Receiver and noise removal method

Abstract

To efficiently eliminate noises.SOLUTION: A receiving device performs diversity synthesis of broadcast waves received on both a first tuner and a second tuner. The receiving device includes an estimation unit and an elimination unit. The estimation unit estimates noises included in broadcast waves received on the first tuner on the basis of a reception signal on the second tuner set to a reception frequency where there is no broadcast wave. The elimination unit eliminates noises estimated by the estimation unit from the broadcast waves received by the first tuner.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a receiving device and a noise removal method. [Background technology]

[0002] Conventionally, there are receiving devices that remove noise components from received broadcast waves. For example, a technology has been proposed for a receiving device that removes noise components from broadcast waves by using a noise signal received by a noise pick antenna that is provided separately from the antenna that receives the broadcast waves (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-56816 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the conventional technology requires a noise pick antenna, so there is room for improvement in terms of increasing the efficiency of noise removal.

[0005] The present invention has been made in view of the above, and has an object to provide a receiving device and a noise removal method that can efficiently remove noise. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, a receiving device according to the present invention is a receiving device that diversity combines broadcast waves received by both a first tuner and a second tuner, and includes an estimation unit and a removal unit. The estimation unit estimates noise contained in the broadcast waves received by the first tuner based on a received signal of the second tuner set to a reception frequency at which no broadcast waves are present. The removal unit removes the noise estimated by the estimation unit from the broadcast waves received by the first tuner. [Effects of the Invention]

[0007] According to the present invention, noise can be removed efficiently. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an outline of a noise removal method. [Figure 2] FIG. 2 is a block diagram of a receiving device according to the first embodiment. [Figure 3A] FIG. 3A is a schematic diagram illustrating an example of processing by an estimation unit according to the first embodiment. [Figure 3B] FIG. 3B is a schematic diagram illustrating an example of processing by the estimation unit according to the first embodiment. [Figure 3C] FIG. 3C is a schematic diagram illustrating an example of processing by the estimation unit according to the first embodiment. [Figure 4] FIG. 4 is a flowchart showing a processing procedure executed by the receiving device according to the first embodiment. [Figure 5] FIG. 5 is a block diagram of a receiving device according to the second embodiment. [Figure 6] FIG. 6 is a diagram illustrating an example of processing by an estimation unit according to the second embodiment. [Figure 7] FIG. 7 is a flowchart showing a processing procedure executed by the receiving device according to the second embodiment. [Figure 8] FIG. 8 is a block diagram of a receiving device according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of a receiving device and a noise removal method disclosed in the present application will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited to the following embodiments.

[0010] (First embodiment) First, an overview of a noise removal method according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a diagram showing an overview of the noise removal method. The noise removal method according to the embodiment is executed, for example, by a receiving device 10, which will be described later with reference to Fig. 2. For example, the receiving device 10 is a receiving device that receives various broadcast waves such as digital radio and one-segment broadcasting.

[0011] However, when a receiving device is mounted on a vehicle, for example, the on-board device may become a noise source and superimpose noise on the broadcast waves received by the receiving device. For example, in the prior art, some devices are provided with a pickup antenna for detecting noise, separate from the antenna for receiving the broadcast waves.

[0012] However, in this case, providing a separate pickup antenna may increase the cost and size of the product, leaving room for improvement in terms of efficiency.

[0013] Therefore, in the noise removal method according to the embodiment, noise is detected by one tuner of a diversity receiving device that diversity combines broadcast waves received by a plurality of tuners.

[0014] For example, as shown in FIG. 1, the noise removal method according to the embodiment uses a first tuner C1 connected to a first antenna A1 and a second tuner C2 connected to a second antenna A2.

[0015] As shown in Fig. 1, for example, a first tuner C1 is set to a broadcast wave reception channel frequency, and a second tuner C2 is set to a noise detection frequency for detecting noise. For example, the broadcast wave received by the first tuner C1 is converted into a first reception signal St1 by the first tuner C1. Note that the first reception signal St1 here is a signal related to the broadcast wave with noise superimposed thereon.

[0016] The noise detection frequency is a frequency different from the reception channel frequency, for example, a frequency at which no broadcast waves are present. For example, the noise detection frequency is preferably a frequency close to the reception channel frequency, for example, a frequency at which noise reception sensitivity is high. Therefore, in the noise removal method according to the embodiment, the reception frequency of the second tuner C2 may be appropriately adjusted so that a reception frequency at which noise reception sensitivity is high is set as the noise detection frequency.

[0017] For example, the second tuner C2 receives noise corresponding to the noise detection frequency and converts it into a second reception signal St2. Then, in the noise removal method according to the embodiment, the noise contained in the first reception signal St1 is estimated from the second reception signal St2 (step S1).

[0018] For example, in the noise removal method according to the embodiment, when the noise source is a DC / DC converter, attention is focused on the fact that noise occurs at regular frequency intervals, and the noise contained in the first received signal St1 is estimated from the second received signal St2.

[0019] 1, peaks P are detected from the second reception signal St2 of the second tuner C2, and the frequency interval of the peaks P is identified. Next, of the multiple frequencies arranged at the identified frequency interval, the one included in the reception frequency band of the reception channel frequency is estimated as the frequency of noise N.

[0020] Thereafter, in the noise removal method according to the embodiment, for example, a noise replica Sn that reproduces the estimated noise N is used to remove the noise N from the first received signal St1 (step S2). This makes it possible to generate an output signal Sb in which the noise replica Sn has been removed from the first received signal St1. Note that the noise removal method is not limited to the method using the noise replica Sn. Specific examples of this point will be described later.

[0021] In this way, in the noise removal method according to the embodiment, one of the multiple tuners in the diversity receiving device is used for noise detection, and therefore, the noise removal method according to the embodiment does not require a separate pickup antenna, and can remove noise efficiently.

[0022] Furthermore, in the noise removal method according to the embodiment, the noise contained in the broadcast wave is estimated from the received signal received by the noise detection tuner, and then the noise in the broadcast wave is removed, so that the noise can be accurately estimated without being affected by the broadcast wave.

[0023] Next, a configuration example of the receiving device 10 according to the embodiment will be described with reference to Fig. 2. Fig. 2 is a block diagram of the receiving device 10 according to the first embodiment. As shown in Fig. 2, the receiving device 10 according to the first embodiment includes a first tuner C1, a second tuner C2, an A / D conversion unit 11, an estimation unit 20, a removal unit 30, and a demodulation unit 40.

[0024] The receiving device 10 includes a computer and various circuits, for example, having a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), a hard disk drive, input / output ports, etc. The CPU of the computer, for example, reads and executes a program stored in the ROM, thereby performing some or all of the following functions:

[0025] The first tuner C1 is connected to a first antenna A1 and receives broadcast waves via the first antenna A1. For example, the first tuner C1 receives broadcast waves in an Orthogonal Frequency Division Multiplexing (OFDM) format. The broadcast waves received by the first tuner C1 are converted from analog to digital signals by an A / D converter 11 and then input to the removal unit 30 as a first received signal St1.

[0026] The second tuner C2 is connected to the second antenna A2 and receives a signal of a predetermined frequency (for example, the above-mentioned noise detection frequency) via the second antenna A2. The signal received by the second tuner C2 is converted from analog to digital by the A / D conversion unit 11 and then input to the estimation unit 20 as a second received signal St2.

[0027] The estimation unit 20 estimates noise contained in the broadcast waves received by the first tuner C1 based on the received signal of the second tuner C2, which is set to a reception frequency where no broadcast waves are present. For example, the estimation unit 20 detects a peak P from the second received signal St2, and estimates noise N contained in the first received signal St1 based on the detected peak P.

[0028] The estimation unit 20 inputs information about the noise N to the removal unit 30. Here, the information about the noise N includes, for example, information about the frequency and occurrence time of the noise N. Note that the information about the noise N may also be information about a noise replica.

[0029] For example, the estimation unit 20 may sequentially set the reception frequency of the second tuner C2 to a plurality of frequencies and estimate the noise N from the second reception signal St2 of the second tuner C2 set to each frequency.

[0030] In this case, for example, the estimation unit 20 sequentially switches the reception frequency of the second tuner C2 and sets the second tuner C2 to a reception frequency that provides high reception sensitivity for the peak P corresponding to the noise N. This can improve the estimation accuracy of the noise N.

[0031] The removal unit 30 removes the noise N estimated by the estimation unit 20 from the broadcast wave received by the first tuner C1. For example, the removal unit 30 removes the noise N from the first received signal St1 of the first tuner C1 based on the information about the noise N received from the estimation unit 20.

[0032] For example, if the noise estimated by the estimation unit 20 is within the reception band of the broadcast wave received by the first tuner C1, the removal unit 30 removes the noise from the broadcast wave. In other words, if the noise estimated by the estimation unit 20 is not included in the first received signal St1, various processes related to noise removal are omitted.

[0033] This allows the noise to be appropriately removed from the first received signal St1. For example, when the removal unit 30 receives information about the frequency of the noise N as information about the noise N, the removal unit 30 reduces the weight and reliability of the frequency in the first received signal St1 and relatively reduces the signal strength of the noise N included in the first received signal St1, thereby removing the noise N from the first received signal St1.

[0034] Furthermore, when the elimination unit 30 receives information regarding the occurrence time of noise N as information regarding noise N, it suppresses or blocks the output of the first reception signal St1 at that occurrence time. That is, in this case, the elimination unit 30 uses the peak P of the second reception signal St2 as a gate signal to suppress or block the output of the first reception signal St1. Here, "suppress" refers to, for example, suppressing the level (e.g., volume) at which the first reception signal St1 is output, and "block" refers to blocking the output of the first reception signal St1, i.e., not outputting it.

[0035] Through these processes, the removal unit 30 can generate a broadcast wave in which the noise N has been suppressed or removed from the first received signal St1 extracted by the first tuner C1.

[0036] The demodulation unit 40, for example, OFDM-demodulates the output signal Sb (see FIG. 1) input from the removal unit 30. For example, the output signal Sb that has been OFDM-demodulated by the demodulation unit 40 is output from a display that displays video and a speaker that outputs audio.

[0037] 3A to 3C, a specific example of the process of estimating noise N by the estimation unit 20 will be described. FIGS. 3A to 3C are schematic diagrams showing an example of the process by the estimation unit 20. In the example shown in FIG. 3A, it is assumed that the estimation unit 20 detects a peak P at frequency f1 in the noise detection frequency received by the second tuner C2.

[0038] In this case, for example, the estimation unit 20 estimates that noise occurs at a frequency f1×n (n is a natural number) using frequency f1 as a reference. In this case, when a value (f1×n) obtained by multiplying frequency f1 by an integer is included in the reception band (reception channel frequency) of the first tuner C1, the estimation unit 20 estimates that this frequency is the frequency of noise N included in the reception channel frequency.

[0039] In the example shown in the figure, "2·f1", which is twice the frequency f1, exists within the reception channel frequency, so it is estimated that the first reception signal St1 contains noise N having a frequency of "2·f1". Note that although the frequency is f1×n (n is a natural number) here, noise N may also be estimated from peak P using frequency f1 / n (n is a natural number).

[0040] 3B, similarly to FIG. 3A, it is assumed that the estimation unit 20 detects a peak P of frequency f1 in the noise detection frequency received by the second tuner C2. In this case, if the frequency (f1+Δf) obtained by shifting the peak P by the difference Δf between the noise detection frequency and the reception channel frequency is within the range of the reception channel frequency, the estimation unit 20 estimates that the first reception signal St1 contains noise N having a frequency of "f1+Δf."

[0041] 3C, the estimation unit 20 first identifies the timing of a peak P detected at the noise detection frequency. Then, the estimation unit 20 estimates the identified timing as the timing of noise N contained in the broadcast wave received by the first tuner C1.

[0042] That is, in the receiving device 10, since the noise generated from the same noise source is received by both the first tuner C1 and the second tuner C2, the estimation unit 20 estimates the timing at which the noise N occurs from the timing at which the peak P occurs.

[0043] This makes it possible to accurately estimate the timing of occurrence of the noise N. For example, in this case, as described above, the removal unit 30 uses the peak P of the second reception signal St2 as a gate signal to suppress or block the output of the first reception signal St1, thereby removing the noise N from the first reception signal St1.

[0044] These processes enable the estimation unit 20 to accurately estimate the noise N. Note that, for example, the estimation unit 20 may estimate the noise N by appropriately combining these processes.

[0045] Next, a processing procedure executed by the receiving device 10 according to the first embodiment will be described with reference to Fig. 4. Fig. 4 is a flowchart showing the processing procedure executed by the receiving device 10 according to the first embodiment. Note that the processing procedure shown below is repeatedly executed by the estimation unit 20 and the removal unit 30.

[0046] As shown in FIG. 4, first, the receiving device 10 acquires the second received signal St2 of the second tuner C2 set to the noise detection frequency (step S101), and estimates the noise N contained in the first received signal St1 of the first tuner C1 set to the receiving channel frequency from the second received signal St2 (step S102).

[0047] Next, the receiving device 10 removes the noise N from the first received signal St1 based on the processing result of step S102 (step S103), and ends the processing.

[0048] As described above, the receiving device 10 according to the embodiment is a receiving device 10 that diversity combines broadcast waves received by both the first tuner C1 and the second tuner C2, and includes an estimation unit 20 that estimates noise contained in the broadcast waves received by the first tuner C1 based on a reception signal from the second tuner C2 that is set to a reception frequency where no broadcast waves are present, and a removal unit 30 that removes the noise estimated by the estimation unit 20 from the broadcast waves received by the first tuner C1. Therefore, the receiving device 10 according to the embodiment can efficiently remove noise.

[0049] (Second embodiment) Next, a receiving device 10A according to a second embodiment will be described with reference to Figures 5 to 7. In the following, the same reference numerals will be used to designate components that have already been described, and duplicated description will be omitted.

[0050] First, a configuration example of a receiving device 10A according to the second embodiment will be described with reference to Fig. 5. Fig. 2 is a block diagram of the receiving device 10A according to the second embodiment. The receiving device 10A according to the second embodiment differs from the receiving device 10 already described in the configurations of an estimation unit 20A and a removal unit 30A, and further includes an adjustment unit 50.

[0051] 5, the estimation unit 20A includes an extraction unit 21 and a generation unit 22. The extraction unit 21 separates the second received signal St2 into a pulse noise component and a random noise component, and extracts the pulse noise component from the second received signal St2.

[0052] The generating unit 22 generates a noise replica Sn based on the pulse noise component extracted by the extracting unit 21. The generating unit 22 outputs the generated noise replica Sn to the adjusting unit 50.

[0053] The adjustment unit 50 adjusts the gain of the noise replica Sn. For example, the adjustment unit 50 is a so-called adaptive filter, and sets the filter coefficient of the noise replica Sn input from the estimation unit 20A using an optimization algorithm such as an LMS (Least Mean Square) algorithm. The adjustment unit 50 also acquires the output signal output from the removal unit 30A and optimizes the filter coefficient.

[0054] The removal unit 30A subtracts the noise replica Sn input from the adjustment unit 50 from the first reception signal St1 input from the first tuner C1 to generate an output signal in which the noise N has been removed from the first reception signal St1. The output signal generated by the removal unit 30A is input to the adjustment unit 50 together with the demodulation unit 40.

[0055] Next, a specific example of processing by the estimation unit 20A will be described with reference to FIG. 6. FIG. 6 is a diagram illustrating an example of processing by the estimation unit 20A according to the second embodiment. As shown in FIG. 6, the extraction unit 21 of the estimation unit 20A separates the second reception signal St2 into a pulse noise component Pp and a random noise component Pr, and extracts the pulse noise component Pp from the second reception signal St2. Note that a known method is used to separate the pulse noise component Pp from the random noise component Pr. For example, as illustrated in FIG. 6, random noise tends to be low-level and appear continuously over time, while pulse noise tends to be high-level and appear intermittently. By utilizing this, it is possible to set a threshold value obtained by averaging the level of the second reception signal St2 over a predetermined period of time, and to separate any component exceeding the threshold value as pulse noise.

[0056] In this case, the generator 22 generates the noise replica Sn by shifting the frequency of the pulse noise component Pp by the difference Δf between the reception channel frequency and the noise detection frequency, for example.

[0057] This makes it possible to generate a noise replica Sn that reproduces even the phase of the pulse noise component Pp, thereby enabling the noise N to be removed from the first received signal St1 with high accuracy. The generator 22 may generate the noise replica Sn by shifting the frequency of the pulse noise component Pp extracted by the extractor 21, or by shifting the frequency of a pulse signal generated based on an average value of the levels, widths, phases, etc. of the extracted multiple pulse noises over a predetermined period (predetermined number). For example, the generator 22 can calculate an average pulse width from the multiple pulse noises and generate a new pulse signal having the same level and phase as the original pulse noise and the calculated average pulse width. Instead of the pulse width, the level or phase may be averaged, or a pulse signal may be generated by averaging two or all of the level, width, and phase.

[0058] Next, a processing procedure executed by the receiving device 10A according to the second embodiment will be described with reference to Fig. 7. Fig. 7 is a flowchart showing the processing procedure executed by the receiving device 10A according to the second embodiment.

[0059] As shown in FIG. 7, first, when the receiving device 10A acquires the second received signal St2 (step S201), it estimates the noise N contained in the first received signal St1 from the second received signal St2 (step S202).

[0060] Next, the receiving device 10A generates a noise replica based on the estimated noise N (step S203), subtracts the noise replica from the first received signal St1 (step S204), and ends the process.

[0061] (Third embodiment) Next, a receiving device 10B according to a third embodiment will be described with reference to Fig. 8. Fig. 8 is a block diagram of the receiving device 10B according to the third embodiment. As shown in Fig. 3, the receiving device 10B according to the third embodiment sets the first tuner C1 and the second tuner C2 to the receiving channel frequency, and then sets the subsequent noise detection tuner C3 to the noise detection frequency.

[0062] That is, in this case, the first tuner C1 and the second tuner C2 receive signals at both broadcast wave reception frequencies and reception frequencies where no broadcast wave is present. The noise detection tuner C3 is connected to either the first tuner C1 or the second tuner C2 by the switch SW. In this case, for example, the first tuner C1 and the second tuner C2 each receive signals including broadcast waves and noise. For this reason, it is preferable that the A / D conversion unit 11 be a wideband A / D converter capable of converting a wider range of frequencies.

[0063] For example, from the received signals (first received signal St1 and second received signal St2) output from the A / D conversion unit 11, a BPF (Band Pass Filter) 15 extracts only broadcast signals in a specific frequency band.

[0064] For example, the estimation unit 20B switches the switch SW1 to estimate noise from each of the first received signal St1 and the second received signal St2, thereby determining which of the first tuner C1 and the second tuner C2 has a higher noise reception sensitivity. That is, the estimation unit 20B uses the antenna that is easier to detect noise from the first antenna A1 or the second antenna A2 as the antenna for noise detection.

[0065] Then, the estimation unit 20B fixes the switch SW so that a received signal is input from a tuner with high noise reception sensitivity. When the switch SW is fixed, the estimation unit 20B estimates the noise N contained in the first received signal St1 and the second received signal St2 from the signal input from the noise detection tuner C3 via the BPF 15, and generates a noise replica based on the estimated noise.

[0066] The noise replicas generated by the estimation unit 20B are input to the respective removal units 30A via the adjustment unit 50. Then, the removal units 30A input the output signals, resulting from removing the noise replicas from the first received signal St1 or the second received signal St2, to the demodulation unit 40. After being demodulated by the demodulation unit 40, the output signals are diversity-combined by the combination unit 60 and output to a speaker or a display (not shown).

[0067] In this way, in the receiving device 10B according to the third embodiment, both the first tuner C1 and the second tuner C2 receive broadcast waves, and the noise detection tuner C3 is set to the noise detection frequency.

[0068] Therefore, in the receiving device 10B according to the third embodiment, even when broadcast waves are received by both the first tuner C1 and the second tuner C2, noise can be appropriately removed.

[0069] In the above-described embodiment, the receiving device 10 is mounted on a vehicle, but the present invention is not limited to this. Also, the configurations of the first to third embodiments may be used in appropriate combinations.

[0070] Further advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. [Explanation of symbols]

[0071] 10, 10A, 10B receiving device 20, 20A, 20B estimation section 30, 30A removal section C1 1st tuner C2 Second tuner C3 Noise Detection Tuner A1 First Antenna A2 Second antenna

Claims

1. A receiving device that performs diversity combining of broadcast waves received by both a first tuner and a second tuner, an estimation unit that estimates noise contained in the broadcast waves received by the first tuner based on a reception signal of the second tuner set to a reception frequency at which no broadcast waves are present when diversity combining is not being performed; a removal unit that removes the noise estimated by the estimation unit from the broadcast wave received by the first tuner; A receiving device comprising:

2. The estimation unit a value obtained by shifting a peak frequency included in the received signal of the second tuner by a difference between a first frequency which is a received frequency of the first tuner and a second frequency which is a received frequency of the second tuner is estimated as the frequency of the noise; 2. The receiving device according to claim 1,

3. The estimation unit When a frequency obtained by integrally multiplying or dividing a peak frequency included in the received signal of the second tuner is included in a reception frequency band of the broadcast wave received by the first tuner, the frequency is estimated as the frequency of the noise.

2. The receiving device according to claim 1,

4. The estimation unit Identifying a frequency interval of peaks included in the received signal of the second tuner, and estimating, as the frequency of the noise, one of a plurality of frequencies arranged at the frequency interval that is included in the reception frequency band of the broadcast wave received by the first tuner.

2. The receiving device according to claim 1,

5. The estimation unit a plurality of second frequencies, which are reception frequencies of the second tuner, are set, and the frequency interval is determined from a peak frequency included in the reception signal of the second tuner set to each of the second frequencies; 5. The receiving device according to claim 4, wherein:

6. The estimation unit Identifying timing of pulse noise included in the received signal of the second tuner, and estimating the timing as timing of pulse noise included in the broadcast wave received by the first tuner.

2. The receiving device according to claim 1,

7. The removal unit Suppressing or cutting off the output of the broadcast wave received by the first tuner in accordance with the timing.

7. The receiving device according to claim 6, wherein:

8. The estimation unit extracting pulse noise contained in the received signal received by the second tuner, and estimating, as the noise, a signal obtained by shifting the frequency of the pulse noise by a difference between a first frequency, which is a reception frequency of the first tuner, and a second frequency, which is a reception frequency of the second tuner; 2. The receiving device according to claim 1,

9. A noise removal method using a receiving device that performs diversity combining of broadcast waves received by both a first tuner and a second tuner, an estimation step of estimating noise contained in the broadcast waves received by the first tuner based on a reception signal of the second tuner set to a reception frequency where no broadcast waves are present when diversity combining is not being performed; a removal step of removing the noise estimated in the estimation step from the broadcast wave received by the first tuner; A noise removal method comprising:

Images