Demodulator

Abstract

A demodulator (100) comprising: a demodulation element (10) which outputs a demodulated signal which is demodulated from a modulated signal; an integration element (60a) which integrates the demodulated signal; a zone detection element (60b) which detects a replacement target zone in the demodulated signal based on an integrated signal output by the integration element (60a); and a replacement element (60c) which replaces a signal of the replacement target zone in the demodulated signal with a replacement target signal; wherein the demodulation element (10) comprises: an orthogonal demodulator (20) which demodulates from the modulated signal, which is FM modulated, an I signal and a Q signal which are orthogonal to each other; an A / D conversion element (30) which converts the I signal and the Q signal, which are in an analog form and are received by the orthogonal demodulator (20), into digital signals;a filter element (40) which cuts out a high-frequency band higher than a predetermined cut-off frequency from the I signal and the Q signal, which have been converted into digital signals by the A / D conversion element (30); and an FM demodulator (50) which outputs the demodulated signal obtained by correcting a differential value of the arctangent of the I signal and the Q signal to lie within a predetermined numerical range, wherein the differential value is obtained by differentiating the arctangent of the I signal and the Q signal received by the filter element (40).

Description

[0001] The contents of the following Japanese patent applications are incorporated herein by reference: Number 2015-170911, submitted on August 31, 2015. Application number PCT / JP 2016 / 074412, submitted on August 22, 2016. BACKGROUND Technical area

[0002] The present invention relates to a demodulator. State of the art

[0003] One modulation method for converting a signal, such as an audio signal, into a radio wave is frequency modulation (FM modulation), which changes the frequency of a carrier wave according to the amplitude of a signal wave. A signal that is FM modulated (FM signal) is demodulated in a demodulator in the following steps: converting the FM signal into I / Q signals that are orthogonal to each other, for example, using an arctangent detection method; obtaining an angle (that is, an arctangent value) θ = tan -1 (Q / I), formed by the I / Q signals; and calculating a time differential value of it (simply called the differential value) Δθ (=dθ / dt).

[0004] In this arctangent detection method, it is known that pulse noise (also referred to as weak electric field noise) is generated when an electric field is weak. Therefore, when demodulating a weak electric field signal, it is necessary to remove this pulse noise. Such pulse noise can be removed by passing a weak electric field signal through a low-pass filter (see, for example, patent document 1). Patent document 1: Japanese patent publication number 2009-296307

[0005] However, when a weak electric field signal passes through a low-pass filter, not only is pulse noise removed, but also a signal component from a high-frequency band, which can lead to degradation of the demodulated signal. Therefore, it is desirable to use a noise suppressor that removes pulse noise from a weak electric field signal. A demodulator that uses a noise suppressor removes weak electric field noise, for example, in the following steps: from values ​​of demodulated signals sampled at a constant interval, comparing a current value with a previously sampled value; and, if a large difference is found, determining that weak electric field noise has been generated, and replacing the demodulated signal with an empty signal (blind signal).

[0006] However, it is specified, for example, that an arctangent value detected during arctangent detection lies within a range of 2π from -π to +π. It is assumed that differential values ​​of arctangent values ​​are normalized accordingly so that they also lie within a range of 2π from -π to +π. For example, if a value of +1.1π is obtained by differentiating detected arctangent values, the differential value is normalized to -0.9π. Accordingly, normalizing differential values ​​of arctangent values ​​in this way can lead to faulty demodulation, such as the misdetection of pulse noise. SUMMARY (Element 1)

[0007] A demodulator can include a demodulation element that outputs a signal demodulated from a modulated signal. The demodulator can include an integration element that integrates the demodulated signal. The demodulator can include a zone detection element that detects a replacement target zone in the demodulated signal based on an integrated signal output by the integration element. The demodulator can include a replacement element that replaces a signal of the replacement target zone in the demodulated signal with a replacement target signal. (Element 2)

[0008] The integration element can include a high-pass filter and integrate the demodulated signal passed through the high-pass filter. (Element 3)

[0009] The integration element can include an absolute value calculation element, which calculates an absolute value of a signal integrated from the demodulated signal. (Element 4)

[0010] The demodulator may further include a reduction filter, which reduces the data rate of the demodulated signal passed through the replacement element. (Element 5)

[0011] The zone detection element can include a comparison element which detects a noise zone of the demodulated signal based on a comparison result of the integrated signal with reference to a reference value.

[0012] The zone detection element can include a determining element that extends the noise zone and determines the replacement target zone. (Element 6)

[0013] The replacement element can include a low-pass filter into which the demodulated signal is input and which outputs the replacement target signal. (Element 7)

[0014] The demodulation element can include an orthogonal demodulator, which demodulates an I signal and a Q signal, which are orthogonal to each other, from the modulated signal, which is FM modulated.

[0015] The demodulation element can include an FM demodulator, which outputs the demodulated signal obtained by differentiating an arctangent of the I signal and the Q signal. (Element 8)

[0016] The FM demodulator can output the demodulated signal obtained by correcting a differential value of the arctangent of the I signal and the Q signal to lie within a predetermined numerical range. (Element 9)

[0017] The replacement target zone can be a zone in which pulse noise is at least present, where the pulse noise is generated due to a normalization of a differential value of an arctangent.

[0018] The summary section need not describe all necessary features of the embodiments of the present invention. The present invention may also be a subcombination of the features described above. List of characters Fig. Figure 1 shows a configuration of a demodulator according to the present embodiment. Fig. Figure 2 shows a configuration of the demodulation element. Fig. Figure 3 shows a configuration of the noise reduction element. Fig. Figure 4A shows an example of arctangent values. Fig. 4B shows an example of differential values ​​which represent the arctangent values ​​from Fig. 4A are calculated, and the demodulated signal, which is calculated by normalizing the differential values. Fig. 4C shows an example of a signal produced by filtering the demodulated signal from Fig. 4B received signal. Fig. Figure 5 schematically shows an output of the integration element included in the noise reduction element. Fig. Figure 6A shows an example of a demodulated signal comprising weak electric field noise. Fig. Figure 6B shows an example of an output from the integration element when the demodulated signal is from Fig. 6A is entered into the noise reduction element. DESCRIPTION OF EXAMPLE EXECUTION FORMS

[0019] The invention is described below in terms of its embodiments. However, the embodiments described below are not intended to limit the claimed invention. Likewise, not all combinations of the features described in the embodiments are necessarily required to achieve the invention.

[0020] Fig. Figure 1 shows a configuration of a demodulator 100 according to the present embodiment. The demodulator 100 It is a device that receives a signal modulated onto a radio wave and demodulates the received signal using arctangent wave detection. During arctangent wave detection, the demodulator normalizes the signal. 100A differential value of an arctangent, for example, is normalized to fall within a range of -π to +π. However, if there is a lot of noise in a weak electric field, the differential value of an arctangent can exceed the range described above due to an error in the arctangent values. Therefore, the demodulator normalizes the value. 100 a differential value of an arctangent to lie within the range described above. For example, if a differential value of an arctangent is equal to +1.1π, the demodulator normalizes it. 100 the differential value to -0.9π. The demodulator 100 According to the present embodiment, it is designed to perform a suitable demodulation process in order to prevent faulty demodulation due to normalization of a differential value of an arctangent value in this way, thereby adequately removing noise from the received signal.

[0021] It should be noted that in the present embodiment it is assumed that the radio wave is directed at V FM = Csin (ω c t + m∫V s dt) by changing the frequency of a carrier wave V c = Csin(ω c t) corresponding to an amplitude of a signal wave V s FM modulated. Here, ω c = 2πf c with a carrier wave frequency f c and m is a constant.

[0022] The demodulator 100 includes a demodulation element 10 , a noise reduction element 60 and a filter element 70 .

[0023] The demodulation element 10 The demodulation element demodulates a signal that is modulated into the received RF signal (modulated signal) and outputs the demodulated signal. 10 includes an orthogonal demodulator 20, an AD conversion element 30 , a filter element 40and an FM demodulation element 50 .

[0024] The orthogonal demodulator 20 receives the radio wave V FM The device uses an antenna to demodulate the received RF signal into an I signal and a Q signal, which are orthogonal to each other. This is the orthogonal demodulator. 20 includes a local transmitter 26 and mixer 22 and 24 The local transmitter 26 generates two orthogonal local signals cos(ω) c t) and sin(ω c t) with a frequency f c, which are orthogonal to each other, and sends the signals to the mixers. 22 and 24 Each one off. The mixer 22 mixes the received signal RF with the orthogonal signal sin(ω) c t) (that is, multiplication) to generate the I signal (I=V) FM sin(w c t)). The mixer 24 multiplies the received RF signal by the orthogonal signal cosine (wc t) to generate the Q signal (Q=V FM cos(w c t)). The generated I and Q signals are sent to the A / D conversion element. 30 issued.

[0025] The AD conversion element 30 It converts the I signal and the Q signal in analog form into digital signals. This is the A / D conversion element. 30 Includes AD converters (ADCs) 32 and 34.

[0026] The AD Converters (ADCs) 32 and 34 are with the mixers 22 and 24 connected to each of the I signal and the Q signal, which are supplied by the mixers 22 and 24 The input signals are converted into digital signals. The sampling rates of the AD converters 32 and 34 are sufficiently higher than the output frequency of the demodulator. 100 , for example, twice or more, up to approximately 100 times. That is, the AD converters 32 and 34Overriding input signals. The converted I and Q signals are sent to the filter element. 40 issued.

[0027] The filter element 40 It reduces the data rates of the signals input into it (that is, downsampling). The filter element 40 includes two reduction filters 42 and 46 and two sampling frequency converters 44 and 48 .

[0028] The reduction filters 42 and 46 receive the I signal and the Q signal from the AD converters 32 and 34 , cut out a section of a high-frequency band and send the signals to the sampling frequency converters 44 and 48 Each one is off. A low-pass filter can be described as a reduction filter. 42 and 46 They can be used. Section frequencies can be determined according to the downsampling rates of the sampling rate converter. 44 and 48 be appropriately determined.

[0029] The sampling frequency converters 44 and 48 are equipped with the reduction filters 42 and 46 connected to download sampling of the I and Q signals, which are supplied by the filters. 42 and 46 are entered, whose sections of the high-frequency band are clipped. The downsampling rates of the sampling frequency converters 44 and 48 are, for example, half or less.

[0030] The filter element 40 removes carrier wave components from the I signal and the Q signal by downsampling the I signal and the Q signal and passes the signals to the FM demodulation element with only a signal wave component 50 This occurs during downsampling through the filter section. 40 the I signal and the Q signal through the sampling frequency converters 44 and 48 via the reduction filters 42 and 46Each one is performed, which prevents aliasing due to down sampling.

[0031] The FM demodulation element 50 is with the filter element 40 connected to receive the RF signal by means of the filter element 40 The input I signal and the Q signal are demodulated. The demodulated signals are then sent to the noise reduction element. 60 The exact configuration of the FM demodulation element is displayed. 50 is described below.

[0032] The noise reduction element 60 is with the FM demodulation element 50 connected to the FM demodulation element 50 The input demodulated signals are processed, and any noise contained within the signal is removed. The demodulated signal, from which the noise has been removed, is then sent to the filter element. 70output. The exact configuration of the noise reduction element. 60 is described below.

[0033] The filter section 70 is with the noise reduction element 60 connected to downsample the demodulated signal, which is then processed by the noise reduction element 60 The input is a distance from which a noise is located. The filter element 70 includes a reduction filter 72 and a sampling frequency converter 74 .

[0034] The reduction filter 72 The demodulated signal is received from the noise reduction element. 60 , cuts off a section of the high-frequency band and sends the signal to the sampling frequency converter 74 A low-pass filter can be described as a reduction filter. 72 can be used. A section frequency can be determined according to a downsampling rate of the sampling rate converter. 74be appropriately determined.

[0035] The sampling frequency converter 74 is with the reduction filter 72 connected to downsample the demodulation signal input from filter 72, which cuts off a section of the high-frequency band. The downsampling rate of the sampling frequency converter 74 For example, half or less.

[0036] In this process, downsampling through the filter occurs. 70 the demodulated signals through the sampling frequency converter 74 via the reduction filter 7 softening is performed, which can prevent aliasing due to downsampling.

[0037] It should be noted that by using the filter elements 40 and 70 In combination, signals which are processed by the AD converter 32 and 34The oversampling rates are reduced to correspond to a specific sampling rate. Accordingly, the downsampling rates of filter elements 40 and 70 are determined such that the reciprocal of their product equals the sampling rates of the respective AD converters. 32 and 34. For example, with reference to approximately 20 times the sampling rate of the AD converter. 32 and 34 The inverse of the product of the respective downsampling rates of filter elements 40 and 70 is approximately one-twentieth. Accordingly, for example, if signals are only processed by the filter element... 40 are oversampled, reduced to belong to a specific sampling rate, where the filter element 70 is not necessarily intended.

[0038] Fig. Figure 2 shows the configuration of the FM demodulation element. 50 The FM demodulation element 50 includes a wave detector 52 and a differentiation element54 .

[0039] The wave detector 52 is a wave detector which uses an arctangent wave detection method and calculates an arctangent value θ = tan -1 (Q / I) using the I signal and the Q signal, which are provided by the filter element 40 The values ​​are entered. Here, the arctangent value θ is calculated so that it falls within a predetermined numerical range, for example, within a range of 2π from -π to +π. The calculation result is then passed to the differentiation element. 54 issued.

[0040] The differentiation element 54 is with the wave detector 52 connected to obtain a differential value for the arctangent values, which are determined by the wave detector 52The input values ​​are used to calculate a time differential Δθ (=dθ / dt) or a difference. This is corrected according to the arctangent value θ, which is calculated so that it falls within the predetermined numerical range for the wave detector. 52 , the differentiation element 54 The differential value of the arctangent is adjusted so that it falls within a predetermined numerical range, which here is the same range as the numerical range of the arctangent θ (also referred to as normalization). The result of the calculation is then applied to the noise reduction element. 60 as the demodulated signal.

[0041] Fig. Figure 3 shows the configuration of the noise reduction element. 60 In the present embodiment, noise suppression is used as the noise removal element. 60 used. The noise reduction element 60includes an integration element 60a, a zone detection element 60b and a replacement element 60c.

[0042] The integration element 60a converts the demodulated signal into a form that allows for the extraction of faulty demodulation due to normalization of the differential value of the arctangent in the FM demodulation element. 50 The integration element 60a is suitable. It is designed to enclose a filter. 61 , of an integration element 62 and an absolute value calculation element 63 .

[0043] The filter 61 receives the demodulated signal from the FM demodulation element 50 , cuts off an offset which includes a section of the high-frequency band, in particular a carrier wave component, and passes the result to the integration element 62 A high-pass filter (HPF) can be described as the filter 61can be used. A section frequency can be suitably determined according to a carrier wave frequency.

[0044] The integration element 62 is with the filter 61 connected to integrate signals input by filter 61, and outputs the result (i.e., the integration result of the demodulated signals) to the absolute value calculation element. 63 out. In the present embodiment, the integration element integrates 62 Input signals are processed over a predetermined zone (also known as partial integration or zone integration). A zone for partial integration can be defined as one suitable for detecting faulty demodulation or pulse noise.

[0045] The absolute value calculation element 63 is with the integration element 62connected to calculate an absolute value of an integration result of the demodulated signal, which is derived from the integration element 62 is entered, and outputs the result as an integrated signal to the zone detection element. 60b This allows faulty demodulation to be detected, regardless of whether the demodulated signal has a positive or negative value.

[0046] The zone detection element 60b It detects a replacement target zone, which is to be replaced in the demodulated signal (a so-called blank zone), using the integrated signal. The zone detection element 60b includes a comparison element 64 and a determining element 65.

[0047] The comparison element 64 is with the integration element 60a connected to the integration element 60aThe input integrated signal is compared to a reference value, and based on the result, a zone of noise (referred to as a noise zone) contained within the demodulated signal is detected. If the integrated signal is higher than the reference value, a logic high pulse is generated and sent to the determining element. 65 The reference value is output as a comparison result signal. It should be noted that the reference value must be determined as a level suitable for extracting a faulty demodulation and removing noise. For example, the reference value can be set to be greater than the amplitude of a weak electric field noise in order to extract only a faulty demodulation and replace the demodulated signal.

[0048] The determining element 65 is an impulse stretcher, which is connected to the comparison element 64is connected to determine the time width of one in which the comparison element is located. 64 The entered comparison result signal included pulses to extend. This allows the determining element to 65 the noise zone for determining a replacement target zone and this as a replacement target zone signal for specifying the replacement target zone to a replacement element 68 outputs which is in the replacement element 60c is included.

[0049] The conductor element 60c The replacement element replaces a signal in the replacement target zone of the demodulated signal with a replacement target signal. 60c includes delay circuits 66a and 66b , a filter 67 and the replaced element 68 .

[0050] The delay circuit 66a receives and delays the demodulated signal from which it originates in the demodulation element. 50and sends the signal to the delay circuit 66b (and the filter) 67 ) off. The delay circuit 66b further delays this through the delay circuit 66a delayed demodulated signal and passes the signal to the replacement element 68 The demodulated signal is sent to the replacement element. 68 through the delay circuits 66a and 66b entered, corresponding to a time at which the replacement target zone signal is sent to the replacement element 68 is entered.

[0051] The filter 67 is connected to the delay circuit 66a to cut out a section of the high-frequency band of the demodulated signal via the delay circuit and to generate the replacement target signal, and outputs the signal to the replacement element 68 A low-pass filter (LPF) can be considered the filter 67can be used. This allows the filter to 67 The replacement target signal is generated, from which a noise peak generated in the demodulated signal is extracted. A delay time of the delay circuit is used in this process. 66b equal to the delay time of the filter 67 set. This allows the filter to 67 the replacement target signal into the replacement element 68 corresponding to a time at which the demodulated signal is entered into the replacement element 68 via the delay circuits 66a and 66b is entered.

[0052] The replacement element 68 replaces the delay circuit 66b input demodulated signal with the filter 67 generated replacement target signal, if the one from the zone detection element 60bThe entered replacement target zone signal is a logical high, meaning that the replacement target zone signal indicates the replacement target zone.

[0053] It should be noted that the noise reduction element described above... 60 Noise is removed by replacing the demodulated signal with the replacement target signal, which is achieved by passing the demodulated signal through the filter. 67 is generated. Alternatively, the noise reduction element can be used. 60 Similarly, the demodulated signal can be replaced with the value of an empty signal or an input signal immediately before the replacement target zone. In such a case, for example, the replacement element can be... 68 (and the filter) 67 ) a D-type flip-flop (not shown) which is triggered by the replacement target zone signal to override the delay circuit 66a to retain the entered demodulated signals.

[0054] A faulty demodulation due to normalization of the differential value of an arctangent is described in more detail.

[0055] Fig. 4A shows an example of the arctangent values ​​obtained by the wave detector 52 of the FM demodulation element 50 are detected. In this example, the arctangent values ​​θ are defined as 0.6π, 0.7π, 0.8π, 0.9π, 0.0π, 1.1π, 1.2π, and 1.3π for eight samples, each at clock times. 0 until 7 calculated.

[0056] Fig. 4B shows differential values ​​(solid lines) which are determined by the differentiation element 54 are to be calculated for the arctangent values ​​from Fig. 4A and the demodulated signal (dashed lines), which are output by normalizing the differential values. The differential values ​​are given as 0.1π, 0.1π, 0.1π, -0.9π, 1.1π, 0.1π, and 0.1π for 7 samples at the respective clock times. 1until 7 calculated. That is, the differential values ​​include noise of a peak shape with a negative and a positive amplitude at each of the clock times. 4 and 5 On the other hand, if the differential values ​​are normalized to fall within a range of 2π from -π to +π, the demodulated signal is output at 0.1π, 0.1π, 0.1π, -0.9π, -0.9π, 0.1π, and 0.1π for the respective 7 samples. In this way, normalizing the differential values ​​of the arctangent values ​​causes faulty demodulation, such that the differential value is 1.1π at the clock. 5 The demodulation signal comprises noise with a peak waveform and a negative amplitude, as well as erroneous demodulation at clock times. 4 and 5 and the corresponding values ​​are the same, which means that this is a broad noise with a negative amplitude of the clock time. 4up to the clock time 5 includes.

[0057] Fig. 4C shows an example of a signal produced by filtering the demodulated signal from Fig. 4B received signal. If the differential values ​​of the arctangent values ​​are as the demodulated signal in which it is in the demodulation element 50 output without being normalized indicates this in the clock times. 4 and 5 in Fig. 4B generated noise with an average value that is neither positively nor negatively biased. Therefore, the noise is considered pulse noise, generated by passing the demodulated signal through the noise reduction element. 60 cut out or as harmonic components by passing the demodulated signal through the attenuation filter 72 , which is in the filter element 70The enclosed area is cut out. As a result, a noise-free signal is output (solid lines). On the other hand, if the differential values ​​of the arctangent values ​​are normalized, the signal value at clock time is... 5 in Fig. 4B equals -0.9π, where its original signal value is 1.1π. Therefore, the signals are demodulated to exhibit strongly negatively charged values, even when the signal values ​​are averaged. Accordingly, the demodulated signal is output without any sections being cut out. Likewise, if the demodulated signal is passed through the filter element... 70 included reduction filters 72When the signal is passed through, it is output with noise (dashed lines). This is because the signal, which has a strong negative bias, lies within the low-frequency band at clock times 4 and 5, even when the values ​​are averaged, and is not appropriately filtered out.

[0058] The principle of noise processing by the noise reduction element 60 is described. An exemplary case is described here, in which the demodulated signal and the differential value of the arctangent are shown in Fig. 4B, into the noise reduction element 60 as an input signal.

[0059] Fig. Figure 5 shows an example of an output (dashed lines) of the integration element. 62 , when the differential values ​​of the arctangent values ​​are entered into the noise reduction element 60The signal is input without being normalized. The demodulated signal passes through the filter. 61 included high-pass filters before passing through the integration element 62 The signal passes through, so that a signal component contained in the demodulated signal which falls within the low-frequency band is suppressed, and a noise component which falls within the high-frequency band is extracted. Signals from which the noise components have been extracted are processed by the integration element. 62 integrated.

[0060] Due to a problem with the cycle time 4 generated noise and one at the clock time 5 The outputs of the integration element show the generated faulty demodulation. 6 strongly negative values ​​for cycle times 4 and 5Accordingly, a faulty demodulation can be detected by detecting an integral value with an absolute value that is greater than the reference value.

[0061] Fig. 6 out Fig. Figure 6B each shows an example of actions of the integration element. 62 (Integration element 60a). Here, as an example, the weak electric field noise component is described in Fig. 6 A shown demodulated signal into the noise reduction element 60The demodulated signal is generally categorized into three components: a monotonically decreasing carrier wave component, a component of a signal source and weak electric field noise, fluctuating with a minimum amplitude relative to the carrier wave component, and a component of faulty demodulation, each increasing sharply at clock times of 7.5 and 8.1 ms. It should be noted that for the clarity of the faulty demodulation component in Fig. 6A Values ​​of the carrier wave component are shown without normalization to fall within a predetermined numerical range (range of 2π from -π to +π).

[0062] The demodulated signal from Fig. 6A is a zone defined by the integration element 62 is so integrated that the in Fig.The integrated signal shown in Figure 6B is output. The integrated signal is generally categorized into three components: a carrier wave component, which is constant over time; a component of a signal wave and weak electric field noise, fluctuating with a minimum amplitude relative to the carrier wave component; and a component of faulty demodulation, which occurs at clock times of 7.5 and 8.1 ms. Two components of faulty demodulation appear as peaks with a large amplitude. Accordingly, by comparison using the comparator element, 64 of the integrated signal from the integration element 60a A faulty demodulation can be clearly distinguished using a reference value and detected from a signal wave and a weak electric field noise.

[0063] It is pointed out that, although the demodulator 100According to the present embodiment, which is described as one that demodulates a radio wave which is FM modulated, this is not limited to this, but can also be a demodulator that demodulates a radio wave which is modulated by a modulation method, such as FSK modulation, for example, which causes faulty demodulation due to a normalization of a differential value of an arctangent.

[0064] It is noted that although the demodulator 100 as described in the present invention, for generating by the orthogonal demodulator 20 of the I signal and the Q signal from the received RF signal and for demodulating the signals by the FM demodulation element 50 included wave detector 52Using the arctangent wave detection method, it can alternatively use a Hilbert converter to pass the received RF signal through the Hilbert converter and then the signal through the wave detector. 52 to demodulate.

[0065] While the embodiments of the present invention have been described, the technical scope of protection of the invention is not limited to the embodiments described above. It is obvious to the person skilled in the art that various modifications and improvements can be added to the embodiments described above. It is equally obvious from the scope of protection of the claims that embodiments added by such modifications or improvements may be included in the technical scope of protection of the invention.

[0066] The operations, procedures, steps, and stages of any process performed by a device, system, program, and method shown in the claims, embodiments, or diagrams may be performed in any order, as long as the order is not specified by "preceding," "before," or similar terms, and as long as the output of a preceding process is not used in a subsequent process. Even if the process flow is described using terms such as "first" or "next" in the claims, embodiments, or diagrams, this does not necessarily mean that the process must be performed in that order.

[0067] As can be clearly seen from the above description, the demodulator can be implemented according to one embodiment of the present invention. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2016 / 074412

[0001]

Claims

[1] A demodulator comprising: a demodulation element that outputs a demodulated signal which is demodulated from a modulated signal; an integration element that integrates the demodulated signal; a zone detection element which detects a replacement target zone in the demodulated signal based on an integrated signal output by the integration element; and a replacement element which replaces a signal of the replacement target zone in the demodulated signal with a replacement target signal. [2] Demodulator according to claim 1, wherein the integration element comprises a high-pass filter and integrates the demodulated signal passing through the high-pass filter. [3] Demodulator according to claim 1, wherein the integration element comprises an absolute value calculation element which calculates an absolute value of a signal integrated from the demodulated signal. [4] Demodulator according to claim 1, further comprising a reduction filter which reduces a data rate of the demodulated signal passing through the replacement element. [5] Demodulator according to claim 1, wherein the zone detection element comprises: a comparison element that detects a noise zone of the demodulated signal based on a comparison result of the integrated signal with respect to a reference value; and a determining element that extends the noise zone and defines the replacement target zone. [6] Demodulator according to claim 1, wherein the replacement element comprises a low-pass filter into which the demodulated signal is input and which outputs the replacement target signal. [7] Demodulator according to claim 1, wherein the demodulation element comprises: an orthogonal demodulator which demodulates from the modulated signal, which is FM modulated, an I signal and a Q signal which are orthogonal to each other; and an FM demodulator which outputs the demodulated signal obtained by differentiating an arctangent of the I signal and the Q signal. [8] Demodulator according to claim 7, wherein the FM demodulator outputs the demodulated signal which is obtained by correcting a differential value of the arctangent of the I signal and the Q signal to lie within a predetermined numerical range. [9] Demodulator according to claim 1, wherein the replacement target zone is a zone in which pulse noise is at least present, wherein the pulse noise is generated due to normalization of a differential value of an arctangent.