JP2011114435A - Receiver including noise reduction function, method of reducing noise, program, and integrated circuit - Google Patents

Abstract

When a signal in which strong peak noise of a specific frequency is mixed with a signal subjected to complex intermodulation is received by a plurality of antennas, it is difficult to remove the peak noise with an existing method, and even if it is applied, a circuit is provided. In the receiving device with a noise reduction function, the average value signals Ave_Sig obtained by suppressing the noise components specific to the antenna by the average value processing are acquired by the average value calculation units 22a to 22c, and the difference calculation is performed. By subtracting the average value signal Ave_Sig from the AC discrete signals AC_Sig [a] to AC_Sig [c] by the units 25a to 25c, respectively, the difference signal Diff_Sig [a] to Diff_Sig [c] is calculated. Then, the difference subtraction unit 27a subtracts the difference signals Diff_Sig [a] to Diff_Sig [c] from the discrete signals Sig [a] to Sig [c], respectively, thereby reducing the noise component specific to the antenna. Output signals Sig_out [a] to Sig_out [c] are acquired.
[Selection] Figure 2

Description

  The present invention relates to a wireless device (receiving device with a noise reduction function) that is provided with a plurality of antennas to improve reception sensitivity for radio waves for broadcasting or communication.

With the spread of digital terrestrial broadcasting, one-segment broadcasting, public wireless LAN, and the like, mobile devices such as mobile phones, in-vehicle TVs, and portable TVs are rapidly increasing. In these mobile devices, improving sensitivity to broadcast waves or communication waves is one of the most important issues in terms of device performance. In order to solve this problem, a diversity antenna system is often used which realizes improvement and stabilization of sensitivity by mounting and mounting a plurality of antennas and comparing and synthesizing received radio waves.
Since this diversity antenna method uses a combination of the received signals of each antenna, if the phase is greatly shifted between the received signals of each antenna, they cancel each other and the received wave is greatly attenuated. Countermeasures for “phenomena” are an issue. As a technique for reducing this problem, for example, there is a technique disclosed in JP-A-10-75235 (Patent Document 1).

Also, in recent digital mobile devices that are equipped with high-speed digital circuits and generate strong high-frequency noise, the antenna receives high-frequency noise generated from the mobile device itself, disturbs the received radio wave, and the number of antennas increases, Alternatively, there is a problem that the problem of “self-poisoning” in which reception noise increases and reception sensitivity decreases as the antenna sensitivity increases is more likely to occur. For example, there is a noise reduction technique disclosed in Japanese Patent Laid-Open No. 2003-219209 (Patent Document 2) as a technique for countermeasures against self-poisoning.
The conventional technology for countermeasures against the “multipath noise fading phenomenon” and “self-poisoning” will be described with reference to FIGS. 7 to 13.
First, the first conventional technique (the technique disclosed in Patent Document 1) for taking measures against the multipath noise fading phenomenon will be described.

FIG. 7 shows an arrangement of frequency bands of digital high-definition signals received by the diversity receiver. FIG. 8 is a schematic configuration diagram of a diversity receiver 900 that reduces the “multipath noise fading phenomenon” proposed in Patent Document 1. In FIG.
In the digital high-definition signal, a basic video signal and an audio signal are transmitted in the left band shown in FIG. 7, and a high-definition signal of the video is transmitted in the right band. When only the video basic signal is received, a low-quality image with rough pixels is obtained, and when both the video basic signal and the high-definition signal are received, a high-quality image with fine pixels is obtained. Note that the image cannot be decoded only with the high-definition signal.
The target digital television signal is generated and transmitted by the following (1) to (4). That is,
(1) The video signal is converted into a digital television signal of a basic signal and a high-definition signal by a hierarchical encoding device.
(2) A QPSK-OFDM signal (an OFDM signal in which each carrier is QPSK-modulated) is generated by converting a signal obtained by multiplexing an audio signal encoded into a basic signal into a high-frequency signal using an OFDM (Orthogonal Frequency Division Multiplexing) method. The
(3) A 16QAM-OFDM signal (an OFDM signal in which each carrier wave is 16QAM-modulated) is generated by multiplexing a signal obtained by converting a high-definition signal into a high-frequency signal using the OFDM method.
(4) The QPSK-OFDM signal and 16QAM-OFDM signal generated in (2) and (3) are transmitted as digital television signals.

When comparing a QPSK-OFDM signal (scheme) and a 16QAM-OFDM signal (scheme), the reception C / N ratio required to obtain a certain error rate is lower in the QPSK-OFDM signal, but the transmission capacity is When the reception condition is poor because the multi-valued 16QAM-OFDM signal is larger, low-quality video and audio information can be obtained only by QPSK-OFDM, and the reception condition is improved. Furthermore, information transmitted by a 16QAM-OFDM signal is added, and high-quality video and audio information with a large amount of information can be obtained.
As shown in FIG. 8, the diversity receiver 900 performs high-frequency signal processing for processing signals received by the first and second antennas 1a and 1b that receive radio waves and the first and second antennas 1a and 1b, respectively. Level detectors 2a and 2b, variable attenuators 3a and 3b for performing variable attenuation processing on signals output from high-frequency signal processing units 2a and 2b, and level detection of signals output from high-frequency signal processing units 2a and 2b. Level detectors 4a and 4b to be performed.

The diversity receiver 900 includes a control circuit 5 that controls the variable attenuators 3a and 3b, a comparison circuit 6 that performs level comparison processing on the outputs from the level detectors 4a and 4b, and variable attenuators 3a and 3b. And a synthesizer 7 for synthesizing the signals output from.
The diversity receiver 900 includes a distributor 8 that distributes the signal output from the combiner 7, orthogonal demodulators 9 a and 9 b that perform orthogonal demodulation processing on the signal distributed by the distributor, and an orthogonal demodulator. FFTs (Fast Fourier Transformers) 10a and 10b that perform FFT processing on the outputs of 9a and 9b.
Furthermore, diversity receiver 900 performs QPSK discriminator 11 that performs QPSK discrimination processing on the output of FFT (Fast Fourier Transformer) 10a and 16QAM discrimination processing on the output of FFT (Fast Fourier Transformer) 10b. 16QAM discriminator, error correction circuits 13a and 13b that perform error correction processing on the outputs of QPSK discriminator 11 and 16QAM discriminator, and hierarchical decoding that performs hierarchical decoding processing on the outputs of error correction circuits 13a and 13b Machine 14 is provided.

  In diversity receiver 900 having such a configuration, there is a phase difference (delay time difference) between the two signals at frequencies where the amplitudes of the reception waveforms of the two signals to be synthesized are equal in the band in which the video basic signal is transmitted. In this case, when the two signals are combined, a ripple is generated in the combined signal, and the basic signal information may be lost. In order to prevent this loss of information, when the bit error rate obtained by the error correction circuit 13a exceeds a specified value, the magnitudes of the two signals to be combined may be different. That is, the magnitude of the signal and the level difference are determined by comparing the magnitudes of the high-frequency signals output from the high-frequency signal processing units 2a and 2b, respectively. If there is a sufficient level difference between the two signals as a result of the determination, the high frequency signal is not attenuated (the attenuation process is not executed). On the other hand, when the level difference between the two signals is small, the attenuators 3a and 3b are such that the smaller the level difference between the two signals, the greater the attenuation of the high-frequency signal with the smaller signal size. Determine the amount of attenuation at.

Thus, diversity receiver 900 can avoid the occurrence of ripples in the combined signal. In the OFDM scheme, when a ripple occurs in the combined signal, particularly when a ripple valley occurs, there is a high possibility that information assigned to a carrier wave having a frequency corresponding to the ripple valley is lost. The diversity receiver 900 can suppress the occurrence of ripples (especially, the occurrence of ripple valleys) in the combined signal by the above processing, so that it is possible to prevent the basic signal information from being lost.
Specifically, as shown in FIG. 8, in the diversity receiver 900, radio waves (signals) received by the antennas 1a and 1b are amplified, tuned, frequency converted, etc. by the high frequency signal processing units 2a and 2b, respectively. These processes are performed and output to the variable attenuators 3a and 3b and the level detectors 4a and 4b.

Furthermore, the variable attenuators 3 a and 3 b appropriately attenuate the received signal according to the control signal from the control circuit 5. The outputs of the variable attenuators 3a and 3b are combined by the combiner 7 and then distributed to the two systems by the distributor 8, and the distributed signals are supplied to the quadrature demodulators 9a and 9b, respectively.
The quadrature demodulator 9a performs quadrature demodulation processing of the video basic signal and audio signal, and the signal on which quadrature demodulation processing has been performed by the quadrature demodulator 9a is output to the FFT 10a. The quadrature demodulator 9b performs quadrature demodulation processing of the high-definition signal, and the signal on which quadrature demodulation processing is executed by the quadrature demodulator 9b is output to the FFT 10b.
Signals input to FFT (Fast Fourier Transformers) 10a and 10b are converted from signals on the time axis to signals on the frequency axis by FFT (Fast Fourier Transformers) 10a and 10b.

Further, the output of the FFT 10a is subjected to error correction by the error correction circuit 13a after the digital information is discriminated and converted into a digital bit string by the QPSK discriminator 11. Similarly, the output of the FFT 10b is subjected to error correction by the error correction circuit 13b after the digital information is discriminated and converted into a digital bit string by the 16QAM discriminator 12. As a result, a basic video signal and an audio signal are acquired from the correction circuit 13a, and a high-definition video signal is acquired from the error correction circuit 13b.
The signals acquired by the correction circuits 13a and 13b (signals output from the correction circuits 13a and 13b) are converted into analog video signals and audio signals by the hierarchical decoder 14.
The outputs of the high frequency signal processing units 2a and 2b are also supplied to the level detectors 4a and 4b, respectively, and the magnitudes (amplitude levels) of the respective high frequency signals are detected by the level detectors 4a and 4b. The

The outputs of the level detectors 4a and 4b are both supplied to the comparison circuit 6 and are compared in level. The comparison result by the comparison circuit 6 is supplied to the control circuit 5 together with the error correction flag obtained by the error correction circuit 13a.
In the diversity receiver 900, the control circuit 5 controls the amount of attenuation of the variable attenuators 3a and 3b based on the comparison result of the comparison circuit 6 and the bit error rate based on the error correction flag, so that the combination ratio in the combiner 7 It is the structure which can be changed. Therefore, even when a signal with a large delay time difference is synthesized by the synthesizer 7, it is possible to reduce the “multipath noise fading phenomenon” by avoiding the loss of information in the ripple valley portion without generating a large ripple. it can.
≪Second conventional technology (in-house poisoning countermeasures) ≫
Next, a second conventional technique (a technique disclosed in Patent Document 2) for taking measures against self-poisoning will be described.

FIG. 9 is a schematic functional block diagram of a noise canceling device 950 according to the second conventional technique for reducing “self-poisoning” proposed in Patent Document 2. FIG. 10 is an operation flow diagram of the noise canceling device 950 when a signal in the horizontal blanking period is used as a known signal level and a noise component superimposed on the demodulated television signal is removed. 11 to 13 show television signal waveforms in each step (each process) of FIG.
As shown in FIG. 9, the noise cancellation device 950 includes a noise detection unit 101, a cancellation signal generation unit 102, and a cancellation signal addition unit 103.
The noise detection unit 101 is a functional unit that executes the processing from S301 to S304 in the flow shown in FIG. Similarly, the cancel signal generation unit 102 is a functional unit that executes the processing of the flow 305. The cancel signal adding unit 103 is a functional unit that executes the processes from S306 to S308 of the flow.

Hereinafter, the noise canceling operation in the noise canceling device 950 will be sequentially described with reference to the operation flowchart of FIG. 10 and the television signal waveforms shown in FIGS. 11 to 13. In the following, the noise canceling operation in the noise canceling device 950 will be described by dividing it into (1) noise detection processing, (2) cancellation signal generation processing, and (3) cancellation signal addition processing.
(First processing (noise detection processing)):
First, the noise detection process will be described.
As shown in FIG. 11, when the signal of the vertical blanking period 200 is input to the noise detecting means 101, the horizontal synchronizing pulse 203 of the horizontal synchronizing signal period 205 following the period 201 of the equivalent pulse is detected. With the synchronization pulse 203 as a trigger, the signal for the horizontal blanking period 405 (see FIG. 12) is captured in the signal for 1H included in the horizontal synchronization signal period 205.

As shown in FIGS. 12 and 13, the captured signal in the horizontal blanking period 405 is a waveform in which the color burst signal 204 and the noise component are superimposed on the back porch 403 of the horizontal synchronization pulse 203 (in FIG. 13A). Equivalent to waveform.) For this reason, the color burst signal 204 (see FIG. 12) superimposed on the back porch 403 (see FIG. 12), the horizontal sync pulse, from the captured signal of the horizontal blanking period 405 (signal in FIG. 13 (a)). 203 (see FIG. 12) and the blanking level 211 (see FIG. 12) are removed (the normal signal (the signal having no noise component) in the horizontal blanking period 405 shown in FIG. 11 is removed). The noise canceling device 950 can extract (detect) a noise component (FIG. 13C) superimposed on the signal in the horizontal blanking interval 405.
(Second process (cancellation signal generation process)):
Next, the cancel signal generation process will be described.

In the cancel signal generation means 102, the noise component extracted (detected) by the noise detection processing (the noise component shown in FIG. 13C) is inverted (by making it in reverse phase), thereby FIG. 13D. The cancel signal shown in FIG. The phase of the cancel signal is based on the rising edge (edge) of the horizontal synchronization pulse 203 (see FIG. 12).
(Third process (cancellation signal addition process)):
Finally, the cancel signal addition process will be described.
The cancel signal adding means 103 adds the cancel signal (signal shown in FIG. 13 (d)) generated by the cancel signal generation process to the television signal (signal shown in FIG. 13 (a)), which is the original signal, thereby generating noise. Cancel ingredients.
Further, the cancel signal adding means 103 performs noise component (see FIG. 13C) in the horizontal blanking period 405 (see FIG. 12) of the signal for 1H included in the horizontal synchronization signal period 205 (see FIG. 11). The cancellation result of the component) is determined, and if the cancellation is insufficient, the cancellation is repeated by adjusting the phase and amplitude of the cancellation signal until a sufficient cancellation result is obtained.

Then, after it is determined that the noise component has been sufficiently canceled by the cancel signal adding unit 103, the video signal is displayed on the display unit 104 with a signal (synchronization signal) from which the noise component has been canceled.
For example, when a periodic noise component is superimposed on a television signal, a beat failure occurs on the television screen. In order to cancel the periodic noise that causes the beat failure, it is assumed that the noise component (FIG. 13C) is superimposed on the horizontal blanking period 405 of all 1H signals. In the cancel device 950, a cancel process is executed.
Thus, in the noise canceling device 950, the noise detection unit 101 detects a noise component using a known signal level, the cancellation signal generation unit 102 inverts the noise component to generate a cancellation signal, The cancel signal adding means 103 adds the cancel signal to the original signal. As a result, the noise canceling device 950 can cancel “self-poisoning” by canceling the noise component superimposed on the demodulated television signal.

Japanese Patent Laid-Open No. 10-75235 JP 2003-219209 A

However, in the first prior art (diversity receiver 900), as in “self-poisoning”, strong peak noise of a specific frequency that is different from the source of the digital high-definition signal is mixed in the received signal in the antennas 1a and 1b. In this case, based on the output of the error correction circuit 13a in the subsequent stage of the QPSK discriminator 11, the control circuit 5 operates (controls) so as to attenuate the output from the antenna having the smaller peak noise. The output is a signal in which the influence of the peak noise is further increased. As a result, the diversity receiver 900 has a problem that image degradation increases rather than a noise reduction effect.
In the second prior art, it is difficult to obtain a known signal level, a synchronization pulse, or the like for a signal subjected to complicated intermodulation such as a digital high-definition signal or a 1-segment television signal. Even if it is possible to obtain a known signal level, synchronization pulse, etc., in the diversity method in which signals are received by a plurality of antennas, it is necessary to perform the same processing as described above for each antenna. There is a problem of increasing.

That is, when receiving a signal in which strong peak noise of a specific frequency is mixed in a signal subjected to complex intermodulation with a plurality of antennas, it is difficult to remove the peak noise in the second conventional technique. Even if the peak noise can be removed, there is a problem that the circuit scale and cost of an apparatus for realizing the peak noise increase.
The present invention solves the above-described problem, and even when a signal in which a peak noise having a specific frequency is mixed into a signal subjected to complex intermodulation is received by a plurality of antennas, the circuit scale and cost are reduced. An object of the present invention is to provide a receiver with a noise reduction function, a noise reduction method, a program, and an integrated circuit that can reduce the influence of self-poisoning and greatly improve the reception sensitivity while suppressing the increase.

The first invention includes N antennas (N is a natural number of N ≧ 2), a discrete value processing unit, an AC discrete value signal acquisition unit, an average value signal calculation unit, a difference calculation unit, A receiving device with a noise reduction function, comprising: a subtracting unit.
N antennas (N ≧ 2 natural number) receive radio waves. The discrete value processing unit performs discrete value processing on the received signals received by the N antennas selected for the same channel, and outputs them as discrete value signals Sig [1] to Sig [N]. . The AC discrete value acquisition unit acquires average values Ave [1] to Ave during a predetermined time T for the discrete values Sig [1] to Sig [N] output from the discrete value processing unit, respectively. [N] is calculated, and the calculated average values Ave [1] to Ave [N] are subtracted from the discrete signals Sig [1] to Sig [N], respectively, so that the AC discrete signals AC_Sig [ 1] to AC_Sig [N] are calculated. The average value signal calculation unit calculates an average value of N signals of the AC discrete value signals AC_Sig [1] to AC_Sig [N] calculated by the AC discrete value signal acquisition unit, and outputs the average value as an average value signal Ave_Sig To do. The difference calculating unit calculates the difference signals Diff_Sig [1] to Diff_Sig [N] by subtracting the average value signal Ave_Sig from the AC discrete values AC_Sig [1] to AC_Sig [N], respectively. The difference subtraction unit subtracts the difference signals Diff_Sig [1] to Diff_Sig [N] from the discrete signals Sig [1] to Sig [N], respectively, to thereby output the output signals Sig_out [1] to Sig_out [N]. calculate.

In this receiver with a noise reduction function, the average value signal Ave_Sig obtained by suppressing the noise component specific to the antenna by the average value processing is acquired by the average value signal calculation unit. Furthermore, in this receiver with a noise reduction function, the difference calculation unit subtracts the average value signal Ave_Sig from each of the AC discrete signals AC_Sig [1] to AC_Sig [N] corresponding to each of the N antennas. Thus, the differential signals Diff_Sig [1] to Diff_Sig [N] in which the noise component specific to the antenna appears remarkably are calculated. The difference subtracting unit subtracts the difference signals Diff_Sig [1] to Diff_Sig [N] from the discrete signals Sig [1] to Sig [N], respectively, thereby reducing the noise component specific to the antenna. Signals Sig_out [1] to Sig_out [N] are acquired.
As a result, in the receiving device with the noise reduction function, even when a signal in which a strong peak noise of a specific frequency is mixed into a signal subjected to complicated cross modulation is received by a plurality of antennas, the circuit scale and cost are reduced. While suppressing the increase, it is possible to reduce noise components unique to the antenna caused by self-poisoning and multipath fading phenomenon. As a result, the receiving device with a noise reduction function can reduce the influence of self-poisoning and multipath fading phenomenon and greatly improve the reception sensitivity.

2nd invention is 1st invention, Comprising: A discrete value processing part is a case where N antennas receive a broadcast wave, Comprising: The received signal input into a discrete value processing part is an intermediate frequency When the signal is a band signal, the received signal is converted into a discrete value at a predetermined period equal to or less than ¼ of the period of the intermediate frequency.
3rd invention is 1st or 2nd invention, Comprising: A discrete value processing part is a case where N antennas receive the broadcast wave by an OFDM system, Comprising: It inputs into a discrete value processing part When the received signal is a frequency domain signal, the received signal is digitized in units of the frequency spectrum of the OFDM scheme.
A fourth invention is any one of the first to third inventions, wherein the received signal is a received signal of digital high-definition broadcasting or one-segment broadcasting.
The fifth invention is any one of the first to fourth inventions, wherein the difference subtracting section is configured to output the difference signals Diff_Sig [1] to Diff_Sig from the discrete signals Sig [1] to Sig [N], respectively. Output signals Sig_out [1] to Sig_out [N] are calculated by subtracting only the positive part of [N].

Thereby, especially the noise component by self-poisoning can be reduced effectively. That is, since the noise component due to self-poisoning is a peak noise component, it appears prominently only in the positive part of the differential signals Diff_Sig [1] to Diff_Sig [N]. Therefore, the noise component due to self-poisoning can be effectively reduced by the receiving device with the noise reduction function.
The sixth invention is any one of the first to fourth inventions, wherein the difference subtracting section is configured to output the difference signals Diff_Sig [1] to Diff_Sig from the discrete signals Sig [1] to Sig [N], respectively. The output signals Sig_out [1] to Sig_out [N] are calculated by subtracting only the negative part of [N].
Thereby, especially the noise component by a multipath fading phenomenon can be reduced effectively. That is, since the noise component due to the multipath fading phenomenon appears as a negative component noise in the frequency domain, subtracting only the negative portion of the difference signal Diff_Sig [1] to Diff_Sig [N] effectively multipath fading. Noise components due to the phenomenon can be suppressed.

A seventh invention is any one of the first to sixth inventions, further comprising a demodulator that performs demodulation processing and error correction processing based on the output signals Sig_out [1] to Sig_out [N]. The difference subtracting unit controls the value to be subtracted from each of the discrete signals Sig [1] to Sig [N] based on error correction information that is information on the result of error correction processing by the demodulating unit.
Thereby, in this receiver with a noise reduction function, a noise reduction process can be appropriately performed based on the error correction information.
For example, in this receiver with a noise reduction function, the difference subtraction unit is
Sig_out [k] = Sig [k] −Diff_Sig [k] × Gain
Thus, the output signal Sig_out [k] (1 ≦ k ≦ N) is obtained. Then, by changing the value of Gain based on the error correction information, the values to be subtracted are controlled from the discrete signals Sig [1] to Sig [N], respectively.

For example, when the error correction rate in the demodulation process is low, the Gain value is decreased, and when the error correction rate in the demodulation process is high, the Gain value is increased.
An eighth invention is a noise reduction method used in a receiving apparatus including N antennas (N is a natural number of N ≧ 2) for receiving radio waves, and includes a discrete value processing step, an AC discrete value signal An acquisition step, an average value signal calculation step, a difference calculation step, and a difference subtraction step are provided.
In the discrete value processing step, the received signals are subjected to discrete value processing by N antennas selected for the same channel, and output as discrete value signals Sig [1] to Sig [N]. . In the AC discrete value acquisition step, the average values Ave [1] to Ave during a predetermined time T are obtained for the discrete values Sig [1] to Sig [N] output from the discrete value processing step. [N] is calculated, and the calculated average values Ave [1] to Ave [N] are subtracted from the discrete signals Sig [1] to Sig [N], respectively, so that the AC discrete signals AC_Sig [ 1] to AC_Sig [N] are calculated. In the average signal calculation step, an average value of N signals of the AC discrete signals AC_Sig [1] to AC_Sig [N] calculated in the AC discrete signal acquisition step is calculated and output as an average signal Ave_Sig. To do. In the difference calculation step, the difference signals Diff_Sig [1] to Diff_Sig [N] are calculated by subtracting the average value signal Ave_Sig from the AC discrete values AC_Sig [1] to AC_Sig [N], respectively. In the difference subtraction step, the output signals Sig_out [1] to Sig_out [N] are obtained by subtracting the difference signals Diff_Sig [1] to Diff_Sig [N] from the discrete signals Sig [1] to Sig [N], respectively. calculate.

Thereby, the noise reduction method which has the same effect as the first invention can be realized.
A ninth invention is a program for causing a computer to execute a noise reduction method used in a receiving device including N antennas (N is a natural number of N ≧ 2) for receiving radio waves. The noise reduction method includes a discrete value processing step, an AC discrete value signal acquisition step, an average value signal calculation step, a difference calculation step, and a difference subtraction step.
In the discrete value processing step, the received signals are subjected to discrete value processing by N antennas selected for the same channel, and output as discrete value signals Sig [1] to Sig [N]. . In the AC discrete value acquisition step, the average values Ave [1] to Ave during a predetermined time T are obtained for the discrete values Sig [1] to Sig [N] output from the discrete value processing step. [N] is calculated, and the calculated average values Ave [1] to Ave [N] are subtracted from the discrete signals Sig [1] to Sig [N], respectively, so that the AC discrete signals AC_Sig [ 1] to AC_Sig [N] are calculated. In the average signal calculation step, an average value of N signals of the AC discrete signals AC_Sig [1] to AC_Sig [N] calculated in the AC discrete signal acquisition step is calculated and output as an average signal Ave_Sig. To do. In the difference calculation step, the difference signals Diff_Sig [1] to Diff_Sig [N] are calculated by subtracting the average value signal Ave_Sig from the AC discrete values AC_Sig [1] to AC_Sig [N], respectively. In the difference subtraction step, the output signals Sig_out [1] to Sig_out [N] are obtained by subtracting the difference signals Diff_Sig [1] to Diff_Sig [N] from the discrete signals Sig [1] to Sig [N], respectively. calculate.

Thus, it is possible to realize a program that causes a computer to execute a noise reduction method that exhibits the same effect as that of the first invention.
A tenth aspect of the invention is an integrated circuit used in a receiving apparatus including N antennas (N is a natural number of N ≧ 2) that receives radio waves, and includes a discrete value processing unit and an AC discrete value signal acquisition Unit, an average value signal calculation unit, a difference calculation unit, and a difference subtraction unit.
The discrete value processing unit performs discrete value processing on the received signals received by the N antennas selected for the same channel, and outputs them as discrete value signals Sig [1] to Sig [N]. . The AC discrete value acquisition unit acquires average values Ave [1] to Ave during a predetermined time T for the discrete values Sig [1] to Sig [N] output from the discrete value processing unit, respectively. [N] is calculated, and the calculated average values Ave [1] to Ave [N] are subtracted from the discrete signals Sig [1] to Sig [N], respectively, so that the AC discrete signals AC_Sig [ 1] to AC_Sig [N] are calculated. The average value signal calculation unit calculates an average value of N signals of the AC discrete value signals AC_Sig [1] to AC_Sig [N] calculated by the AC discrete value signal acquisition unit, and outputs the average value as an average value signal Ave_Sig To do. The difference calculating unit calculates the difference signals Diff_Sig [1] to Diff_Sig [N] by subtracting the average value signal Ave_Sig from the AC discrete values AC_Sig [1] to AC_Sig [N], respectively. The difference subtraction unit subtracts the difference signals Diff_Sig [1] to Diff_Sig [N] from the discrete signals Sig [1] to Sig [N], respectively, to thereby output the output signals Sig_out [1] to Sig_out [N]. calculate.

  Thus, an integrated circuit that exhibits the same effect as that of the first invention can be realized.

  According to the present invention, even when a signal in which peak noise having a specific frequency is mixed with a signal subjected to complex intermodulation is received by a plurality of antennas, the increase in circuit scale and cost can be suppressed and It is possible to realize a receiver with a noise reduction function, a noise reduction method, a program, and an integrated circuit that can reduce the influence of poisoning and greatly improve reception sensitivity.

1 is a schematic configuration diagram of a receiving device (digital high-vision receiving device) 100 with a noise reduction function according to a first embodiment. The schematic block diagram of the noise reduction apparatus 20 of 1st Embodiment. The signal waveform figure of the noise reduction apparatus 20 of 1st Embodiment. The schematic block diagram of the receiver (digital high-vision receiver) 200 with a noise reduction function of 2nd Embodiment. The schematic block diagram of 20 A of noise reduction apparatuses of 2nd Embodiment. The signal wave form diagram of 20 A of noise reduction apparatuses of 2nd Embodiment. Hi-Vision signal frequency band layout The block diagram of the diversity receiver 900 of the 1st prior art. The block diagram of the noise cancellation apparatus 950 of a 2nd prior art. The operation | movement flowchart at the time of the noise cancellation of 2nd prior art. The figure which shows the signal waveform of the vertical blanking period of the 2nd prior art. The figure which shows the signal waveform of the horizontal blanking period of the 2nd prior art. Explanatory drawing of the signal waveform into which the noise of the 2nd prior art was mixed.

Embodiments of the present invention will be described with reference to the drawings.
[First embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 3.
<1.1: Configuration of Receiver with Noise Reduction Function (Digital Hi-Vision Receiver)>
FIG. 1 is a schematic configuration diagram of a digital high-vision receiving device 100 equipped with a noise reduction device according to the present embodiment. FIG. 2 is a schematic configuration diagram of the noise reduction device 20. In the following, for convenience of explanation, the digital high-definition receiver 100 having three antennas will be described as an example.
As shown in FIG. 1, a digital high-definition receiving apparatus 100 includes a plurality of antennas 1a, 1b, and 1c that receive broadcast waves by a diversity method, and a high frequency that is installed for each antenna and is received by the plurality of antennas 1a, 1b, and 1c. High-frequency signal processing units 2a, 2b, and 2c that perform high-frequency signal processing on signals are provided.

In addition, the digital high-definition receiver 100 synthesizes a noise reduction device 20 that performs noise reduction processing and a plurality of outputs of the noise reduction device 20 with respect to outputs of the high-frequency signal processing units 2a, 2b, and 2c, respectively. Part 7.
The digital high-definition receiver 100 further includes an orthogonal demodulation unit 9 that performs orthogonal demodulation processing on the output of the combining unit 7 and an FFT unit (fast Fourier transformer) 10 that performs FFT processing on the output of the orthogonal demodulation unit 9. And a demodulator 14 that performs a demodulation process on the output of the FFT unit 10.
The plurality of antennas 1a, 1b, and 1c are antennas for receiving broadcast waves by a diversity method. The plurality of antennas 1a, 1b, and 1c output the received high-frequency signals to the high-frequency signal processing units 2a, 2b, and 2c, respectively.

The high-frequency signal processing units 2a, 2b, and 2c are connected to the plurality of antennas 1a, 1b, and 1c, respectively, and receive high-frequency signals output from the plurality of antennas 1a, 1b, and 1c. The high-frequency signal processing units 2a, 2b, and 2c perform high-frequency signal processing (processing such as amplification, tuning, and frequency conversion) on the high-frequency signals output from the plurality of antennas 1a, 1b, and 1c, respectively. Then, the high-frequency signal processing units 2a, 2b, and 2c each output a signal that has been subjected to the high-frequency signal processing to the noise reduction device 20.
As illustrated in FIG. 2, the noise reduction device 20 includes discrete value signal processing units 201 a to 201 c, an average value signal calculation unit 202, and noise signal reduction units 203 a to 203 c.
The discrete value signal processing units 201a to 201c receive the outputs of the high frequency signal processing units 2a to 2c, respectively. The discrete value signal processing units 201a to 201c include discrete value conversion processing units 21a to 21c, average value calculation units 22a to 22c, and average value subtraction units 23a to 23c, respectively.

The discrete value signal processing unit 201a receives the signal output from the high frequency signal processing unit 2a and performs a discrete value processing (A / D conversion processing) on the signal output from the high frequency signal processing unit 2a. Then, the discrete value signal processing unit 201a outputs the discrete signal to the noise signal reducing unit 203a and the average value subtracting unit 23a as a discrete value signal Sig [a].
The average value calculation unit 22a receives the output of the discretization processing unit 21a as an input, and calculates an average value for a predetermined time of the signal that has been discretized by the discretization processing unit 21a. Then, the average value calculation unit 22a outputs the calculated average value Ave [a] to the average value subtraction unit 23a.
The average value subtraction unit 23a receives the output of the discrete value conversion processing unit 21a and the output of the average value calculation unit 22a as inputs. The average value subtracting unit 23a subtracts the output signal of the average value calculating unit 22a from the output signal of the discrete value processing unit 21a, that is,
AC_Sig [a] = Sig [a] -Ave [a]
The process corresponding to is executed. Then, the average value subtracting unit 23a outputs the signal acquired by subtraction to the average value signal calculating unit 202 and the noise signal reducing unit 203a as an AC discrete value signal AC_Sig [a].

The processing of the discrete value signal processing units 201b and 201c is the same as the processing of the discrete value signal processing unit 201a.
The average value signal calculation unit 202 receives three signals output from the average value subtraction units 23a to 23c of the discrete value signal processing units 201a to 201c, respectively, and performs an averaging process on the three signals. Do. The average value signal calculation unit 202 outputs the signal calculated by the averaging process to the difference calculation units 25a to 25c of the noise signal reduction units 203a to 203c as an average value signal Ave_Sig.
The noise signal reduction units 203a to 203c include difference calculation units 25a to 25c, difference subtraction units 27a to 27c, and D / A converters (DACs) 28a to 28c, respectively.
The difference calculation unit 25a of the noise signal reduction unit 203a includes an average value signal Ave_Sig output from the average value signal calculation unit 202 and an AC discrete value signal AC_Sig output from the average value subtraction unit 23a of the discrete value signal processing unit 201a. [A] is an input. And the difference calculation part 25a is with respect to an average value signal and AC discrete value signal AC_Sig [a].
Diff_Sig [a] = AC_Sig [a] −Ave_Sig
The difference process corresponding to is performed, and the difference signal Diff_Sig [a] is acquired. Then, the difference calculation unit 25a outputs the difference signal Diff_Sig [a] to the difference subtraction unit 27a.

The difference subtraction unit 27a receives the signal Sig [a] output from the discrete value processing unit 21a of the discrete value signal processing unit 201a and the difference signal Diff_Sig [a] output from the difference calculation unit 25a. Then, the difference subtraction unit 27a
Sig_out [a] = Sig [a] −Diff_Sig [a]
The difference subtraction process corresponding to is performed to obtain the difference subtraction signal Sig_out [a]. Then, the difference subtraction unit 27a outputs the difference subtraction signal Sig_out [a] to the D / A converter (DAC) 28a.
The D / A converter (DAC) 28a receives the difference subtraction signal Sig_out [a] output from the difference subtraction unit 27a, and executes D / A conversion processing on the difference subtraction signal Sig_out [a]. Then, the D / A converter (DAC) 28 a outputs the signal after the D / A conversion processing to the combining unit 7.

Note that the processing of the noise signal reduction units 203b and 203c is the same as the processing of the noise signal reduction unit 203a.
The synthesizing unit 7 receives the three signals output from the noise signal reducing units 203a to 203c of the noise reducing device 20, and synthesizes the three signals. The synthesizer 7 outputs the synthesized signal to the orthogonal demodulator 9.
The quadrature demodulator 9 receives the output from the synthesizer 7 and performs orthogonal demodulation processing on the signal output from the synthesizer 7. Then, the quadrature demodulation unit 9 outputs the signal on which the quadrature demodulation process has been performed to the FFT unit 10.
The FFT unit 10 receives the output from the quadrature demodulator 9 and performs an FFT process on the signal output from the quadrature demodulator 9. Then, the FFT unit 10 outputs the signal subjected to the FFT process to the demodulation unit 14.

The demodulator 14 receives the output from the FFT unit 10, performs demodulation processing on the signal output from the FFT unit 10, and obtains a TS signal (transport stream signal).
<1.2: Operation of receiver with digital noise reduction function (digital high-definition receiver)>
The operation of the digital high-definition receiving apparatus 100 configured as described above will be described below.
In the digital high-definition receiver 100, the digital high-definition signals received by the antennas 1a, 1b, and 1c are respectively selected and amplified by the high-frequency signal processing units 2a, 2b, and 2c on the same channel. Is output to the noise reduction device 20 from the high frequency signal processing units 2a, 2b, and 2c as a digital signal having an intermediate frequency of about 57 MHz shown in FIG.

Processing shown in the following (1) to (7) is performed on the signal input to the noise reduction device 20.
(1) The signals output from the high-frequency signal processing units 2a, 2b, and 2c are each 1/4 of the period of the intermediate frequency (for example, an intermediate frequency of about 57 MHz) by the discrete value processing units 21a, 21b, and 21c. It is sampled in the following minute time, and becomes a discrete signal Sig [a] to Sig [c]. An example of the signal waveforms of the discretized signals Sig [a] to Sig [c] is shown in the state “21, 22” column of FIG.
(2) In the average value calculation units 22a, 22b, and 22c, the average values Ave [a] and Ave [b] of the discrete signals Sig [a], Sig [b], and Sig [c] within a predetermined time, respectively. , Ave [c] is calculated.
(3) In the average value subtraction units 23a, 23b, and 23c, the average level values Ave [a] to Ave [c] calculated by the average value calculation units 22a, 22b, and 22c, respectively, are converted into the discrete signal Sig [a]. By subtracting ~ Sig [c], AC discrete values AC_Sig [a] to AC_Sig [c] are obtained. That is, in the average value subtracting units 23a, 23b, and 23c,
AC_Sig [a] = Sig [a] -Ave [a]
AC_Sig [b] = Sig [b] −Ave [b]
AC_Sig [c] = Sig [c] −Ave [c]
Thus, AC discrete value signals AC_Sig [a] to AC_Sig [c] are acquired.

An example of the signal waveforms of the AC discrete signals AC_Sig [a] to AC_Sig [c] is shown in the state “23” column of FIG.
(4) The average value signal calculation unit 202 performs an average process on the AC discrete values AC_Sig [a] to AC_Sig [c]. Specifically, the average value signal calculation unit 202 has discrete values (sample values) (three discrete values) at the same point on the time axis in the AC discrete signals AC_Sig [a] to AC_Sig [c], respectively. The average value is calculated from the above, and the calculated average value is set as the average value at the same point on the time axis. The average value signal Ave_Sig for the time to be subjected to the discrete value processing is acquired by the average value signal calculation unit 202 by repeatedly executing this for the time to be subjected to the discrete value processing.
An example of the signal waveform of the average value signal Ave_Sig is shown in the column of state “24” in FIG.
(5) The difference calculation units 25a, 25b, and 25c perform processing for obtaining a difference between the AC discrete values AC_Sig [a] to AC_Sig [c] and the average value signal Ave_Sig, respectively. That is, in the difference calculation units 25a, 25b, and 25c,
Diff_Sig [a] = AC_Sig [a] −Ave_Sig
Diff_Sig [b] = AC_Sig [b] −Ave_Sig
Diff_Sig [c] = AC_Sig [c] −Ave_Sig
Thus, the differential signals Diff_Sig [a] to Diff_Sig [c] are acquired.

An example of the signal waveforms of the differential signals Diff_Sig [a] to Diff_Sig [c] is shown in the state “25” column of FIG.
(6) The difference subtraction units 27a, 27b, and 27c perform processing for subtracting the difference signals Diff_Sig [a] to Diff_Sig [c] from the discrete signals Sig [a] to Sig [c], respectively. That is, in the difference subtraction units 27a, 27b, and 27c,
Sig_out [a] = Sig [a] −Diff_Sig [a]
Sig_out [b] = Sig [b] −Diff_Sig [b]
Sig_out [c] = Sig [c] −Diff_Sig [c]
Thus, the difference subtraction signals Sig_out [a] to Sig_out [c] are acquired.
An example of the signal waveform of the difference subtraction signals Sig_out [a] to Sig_out [c] is shown in the state “27” column of FIG.
(7) In the DACs 28a, 28b, and 28c, the D / A conversion process is performed on the difference subtraction signals Sig_out [a] to Sig_out [c]. Then, the D / A converted signals (three signals) are output to the synthesis unit 7.

Note that a signal (original intermediate frequency signal) after D / A conversion processing is performed on the difference subtraction signals Sig_out [a] to Sig_out [c] is shown in the column of state “28” in FIG.
As described above, by executing the processing shown in the above (1) to (7) by the noise reduction device 20, a plurality of specific frequencies generated outside the circuit of the receiving device (digital high-vision receiving device 100) shown in FIG. Even when the peak noise is individually mixed in the antennas 1a, 1b, and 1c due to the “self-poisoning” phenomenon, the peak noise generated by the self-poisoning phenomenon can be appropriately removed.
For example, in the signal waveform shown in the column “2” in FIG. 3, the peak noises PA1, PA2, and PA3 generated in the signal received by the antenna 1a are not generated in the signals received by the antennas 1b and 1c. . That is, the peak noises PA1, PA2, and PA3 are generated only in the signal received by the antenna 1a. The difference signal Diff_Sig [a] (the signal waveform shown in the column of the state “25” in FIG. 3) is obtained by converting an average value signal Ave_Sig obtained by averaging the AC discrete values AC_Sig [a] to AC_Sig [c] into an alternating current. Since the signal is subtracted from the discrete signal AC_Sig [a], a peak noise component received only by the antenna 1a appears significantly in the differential signal Diff_Sig [a]. In the case of FIG. 3, the peak noises PA4 to PA5 of the differential signal Diff_Sig [a] correspond to the peak noises PA1 to PA3 of the signals received by the antennas 1b and 1c.

Then, by subtracting the differential signal Diff_Sig [a] from which the peak noise component received only by the antenna 1a appears significantly from the discrete signal Sig [a], the peak noise component received only by the antenna 1a is effectively suppressed. The signal Sig_out [a] (signal waveform shown in the column of the state “26” in FIG. 3) can be acquired.
Note that the peak noise PB1 of the signal of the antenna 1b shown in FIG. 3 (corresponding to the peak noise PB2 in the differential signal Diff_Sig [b]), the peak noise PC1 and PC2 of the signal of the antenna 1c (the peak in the differential signal Diff_Sig [c]). The same applies to the noises PC3 and PC4.
The processes (1) to (7) are executed by the noise reduction device 20, and the signals (three signals) in which the peak noise components due to the self-addiction phenomenon are reduced are output to the synthesis unit 7.

In the synthesizer 7, the three outputs from the noise reduction device 20 are synthesized, and the synthesized signal is output to the orthogonal demodulator 9. Specifically, the synthesizer 7 performs sensitivity improvement by combining, countermeasures for multipath noise, and the like.
In the orthogonal demodulation unit 9, orthogonal demodulation processing is performed on the signal combined by the combining unit 7, and the signal subjected to the orthogonal demodulation processing is output to the FFT unit 10.
In the FFT unit 10, the FFT process is performed on the signal on which the orthogonal demodulation process has been performed, and the signal on which the FFT process has been performed is output to the demodulation unit 14. Specifically, in the FFT unit 10, the signal on which the orthogonal demodulation processing has been performed is separated into signals for each frequency component.
In the demodulator 14, demodulation processing (carrier demodulation processing, error correction processing, etc.) is performed on the signal on which the FFT processing has been performed, and a TS signal is acquired. Specifically, in the demodulator, a process of acquiring a TS signal that is an encoded and compressed moving image signal is executed.

Note that some digital high-vision tuners include functional units from the high-frequency signal processing unit 2 to the demodulation unit 14 and those having only the high-frequency signal processing unit 2a. The noise reduction device 20 according to the present embodiment includes: The present invention is applied by being configured (installed) inside a tuner having functional units from the high-frequency signal processing unit 2 to the demodulation unit 14. Further, the present invention is applied to the noise reduction device 20 of the present embodiment by being installed in the subsequent stage of a tuner having only high-frequency signal processing.
As described above, in the digital high-definition receiver 100 equipped with the noise reduction device 20, even when a signal in which strong peak noise of a specific frequency is mixed into a signal subjected to complicated cross modulation is received by a plurality of antennas, By installing the noise reduction device 20, it is possible to reduce the influence of self-poisoning and greatly improve reception sensitivity while suppressing an increase in circuit scale and cost.

In the digital high-definition receiver 100 equipped with the noise reduction device 20, the digital high-definition signal mixed with a plurality of peak noises is selected and amplified to the same channel by the high-frequency signal processing units 2a, 2b, and 2c, and a plurality of peak noises are mixed. It is input to the noise reduction device 20 as a digital signal having an intermediate frequency of about 57 MHz. In the digital high-definition receiver 100, since the high-frequency signal processing units 2a, 2b, and 2c are tuned to the same channel, ideally, the signal input to the noise reduction device 20 is transmitted to the antennas 1a, 1b, and 1c. Although it should be the same signal that does not depend on, in reality, signals having different noise components due to the aforementioned “multipath noise fading phenomenon” or “self-poisoning” are input to the noise reduction device 20.
The noise reduction device 20 of the digital high-definition receiver 100 extracts only a noise component peculiar to each antenna (noise component due to “multipath noise fading phenomenon” or “self-poisoning”), and a signal obtained by reducing the extracted noise component. Can be output.

In mobile devices equipped with high-speed digital circuits, the frequency used varies depending on the circuit, so multiple antennas mounted on the digital high-definition receiver each cause “self-poisoning” from the nearest digital circuit. It is considered that peak noise components are mixed strongly.
In the noise reduction device 20 of the digital high-definition receiver 100, discrete value processing is performed in a very short time, and since the output signal of each antenna also includes phase difference information, the noise reduction device 20 By averaging the output signals of each antenna, the influence of the “multipath noise fading phenomenon” can be reduced.
As a matter of course, since the noise component mixed in all the antennas cannot be reduced, it is preferable to install the antennas as far apart as possible in the digital high-vision receiver 100.

In the present embodiment, the number of antennas is three. However, if the number of antennas is two or more, the effects of the present invention can be obtained. Since the difference from the average value signal Ave_Sig is enlarged, the effect is also increased.
Moreover, in this embodiment, although the noise reduction apparatus 20 is inserted between the high frequency signal processing unit 2 and the synthesis unit 7, it may be inserted after the channel selection unit in the high frequency signal processing unit.
In the digital high-definition receiver 100, it is also possible to optimize the noise reduction effect by controlling the subtraction levels of the difference subtraction units 27a, 27b, and 27c from the information that has been subjected to error correction by the demodulation unit 14.
[Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described with reference to FIGS.

In addition, about the part similar to the said embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.
<2.1: Configuration of receiver with digital noise reduction function (digital high-definition receiver)>
FIG. 4 is a schematic configuration diagram of a receiver 200 with a noise reduction function (digital high-vision receiver) 200 according to the second embodiment.
As shown in FIG. 4, the digital high-definition receiver 200 includes a plurality of antennas 1a to 1c, high-frequency signal processing units 2a to 2c, orthogonal demodulation units 9a to 9b, FFT units 10a to 10b, and a noise reduction device 20. And a synthesizing unit 7 and a demodulating unit 14.
In the digital high-definition receiver 100 of the first embodiment, the noise reduction device 20 is installed between the high-frequency signal processing units 2a to 2c and the combining unit 7, but the digital high-definition receiver 200 of the second embodiment. Then, the noise reduction apparatus 20 is installed after the FFT units 10a to 10b and the combining unit 7 in the subsequent stage of the FFT units 10a to 10b. In this respect, the digital high-definition receiver 200 of the second embodiment is different from the digital high-definition receiver 100 of the first embodiment.

Note that the quadrature demodulation units 9a to 9c of the present embodiment have the same functions as the quadrature demodulation unit 9 of the first embodiment. Further, the FFT units 10a to 10c of the present embodiment have the same functions as the FFT unit 10 of the first embodiment.
(2.1.1: Configuration of noise reduction device 20A)
As illustrated in FIG. 5, the noise reduction device 20 </ b> A includes discrete average value processing units 204 a to 204 c, an average value signal calculation unit 205, and noise signal reduction units 206 a to 206 c.
As shown in FIG. 5, the discrete average value processing unit 204a includes an average value calculation unit 22a and an average value subtraction unit 23a.
The average value calculation unit 22a receives the signal output from the FFT unit 10a and calculates an average value of the signal output from the FFT unit 10a for a predetermined time. Then, the average value calculation unit 22a outputs the calculated average value Ave [a] to the average value subtraction unit 23a.

The average value subtracting unit 23a receives the output Sig [a] of the FFT unit 10a and the output of the average value calculating unit 22a. The average value subtracting unit 23a subtracts the output signal of the average value calculating unit 22a from the output signal of the FFT unit 10a, that is,
AC_Sig [a] = Sig [a] -Ave [a]
The process corresponding to is executed. Then, the average value subtraction unit 23a outputs the signal acquired by the subtraction to the average value signal calculation unit 205 and the noise signal reduction unit 206a as an AC discrete value signal AC_Sig [a].
Note that the processing of the discrete average value processing units 204b and 204c is the same as the processing of the discrete average value processing unit 204a.
The average value signal calculation unit 205 receives three signals output from the average value subtraction units 23a to 23c of the discrete average value processing units 204a to 204c, respectively, and performs an averaging process on the three signals. Do. The average value signal calculation unit 205 outputs the signal calculated by the averaging process to the difference calculation units 25a to 25c of the noise signal reduction units 206a to 206c as the average value signal Ave_Sig.

The noise signal reduction units 206a to 206c include difference calculation units 25a to 25c, positive / negative separation units 26a to 26c, difference subtraction units 27a to 27c, and D / A converters (DACs) 28a to 28c, respectively.
The difference calculation unit 25a of the noise signal reduction unit 206a includes an average value signal Ave_Sig output from the average value signal calculation unit 205 and an AC discrete value signal AC_Sig output from the average value subtraction unit 23a of the discrete average value processing unit 204a. [A] is an input. And the difference calculation part 25a is with respect to an average value signal and AC discrete value signal AC_Sig [a].
Diff_Sig [a] = AC_Sig [a] −Ave_Sig
The difference process corresponding to is performed, and the difference signal Diff_Sig [a] is acquired. Then, the difference calculation unit 25a outputs the difference signal Diff_Sig [a] to the positive / negative separation unit 26a.

The positive / negative separator 26a receives the output from the difference calculator 25a as input, and separates the positive and negative of the differential signal Diff_Sig [a]. That is, only the positive part or the negative part of the difference signal Diff_Sig [a] is extracted. Here, a case where a positive part is extracted will be described. Therefore, the positive / negative separator 26a is
Positive_diff [a] = Clip (Diff_Sig [a], 0)
Thus, a signal obtained by extracting only the positive part of the differential signal Diff_Sig [a] is acquired. Clip (x, th) is a function that outputs “0” when x <th, and outputs “x” when x ≧ th.
The difference subtraction unit 27a receives the signal Sig [a] output from the discrete average value processing unit 204a (FFT unit 10a) and the difference signal Positive_diff [a] output from the positive / negative separation unit 26a. Then, the difference subtraction unit 27a
Sig_out [a] = Sig [a] -Positive_diff [a]
The difference subtraction process corresponding to is performed to obtain the difference subtraction signal Sig_out [a]. Then, the difference subtraction unit 27a outputs the difference subtraction signal Sig_out [a] to the D / A converter (DAC) 28a.

The D / A converter (DAC) 28a receives the difference subtraction signal Sig_out [a] output from the difference subtraction unit 27a, and executes D / A conversion processing on the difference subtraction signal Sig_out [a]. Then, the D / A converter (DAC) 28 a outputs the signal after the D / A conversion processing to the combining unit 7.
Note that the processing of the noise signal reduction units 206b and 206c is the same as the processing of the noise signal reduction unit 206a.
<2.2: Operation of receiver with noise reduction function (digital high-vision receiver)>
The operation of the receiving apparatus with noise reduction function (digital high-vision receiving apparatus) 200 configured as described above will be described below. Note that description of the same parts as in the first embodiment is omitted.

In the digital high-definition receiver 200, the digital high-definition signals received by the antennas 1a, 1b, and 1c are selected and amplified to the same channel by the high-frequency signal processing units 2a, 2b, and 2c, and are shown in a state “2” in FIG. The high frequency signal processing units 2a, 2b, and 2c are output to the orthogonal demodulation units 9a, 9b, and 9c as digital signals having an intermediate frequency of about 57 MHz. Further, the signals subjected to the orthogonal demodulation processing by the orthogonal demodulation units 9a, 9b, and 9c are output to the FFT units 10a, 10b, and 10c.
In the FFT units 10a, 10b, and 10c, the signals demodulated by the orthogonal demodulation units 9a, 9b, and 9c are separated into signals for each frequency component, and then output to the noise reduction device 20A.
As shown in FIG. 2, the signal input to the noise reduction device 20A is subjected to the following processes (1) to (8).
(1) Since the outputs of the FFT units 10a, 10b, and 10c have already been discrete values for each frequency component, the noise reduction device 20A does not perform the discrete value processing. An example of the signal waveforms of the discrete signals Sig [a] to Sig [c] input to the noise reduction device 20A is shown in the column of state “21, 22” in FIG.
(2) In the average value calculation units 22a, 22b, and 22c, the average values Ave [a] and Ave [b] of the discrete signals Sig [a], Sig [b], and Sig [c] within a predetermined time, respectively. , Ave [c] is calculated.
(3) In the average value subtraction units 23a, 23b, and 23c, the average level values Ave [a] to Ave [c] calculated by the average value calculation units 22a, 22b, and 22c, respectively, are converted into the discrete signal Sig [a]. By subtracting ~ Sig [c], AC discrete values AC_Sig [a] to AC_Sig [c] are obtained. That is, in the average value subtracting units 23a, 23b, and 23c,
AC_Sig [a] = Sig [a] -Ave [a]
AC_Sig [b] = Sig [b] −Ave [b]
AC_Sig [c] = Sig [c] −Ave [c]
Thus, AC discrete value signals AC_Sig [a] to AC_Sig [c] are acquired.

An example of the signal waveforms of the AC discrete values AC_Sig [a] to AC_Sig [c] is shown in the state “23” column of FIG.
(4) The average value signal calculation unit 205 performs an average process on the AC discrete values AC_Sig [a] to AC_Sig [c]. Specifically, in the average value signal calculation unit 205, in the AC discrete values AC_Sig [a] to AC_Sig [c], discrete values (sample values) (three discrete values) at the same point on the time axis, respectively. The average value is calculated from the above, and the calculated average value is set as the average value at the same point on the time axis. The average value signal Ave_Sig for the time to be subjected to the discretization processing is acquired by the average value signal calculation unit 205 by repeatedly executing this for the time to be subjected to the discretization processing.
An example of the signal waveform of the average value signal Ave_Sig is shown in the state “24” column of FIG.
(5) The difference calculation units 25a, 25b, and 25c perform processing for obtaining a difference between the AC discrete values AC_Sig [a] to AC_Sig [c] and the average value signal Ave_Sig, respectively. That is, in the difference calculation units 25a, 25b, and 25c,
Diff_Sig [a] = AC_Sig [a] −Ave_Sig
Diff_Sig [b] = AC_Sig [b] −Ave_Sig
Diff_Sig [c] = AC_Sig [c] −Ave_Sig
Thus, the differential signals Diff_Sig [a] to Diff_Sig [c] are acquired.

An example of the signal waveforms of the differential signals Diff_Sig [a] to Diff_Sig [c] is shown in the state “25” column of FIG.
(6) Each of the positive / negative separators 26a, 26b, and 26c performs a process of extracting only positive portions of the difference signals Diff_Sig [a] to Diff_Sig [c]. That is, in the positive / negative separators 26a, 26b, 26c,
Positive_diff [a] = Clip (Diff_Sig [a], 0)
Positive_diff [b] = Clip (Diff_Sig [b], 0)
Positive_diff [c] = Clip (Diff_Sig [c], 0)
Thus, signals Positive_diff [a] to Positive_diff [c] obtained by extracting only positive portions of the differential signals Diff_Sig [a] to Diff_Sig [c] are acquired. Here, Clip (x, th) is a function that outputs “0” when x <th and outputs “x” when x ≧ th.

An example of signal waveforms of the signals Positive_diff [a] to Positive_diff [c] is shown in the column of the state “26” in FIG.
(7) The difference subtraction units 27a, 27b, and 27c perform processing of subtracting the signals Positive_diff [a] to Positive_diff [c] from the discrete signals Sig [a] to Sig [c], respectively. That is, in the difference subtraction units 27a, 27b, and 27c,
Sig_out [a] = Sig [a] -Positive_diff [a]
Sig_out [b] = Sig [b] −Positive_diff [b]
Sig_out [c] = Sig [c] −Positive_diff [c]
Thus, the difference subtraction signals Sig_out [a] to Sig_out [c] are acquired.
An example of the signal waveform of the difference subtraction signals Sig_out [a] to Sig_out [c] is shown in the column of state “27” in FIG.
(8) In the DACs 28a, 28b, and 28c, the D / A conversion process is performed on the difference subtraction signals Sig_out [a] to Sig_out [c]. Then, the D / A converted signals (three signals) are output to the synthesis unit 7.

Note that a signal (original intermediate frequency signal) after D / A conversion processing is performed on the difference subtraction signals Sig_out [a] to Sig_out [c] is shown in a state “28” column in FIG. 6.
As described above, the noise reduction apparatus 20A executes the processes shown in the above (1) to (8), and thereby, a plurality of specific frequencies generated outside the circuit of the reception apparatus (digital high-vision reception apparatus 100) shown in FIG. Even when the peak noise is individually mixed in the antennas 1a, 1b, and 1c due to the “self-poisoning” phenomenon, the peak noise generated by the self-poisoning phenomenon can be appropriately removed.
In the signals Positive_diff [a] to Positive_diff [c] acquired by the noise reduction device 20A, as can be seen from FIG. 6, the peak noise component received by a specific antenna appears remarkably. Therefore, a signal in which peak noise components received only by a specific antenna are effectively suppressed by subtracting signals Positive_diff [a] to Positive_diff [c] from discrete values signals Sig [a] to Sig [c]. Sig_out [a] to Sig_out [c] can be acquired.

The noise reduction device 20A executes the processes (1) to (8), and the signals (three signals) in which the peak noise components due to the self-addiction phenomenon are reduced are output to the synthesis unit 7.
In the synthesis unit 7, the three outputs from the noise reduction device 20 are synthesized, and the synthesized signal is output to the demodulation unit 14. Specifically, the synthesizer 7 performs sensitivity improvement by combining, countermeasures for multipath noise, and the like.
In the demodulator 14, demodulation processing (carrier demodulation processing, error correction processing, etc.) is performed on the signal output from the synthesis unit 7, and a TS signal is acquired. Specifically, in the demodulator, a process of acquiring a TS signal that is an encoded and compressed moving image signal is executed.
As described above, in the digital high-definition receiver 100 equipped with the noise reduction device 20A, even when a signal in which strong peak noise of a specific frequency is mixed into a signal subjected to complicated cross modulation is received by a plurality of antennas, By installing the noise reduction device 20, it is possible to reduce the influence of self-poisoning and greatly improve reception sensitivity while suppressing an increase in circuit scale and cost.

In the digital high-definition receiver 200 equipped with the noise reduction device 20A, a plurality of peak noises of a specific frequency generated outside the circuit of the digital high-definition receiver 200 (receiver) shown in FIG. When individually mixed in 1c, digital high-definition signals mixed with a plurality of peak noises are selected and amplified to the same channel by the high-frequency signal processing units 2a, 2b, 2c, and then a plurality of signals are processed by the FFT units 10a, 10b, 10c. A signal for each frequency component mixed with peak noise is input to the noise reduction device 20A.
In the digital high-definition receiver 200, since the high-frequency signal processing units 2a, 2b, and 2c are tuned to the same channel, ideally, the signal input to the noise reduction device 20 is transmitted to the antennas 1a, 1b, and 1c. Although it should be the same signal that does not depend on, in reality, signals having different noise components due to the aforementioned “multipath noise fading phenomenon” or “self-poisoning” are input to the noise reduction device 20A.

In the noise reduction device 20A of the digital high-definition receiver 200, only a noise component peculiar to each antenna (a noise component due to “multipath noise fading phenomenon” or “self-poisoning”) is extracted, and the extracted noise component is reduced. Can be output.
In the noise reduction device 20A, the peak noise of “self-poisoning” is observed as a peak noise even in the frequency component.
(1) In the noise reduction device 20A, the difference signals a, b, and c are separated into a positive part and a negative part by positive and negative separators 26a, 26b, and 26c,
(2) The difference subtracting units 27a, 27b, and 27c subtract signals Positive_diff [a] to Positive_diff [c], which are signals of only the positive part of the difference signal, from the discrete signals Sig [a] to Sig [c]. ,
(3) Thereafter, the DACs 28a, 28b, and 28c restore the original intermediate frequency signal.

Moreover, in the above, in the noise reduction apparatus 20A, the signal of only the positive part of the difference signal is subtracted from the discrete signals Sig [a] to Sig [c], and in particular, peak noise due to self-poisoning is suppressed. In the noise reduction device 20A, the signal of only the negative part of the difference signal may be subtracted from the discrete value signals Sig [a] to Sig [c]. By subtracting the negative part of the difference signal from the discrete signals Sig [a] to Sig [c], the specific frequency component is reduced due to the multipath fading phenomenon (the specific frequency component is extremely small). Can be corrected appropriately.
[Other Embodiments]
In the noise reduction device described in the above embodiment and the digital high-definition reception device equipped with the noise reduction device, each block may be individually made into one chip by a semiconductor device such as an LSI, or may include some or all of the blocks. Alternatively, one chip may be used.

Here, although LSI is used, it may be called IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.
Further, the method of circuit integration is not limited to LSI, and implementation with a dedicated circuit or a general-purpose processor is also possible. An FPGA (Field Programmable Gate Array) that can be programmed after manufacturing the LSI or a reconfigurable processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used.
Further, if integrated circuit technology comes out to replace LSI's as a result of the advancement of semiconductor technology or a derivative other technology, it is naturally also possible to carry out function block integration using this technology. Biotechnology can be applied as a possibility.
Moreover, each process of the said embodiment may be implement | achieved by hardware, and may be implement | achieved by software. Further, it may be realized by mixed processing of software and hardware. Needless to say, when the noise reduction apparatus according to the above embodiment and the digital high-definition reception apparatus equipped with the noise reduction apparatus are realized by hardware, it is necessary to perform timing adjustment for performing each process. In the above embodiment, for convenience of explanation, details of timing adjustment of various signals generated in actual hardware design are omitted.

  The specific configuration of the present invention is not limited to the above-described embodiment, and various changes and modifications can be made without departing from the scope of the invention.

  The reception device with noise reduction function, the noise reduction method, the program, and the integrated circuit according to the present invention are cases in which a signal in which peak noise of a specific frequency is mixed with a signal subjected to complicated cross modulation is received by a plurality of antennas. However, while suppressing an increase in circuit scale and cost, it is possible to reduce the influence of self-poisoning and greatly improve reception sensitivity. Therefore, the present invention is useful in the fields related to antennas and video equipment, and can be implemented in this field.

100, 200 Digital Hi-Vision receiver (receiver with noise reduction function)
1a, 1b, 1c Antenna 2a, 2b, 2c High-frequency signal processing unit 3a, 3b, 3c Variable attenuator 4a, 4b Level detector 5 Control circuit 6 Comparison circuit 7 Combining unit 8 Distribution unit 9, 9a, 9b Orthogonal demodulation unit 10 10a, 10b, 10c FFT unit 11 QPSK discriminator 12 16QAM discriminator 13a, 13b Error correction circuit 14 Demodulator 20, 20A Noise reduction device 201a, 201b, 201c Discrete value signal processing unit 21a, 21b, 21c Discrete value processing Unit 22a, 22b, 22c average value calculation unit 23a, 23b, 23c average value subtraction unit 202, 205 average value signal calculation unit 203a, 203b, 203c noise signal reduction unit 204a, 204b, 204c discrete average value processing unit 206a, 206b, 206c Noise signal reduction unit 25a, 25b, 25c Difference Calculation unit 26a, 26b, 26c sign separating unit 27a, 27b, 27c difference subtraction portion 28a, 28b, 28c DAC

Claims (10)

N antennas (N is a natural number N ≧ 2) for receiving radio waves,
A discrete value processing unit that performs discrete value processing on the received signals by the N antennas selected for the same channel and outputs them as discrete value signals Sig [1] to Sig [N]; ,
For the discrete signals Sig [1] to Sig [N] output from the discrete processing unit, average values Ave [1] to Ave [N] during a predetermined time T are calculated, respectively. The average values Ave [1] to Ave [N] are subtracted from the discrete values Sig [1] to Sig [N], respectively, so that the AC discrete values AC_Sig [1] to AC_Sig [N AC discrete value signal acquisition unit for calculating
Average value signal calculation for calculating an average value of N signals of the AC discrete value signals AC_Sig [1] to AC_Sig [N] calculated by the AC discrete value signal acquisition unit and outputting as an average value signal Ave_Sig And
A difference calculation unit that calculates difference signals Diff_Sig [1] to Diff_Sig [N] by subtracting the average value signal Ave_Sig from the AC discrete values AC_Sig [1] to AC_Sig [N], respectively;
Differences for calculating output signals Sig_out [1] to Sig_out [N] by subtracting the difference signals Diff_Sig [1] to Diff_Sig [N] from the discrete signals Sig [1] to Sig [N], respectively. A subtraction unit;
A receiver with a noise reduction function. The discrete value processing unit includes:
When the N antennas receive a broadcast wave, and the received signal input to the discrete value processing unit is an intermediate frequency band signal, the received signal is transmitted at a period of the intermediate frequency. Discrete values with a predetermined period of 1/4 or less,
The receiving device with a noise reduction function according to claim 1. The discrete value processing unit includes:
When the N antennas receive broadcast waves based on OFDM, and the received signal input to the discrete value processing unit is a frequency domain signal, the received signals are converted to OFDM frequency. Discrete values in spectrum units,
The receiver with a noise reduction function according to claim 1 or 2. The received signal is a received signal of digital high-definition broadcast or one segment broadcast.
The receiving apparatus with a noise reduction function according to claim 1. The difference subtraction unit subtracts only the positive part of the difference signals Diff_Sig [1] to Diff_Sig [N] from the discrete signals Sig [1] to Sig [N], respectively, thereby outputting the output signal Sig_out [1]. ] To Sig_out [N],
The receiving apparatus with a noise reduction function according to claim 1. The difference subtraction unit subtracts only the negative part of the difference signals Diff_Sig [1] to Diff_Sig [N] from the discrete signals Sig [1] to Sig [N], respectively, thereby outputting the output signal Sig_out [1]. ] To Sig_out [N],
The receiving apparatus with a noise reduction function according to claim 1. A demodulator that performs demodulation processing and error correction processing based on the output signals Sig_out [1] to Sig_out [N];
The difference subtraction unit controls a value to be subtracted from each of the discrete signals Sig [1] to Sig [N] based on error correction information that is information on an error correction processing result by the demodulation unit. ,
The receiving device with a noise reduction function according to claim 1. A noise reduction method used for a receiving device including N antennas (N is a natural number of N ≧ 2) for receiving radio waves,
Discrete value processing steps for discretely processing the received signals received by the N antennas selected for the same channel and outputting them as discrete value signals Sig [1] to Sig [N]; ,
For the discrete signals Sig [1] to Sig [N] output from the discrete processing step, average values Ave [1] to Ave [N] during a predetermined time T are calculated, respectively. The average values Ave [1] to Ave [N] are subtracted from the discrete values Sig [1] to Sig [N], respectively, so that the AC discrete values AC_Sig [1] to AC_Sig [N AC discrete value signal acquisition step for calculating
An average value signal calculation that calculates an average value of N signals of the AC discrete value signals AC_Sig [1] to AC_Sig [N] calculated by the AC discrete value signal acquisition step and outputs the average value as an average value signal Ave_Sig Steps,
A difference calculating step of calculating difference signals Diff_Sig [1] to Diff_Sig [N] by subtracting the average value signal Ave_Sig from the AC discrete values AC_Sig [1] to AC_Sig [N], respectively;
Differences for calculating output signals Sig_out [1] to Sig_out [N] by subtracting the difference signals Diff_Sig [1] to Diff_Sig [N] from the discrete signals Sig [1] to Sig [N], respectively. A subtraction step;
A noise reduction method comprising: A program for causing a computer to execute a noise reduction method used in a receiving device including N antennas (N is a natural number of N ≧ 2) for receiving radio waves,
Discrete value processing steps for discretely processing the received signals received by the N antennas selected for the same channel and outputting them as discrete value signals Sig [1] to Sig [N]; ,
For the discrete signals Sig [1] to Sig [N] output from the discrete processing step, average values Ave [1] to Ave [N] during a predetermined time T are calculated, respectively. The average values Ave [1] to Ave [N] are subtracted from the discrete values Sig [1] to Sig [N], respectively, so that the AC discrete values AC_Sig [1] to AC_Sig [N AC discrete value signal acquisition step for calculating
An average value signal calculation that calculates an average value of N signals of the AC discrete value signals AC_Sig [1] to AC_Sig [N] calculated by the AC discrete value signal acquisition step and outputs the average value as an average value signal Ave_Sig Steps,
A difference calculating step of calculating difference signals Diff_Sig [1] to Diff_Sig [N] by subtracting the average value signal Ave_Sig from the AC discrete values AC_Sig [1] to AC_Sig [N], respectively;
Differences for calculating output signals Sig_out [1] to Sig_out [N] by subtracting the difference signals Diff_Sig [1] to Diff_Sig [N] from the discrete signals Sig [1] to Sig [N], respectively. A subtraction step;
A program that causes a computer to execute a noise reduction method. An integrated circuit used in a receiving device including N antennas (N is a natural number of N ≧ 2) for receiving radio waves,
A discrete value processing unit that performs discrete value processing on the received signals by the N antennas selected for the same channel and outputs them as discrete value signals Sig [1] to Sig [N]; ,
For the discrete signals Sig [1] to Sig [N] output from the discrete processing unit, average values Ave [1] to Ave [N] during a predetermined time T are calculated, respectively. The average values Ave [1] to Ave [N] are subtracted from the discrete values Sig [1] to Sig [N], respectively, so that the AC discrete values AC_Sig [1] to AC_Sig [N AC discrete value signal acquisition unit for calculating
Average value signal calculation for calculating an average value of N signals of the AC discrete value signals AC_Sig [1] to AC_Sig [N] calculated by the AC discrete value signal acquisition unit and outputting as an average value signal Ave_Sig And
A difference calculation unit that calculates difference signals Diff_Sig [1] to Diff_Sig [N] by subtracting the average value signal Ave_Sig from the AC discrete values AC_Sig [1] to AC_Sig [N], respectively;
Differences for calculating output signals Sig_out [1] to Sig_out [N] by subtracting the difference signals Diff_Sig [1] to Diff_Sig [N] from the discrete signals Sig [1] to Sig [N], respectively. A subtraction unit;
An integrated circuit comprising:

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