JPH06350466A - Noise suppression device - Google Patents

Abstract

PURPOSE:To provide a noise suppression device capable of obtaining a sifficient noise suppression effect. CONSTITUTION:This device is equipped with a signal detecting means 1 which detects the signals A, B of signal lines, respectively, a sum signal generating means 21 which takes the sum of each detected signal, a differential signal generating means 22 which takes difference between the detected signals. a noise canceller means 3 which suppresses or eliminates a noise component included in a differential signal generated by the differential signal generating means 22, and a signal separation means 4 which separates the signal to the one in accordance with each signal line based on the differential signal and a sum signal in which the noise component is suppressed or eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise suppressing device which suppresses or removes noise contained in a stereo signal or the like which is mainly received and processed by an FM receiver or the like.

[0002]

2. Description of the Related Art Conventionally, a transmission system in which each signal is transmitted to a plurality of signal lines, for example, R (right) and L (left) of stereo etc.
In a transmission system having two signals, the noise component contained in each signal is suppressed or removed by providing a noise suppression device for each of the R signal and the L signal to suppress or remove the noise component. The noise suppressor is a noise limiter that simply limits the noise level above the signal level, divides the signal into a plurality of frequency bands, and determines what the noise component contained in the signal is, Based on the determination result, a filter coefficient that cuts the noise component is supplied to a band-pass filter (BPF) having a controllable pass band characteristic provided for each frequency band to suppress the noise component. A method of adding frequency components is used. The above noise suppressing device is similarly applied to a balanced type transmission system, particularly regarding noise.

[0003]

However, in the above noise suppression method, when the noise component is small,
There is a problem in that it is difficult to determine what the noise component included in the signal is, and a sufficient noise suppression effect cannot be obtained.

An object of the present invention is to provide a noise suppressor capable of obtaining a sufficient noise suppressing effect in consideration of such problems of the conventional noise suppressing device.

[0005]

According to the present invention of claim 1, in a balanced type signal transmission system, a signal detecting means for detecting each signal of each signal line and a sum of the detected signals are obtained. A noise suppressing device comprising a sum signal creating means, a difference signal creating means for taking a difference between detected signals, and a difference signal canceling means for suppressing or removing the difference signal created by the difference signal creating means. .

According to a second aspect of the present invention, in a signal transmission system of a balance type with respect to a noise component, a signal detecting means for detecting each signal of each signal line and a sum signal generation for summing the detected signals. Means, a difference signal creating means for taking a difference between the detected signals, a noise canceling means for suppressing or removing a noise component included in the difference signal created by the difference signal creating means, and a noise component for suppressing or eliminating the noise component. It is a noise suppression device comprising a signal separation means for separating the signal corresponding to each signal line based on the removed difference signal and sum signal.

According to a fourteenth aspect of the present invention, in a noise suppression or removal method using a spectral subtraction method,
It is a noise suppression device that changes parameters according to a frequency band and multipath.

According to a nineteenth aspect of the present invention, a signal transmitting means for transmitting a signal to be transmitted and an inverted signal obtained by inverting the phase of the signal to a predetermined signal transmission system, a signal transmitted by the signal transmission system, and A signal mixing unit that mixes the inverted signals, a noise canceling unit that suppresses or removes noise that is input in the signal transmission system based on the mixed signal that is mixed and the signal or the inverted signal are provided. It is a noise suppressor which is similarly mounted on the inside signal and the inverted signal.

According to a twentieth aspect of the present invention, a tuning control means for controlling tuning of the receiving means, a detuning degree detecting means for detecting a detuning degree in the receiving means, and a receiving means for receiving the detuning degree according to the detected detuning degree. And a noise canceling unit that suppresses or removes a noise component included in the generated signal.

According to the twenty-first aspect of the present invention, the receiving means is a TV receiver, and the ghost detecting means for detecting a ghost from a video signal among the signals received by the TV receiver, and the detected ghost. Based on the above, the noise suppressing device includes a noise canceling unit that suppresses or removes a noise component included in the audio signal of the signal received by the TV receiver.

[0011]

According to the present invention of claim 1, the signal detecting means detects the respective signals of the respective signal lines, the sum signal producing means takes the sum of the detected signals, and the difference signal producing means detects the respective signals. The difference between the signals is taken, and the difference signal canceling means suppresses or removes the difference signal created by the difference signal creating means.

According to the present invention of claim 2, the signal detecting means detects the respective signals of the respective signal lines, the sum signal producing means takes the sum of the detected signals, and the difference signal producing means detects the respective signals. The difference between the signals is taken, the noise canceling means suppresses or removes the noise component included in the difference signal created by the difference signal creating means, and the signal separating means based on the difference signal and the sum signal in which the noise component is suppressed or removed. , Signals corresponding to each signal line are separated.

In the fourteenth aspect of the present invention, the parameters used in the noise suppression or removal method using the spectral subtraction method are changed according to the frequency band and multipath.

In the nineteenth aspect of the present invention, the signal transmitting means sends out a signal and an inverted signal obtained by inverting the phase of the signal to a predetermined signal transmission system, and the signal mixing means transmits the signal by the signal transmission system. And the inversion signal are mixed, and the noise canceling means suppresses or removes the noise that is similarly applied to the signal being transmitted and the inversion signal in the signal transmission system based on the mixed signal and the signal or the inversion signal. .

In the twentieth aspect of the present invention, the tuning control means controls the tuning of the receiving means, the detuning degree detecting means detects the detuning degree in the receiving means, and the noise canceling means receives in accordance with the detected detuning degree. The noise component included in the signal received by the means is suppressed or removed.

According to the twenty-first aspect of the present invention, the ghost detecting means detects a ghost from the video signal of the signals received by the TV receiver, and the noise canceling means receives the ghost by the TV receiver. The noise component included in the audio signal of the received signal is suppressed or removed.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing its embodiments.

FIG. 1 is a block diagram of a noise suppressing apparatus according to a first embodiment of the present invention. That is, the noise suppression device is provided with the signal detection means 1 for detecting each signal, for example, the signal A and the signal B from a plurality of (here, two) signal lines, and the output of the signal detection means 1 is It is connected to the signal mixing section 2 which is composed of a sum signal creating means 21 for creating a sum signal from the signals A and B and a difference signal creating means 22 for similarly creating a difference signal. The output of the difference signal creating means 22 is connected to the noise canceling means 3 for suppressing or removing the noise component included in the difference signal, and the output of the noise canceling means 3 and the sum signal creating means 2 described above.
The output of 1 is connected to the signal separation means 4 which separates each signal (signal A'corresponding to the signal A and signal B'corresponding to the signal B) from the sum signal and the difference signal.

Next, the operation of the noise suppressor of the above embodiment will be described.

First, the signal transmission system in FIG. 1 is a balanced type transmission system with respect to noise. One signal A contains noise e _a and the other signal B contains noise e _b. Be present. Then, the signal detected by the signal detection means 1 can be represented by the signal (A + e _a ) and the signal (B + e _b ).

Next, the signals are mixed by the signal mixing unit 2. That is, in the sum signal generating means 21, creates a sum signal (A + B) + (e a + e b) is, the difference signal generation means 22, the difference signal (A-B) + (e a -e b) is created It However, in the balanced type transmission system, since the absolute values of the noise e _a and the noise e _b are almost equal and the phases are opposite to each other, the noise component (e _a + e _b ) of the sum signal becomes almost 0 and the noise is removed. can do. Therefore, the signal output from the sum signal creating means 21 is (A + B).
On the other hand, the noise component of the difference signal (e _a -e _b) is twice the noise e _a or e _b, it becomes easier to determine whether there are noise components What, noise suppression or removal Easier to do.

Here, the difference signal (A−B) + (e _a −e _b )
As the difference signal (A−B) + 2 · e _a , this difference signal is input to the noise canceling means 3. The noise canceling means 3 cancels the noise component 2 · e _{a and} outputs a difference signal (AB) ′ (here, (AB) ′.
The reason is that the signal component is slightly deformed when canceling the noise).

The sum signal and the difference signal from which the noise components have been suppressed or removed as described above are input to the signal separation means 4, where the signal A'and the signal B'corresponding to the input signal are input.
Is separated into

In the above embodiment, the suppression or removal of noise in the balanced type signal transmission system with respect to the noise component is shown, but the present invention is not limited to this, and the difference signal of each signal in the balanced type signal transmission system is suppressed or eliminated. It may be configured to be removed.

FIG. 2 is a block diagram of the noise suppressing apparatus of the second embodiment according to the present invention. 2 is different from the first embodiment shown in FIG. 1 in that a noise memory 5 having a noise pattern stored therein is connected to the noise canceling means 3, and other configurations are the same as those in FIG. is there. Therefore, the noise canceling unit 3 uses the noise pattern stored in the noise memory 5 when suppressing or removing the noise component included in the difference signal. Other basic operations are similar to those of the first embodiment.

FIG. 3 is a block diagram of a noise suppressing apparatus according to a third embodiment of the present invention. 3 is different from the second embodiment shown in FIG. 2 in that the noise canceling means 3 is connected to the noise canceling control means 6, and other configurations are similar to those in FIG. The noise cancellation control means 6 outputs a parameter used when the noise cancellation means 3 suppresses or removes a noise component. Therefore, the noise canceling unit 3 uses the noise pattern stored in the noise memory 5 and the parameter output from the noise canceling control unit 6 when suppressing or removing the noise component included in the difference signal. Further, the noise cancellation control means 6 and the noise memory 5
A dotted line connecting and indicates a modified embodiment configured to update the noise pattern of the noise memory 5 according to the parameter output from the noise cancellation control means 6. The basic operation is similar to that of the first embodiment.

FIG. 4 is a block diagram of a noise suppressing device according to a fourth embodiment of the present invention. 4 is different from the third embodiment shown in FIG. 3 in that a receiving means 7 for receiving a radio wave signal for obtaining a signal input to the signal detecting means 1 is provided, and the receiving means 7 receives the signal. The reception state detecting means 8 for detecting the reception state of the received signal is provided, and the output of the reception state detecting means 8 is input to the noise cancellation control means 6. The noise cancellation control means 6 outputs a parameter to the noise cancellation means 3 based on the reception state detected by the reception state detection means 8 and updates the noise pattern of the noise memory 5. Here, the radio wave signal is, for example, an FM stereo broadcast wave or the like, and the reception state is, for example, the input signal level, the electric field strength of the received radio wave, or the like.

FIG. 5 is a block diagram of a noise suppressing apparatus according to the fifth embodiment of the present invention. The noise suppressor of this embodiment is an example of application to a receiver of FM stereo broadcast waves.

In FIG. 5, the noise suppressor receives an FM stereo broadcast wave and converts the received stereo signal into a right channel signal (hereinafter referred to as R signal) and a left channel signal (hereinafter referred to as L signal). FM receiver 9 for separation
The FM receiving section 9 is connected to the electric field information detecting means 10 for detecting electric field information of the received signal, and the output R signal and L signal are A / D for converting an analog signal into a digital signal. It is input to the converter 11.

The A / D converter 11 produces a sum signal and a difference signal of the R signal and the L signal from the signal mixing section 2
The output of the difference signal is connected to the noise canceling means 3 that suppresses or removes the noise component included in the difference signal. In the signal mixing unit 2, the sum signal creating means for creating the sum signal is composed of the adder 23 and the high speed Hartley converter (hereinafter referred to as FHT) 25, and the difference signal creating means for creating the difference signal is the subtractor. 24 and FHT2
It is composed of six.

The output of the signal mixing section 2 (sum signal) and the output of the noise canceling means 3 (noise canceled difference signal) correspond to the R signal and the L signal based on the sum signal and the noise canceled difference signal. It is connected to a signal separation means 4 for separating an R ′ signal and an L ′ signal, and the output of the signal separation means 4 is connected to a D / A converter 12 for converting a digital signal into an analog signal. In the signal separating means 4 described above, the circuit for generating the R ′ signal is composed of the adder 43 and the inverse fast Hartley converter (hereinafter referred to as IFHT) 45, and the circuit for generating the L ′ signal is the subtractor 44 and the IFHT 46. It is composed by.

On the other hand, the electric field information detector 10 is connected to the noise cancellation control means 6 which outputs parameters used when the noise cancellation means 3 suppresses or removes noise components. Further, a noise memory 5 storing a noise pattern is connected to the noise canceling means 3. Here, as shown by the dotted line as in FIG. 4, the noise pattern may be updated by parameters.

The FM receiving section 9 is a receiving means, and the electric field information detecting means 10 is a receiving state detecting means.

Next, an example of the processing method of the noise canceling means 3 of the fifth embodiment will be described. here,
The noise pattern subtraction process is performed for each frequency component in each fixed band.

As shown in FIG. 17, first, the power spectrum | X (k) | ² of the output H (k) which has been subjected to the fast Hartley conversion by the FHT 26 is calculated by the following equation (Equation 1) (step S1).

[0036]

## EQU1 ## | X (k) | ² = (H ² (k) + H ² (N−k)) / 2 Next, the square root of the obtained power spectrum is calculated by the following equation (Equation 2) (step 2). S2).

[0037]

√x = -0.1985987x ² + 0.8803385x + 0.3175231 (10-bit accuracy) After that, the calculated value and the noise pattern output from the noise generation unit (noise memory 5 in FIG. 5) | W
Based on (k) |, the subtraction process of the noise spectrum is performed using the following equation (Equation 3) (step S3).

[0038]

## EQU00003 ## S (k) = H (k) * (1-.alpha. | W (k) | / | X (k) |) S (Nk) = H (Nk) * (1-.alpha. | W (k) | / | X (k) |) However, correction to (1-α | W (k) | / | X (k) |) ≧ β Setting of α and β α: 0.5 (very weak Electric field) 0.9 (strong electric field) β: 0.2 to 0.6 where α is a cancellation coefficient that determines the amount of subtraction when subtracting the noise pattern, and β is the adverse effect of noise removal. In order to suppress as much as possible, it is a clamp coefficient that controls the cancellation coefficient when canceling noise.

Next, the principle of noise suppression of the fifth embodiment will be described.

[0040] Now, the right ch signal, including the noise R ', the left-ch signal L' and, each signal that does not contain the noise R, L, noise and E _R, and the E _L,

[0041]

## EQU00004 ## R '= R + E _R

[0042]

## EQU5 ## L '= L + _EL Here, (R' + L ') and (R'-L') are considered.

[0043]

## EQU6 ## A = (R '+ L') / 2 = (R + L) / 2 + (E _R + E _L ) / 2

[0044]

Equation 7] B = (R'-L ') / 2 = (R-L) / 2 + (E R -E L) / 2 of the hearing test results, the noise level of the A signal is very small, B signals It was confirmed that the noise level of was extremely high.

Therefore, if E _R + E _L ≈0,

[0046]

(Equation 8) E _R ≈−E _L , and the following equation is obtained from (Equation 6), (Equation 7) and (Equation 8).

[0047]

[Equation 9] A≈ (R + L) / 2

[0048]

[Equation 10] B≈ (R−L) / 2−E _L ≈ (R−L) / 2 + E _R Next, noise suppression is performed in the state of (Equation 10) (E _L ′,
_{E R '), A + B} , obtains the A-B.

[0049]

Equation 11] A + B = (R + L ) / 2 + (R-L) / 2-E L '= R-E L' = R + E R '

[0050]

[Equation 12] AB = (R + L) / 2 − ((RL) / 2− _EL ′) = L + _EL ′ (Equation 11) and (Equation 12) are (Equation 4) and (Equation 5). ) Is less noise.

Next, details of the above noise suppression will be described.

For each signal R, L and each noise E _R , E _L , each signal and each noise after noise suppression are respectively R _S ,
When L _S , E _RS , and E _LS are used, when the noise is suppressed in (Equation 7), the following equation (Equation 13) is obtained.

[0053]

B ′ = (R _S −L _S ) / 2 + (E _RS −E _LS ) / 2 Next, A + B ′ and A−B ′ are obtained.

[0054]

Equation 14] A + B '= (R + R S) / 2 + (L-L S) /
2+ (E _R + E _RS + E _L −E _LS ) / 2

[0055]

## EQU15 ## A−B ′ = (R−R _S ) / 2 + (L + L _S ) /
_{2+ (E R -E RS + E} L + E LS) / 2 _{where, E R = -E L R S} = R-R SD R SD: erroneous cancellation component _{L S = L-L SD L} SD: the erroneous cancellation min Then,

[0056]

[Equation 16] A + B ′ = R−R _SD / 2 + L _SD / 2 + (E _RS −E _LS ) / 2 = R + (L _SD −R _SD ) / 2 + (E _RS −E _LS ) / 2

[0057]

A−B ′ = L− (L _SD −R _SD ) / 2− (E _RS −E _LS ) / 2 Next, the Rch and Lch signals are noise-suppressed separately.

[0058]

[Expression 18] R _S '= R-R _SD ' + E _RS '

[0059]

[Formula 19] L _S ′ = L−L _SD ′ + E _LS ′ Above (Formula 16), (Formula 18) and (Formula 17), (Formula 1)
Consider the effect of noise suppression by comparing 9).

The suppression error component is (L _SD −R _SD ) / 2
In R _SD 'and L _SD ',

[0061]

It is assumed that | (L _SD −R _SD ) / 2 | <| R _SD '|, | L _SD ' |

[0062]

[Expression 21] ∵ │R-R│ <| L |, | R | (Normally, the above formula holds if there is an in-phase component of L and R) When the clamp coefficient is β = 50% (Expression 21) ), The left side becomes smaller. Therefore, the degree of influence of the signal component is small.

Next, (Equation 16), (Equation 18) and (Equation 1)
7) Consider the residual noise components of (Equation 19). (E _RS- E
_LS ) / 2 and E _RS 'and E _LS ',

[0064]

[Equation 22] (E _RS −E _LS ) / 2 ≈ E _RS ′, E _LS ′ is presumed to be, but since the influence on the signal component is smaller than in (Equation 20), the noise suppression degree is large. It can be set to

From (Equation 7), the component of (E _R -E _L ) is
Since it is larger than E _R and E _L , the noise component can be easily identified. Therefore, the noise includes a lot of opposite phase components in L and R. For example, the noise component can be specified by comparing (Equation 6) and (Equation 7). Normally, | R + L | <
It becomes as follows when a large amount of noise that is | RL | (when there is no anti-phase component) is included.

[0066]

[Equation 23] | A | <| B | From the above, by obtaining L'-R ', noise of the anti-phase component can be specified, and noise can be suppressed effectively, and
The noise suppression in L'-R 'can reduce the influence on the original signal.

Next, the operation of the noise suppressor of the fifth embodiment will be described.

First, the stereo signal received by the FM receiver 9 is separated into an R signal and an L signal and output to the A / D converter 11. In the A / D converter 11, the R signal and the L signal are each converted into a digital signal and input to the signal mixing unit 2. Here, it is assumed that the R signal and the L signal include noise components having substantially the same absolute value and opposite phases.

Then, in the adder 23, the R signal and L
As a result, as described above, the noise components cancel each other and become almost 0, and the sum signal (R +
L). The sum signal (R + L) is then fast Hartley transformed by the FHT 25 to facilitate processing of the noise pattern. On the other hand, in the subtractor 24, the R signal and the L signal are subtracted, and as a result, the noise component is approximately doubled, resulting in a difference signal (RL) +2 times the noise component. After that, this difference signal (RL) + double noise component is FHT.
High-speed Hartley conversion is performed by 26. Where FHT
H (k) which is the output of is calculated using the following equation (Equation 24).

[0070]

[Equation 24]

Next, since the sum signal (R + L) has noise removed, it is directly input to the signal separating means 4. On the other hand, the difference signal (R−L) +2 times the noise component is input to the noise canceling means 3 in order to suppress or remove the noise component.

On the other hand, the noise cancellation control means 6 outputs a parameter to the noise cancellation means 3 based on the electric field information of the reception signal detected by the electric field information detector 10 (may be a simple input signal level). In addition, the noise pattern corresponding to the electric field information is read from the noise memory 5 into the noise canceling means 3. For example, when the noise pattern is subtracted from the noise component included in the difference signal, the above-mentioned parameter changes the degree of the subtraction according to the electric field information to suppress the noise component by reducing the influence of the subtraction on the signal as much as possible. It can be so. Furthermore, if this parameter is taken as the cancellation coefficient α of the parameter that multiplies the noise pattern, the value of the cancellation coefficient α is increased when the antenna input level is relatively large with the electric field information as the antenna input level, and conversely When is relatively small, the value of the cancellation coefficient α is reduced.

As the above noise pattern, for example, FIG.
As shown in (a), (b) and (c), a noise pattern for each input signal level is obtained and stored in the noise memory 5, and the noise pattern for the detected input signal level is calculated from the stored noise pattern. It may be determined by an interpolation method or the like.

The difference signal (R−L) ′ (represented by (R−L) ′ because the signal is transformed by the noise canceling means 3) whose noise component is suppressed is input to the signal separating means 4. To be done. In the signal separation means 4, the sum signal (R +
L) and the difference signal (R−L) ′ are added by the adder 43 and then inverse Hartley transformed by the IFHT 45,
Further, the sum signal (R + L) and the difference signal (R−L) ′ are subtracted by the subtractor 44, and then inverse Hartley conversion is performed by the IFHT 46, and as a result, the IF ′ 45 outputs an R ′ signal corresponding to the R signal. , From IFHT46 is L
The L'signal corresponding to the signal is output. The R ′ signal and the L ′ signal are converted into analog signals by the D / A converter 12.

In the fifth embodiment, the high speed Hartley conversion process in the signal mixing unit 2 is performed after the signals are mixed. On the contrary, the high speed Hartley conversion is performed before the signals are mixed. It may be configured to perform processing.

In the fifth embodiment, the inverse high-speed Hartley conversion process in the signal separating means 42 is performed after the signals are separated. On the contrary, the inverse high-speed Hartley conversion is performed before the signals are separated. It may be configured to perform conversion processing.

Further, in the fifth embodiment, the noise canceling means 3 is provided only in the difference signal system, but the invention is not limited to this and may be provided in the sum signal system.

In the fifth embodiment, the electric field information is set to the input signal level, and the noise component is suppressed or removed from each input signal level. However, the present invention is not limited to this, and the electric field information is multi-valued. A path may be used, and a noise component due to the influence of multipath may be suppressed or removed. In this case, a noise pattern for each multipath may be used as the noise pattern.

In the fifth embodiment, the difference signal (R
-L) is always the object of noise cancellation, but instead of this, for example, as shown in FIG. 15, the sum signal (R +
L) magnitude | R + L | and difference signal (RL) magnitude |
R−L | is compared (step S1), and as a result of the comparison, if the difference signal (R−L) is larger, the difference signal (R−L) is targeted for noise cancellation (step S2) and vice versa. When the sum signal (R + L) has a large modulus, the sum signal (R + L) is multiplied by a predetermined constant k, for example, 0.5, and k × | R + L
| And | RL | are compared (step S3). As a result of comparison, if k × | R + L | is larger, the difference signal (R
-L) is increased or the sum signal (R + L) is targeted for noise cancellation (step S4), and conversely k × | R + L
If | is smaller, it may be left as it is.

FIG. 7 is a block diagram of the noise suppressing apparatus of the sixth embodiment according to the present invention. The noise suppression apparatus of this embodiment is provided for one or both signals, for example, between the output of the signal separation means 4 and the input of the D / A converter 12 in FIG.

In FIG. 7, the noise suppressing device is provided with a signal noise canceling means 13 for suppressing or removing a noise component contained in the signal inputted from the signal separating means, and the output of the signal noise canceling means 13 and the signal. A mixer 15 is provided for mixing the signals input from the separating means. In the signal noise canceling means 13,
Noise generation means 1 for generating noise based on electric field information
4 is connected, and the mixer 15 is responsive to the electric field information.
The mixing ratio of the above two signals is changed.

Here, the electric field information is multipath, and based on the multipath, the noise pattern is output from the noise generating means 14 to the signal noise canceling means 13 and the noise included in the signal output from the signal separating means. Suppress the component. The noise generation unit 14 is, for example, a noise memory that stores a noise pattern for multipath. The mixer 15 mixes the signal from the signal separation means and the signal in which the noise component of the signal is suppressed by changing the mixing ratio based on multipath. This mixing ratio increases the ratio of the signal after noise suppression in the portion where the multipath is large, and increases the ratio of the signal from the signal separating unit in the portion where the multipath is small.

FIG. 8 is a block diagram of the noise suppressing apparatus of the seventh embodiment according to the present invention. In this embodiment, the noise memory is composed of a static characteristic noise memory 51 in which a static noise noise pattern is stored and a multipath noise memory 52 in which a noise noise pattern due to the influence of multipath is stored. The noise component is suppressed by the noise selection unit 50 according to the reception state (here, antenna input level) detected by the reception state detection unit 8 when the antenna input level is small, and the static characteristic noise memory 51 is used. If the antenna input level is high, the multipath noise memory 52 is selected and the noise pattern of the selected noise memory is used. The antenna input level criterion for this selection is about 30 dBμ for an FM receiver, for example.
The basic operation is the same as in the above case.

FIG. 9 is a block diagram of the noise suppressing apparatus of the eighth embodiment according to the present invention. In this embodiment, the noise memory is composed of a monaural noise memory 53 (L−R) in which a noise pattern of a noise component included in the (L + R) signal is stored.
(R) A stereo noise memory 54 in which a noise pattern of a noise component included in the signal is stored, and a multipath noise memory 55 in which a noise pattern of noise due to the influence of multipath is stored. The noise canceling means 3 is provided in each signal system of the R signal and the L signal output from the stereo demodulator (not shown) of the FM receiver 9. The suppression of the noise component by the noise canceling means 3 is performed according to the electric field information (here, the antenna input level) detected by the electric field information detector 10.
The memory switching means 60 switches the noise memory to select an optimum noise pattern. The condition for this switching is whether or not the stereo pilot signal is output from the stereo demodulator (that is, monaural signal).
When the antenna input level is low, the monaural noise memory 53 is selected and the stereo pilot signal is output, and when the antenna input does not include the 19 kHz and 38 kHz signals, the stereo noise memory 54 is selected and the stereo pilot signal is output. If the antenna input contains 19 kHz and 38 kHz signals, the multipath noise memory 55 is selected.

FIG. 10 is a block diagram of a noise suppressing apparatus according to the ninth embodiment of the present invention. In this embodiment, the intermediate frequency level detecting means 91 detects the reception state (here, the intermediate frequency signal level) from the intermediate frequency signal of the FM receiving section 9, and the pilot signal detecting means 92 detects the stereo pilot signal (from the intermediate frequency signal). 19 kHz
Component and its multiple frequency components). The detected intermediate frequency signal (IF) level and the stereo pilot signal (SP) are input to the noise cancellation control means 6 after the signal state is determined by the signal determiner 93. The noise cancellation control means 6 outputs the parameter to the noise cancellation means 3 according to the determination result. As shown in FIG. 11, the noise cancellation control means 6 includes a signal judging device 9
When the intermediate frequency signal (IF) level is large and the stereo pilot signal (SP) is small (A in FIG. 11), the determination result of No. 3 shows that the cancellation coefficient α, which is one of the parameters, is small to
When the IF level is high and the SP signal is high (B in FIG. 11), the cancel coefficient α is set to medium and the IF level is low and the SP signal is low (C in FIG. 11). The cancellation coefficient α is set small, and when the IF level is small and the SP signal is large (D in FIG. 11), the cancellation coefficient α is set large.

FIG. 12 is a block diagram of a noise suppressing apparatus according to the tenth embodiment of the present invention. In the present embodiment, when a signal is transmitted by a relatively long distance signal transmission system, noise mixed in the signal transmission system is removed. In FIG. 11, the signal transmitting means 101 for transmitting the signal to the signal transmission system 102 is provided with the phase inverting means 105 for inverting the phase of the signal, and the signal S and the inverted signal (-S) are transmitted.

When noise N occurs in the signal S and the inverted signal (-S) during the transmission through the signal transmission system 102, the transmission has been performed under substantially the same conditions such as the arrangement of each transmission line of the signal transmission system 102. The signals are (S + N) and (-S + N). The signals (S + N) and (-S + N) are added and halved by the signal mixing means 103. Then,
The signal S and the inverted signal (-S) cancel each other and only the noise N is output. In the noise canceling means 104, the signal (S + N) and the noise N from the signal mixing means 103 are subtracted, the noise N is removed, and only the signal S is output.

In the tenth embodiment, the noise canceling means 104 subtracts the noise N output from the signal mixing means 103 from the signal (S + N), but instead of this, the noise N is converted to the signal (-S + N). ) May be subtracted.

FIG. 13 is a block diagram of a noise suppressing apparatus according to the eleventh embodiment of the present invention. In this embodiment, the tuning of the receiving means 7 is automatically controlled by the tuning control means 121, and the detuning degree of the receiving means 7 at that time is detected by the detuning degree detecting means 122. The noise prediction controller 123 and the noise generator 124 generate a noise pattern for detuning based on the detected detuning degree, and output the noise pattern to the noise canceling unit 3. Noise canceling means 3
Correspondingly suppresses a noise component caused by detuning. As described above, noise increases as the degree of detuning increases, but noise due to detuning can be suppressed.
Further, the degree of detuning may be detected by using a tuning control signal of synthesizer tuning control.

FIG. 14 is a block diagram of a noise suppressing apparatus according to the twelfth embodiment of the present invention. In the present embodiment, the case where the receiving means is the TV receiver 131 is shown. The ghost detection means 132 detects a ghost from the video signal of the TV receiver 131, and based on the detected ghost,
The noise prediction controller 133 and the noise generator 134 generate a noise pattern for multipath (TV
Ghosts in are caused by multipath). The noise canceling unit 3 is provided for the audio signal of the TV receiver 131, and suppresses the noise component for the multipath included in the audio signal according to the noise pattern output from the noise generator 134.

FIG. 16 is a diagram showing an example of a configuration in which the noise canceling means 3 used in the above embodiment divides a signal into bands to suppress or remove noise.

In FIG. 16, a signal including a noise component (here, noise due to the influence of multipath) is divided into a plurality of (four in this example) frequency bands by the band divider 161, and the division is performed. The generated signals are input to the spectral subtraction 162, which is one type of noise canceling means provided for each band.

On the other hand, the multipath detected by the multipath detecting means or the like is input to the noise cancellation control means 163, and the noise cancellation control means 163, based on the multipath, subtracts the spectrum subtraction 16 from the spectrum subtraction 16.
The control is performed so as to suppress the noise with respect to the multipath in 2. This control controls, for example, the cancellation coefficient α and the clamp coefficient β of the parameters in the spectral subtraction 162. Although not shown, noise suppression uses a noise pattern for the multipath stored in the noise memory.

In the above embodiment, the method of spectral subtraction is shown as an example of the noise canceling means 3, but the invention is not limited to this, and for example, an adaptive filter, bandpass filter, muting method or the like may be used.

[0095]

As is apparent from the above description, the present invention provides a sum signal creating means for taking a sum of respective signals, a difference signal creating means for taking a difference between detected signals, and a difference signal creating means thereof. Since the noise canceller that suppresses or removes the noise component included in the difference signal created by is provided, there is an advantage that a sufficient noise suppression effect can be obtained even when the noise component is small.

Further, the signal mixing means for mixing the signal transmitted by the signal transmission system and the inverted signal, the mixed signal mixed and the noise introduced in the signal transmission system based on the signal or the inverted signal. Since the noise canceling means for suppressing or eliminating the noise is provided, there is an advantage that the noise coming in the signal transmission system can be eliminated.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a noise suppression device according to a first exemplary embodiment of the present invention.

FIG. 2 is a configuration diagram of a noise suppression device according to a second exemplary embodiment of the present invention.

FIG. 3 is a configuration diagram of a noise suppressing device according to a third exemplary embodiment of the present invention.

FIG. 4 is a configuration diagram of a noise suppression apparatus according to a fourth exemplary embodiment of the present invention.

FIG. 5 is a block diagram of a noise suppression apparatus according to a fifth exemplary embodiment of the present invention.

FIGS. 6A, 6B, and 6C are diagrams showing examples of noise patterns for respective input signal levels.

FIG. 7 is a configuration diagram of a noise suppression apparatus according to a sixth exemplary embodiment of the present invention.

FIG. 8 is a configuration diagram of a noise suppression apparatus according to a seventh exemplary embodiment of the present invention.

FIG. 9 is a configuration diagram of a noise suppression device according to an eighth exemplary embodiment of the present invention.

FIG. 10 is a configuration diagram of a noise suppressing device according to a ninth exemplary embodiment of the present invention.

FIG. 11 is a diagram showing an operation of the noise cancellation control means 6 in the ninth embodiment.

FIG. 12 is a configuration diagram of a noise suppressing device according to a tenth embodiment of the present invention.

FIG. 13 is a configuration diagram of a noise suppressing device according to an eleventh embodiment of the present invention.

FIG. 14 is a configuration diagram of a noise suppressing device according to a twelfth embodiment of the present invention.

FIG. 15 is a flowchart showing an example of a noise canceling method in the noise canceling means.

FIG. 16 is a diagram showing a configuration of an example of noise canceling means.

FIG. 17 is a flowchart showing the operation of an example of noise canceling means.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 signal detecting means 2 signal mixing section 3 noise canceling means 4 signal separating means 5 noise memory 6 noise canceling control means 7 receiving means 8 receiving state detecting means 21 sum signal creating means 22 difference signal creating means

Claims (21)

[Claims] 1. In a balanced type signal transmission system,
Signal detection means for detecting each signal of each signal line, sum signal generation means for obtaining the sum of the detected signals, difference signal generation means for obtaining the difference between the detected signals, and the difference signal thereof A noise suppression device comprising: a difference signal canceling unit that suppresses or removes the difference signal created by the creating unit. 2. In a balanced type signal transmission system with respect to a noise component, a signal detecting means for detecting each signal of each signal line, a sum signal generating means for taking a sum of the respective detected signals, and the detected signal. And a noise canceling means for suppressing or removing a noise component included in the difference signal created by the difference signal creating means, and a difference signal with the noise component suppressed or removed. And a signal separation means for separating the signal corresponding to each of the signal lines based on the sum signal. 3. The noise suppressing device according to claim 2, further comprising a noise memory that stores a noise pattern used for suppressing or removing the noise component by the noise canceling means. 4. The noise suppressing device according to claim 3, further comprising noise canceling control means for outputting a parameter used for suppressing or removing the noise component by the noise canceling means. 5. The noise pattern of the noise memory comprises:
The noise suppression device according to claim 4, wherein the noise suppression device is updated by the parameter. 6. A reception means for receiving a signal for obtaining each signal of each signal line, and a reception state detection means for detecting a reception state of the reception means, wherein the noise cancellation control means comprises: 6. The noise suppression device according to claim 4, wherein the parameter is output according to the reception state detected by the reception state detection means. 7. The reception state detection means detects the level of a reception signal, and the noise cancellation control means outputs a parameter for reducing the noise pattern when the detection level is relatively low. The noise suppression device according to claim 6, wherein the noise suppression device is a device. 8. An A / D converter for converting an analog signal received by the receiving means into a digital signal, and a D / A converter for converting a digital signal output from the signal separating means into an analog signal. 7. The noise suppressing device according to claim 6, wherein the noise component is suppressed or removed by a digital signal. 9. The receiving means is a receiver for receiving a stereo signal, and the signal detecting means is an L of the stereo signal.
7. A signal and an R signal are detected.
Alternatively, the noise suppression device according to item 8. 10. If not | R + L |> | R−L |, then (R−L) is a target for noise suppression or removal, and in other cases, (R + L) is a target for noise suppression or removal. 10. The noise suppression device according to claim 9, wherein (RL) is enhanced, or noise is not suppressed or removed. 11. From the signal received by the receiving means:
Multipath detecting means for detecting multipath, and signal noise canceling means for suppressing or removing noise components included in each signal output from the signal separating means, respectively, the signal noise canceling means, 10. The noise suppression device according to claim 6, wherein the noise component is suppressed or removed based on the multipath. 12. The signal noise canceling means comprises, for each of the signals, a noise canceling means for suppressing or removing a noise component based on the multipath, and an output signal of the noise canceling means and the respective signals. The noise suppression device according to claim 11, further comprising a mixer that mixes and outputs based on multipath. 13. The noise canceling means includes a band dividing means for dividing a signal into predetermined frequency bands, and a noise canceling section provided for each of the divided bands. , 9 or 11 noise suppression apparatus. 14. A noise suppressing device using a spectral subtraction method, wherein a parameter is changed according to a frequency band and multipath. 15. The noise memory comprises a static characteristic noise memory for storing a noise pattern of static noise and a multipath noise memory for storing a noise pattern of noise due to the influence of multipath, and the reception state detecting means. For detecting a received signal level, if the detected received signal level is below a predetermined value, select the noise memory of the static characteristic noise memory, and if the received signal level is above the predetermined value, 7. The noise suppressing device according to claim 6, further comprising noise selecting means for selecting a noise pattern of the multipath noise memory. 16. The noise memory has a plurality of memories for respectively storing different noise patterns, and based on a reception state detected by the reception state detection means and a stereo pilot signal received by the reception means, The noise suppression device according to claim 9, further comprising a memory switching unit that switches the plurality of memories. 17. The different noise patterns include noise (L + R) included in the (L + R) signal of the L signal and the R signal.
17. The noise suppression device according to claim 16, wherein each of the noise patterns is a noise included in the signal (R) and a noise caused by the influence of multipath. 18. The noise canceller comprises: an intermediate frequency level detecting means for detecting a receiving state from the intermediate frequency signal output by the receiving means; and a pilot signal detecting means for detecting the stereo pilot signal from the intermediate frequency signal. 10. The noise suppression device according to claim 9, wherein the control means outputs a parameter based on the detected reception state and the stereo pilot signal. 19. A signal transmitting means for transmitting a signal to be transmitted and an inverted signal obtained by inverting the phase of the signal to a predetermined signal transmission system, and a signal and an inverted signal transmitted by the signal transmission system are mixed. A signal mixing unit, a noise canceling unit that suppresses or removes noise that is input in the signal transmission system based on the mixed signal and the signal or the inverted signal are provided. A noise suppression device, characterized in that the signal and the inverted signal are similarly applied. 20. Tuning control means for controlling tuning of a receiving means, detuning degree detecting means for detecting a detuning degree in the receiving means, and a signal received by the receiving means according to the detected detuning degree. A noise suppressing device comprising: a noise canceling unit that suppresses or removes included noise components. 21. The receiving means is a TV receiver, the ghost detecting means for detecting a ghost from a video signal in the signal received by the TV receiver, and the TV receiver based on the detected ghost. And a noise canceling unit that suppresses or removes a noise component included in a voice signal of the signal received by the noise suppressing device.