaptive FIR filter that generates a pseudo signal that minimizes the difference signal between the first and second signals, and whether or not the first signal and the pseudo signal have the same content based on the filter coefficient of the adaptive FIR filter. A detector for judging and outputting the judgment result, and a memory circuit for storing the judgment result,
Selecting a next selection signal whose content is the same as the content of the first signal from the plurality of input signals based on the determination result stored in the storage circuit when the switching control signal is input; A control unit for switching the first signal to the next selection signal from the signal selected before the switching control signal is input by causing the first selector to select the next selection signal. It is characterized by

In the present invention, it is determined whether the first signal and the pseudo signal have the same contents based on the filter coefficient of the adaptive FIR filter. Since the filter coefficient is less susceptible to the noise contained in the input signal,
It is possible to suppress the influence of the noise component on the determination as to whether the content of the first signal and the content of the pseudo signal match. As a result, even when the input signal contains a lot of noise, the determination can be accurately performed.

Further, the detector can judge whether or not the selection signal and the pseudo signal have the same contents by evaluating the degree of concentration of the power of the filter coefficient in the adaptive FIR filter. . As a result, the judgment can be made quantitatively, so that the judgment can be made accurately and promptly.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be specifically described below with reference to the accompanying drawings. 1 is a block diagram showing a configuration of a signal comparison / detection switching device according to a first embodiment of the present invention, FIG. 2 is a block diagram showing a configuration of the signal detection / switching device shown in FIG. 1, and FIG. FIG. 3 is a block diagram showing a configuration of the adaptive filter shown in FIG. 2, and FIG. 4 is a block diagram showing a configuration of the determination control unit shown in FIG. The signal comparison / detection switching device according to the present embodiment is mounted in, for example, a vehicle-mounted network follow radio receiver.

As shown in FIG. 1, in the signal comparison / detection switching apparatus 100 according to this embodiment, a selector 103 to which the input signal group 101 is input, a selector 104 to which the input signal group 102 is input, and a signal detection A switch 106 and a signal selection control unit 105 are provided. The input signal groups 101 and 102 each include a plurality of signals, and the plurality of signals also include signals having the same content. Further, the control signal 110 is input to the selectors 103 and 104. The selector 103 selects and outputs one signal from the input signal group 101 based on the control signal 110. Similarly, the selector 104 selects and outputs one signal from the input signal group 102 based on the control signal 110. When the signal comparison / detection switching device 100 is mounted in, for example, a vehicle-mounted network follow type radio receiver, the input signal groups 101 and 102 are radio reception signals received by an antenna (not shown). The input signal groups 101 and 102 may be received by the same antenna or may be received by different antennas. In addition, the selector 10
Tuners 3 and 104 are, for example, tuners that select and demodulate received signals. In this case, controlling the selectors 103 and 104 is equivalent to switching the tuner selection.

The output signal of the selector 103 (hereinafter referred to as the input signal 201) and the output signal of the selector 104 (hereinafter referred to as the input signal 202) are input to the signal detection switch 106. There is. A switching control signal 108 is input to the signal detection switch 106 from outside the signal comparison detection switching device 100. Signal detection switch 10
Reference numeral 6 designates the input signal 201 and the input signal 202, respectively, and outputs one of the filtered signals to the output signal 1
The output signal 107 is output, and the output signal 107 is compared with another filtered signal and the result is stored. In the process, the selection control signal 109 is output to the selection control unit 105, the signal selection control unit 105 is caused to switch the signal selected by the selector 103 or 104, and the input signals to be compared with the output signal 107 are successively output. Switch to. This is because when the selectors 103 and 104 are tuners of radio receivers, in order to search for another broadcast having the same content as the broadcast currently selected and viewed by one tuner, the tuner of another tuner is selected. Is equivalent to switching one after another. Further, the output signal 107 corresponds to the viewing signal that the user is listening to.

Then, the signal detection switching device 106 outputs the output signal 107 based on the switching control signal 108 input from the outside of the signal comparison detection switching device 100.
Switching from one of the filtered signal of 1 and the filtered signal of the input signal 202 to the other. On the other hand, the signal selection control unit 105 sends the control signal 11 to the selectors 103 and 104 based on the selection control signal 109.
It outputs 0 and controls the selectors 103 and 104.

As shown in FIG. 2, in the signal detection switch 106 shown in FIG. 1, the switch circuit 203, the adaptive filter 206, the judgment controller 210 and the mixer switch 209.
Is provided. The switch circuit 203 receives the input signal 20
1 and 202 and the switching signal 213 are input, and the signal x
205 and the signal y204 are output. The switch circuit 203 outputs the input signal 201 as one of the signal x205 and the signal y204 based on the switching signal 213, and outputs the input signal 202 as the signal x205 and the signal y.
It outputs as the other of 204. That is, the switch circuit 203 associates the input signals 201 and 202 with the signal x205 and the signal y204 on a one-to-one basis, but the combination thereof is switched based on the switching signal 213.

The signal x205 and the signal y204 are input to the adaptive filter 206 from the switch circuit 203, and the switching signal 213 is input from the determination control unit 210. Then, the signal y204 is filtered to generate the selection signal 207, the signal x205 is filtered to generate the pseudo signal 208, the difference signal 211 between the selection signal 207 and the pseudo signal 208 is generated, and the signal x20 is generated.
5 when the pseudo signal 208 is generated from the filter coefficient 21
2 is output. The configuration of the adaptive filter 206 will be described later.

Further, the judgment control section 210 receives the selection signal 207, the difference signal 211 and the filter coefficient 212 output from the adaptive filter 206, and the signal x205 output from the switch circuit 203, Further, the switching control signal 108 is input. The determination control unit 210 uses the selection signal 207, the difference signal 211, and the filter coefficient 212 to select the selection signal 207 and the pseudo signal 20.
Judgment as to whether or not 8 have the same content
It is called a discrepancy judgment) and the result is stored. Further, at the end of this detection determination processing, the selection control signal 109 is output to the above-mentioned signal selection control unit 105 in order to fetch the next candidate signal.

Further, when the switching control signal 108 is input, the judgment control section 210 outputs a switching signal 213 to the adaptive filter 206, the switch circuit 203 and a mixer switching unit 209 described later. As a result, the mixer switching device 2
In step 09, the component of the output signal 107 is switched stepwise from the selection signal 207 to the pseudo signal 208, and then the switch circuit 203 and the adaptive filter 206 are interlocked to change the signal that was the pseudo signal 208 before the switching to the selection signal 207.
Then, the mixer switch 209 is caused to return the component of the output signal 207 from the pseudo signal 208 to the selection signal 207.
As a result, the output signal 107 of the mixer switch 209 is switched from the selection signal 207 to the pseudo signal 208. The configuration of the judgment control unit 210 will be described later.

Furthermore, the selection signal 207 and the pseudo signal 208 output from the adaptive filter 206 are input to the mixer switching unit 209, and the switching signal 213 output from the determination control unit 210 is input. It The mixer switching unit 209 selects one of the three types of signals of the selection signal 207, the pseudo signal 208, and the mixed signal in which the selection signal 207 and the pseudo signal 208 are mixed at an arbitrary ratio based on the switching signal 213. It is selected and output.

As shown in FIG. 3, the adaptive filter 206 shown in FIG. 2 is provided with an FIR (finite impulse response) filter 303, an adaptive FIR filter 308, a subtractor 312 and a coefficient storage circuit 310. ing. The FIR filter 303 receives the signal y204 as an input signal, filters this signal, delays it for an appropriate time, and outputs it as a selection signal 207. The filter coefficient in this filter processing is given by the coefficient output signal 305 output from the coefficient storage circuit 310. The FIR filter is for convoluting and integrating each filter coefficient and the input signal, and its operation includes only a delay element, a multiplication element and an addition element.

The signal x205 is input to the adaptive FIR filter 308 as a reference signal, and the signal x205 is filtered to generate a pseudo signal 208. Also, a difference signal 211 obtained by subtracting the pseudo signal 208 from the selection signal 207.
Is input, the filter coefficient 212 is updated so as to minimize the difference signal 211, and this is output.

The subtractor 312 outputs the selection signal 207 output from the FIR filter 303 and the adaptive FIR filter 3
The pseudo signal 208 output from 08 is input. Then, the subtractor 312 changes the selection signal 207 to the pseudo signal 208.
The difference signal 211 is generated by subtracting from and output to the adaptive FIR filter 308 and the judgment control unit 210 (see FIG. 2).

The filter coefficient 212 output from the adaptive FIR filter 308 and the switching signal 213 output from the determination control unit 210 are input to the coefficient storage circuit 310. The coefficient storage circuit 310 stores the filter coefficient 212, and when the switching signal 213 is input, outputs the coefficient output signal 305 to the FIR filter 303 and
The filter coefficient of the filter 303 is rewritten.

As shown in FIG. 4, the detection control unit 210 shown in FIG. 2 has a detector 406, a storage circuit 408 and a control unit 4.
10 are provided. To the detector 406, the selection signal 207, the difference signal 211 and the filter coefficient 212 output from the adaptive filter 206 (see FIG. 2) are input, and the signal x205 output from the switch circuit 203 (see FIG. 2) is input. To be done. The detector 406 selects the selection signal 20
7 and the difference signal 211 are compared in level to select the selection signal 2
07 and the pseudo signal 208 determine whether they are signals having the same content (match / mismatch determination), monitor the filter coefficient 212 to determine match / mismatch, and output these results as a detection result 407. To do. The storage circuit 408 also stores the detection result 40 output from the detector 406.
7 and the comparison information 409 output from the control unit 410 are input and stored.

The control unit 410 outputs the comparison information 409 indicating the selected channel and the channel to be compared to the storage circuit 408, and at the same time, the selection control signal 10
9 is output to the signal selection control unit 105 (see FIG. 1) to cause the selector 103 or 104 (see FIG. 1) to select the next candidate input signal. This allows the adaptive FIR
The reference signal x205 input to the filter 308 is switched. Further, when the switching control signal 108 is input, the control unit 410 is optimal as another signal (hereinafter referred to as the next selection signal) having the same content as the selection signal 207 from the information stored in the storage circuit 408 at that time. Select the signal,
The switching signal 213 is supplied to the switch circuit 203 (see FIG. 2), the coefficient storage circuit 310 (see FIG. 3), and the mixer switch 209.
(See FIG. 2). As a result, the coefficient storage circuit 310 updates the filter coefficient of the FIR filter 303, and the switch circuit 203 and the mixer switch 209 switch their outputs to switch the output signal 107. This operation will be described later.

Next, the operation of the signal comparison / detection switching device 100 according to this embodiment will be described. 5 is a flowchart showing the operation of the detector 406 shown in FIG. 4, and FIG. 6 is a flowchart showing the operation of the control unit 410 shown in FIG. The operation of the signal comparison / detection switching device 100 is roughly classified into an operation in a state where the switching control signal 108 is not input and an operation in a case where the switching control signal 108 is input. That is, when the switching control signal 108 is not input, a predetermined selection signal 20 is output as the output signal 107.
7 is continuously output, and other input signals are output as signal x205.
Are sequentially taken in, and it is determined whether or not this input signal has the same content as the selection signal 207, and the result is stored.

On the other hand, when the switching control signal 108 is input, the optimum signal is selected as the next selection signal based on the judgment result, and the output signal 107 is switched from the selection signal 207 to the next selection signal. For example, when the signal comparison / detection switching device 100 is installed in a network follow type radio receiver, the next selection signal is a broadcast signal having the same content as the selection signal 207 and a better reception state. For example, when the reception state of the output signal 107 deteriorates, a higher-level determination device (not shown) provided outside the signal comparison / detection switching device 100 in the radio receiver.
Decides to switch the content of the output signal 107,
The switching control signal 108 is output to the signal comparison detection switching device 100.

First, the operation when the switching control signal 108 is not input will be described. As shown in FIG. 1, the input signal group 101 is input to the selector 103, and the input signal group 102 is input to the selector 104. Selector 1
03 selects one signal from the input signal group 101 based on the control signal 110, and outputs it as the input signal 201 to the signal detection switch 106. Similarly, the selector 104
1 to 1 based on the control signal 110.
Signal is selected and output as the input signal 202 to the signal detection switch 106.

As shown in FIG. 2, the input signals 201 and 2
02 is input to the switch circuit 203 of the signal detection switch 106. Based on the switching signal 213, the switch circuit 203 outputs one of the input signals 201 and 202 as the signal y2.
04 to the adaptive filter 206, and the other to the adaptive filter 206 and the judgment control unit 210 as a signal x205. For example, the input signal 201 is output as the signal y204, and the input signal 202 is output as the signal x20.
Output as 5.

As shown in FIG. 3, the signal y204 is input to the FIR filter 303 of the adaptive filter 206. F
The IR filter 303 filters the signal y204 based on the coefficient output signal 305 and delays it by an appropriate time,
As the selection signal 207, the subtracter 312 and the determination control unit 210
(See FIG. 2) and the mixer switching unit 209 (see FIG. 2). On the other hand, the signal x205 is input to the adaptive FIR filter 308 as a reference signal. The adaptive FIR filter 308 filters the signal x205 to generate the pseudo signal 208, and subtracts the signal from the subtractor 312 and the mixer switch 209.
Output to. Mixer switch 209 (see FIG. 2)
Outputs the selection signal 207 as the output signal 107.
Therefore, for example, when the signal comparison / detection switching device 100 is installed in a network follow type radio receiver, the selection signal 207 becomes a viewing signal.

The pseudo signal 208 is a signal generated by filtering the signal x205 as a reference signal,
When the content of the signal y204 and the content of the signal x205 are the same, the selection signal 207 and the pseudo signal 208 are the same signal. However, in this case, the selection signal 207 and the pseudo signal 208 are not digitally the same signal, and both have a linear relationship. For example, the difference between the two is −
It becomes 30 dB. When the content of the signal y204 and the content of the signal x205 are different from each other, for example, when different broadcasts are received, the signal selection signal 207 and the pseudo signal 20
The signals are different from each other and have no linear relationship.

The pseudo signal at time t is y_hat
(T), the i-th filter coefficient at time t is w
i (t), the reference signal is x (t), and the number of taps is N
Then, the pseudo signal y_hat (t) is given by Equation 1 below.

[0042]

[Equation 1]

Next, the subtracter 312 subtracts the pseudo signal 208 from the input selection signal 207 and subtracts the difference signal 211.
To generate the adaptive FIR filter 308 and the judgment control unit 2
10 (see FIG. 2). The selection signal 207 at time t is y (t), and the difference signal 211 is e
If (t), the difference signal e (t) is given by the following mathematical formula 2.

[0044]

[Equation 2]

The adaptive FIR filter 308 then filters the filter coefficient 212 so as to minimize the difference signal 211.
Is updated, and this is updated by the coefficient storage circuit 310 and the determination control unit 2.
10 (see FIG. 2). Coefficient storage circuit 31
0 stores this filter coefficient 212. If the step size at time t is μ (t), the filter coefficient w
i (t + 1) is given by Equation 3 below.

[0046]

[Equation 3]

If the power of the reference signal x (t) is PX (t) and μ0 is a positive constant affecting the convergence speed,
The step size μ (t) is given by Equation 4 below. Further, PX (t) is given by the following Equation 5.
The processing shown in the following equations 4 and 5 is performed by the learning identification method (norm
alized Least Mean Square). By adjusting the coefficient μ0, noise resistance and the like can be controlled.

[0048]

[Equation 4]

[0049]

[Equation 5]

Since a true filter coefficient cannot be obtained for an input signal having a high autocorrelation such as a tone signal, tone signal detection is performed on the reference signal x and the selection signal y to perform estimation processing. May be stopped.

Then, as shown in FIG.
7, difference signal 211, filter coefficient 212 and signal x2
05 is input to the detector 406 of the determination control unit 210.

As shown in FIG. 5, the detector 406 compares the levels of the selection signal 207 and the difference signal 211, monitors the filter coefficient 212, and selects the selection signal 207.
It is determined whether or not the pseudo signal 208 and the pseudo signal 208 have the same content (match / mismatch determination), and these results are output as the detection result 407. That is, step S1 of FIG.
1, the level of the signal x205 (LEV_x)
Is greater than or equal to a preset threshold (Th_x), and if the level of the signal x205 is greater than or equal to the threshold, the process proceeds to step S12. Next, as shown in step S12, it is determined whether or not the level (LEV_y) of the selection signal 207 is equal to or higher than a preset threshold value (Th_y),
If the level of the selection signal 207 is equal to or higher than the threshold value, the process proceeds to step S14. In Step S14, Tim0
Has an initial value of 0, and is incremented by 1 each time the step S14 is passed. Th_ with a preset value of Tim0
If it is less than or equal to the value of tim0, the process returns to step S11. When the value of Tim0 becomes larger than the value of Th_tim0, the process proceeds to steps S15 and S16. By the step S14, it is possible to provide a waiting process for making a determination in the steps S15 and S16 and thereafter.

On the other hand, when the level of at least one of the signal x205 and the selection signal 207 is less than the threshold value, the process proceeds to step S13. In step S13, Ti
The initial value of m1 is 0, and it is incremented by 1 each time it passes through step S13. The value of Tim1 is preset to T
If it is less than the value of h_tim1, the process returns to step S11. When the value of Tim1 becomes equal to or larger than the value of Th_tim1, the process proceeds to steps S15 and S16. This gives the signal x
Time-out processing can be provided when the level of at least one of 205 and the selection signal 207 continues to be less than the threshold value.

Next, in step S15, the level of the differential signal 211 is subtracted from the level of the selection signal 207 to calculate the erase amount (= LEV_y-LEV_e). When the contents of the selection signal 207 and the contents of the pseudo signal 208 match, the erase amount becomes large. That is, the signal level remaining after erasing becomes small. On the contrary, when the contents of the selection signal 207 and the contents of the pseudo signal 208 do not match, the erase amount becomes small. Therefore, by quantitatively evaluating the erased amount, it is possible to make a match / mismatch determination. The reason for making this match / mismatch determination based on the amount of erasure instead of the absolute value of the level (LEV_e) of the difference signal 211 is that the level of the difference signal 211 is affected by the level of the selection signal 207 and When the level is originally low, the difference signal 21
This is because the level of 1 also becomes low.

Further, in step S16, the filter coefficient 212 is monitored, and it is evaluated whether or not most of the total power of the filter coefficient 212 (for example, 90%) is concentrated in two continuous filter coefficients. When the content of the selection signal 207 and the content of the pseudo signal 208 match, the difference between the two signals is only the delay difference, the phase difference, or the amplitude difference, and therefore, only the absolute value of 1 or 2 consecutive filter coefficients is inevitable. Becomes larger and other filter coefficients become smaller. When the contents of the selection signal 207 and the contents of the pseudo signal 208 do not match, such concentration of power of the filter coefficient does not occur. Therefore, by monitoring the power concentration of the filter coefficient, the content of the selection signal 207 and the signal x20
It is possible to judge the match / mismatch with the contents of item 5.

Specifically, when the maximum value of the sums of two consecutive filter coefficient powers is M and the total sum of filter coefficient powers is A, the (M / A) ratio is, for example, 0.9.
Determine if it is greater than. When the (M / A) ratio is larger than 0.9, that is, when the power of the filter coefficient is concentrated, DET = 1 is set in step S17,
When the (M / A) ratio is 0.9 or less, that is, when the power of the filter coefficient is not concentrated, step S18
At DET = 0, the DET value is output.

The erasing amount and the (M / A) ratio described above are both indexes for judging whether the contents of the selection signal 207 and the contents of the pseudo signal 208 match or not, but the erasing amount is affected by noise. Cheap. That is, if the selection signal 207 or the pseudo signal 208 contains a lot of noise, the amount of erasure becomes small, and it becomes difficult to determine whether the match / mismatch occurs. On the other hand, since the (M / A) ratio is less susceptible to noise,
When there is a lot of noise, the determination based on the (M / A) ratio is effective. On the contrary, the erasure amount can be used as an index for evaluating the noise component.

Next, in step S19, both the erase amount and the DET value are output as the detection result 407 and stored in the memory circuit 408. At this time, the values of Tim0 and Tim1 described above are returned to 0.

Next, in step S20, the control unit 4
10 waits for the signal x205 to be switched to the next signal to be compared, and when the switching is completed, the process returns to step S11 to perform the above-described processing on the new signal x205.

As shown in FIG. 6, the control unit 410 first initializes in step S31, and then in step S32.
Wait for detector 406 to finish processing at. If the processing of the detector 406 is completed, in step S33, the comparison information 409 indicating the selected channel and the channel to be compared is output to the storage circuit 408, and the comparison information 409 is output to the storage circuit 408. Remember. Then, in step S34, it is determined whether or not the switching control signal 108 is input. If not input, the selection control signal 109 is sent to the signal selection control unit 105 (see FIG. 1).
Output to the selector 103 or 104 (see FIG. 1).
(See) selects the next candidate input signal. After that, the process returns to step S32, the detection process of the detector 406 is waited for again, and the processes shown in steps S33 and S34 are repeated.

As a result, the signal x205 to be compared with the selection signal 207 is sequentially switched, a pseudo signal 208 is generated from the signal x205, and it is determined whether the content matches or does not match the selection signal 207. The determination result is stored in the storage circuit 408. In this way, the determination result stored in the storage circuit 408 is constantly updated with the latest information.

Next, the case where the switching control signal 108 is input will be described. As the switching control signal 108, the output signal 107 of the signal comparison / detection switching device 100 is changed to the selection signal 20.
7 is a signal for instructing switching from 7 to another signal (next selection signal) having the same content as the selection signal 207. The switching control signal 108 is input from the outside of the signal comparison / detection switching device 100 to the control unit 410 of the determination control unit 210 of the signal detection / switching unit 106.

When the switching control signal 108 is input, the control section 410 receives steps S34 to S shown in FIG.
Proceed to 35. Then, in step S35, the information stored in the storage circuit 408 is checked, and at that time, the optimum signal is selected as the next-stage selection signal. Then, in step S36, the switching signal 213 is output to the mixer switching unit 209 and the selection control signal 109 is output to the signal selection control unit 105.

As a result, as shown in FIGS. 1 to 3,
Based on the selection control signal 109, the signal selection control unit 105 causes the selector (for example, the selector 104), which has selected the signal x205, of the selectors 103 and 104 to select the next selection signal. As a result, for example, the input signal 202 becomes the next selection signal and the signal x205 becomes the next selection signal. As a result, the adaptive FIR filter 308 generates the pseudo signal 208 based on the next selection signal and outputs it to the mixer switch 209.

The mixer switching unit 209 sets the ratio between the selection signal 207 and the pseudo signal 208 to, for example, 100: 0, 90: 1.
0:80:20, ..., 10:90, 0: 100, and the output signal 107 is switched stepwise from the selection signal 207 to the pseudo signal 208. At this time, since the signals are switched step by step, almost no noise is generated due to the switching.

After that, as shown in step S37 of FIG. 6, the control unit 410 sends the switching signal 213 to the switch circuit 203, the coefficient storage circuit 310 and the mixer switching unit 209.
Is output. As a result, the switch circuit 203 switches the output signal based on the input switching signal 213. For example, if the input signal 202 was output as the signal x205 until then, the input signal 20 is switched by switching.
2 is output as the signal y204. This switch circuit 2
At the same time as switching 03, the coefficient storage circuit 310 outputs the coefficient output signal 305 to the FIR filter 303,
The filter coefficient of the FIR filter 303 is rewritten. As a result, the input signal 202 is input to the FIR filter 303, and the filter coefficient of the FIR filter 303 is rewritten to a filter coefficient suitable for generating the pseudo signal 208 from the input signal 202. The same signal as signal 208 is selected signal 207
Will be output as. That is, until then adaptive FIR
Pseudo signal 20 generated by passing through the filter 308
8 will be generated by passing through the FIR filter 303.

Simultaneously with the switching of the switch circuit 203 and the rewriting of the filter coefficient of the FIR filter 303, the mixer switching unit 209 restores the ratio of the selection signal 207 and the pseudo signal 208 to the initial state of 100: 0. As a result, the selection signal 207 is output again as the output signal 107.
Will be output. It should be noted that at the time of this switching, the selection signal 207 and the pseudo signal 208 are exactly the same signal, so that noise due to switching does not occur.

As described above, in this embodiment, the adaptive F
The signal x205 to be compared by the IR filter 308
A pseudo signal 208 is generated from the output signal, a level difference between the selection signal 207 and the difference signal 211, that is, an erasing amount is calculated, and it is determined whether the content of the selection signal 207 and the content of the pseudo signal 208 match. There is. For this reason, even if there is a delay difference, a signal level difference, a phase inversion, or noise mixing between the selection signal 207 and the signal x205, it is possible to cancel these and perform a correct match / mismatch determination. As a result, it is possible to reduce the occurrence of judgment errors. Further, since this judgment can be made quantitatively, the judgment processing can be speeded up.

Further, in the present embodiment, the selection signal 20
7 and the pseudo signal 208, the contents of the selection signal 207 and the pseudo signal are also obtained by obtaining the filter coefficient 212 of the adaptive FIR filter 308 that minimizes the difference signal 211 and evaluating the power concentration degree of the filter coefficient 212. 20
It is determined whether the contents of 8 match. As a result, the filter coefficient is less likely to be affected by noise, so that even if the selection signal 207 or the signal x205 contains a lot of noise, it is possible to reliably determine the match / mismatch and reduce the detection error.

Further, the memory circuit 408 stores the detection result 407 of the signal x205 which is a candidate for the next selection signal and the comparison information 4
09 is constantly updated and stored, so that when there is a switching request, that is, when the switching control signal 108 is input, the optimum signal is quickly selected as the next selection signal, and the selection signal is set to the next signal. It becomes possible to switch to the selection signal.

Further, the adaptive FIR filter 308 generates the pseudo signal 208, and when the switching control signal 108 is input, the mixer switching unit 209 outputs the selection signal 207 to the pseudo signal 2.
Since it is switched to 08 in a stepwise manner, it is possible to suppress the generation of noise accompanying the switching process.

In the present invention, the mixer switching unit 20
9 may be omitted. Further, the coefficient storage circuit 310 may be configured by a coefficient transfer circuit. Further, in the present embodiment, an example in which the signal comparison / detection switching device 100 is mounted on a vehicle-mounted network follow type radio receiver has been shown, but the signal comparison / detection switching device of the present invention arbitrarily selects from a plurality of signals. It can be used for any application as long as it is necessary to judge whether the contents of two selected signals match and to switch those signals from one to the other.

Next, a second embodiment of the present invention will be described. FIG. 7 is a block diagram showing the configuration of the adaptive filter according to the second embodiment. The signal comparison / detection switching apparatus according to the present embodiment is provided with a delay estimation circuit 313 in the adaptive filter 206a. The delay estimation circuit 313 has
The selection signal 207 output from the FIR filter 303 and the signal x205 output from the switch circuit 203 (see FIG. 2) are input. Then, the delay estimation circuit 313 estimates the temporal difference between the selection signal 207 and the signal x205 by monitoring the selection signal 207 and the signal x205, and the estimation result is obtained by the adaptive FIR filter 30.
Output to 8. Thereby, the adaptive FIR filter 308 adjusts the tap position when performing the arithmetic processing. The configuration and operation of the signal comparison / detection switching device of the present embodiment other than the above are the same as the configuration and operation of the signal comparison / detection switching device 100 according to the first embodiment described above.

In this embodiment, the delay estimation circuit 313 is used.
Estimates the amount of delay between the selection signal 207 and the signal x205, thereby limiting the tap position to be estimated by the adaptive FIR filter 308. Therefore, in addition to the effects of the first embodiment described above, the amount of calculation performed by the adaptive FIR filter 308 can be reduced, and the time required to generate the pseudo signal 308 can be shortened. As a result, the detection time can be further shortened.

[0075]

As described in detail above, according to the present invention,
Even if there is a delay difference, a signal level difference, a phase inversion, or noise mixing between input signals, it is possible to obtain a signal comparison / detection switching device that can reduce detection error and shorten detection time. Further, it is possible to obtain a signal comparison / detection switching device that has less noise when switching signals.
If this signal comparison / detection switching device is incorporated into, for example, a network follow type radio receiver, there will be few mistakes in the selection of received signals, and moreover, the received signals can be swiftly and smoothly responded to changes in the receiving state due to traveling of the vehicle. It is possible to obtain a network follow-up radio receiver that can switch to the optimum signal. This makes it possible to provide a higher quality hearing means.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a signal comparison / detection switching device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a signal detection switch in the first embodiment.

FIG. 3 is a block diagram showing a configuration of an adaptive filter in the first embodiment.

FIG. 4 is a block diagram showing a configuration of a determination control unit in the first embodiment.

FIG. 5 is a flowchart showing the operation of the detector in the first embodiment.

FIG. 6 is a flowchart showing the operation of the control unit in the first embodiment.

FIG. 7 is a block diagram showing a configuration of an adaptive filter according to a second exemplary embodiment of the present invention.

FIG. 8 is a block diagram showing a configuration of a conventional signal comparison and detection device.

[Explanation of symbols]

100; Signal comparison detection switching device 101, 102; input signal group 103, 104; selector 105; Selection control unit 106; Signal comparison switch 107; Output signal 108; Switching control signal 109; selection control signal 110; control signal 201, 202; input signal 203; switch circuit 204; signal y 205; signal x 206, 206a; adaptive filter 207; Selection signal 208; Pseudo signal 209: Mixer switching device 210; Judgment control unit 211; Difference signal 212; Filter coefficient 213; switching signal 303; FIR filter 305; coefficient output signal 308; Adaptive FIR filter 310; Coefficient storage circuit 312; Subtractor 313: Delay estimation circuit 406; Detector 407; Detection result 408; Memory circuit 409; Comparison information signal 410; Control unit 701, 702; input signal 703; silence detector 704; Match detection unit 705; Judgment control circuit 706; Match / mismatch discrimination output

Claims (8)

[Claims] 1. A first selector that selects one input signal from a plurality of input signals and outputs it as a first signal, and one input signal that selects one input signal from a plurality of input signals as a second signal. A second selector for outputting and the first signal from the second signal.
An adaptive FIR filter that generates a pseudo signal that minimizes the difference signal between the first signal and the differential signal, and the same contents of the first signal and the pseudo signal based on the difference between the first signal and the difference signal. A detector that determines whether or not the signal is a signal and outputs the determination result, a storage circuit that stores the determination result, and the determination result that is stored in the storage circuit when the switching control signal is input. The contents are based on the first
The next selection signal having the same content as that of the signal is selected from the plurality of input signals, and the first selector is caused to select the next selection signal, whereby the switching control signal is input to the first signal. And a control unit for switching the signal selected before the switching to the next selection signal. 2. A first and second selector for selecting one input signal from a plurality of input signals respectively, and one of the output signals of the first and second selectors for selecting a first input signal. A switch circuit that outputs as a signal and the other as a second signal, and an F that generates a selection signal from the first signal.
An IR filter and an adaptive F for generating a pseudo signal that minimizes a difference signal between the second signal and the selection signal.
An IR filter, a coefficient storage circuit that stores the filter coefficient of the adaptive FIR filter, and whether the selection signal and the pseudo signal have the same content based on the difference between the selection signal and the difference signal. A detector for judging and outputting the judgment result, a memory circuit for storing the judgment result, the selection signal and the pseudo signal are input, and the selection signal, the pseudo signal and the selection signal and the pseudo signal are A mixer switching device that selects and outputs one of the mixed signals mixed at an arbitrary ratio, and its contents based on the determination result stored in the storage circuit when the switching control signal is input. A next selection signal having the same content as the selection signal is selected from the plurality of input signals, and the next selection is selected by the selector outputting the second signal of the first and second selectors. A signal is selected, and the output signal of the mixer detector is gradually switched from the selection signal to the pseudo signal, and then the switch circuit is switched between the first signal and the second signal. And the filter coefficient of the next-generation selection signal stored in the coefficient storage circuit is input to the FIR filter, and the output signal of the mixer detector is switched from the pseudo signal to the selection signal. And a control unit for switching an output signal of the detector from the selection signal to the next selection signal. 3. The detector according to claim 1, wherein the detector determines whether the selection signal and the pseudo signal have the same contents based on a filter coefficient of an adaptive FIR filter. The signal comparison detection switching device described. 4. A first selector that selects one input signal from a plurality of input signals and outputs it as a first signal, and one input signal that selects one input signal from a plurality of input signals as a second signal. A second selector for outputting and the first signal from the second signal.
An adaptive FIR filter that generates a pseudo signal that minimizes the difference signal from the signal of No. 1, and whether the first signal and the pseudo signal have the same content based on the filter coefficient of the adaptive FIR filter. A detector that determines whether or not to output the determination result, a storage circuit that stores the determination result, and a content based on the determination result that is stored in the storage circuit when the switching control signal is input. The switching control of the first signal is performed by selecting the next selection signal having the same content as the first signal from the plurality of input signals and causing the first selector to select the next selection signal. A signal comparison / detection switching device, comprising: a control unit that switches a signal selected before a signal is input to the next selection signal. 5. The determination as to whether the selection signal and the pseudo signal have the same content based on the filter coefficient of the adaptive FIR filter is performed by evaluating the power concentration degree of the filter coefficient. The signal comparison / detection switching device according to claim 3 or 4. 6. A signal selection control unit for controlling the operation of the first and second selectors based on a signal output from the control unit. The signal comparison and detection switching device according to the item. 7. A network follow type radio receiver, wherein a radio broadcast signal is input as the plurality of input signals and a viewing signal is output as the selection signal. 2. The signal comparison / detection switching device according to item 1. 8. The signal comparison / detection switching device according to claim 7, wherein the first and second selectors are tuners.