JP2017055201A - Radio wave receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio wave receiver capable of receiving radio waves more accurately.SOLUTION: A radio wave receiver has a bandpass filter, a frequency detector, a first extraction unit, a second extraction unit, and a determination unit. The bandpass filter passes a reception signal of a predetermined frequency band out of the reception signals. The frequency detector detects a first frequency indicating a higher signal level than a reference level, in a lower frequency band than the reference frequency included in the predetermined frequency band. The first extraction unit extracts a reception signal of a first frequency from the reception signals. The second extraction unit extracts a reception signal of a second frequency, two times that of the first frequency, from the reception signals. The determination unit determines whether or not a fundamental wave and a higher harmonic wave of the reception signal are included in the predetermined frequency band, on the basis of a relationship of the reception signal of the first frequency, and the reception signal of the second frequency.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a radio wave receiver.

  There is a growing need to widen the frequency band that can be received by radio wave receivers. However, the wider the receivable frequency band, the higher the possibility of receiving a harmonic component received signal in addition to the fundamental component received signal. For this reason, in the radio wave receiving device, the wider the dynamic range of the received signal, the higher the possibility of misrecognizing the received signal of the higher harmonic component of the received signal as the received signal of the fundamental wave component. Could not be received.

JP 2007-208790 A

  The problem to be solved by the present invention is to provide a radio wave receiver that can receive radio waves more accurately.

  The radio wave receiving apparatus according to the embodiment includes a bandpass filter, a frequency detection unit, a first extraction unit, a second extraction unit, and a determination unit. The band-pass filter passes a reception signal in a predetermined frequency band among reception signals received by an antenna. The frequency detection unit detects a first frequency indicating a signal level higher than a reference level in a frequency band included in the predetermined frequency band and lower than a reference frequency included in the predetermined frequency band. The first extraction unit extracts a reception signal having a first frequency detected by the frequency detection unit from a reception signal received by the antenna. The second extraction unit extracts a reception signal having a second frequency that is twice the first frequency detected by the frequency detection unit from the reception signal received by the antenna. The determination unit is configured to determine the predetermined frequency based on a relationship between a reception signal having a first frequency extracted by the first extraction unit and a reception signal having a second frequency extracted by the second extraction unit. It is determined whether the fundamental wave and the harmonics of the received signal are included in the frequency band.

The block diagram which shows the structure of the electromagnetic wave receiver 1 of 1st Embodiment. The figure which shows the frequency band of the received signal passed by BPF14 and 1st DDC21 in 1st Embodiment. The block diagram which shows the structural example of DDC of 1st Embodiment. The figure which shows the signal contained in the frequency spectrum signal produced | generated by the FFT process part 23 in 1st Embodiment. The figure which shows the pass frequency band BW (DDC2) of 2nd DDC34 and the pass frequency band BW (DDC3) of 3rd DDC36 in 1st Embodiment. The figure which shows an example of the relationship between I signal and Q signal (IQ1) and I signal and Q signal (IQ2) in 1st Embodiment. The figure which shows another example of the relationship between I signal and Q signal (IQ1) and I signal and Q signal (IQ2) in 1st Embodiment. The block diagram which shows the structure of the electromagnetic wave receiver 1A of 2nd Embodiment. The figure which shows the filter characteristic table 39 in 2nd Embodiment. The figure which shows the relationship between the frequency spectrum of the received signal in 2nd Embodiment, and the pass frequency band of BPF14 and 1st DDC21. The figure which shows the level of the signal suppressed by BPF14 and 1st DDC21 in 2nd Embodiment. The figure explaining increasing the level of the received signal suppressed by BPF14 and 1st DDC21 in 2nd Embodiment. The figure explaining the signal level in the low frequency side rather than the pass frequency band BW of BPF14 and 1st DDC21 in 2nd Embodiment. The block diagram which shows the modification of embodiment.

  Hereinafter, a radio wave receiving apparatus according to an embodiment will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram illustrating a configuration of a radio wave receiver 1 according to the first embodiment. The radio wave receiver 1 according to the first embodiment includes a reception antenna 10, a reception amplifier 12, a BPF (Band-pass filter) 14, an AD (Analog-to-digital) converter 16, a reception signal processing unit 20, and the like. The harmonic determination unit 30 is provided.

  The receiving antenna 10 receives a radio wave radiated into space and generates a received signal. The reception signal generated by the reception antenna 10 is supplied to the reception amplifier 12. The reception amplifier 12 amplifies the amplitude of the reception signal. The BPF 14 passes a reception signal in a desired frequency band among frequency bands of the reception signal that is an analog signal. The AD converter 16 converts the reception signal that has passed through the BPF 14 into a digital signal and outputs the digital signal to the reception signal processing unit 20 and the harmonic determination unit 30.

  The reception signal processing unit 20 includes a first DDC (Digital Down Converter) 21, a first NCO (Numerically Controlled Oscillator) 22, an FFT processing unit 23, and a reception processing unit 24.

  The first DDC 21 passes a received signal in a desired frequency band (first frequency band) in the frequency band of the received signal among the received signals output from the AD converter 16. FIG. 2 is a diagram illustrating a frequency band of a reception signal that is passed by the BPF 14 and the first DDC 21 in the first embodiment. The first DDC 21 is supplied with a reception signal having a sampling frequency fs (for example, 1 GHz) in the AD converter 16. The first DDC 21 passes the received signal in the pass frequency band BW (DDC) of the frequencies fb1 to fb2 narrower than the pass frequency band BW (BPF) of the BPF 14.

  FIG. 3 is a block diagram illustrating a configuration example of the DDC according to the first embodiment. The first DDC 21 includes, for example, mixers 100 and 104 and decimation filters 102 and 106. The decimation filters 102 and 106 are digital filters such as a CIC (Cascaded Integration-Comb) filter and an FIR (Finite Impulse-Response) filter, for example.

  The reception signals output from the AD converter 16 are supplied to the mixers 100 and 104, respectively. The mixer 100 is supplied with the Sin wave generated by the first NCO 22, and the mixer 104 is supplied with the Cos wave generated by the first NCO 22. For example, when it is desired to tune to a reception signal having a frequency of 1/4 fs, the mixer 100 is multiplied by a Sin (1/4 fs) wave, and the mixer 104 is multiplied by a Cos (1/4 fs) wave. Converts a 1/4 fs input signal into a DC (direct current component) signal. Thereafter, the converted signal is suppressed to a signal in a necessary band by a decimation filter (102 or 106). For example, the decimation filter 102 performs 1/2 decimation processing in which the frequency band of the received signal is halved, and outputs a baseband signal (I (In-phase) signal) to the FFT processing unit 23. The decimation filter 106 performs, for example, a 1/2 decimation process in which the frequency band of the received signal is halved, and a baseband signal (Q (Quadrature-phase) whose phase is shifted by 90 degrees with respect to the I signal. Signal) to the FFT processor 23.

  The FFT processing unit 23 performs a Fourier transform process on the I signal or the Q signal output from the first DDC 21 for each processing period for processing the received radio wave. Thereby, the FFT processing unit 23 generates a frequency spectrum signal representing a signal level for each frequency in the frequency band that has passed through the first DDC 21. The FFT processing unit 23 outputs the frequency spectrum signal to the reception processing unit 24 and the harmonic determination unit 30.

  The reception processing unit 24 performs reception processing using the frequency spectrum signal output from the FFT processing unit 23. Based on the determination result of the harmonic determination unit 30, the reception processing unit 24 removes a signal corresponding to the reception signal of the harmonic component from the signals included in the frequency spectrum signal. For example, the reception processing unit 24 performs a process of analyzing a received radio wave arriving at the reception antenna 10 as a reception process.

  The harmonic determination unit 30 determines whether or not the reception signal of the harmonic component with respect to the reception signal of the fundamental wave component is included in the reception signal. The harmonic determination unit 30 includes a band extraction unit 31, an oscillation control unit 32, a delay unit 33, a second DDC 34, a second NCO 35, a third DDC 36, a second NCO 37, and a determination unit 38.

  The band extraction unit 31 extracts a frequency spectrum signal in a frequency band lower than the reference frequency Fref from the frequency spectrum signal generated by the FFT processing unit 23. FIG. 4 is a diagram illustrating signals included in the frequency spectrum signal generated by the FFT processing unit 23 in the first embodiment. In the band extraction unit 31, for example, a reference frequency Fref is set based on an operation of an administrator who uses the radio wave receiver 1. The reference frequency Fref is an upper limit frequency of a frequency band in which both the fundamental wave and the second harmonic wave may be included in the frequency band of the received signal that has passed through the BPF 14 and the first DDC 21. The band extraction unit 31 desirably lowers the frequency of the reference frequency Fref from the viewpoint of suppressing the processing load on the frequency spectrum signal.

  As shown in FIG. 4, when the fundamental wave reception signal F0 (1) having the frequency fr (for example, 0.1 GHz) is present in the lower frequency band of the passing frequency band BW (DDC1) of the first DDC 21, the fundamental wave Of the first DDC 21 is present in the pass frequency band BW (DDC1) of the first DDC 21. The received signal 2F0 (1) of the second harmonic wave is present in the pass frequency band BW (DDC1) of the first DDC 21, so that the level is not suppressed by the BPF 14 and the first DDC 21, and is erroneously recognized as a signal based on the received radio wave. there is a possibility. On the other hand, when the received signal F0 (2) of the fundamental wave is present in a higher frequency band in the pass frequency band BW (DDC1) of the first DDC 21, the received signal 2F0 (2) of the second harmonic is the pass frequency band of the first DDC 21. It exists outside BW (DDC1). Since the second harmonic reception signal 2F0 (2) is outside the pass frequency band BW (DDC1) of the first DDC 21, the level is suppressed by the BPF 14 and the first DDC 21, and may be erroneously recognized as a signal based on the received radio wave. Is low.

  The oscillation control unit 32 detects a frequency (first frequency) indicating a signal level higher than the reference level Lref from the frequency spectrum signal extracted by the band extraction unit 31 (frequency detection unit). In the oscillation control unit 32, for example, a reference level Lref is set based on an operation of an administrator who uses the radio wave receiver 1. The reference level Fref is, for example, a signal level of the frequency spectrum signal extracted by the band extraction unit 31 that is processed as a reception signal instead of noise in the reception processing unit 24. The reference level Lref is preferably changed based on the distortion characteristic of the reception amplifier 12 with respect to the second harmonic and the dynamic range of the reception signal. The oscillation control unit 32 determines whether there is a frequency indicating a signal level that exceeds the reference level Lref included in the frequency spectrum signal.

  When the oscillation control unit 32 detects a frequency having a signal level exceeding the reference level Lref from the frequency spectrum signal, the oscillation control unit 32 oscillates the pseudo fundamental wave signal that changes at the frequency rf (first frequency) of the signal level. Is supplied to the second NCO 35. The oscillation control unit 32 outputs a control signal C2 for oscillating a pseudo second harmonic signal that changes at a frequency 2fr (second frequency) twice the pseudo fundamental wave signal frequency to the second NCO 37 at the same time as outputting the control signal C1. To do.

  Similar to the first DDC 21, the second DDC 34 and the third DDC 36 include mixers 100 and 104 and decimation filters 102 and 106. The mixer 100 and 104 of the second DDC 34 and the third DDC 36 are supplied with a received signal from the delay unit 33 during a processing period for processing the received radio wave. The delay unit 33 delays the reception signal output from the AD converter 16 by a predetermined time and outputs the delayed signal to the second DDC 34 and the third DDC 36. For example, the delay unit 33 delays the output of the reception signal for a period from the time when the reception signal is output by the AD converter 16 to the time when the control signals C1 and C2 are supplied to the second NCO 35 and the second NCO 37 and oscillated. Further, the Sin wave and the Cos wave (pseudo fundamental wave signal) oscillated by the second NCO 35 are supplied to the mixers 100 and 104 of the second DDC 34. The Sin wave and Cos wave (pseudo second harmonic signal) oscillated by the second NCO 37 are supplied to the mixers 100 and 104 of the third DDC 36.

  As a result, the second DDC 34 passes the reception signal in the pass frequency band BW (DDC2) centered on the frequency of the pseudo fundamental wave signal (first frequency) among the reception signals output from the AD converter 16. As a result, the second DDC 34 extracts the reception signal of the first frequency detected by the oscillation control unit 32 (frequency detection unit) from the reception signal received by the reception antenna 10 (first extraction unit).

  The third DDC 36 passes the reception signal in the pass frequency band BW (DDC3) centered on the frequency (second frequency) of the pseudo second harmonic signal among the reception signals output from the AD converter 16. As a result, the third DDC 36 extracts a reception signal having a second frequency that is twice the first frequency detected by the oscillation control unit 32 (frequency detection unit) from the reception signal received by the reception antenna 10. (Second extraction unit).

  FIG. 5 is a diagram illustrating the pass frequency band BW (DDC2) of the second DDC 34 and the pass frequency band BW (DDC3) of the third DDC 36 in the first embodiment. The pass frequency band BW (DDC2) and the pass frequency band BW (DDC2) are set to predetermined frequency bands narrower than the pass frequency band BW (DDC1).

  The second DDC 34 raises the I signal and the Q signal (IQ1) during a period in which a signal in the pass frequency band BW (DDC2) centered on the frequency fr of the pseudo fundamental wave signal is included in the received signal. The second DDC 34 raises the I signal and the Q signal (IQ2) during a period in which the signal of the pass frequency band BW (DDC3) centered on the frequency 2fr of the pseudo second harmonic signal is included in the received signal.

  The determination unit 38 is supplied with the I and Q signals (IQ1) output from the second DDC 34 and the I and Q signals (IQ2) output from the third DDC 36. Based on the relationship between the I signal and the Q signal (IQ1, the received signal of the first frequency) and the I signal and the Q signal (IQ2, the received signal of the second frequency), the determining unit 38 passes the pass frequency band BW ( It is determined whether or not both the fundamental wave and the second harmonic wave of the received signal are included in DDC1) (determination unit).

  FIG. 6 is a diagram illustrating an example of a relationship between the I signal and the Q signal (IQ1) and the I signal and the Q signal (IQ2) according to the first embodiment. FIG. 7 is a diagram illustrating another example of the relationship between the I signal and Q signal (IQ1) and the I signal and Q signal (IQ2) according to the first embodiment. IQ1 and IQ2, for example, are substantially the case when both the received signal F0 (1) of the fundamental wave of the frequency rf and the received signal 2F0 (1) of the second harmonic of the frequency 2fr are included as shown in FIG. It rises at the same time t1 and falls at substantially the same time t2. On the other hand, IQ1 and IQ2 rise at different times (t1 and t11) or different times when the received signal having the frequency of the pseudo fundamental wave signal and the received signal having the frequency of the pseudo second harmonic signal are different signals. It falls at (t2 and t12).

  When the relationship between IQ1 and IQ2 is as shown in FIG. 6, the determination unit 38 determines that the received signal of the pseudo second harmonic signal having the frequency 2rf is a second harmonic of the received signal having the frequency rf. It is determined that the received signal is 2F0. When the relationship between IQ1 and IQ2 is as shown in FIG. 7, the determination unit 38 receives a second harmonic wave of the received signal having the frequency of the pseudo second harmonic signal relative to the received signal having the frequency rf. It is determined that it is not a signal. The determination unit 38 outputs the determination result to the reception processing unit 24. The reception processing unit 24 performs reception processing by reducing the signal level of the frequency 2fr determined by the determination unit 38 as the second harmonic reception signal 2F0 from the frequency spectrum signal output by the FFT processing unit 23. . That is, the reception processing unit 24 processes the received signal while reducing the influence of the harmonics determined by the determination unit 38 to be included in the pass frequency band BW (DDC1).

  Further, the harmonic determination unit 30 determines whether or not the fundamental wave and the second harmonic wave are present in the pass frequency band BW (DDC1), but the fundamental wave, the second harmonic wave, and the third harmonic wave are passed through the pass frequency band BW. It may be determined whether or not it exists in (DDC1), and it may be determined whether or not higher harmonics are present in the pass frequency band BW (DDC1).

  According to the first embodiment described above, the reception signal received by the reception antenna 10 is included in the BPF 14 that passes the reception signal of the predetermined pass frequency band BW (DDC1) and the pass frequency band BW (DDC1). In addition, in a frequency band lower than the reference frequency Fref included in the pass frequency band BW (DDC1), a band extraction unit 31 and an oscillation control unit 32 (frequency detection) that detect a first frequency indicating a signal level higher than the reference level Lref. A second DDC 34 (first extraction unit) that extracts a reception signal of the first frequency detected by the band extraction unit 31 and the oscillation control unit 32 from the reception signal received by the reception antenna 10, and the reception antenna 10 Of the first frequency detected by the band extractor 31 and the oscillation controller 32 from the received signal received by the A third DDC 36 (second extraction unit) that extracts a reception signal of the second frequency, which is a double frequency, a reception signal of the first frequency extracted by the second DDC 34, and a second frequency extracted by the third DDC 36 And a determination unit 38 for determining whether the fundamental frequency and the harmonics of the reception signal are included in the pass frequency band BW (DDC1) based on the relationship with the frequency reception signal. According to the first embodiment, when both the fundamental wave and the harmonics of the received signal are included, it can be determined that the harmonics are included in the pass frequency band BW (DDC1). It is possible to receive radio waves more accurately by reducing the influence of harmonics from the signal.

(Second Embodiment)
Hereinafter, the radio wave receiver of the second embodiment will be described with reference to the drawings. In the following description of the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 8 is a block diagram illustrating a configuration of a radio wave receiver 1A according to the second embodiment. The harmonic determination unit 30A in the radio wave receiving device 1A of the second embodiment includes a filter characteristic table 39 in addition to the functions of the harmonic determination unit 30 in the first embodiment. FIG. 9 is a diagram illustrating a filter characteristic table 39 according to the second embodiment. The filter characteristic table 39 is data in which a correspondence relationship between the frequency band of the received signal and the suppression level [dB] of the received signal by the BPF 14 and the first DDC 21 is set. The frequency band of the received signal set in the filter characteristic table 39 is a lower frequency band than the frequency band through which the BPF 14 passes the received signal. The filter characteristic table 39 is set by the BPF 14 and the first DDC 21 to suppress, for example, the level of the 20 MHz reception signal by 30 dB and the level of the 90 MHz reception signal by 10 dB.

  The band extraction unit 31 refers to the filter characteristic table 39 and restores the decrease in the signal level suppressed by the BPF 14 among the signal levels included in the frequency spectrum signal. The band extraction unit 31 adds the suppression level for each frequency included in the filter characteristic table 39 to the signal level for each frequency included in the frequency spectrum signal. For example, the band extraction unit 31 adds a signal level of 40 dB set corresponding to 10 MHz in the filter characteristic table 39 to a signal level of 10 MHz in the frequency spectrum signal. The band extraction unit 31 adds the signal level of 10 dB set to 90 MHz in the filter characteristic table 39 to the signal level of 90 MHz in the frequency spectrum signal.

  FIG. 10 is a diagram showing the relationship between the frequency spectrum of the received signal and the pass frequency band of the BPF 14 and the first DDC 21 in the second embodiment. FIG. 11 is a diagram illustrating signal levels suppressed by the BPF 14 and the first DDC 21 in the second embodiment. FIG. 12 is a diagram for explaining increasing the level of the reception signal suppressed by the BPF 14 and the first DDC 21 in the second embodiment.

  The reception signal output by the reception amplifier 12 includes, for example, a reception signal F0 (3) of the fundamental wave component as shown in FIG. The frequency fr of the reception signal F0 (3) is a frequency on the lower frequency side than the pass frequency band of the BPF 14 and the first DDC 21. Therefore, the received signal F0 (3) is passed through the BPF 14 and the first DDC 21, so that the signal level is suppressed from L1 to L2, and becomes a signal level lower than the reference level Lref. For this reason, the frequency of the reception signal F0 (3) is not detected as the fundamental frequency by the oscillation control unit 32. On the other hand, the reception signal 2F0 (3), which is a double wave of the reception signal F0 (3), is not suppressed by the BPF 14 even if the signal level is lower than the reception signal F0 (3) of the fundamental wave as shown in FIG. Furthermore, as shown in FIG. 11, the signal level is higher than the reference level Lref. For this reason, the frequency of the reception signal 2F0 (3) is detected by the oscillation control unit 32 as a frequency having a signal level higher than the reference level Lref. As a result, the frequency of the received signal 2F0 (3) may be erroneously recognized as the frequency of the signal level generated as a result of receiving the received radio wave by the receiving antenna 10.

  Therefore, the band extracting unit 31 restores the decrease in the signal level suppressed by the BPF 14 in a frequency band lower than the cut-off frequency on the low frequency side of the BPF 14, thereby showing a signal level higher than the reference level Lref. A first frequency is detected (frequency detection unit). Specifically, the band extraction unit 31 adds the suppression levels of the BPF 14 and the first DDC 21 to the signal level of the frequency band lower than the pass frequency band of the BPF 14 and the first DDC 21 in the frequency spectrum signal. As a result, the band extraction unit 31 increases the signal level of the reception signal F0 (3) in the frequency spectrum signal from L2 to L3 as shown in FIG. 12, and reduces the decrease in the signal level suppressed by the BPF 14. Restore. As a result, the signal level L3 of the reception signal F0 (3) in the frequency spectrum signal becomes higher than the reference level Lref. As a result, the frequency of the reception signal F0 (3) is detected by the oscillation control unit 32 as the first frequency indicating a signal level higher than the reference level Lref.

  FIG. 13 is a diagram illustrating signal levels on the lower frequency side than the pass frequency band BW of the BPF 14 and the first DDC 21 in the second embodiment. The frequency band lower than the pass frequency band of the BPF 14 and the first DDC 21 is a frequency from a cutoff frequency (fb1) on the low frequency side of the BPF 14 to a frequency f (low) at which the signal level is suppressed to a predetermined level or less by the BPF 14. It is a band. The frequency f (low) is set by the signal level of the reception signal output from the reception amplifier 12 and the signal level suppressed by the BPF 14 and the first DDC 21. As a result, the band extracting unit 31 uses the reference level Lref in the frequency band from the cutoff frequency (fb1) on the low frequency side of the BPF 14 to the frequency f (low) at which the signal level is suppressed to a predetermined level or less by the BPF 14. A first frequency exhibiting a higher signal level is detected.

  When detecting the frequency of the signal level L3 exceeding the reference level from the frequency spectrum signal, the oscillation control unit 32 oscillates the pseudo fundamental wave signal that changes at the same frequency fr as the frequency of the reception signal F0 (3). Is supplied to the second NCO 35. The oscillation control unit 32 outputs the control signal C1 to the second NCO 37 at the same time as outputting the control signal C1 to oscillate the pseudo second harmonic signal that changes at a frequency 2fr that is twice the frequency of the pseudo fundamental wave signal. Thereby, the second NCO 35 outputs the pseudo fundamental wave signal to the second DDC 34. The second NCO 37 outputs a pseudo second harmonic signal to the third DDC 36.

  As a result, the second DDC 34 passes the reception signal in the pass frequency band BW (DDC2) centered on the frequency of the pseudo fundamental wave signal (first frequency) among the reception signals output from the AD converter 16. As a result, the second DDC 34 extracts the reception signal of the first frequency detected by the oscillation control unit 32 (frequency detection unit) from the reception signal received by the reception antenna 10 (first extraction unit). The pass frequency band BW (DDC2) of the second DDC 34 is narrower than the pass frequency band BW (DDC1) with the frequency fr as the center.

  The third DDC 36 passes the reception signal in the pass frequency band BW (DDC3) centered on the frequency (second frequency) of the pseudo second harmonic signal among the reception signals output from the AD converter 16. As a result, the third DDC 36 extracts a reception signal having a second frequency that is twice the first frequency detected by the oscillation control unit 32 (frequency detection unit) from the reception signal received by the reception antenna 10. (Second extraction unit). Note that the pass frequency band BW (DDC3) of the third DDC 36 is narrower than the pass frequency band BW (DDC1) with the frequency 2fr as the center.

  The determination unit 38 is supplied with the I and Q signals (IQ1) output from the second DDC 34 and the I and Q signals (IQ2) output from the third DDC 36. Based on the relationship between the I signal and the Q signal (IQ1, the received signal of the first frequency) and the I signal and the Q signal (IQ2, the received signal of the second frequency), the determining unit 38 passes the pass frequency band BW ( It is determined whether or not both the fundamental wave and the second harmonic wave of the received signal are included in DDC1) (determination unit).

  As illustrated in FIG. 6, when the determination unit 38 determines that IQ1 and IQ2 rise and fall almost simultaneously, the frequency 2fr of the reception signal 2F0 (3) is higher than the harmonic of the reception signal F0 (3). It is determined that the frequency of the component. When determining unit 38 determines that IQ1 and IQ2 do not rise substantially simultaneously or IQ1 and IQ2 do not fall substantially simultaneously, as shown in FIG. 7, frequency 2fr of received signal 2F0 (3) is , It is determined that it is not the frequency of the harmonic component of the received signal F0 (3).

  The reception processing unit 24 performs reception processing by reducing the signal level of the frequency 2fr determined by the determination unit 38 to be a second harmonic reception signal out of the frequency spectrum signal output from the FFT processing unit 23. That is, the reception processing unit 24 processes the received signal while reducing the influence of the harmonics determined by the determination unit 38 to be included in the pass frequency band BW (DDC1).

  According to the second embodiment described above, from the BPF 14 that extracts the received signal in the predetermined pass frequency band BW (DDC1) from the received signal received by the receiving antenna 10, and the cutoff frequency on the low frequency side of the BPF 14 In the lower frequency band, the band extraction unit 31 and the oscillation control unit 32 (frequency) for detecting the first frequency indicating a signal level higher than the reference level Lref by restoring the decrease in the signal level suppressed by the BPF 14 Detection unit), a second DDC 34 (first extraction unit) that extracts a reception signal of the first frequency detected by the band extraction unit 31 and the oscillation control unit 32 from the reception signal received by the reception antenna 10, and the reception antenna 10 of the first frequency detected by the band extracting unit 31 and the oscillation control unit 32 from the received signal received by Based on the relationship between the third DDC 36 (second extraction unit) that extracts the reception signal of the second frequency that is the frequency of the second frequency and the reception signal of the second frequency that is extracted by the third DDC 36, the pass frequency band BW ( And DDC 1) having a determination unit 38 for determining whether the fundamental wave and the harmonics of the received signal are included. According to the second embodiment, when a harmonic of the received signal is included in the pass frequency band BW (DDC1), the harmonic can be detected, and the influence of the harmonic is reduced from the received signal. Radio waves can be received more accurately.

(Modification)
FIG. 14 is a block diagram illustrating a radio wave receiver 1B according to a modification of the embodiment. The radio wave receiving apparatus 1B according to the modification includes a plurality of harmonic determination units 30-1 to 30N (N is an arbitrary natural number). The plurality of harmonic determination units 30-1 to 30N respectively receive the reception signals output from the AD converter 16, and simultaneously detect the presence of double waves having different frequencies in the reception signals. In this case, the plurality of harmonic determination units 30-1 to 30N oscillate the pseudo fundamental wave signal and the pseudo second harmonic signal with respect to a plurality of signal levels exceeding the reference level Lref among the frequency spectrum signals, respectively, and IQ1 and IQ2 Based on the relationship, whether or not both the fundamental wave and the second harmonic wave are included in the pass frequency band BW (DDC1) is determined. According to the radio wave receiving device 1B of the modified example, it is possible to determine in parallel whether there is a set of the fundamental wave and the second harmonic wave included in the frequency spectrum signal by the plurality of harmonic determination units 30-1 to 30N. it can. FIG. 14 shows a modification of the first embodiment, but the second embodiment can be similarly modified.

  Note that the radio wave receiver of the embodiment may have both the function of the radio wave receiver 1 of the first embodiment and the function of the radio wave receiver 1A of the second embodiment. The radio wave receiver of this embodiment detects both harmonics corresponding to the fundamental wave included in the pass frequency band of the BPF 14 and harmonics corresponding to the fundamental wave on the lower frequency side than the pass frequency band of the BPF 14. Can do.

  According to at least one embodiment described above, the second DDC 34 (second extraction unit) that extracts a reception signal having a frequency higher than the reference level among the reception signals received by the antenna, and the reception signal received by the antenna. Among the third DDC 36 (third extraction unit) that extracts a received signal having a frequency twice as high as the reference level, a result extracted by the second DDC 34, and a result extracted by the third DDC 36 And the determination unit 38 for determining whether or not the harmonics of the received signal are included in the pass frequency band, the harmonics of the received signal are included in the pass frequency band. Harmonics can be detected, and radio waves can be received more accurately by reducing the influence of harmonics from the received signal.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1, 1A, 1B ... Radio wave receiving apparatus, 10 ... Reception antenna, 12 ... Reception amplifier, 14 ... BPF, 16 ... AD converter, 20 ... Reception signal processing part, 21 ... 1st DDC, 22 ... 1st NCO, 23 ... FFT processing 24, reception processing unit, 30, 30A, 30-1, 30-N, harmonic determination unit, 31 band extraction unit, 32 oscillation control unit, 33 delay unit, 38 determination unit, 39 filter Characteristic table, 100, 104 ... mixer, 102, 106 ... decimation filter

Claims (4)

A band-pass filter that passes a reception signal of a predetermined frequency band among reception signals received by an antenna;
A frequency detection unit that detects a first frequency indicating a signal level higher than a reference level in a frequency band included in the predetermined frequency band and lower than a reference frequency included in the predetermined frequency band;
A first extraction unit that extracts a reception signal of a first frequency detected by the frequency detection unit from a reception signal received by the antenna;
A second extraction unit that extracts a reception signal having a second frequency that is twice the first frequency detected by the frequency detection unit from the reception signal received by the antenna;
Based on the relationship between the reception signal of the first frequency extracted by the first extraction unit and the reception signal of the second frequency extracted by the second extraction unit, reception is performed in the predetermined frequency band. A radio wave receiving apparatus comprising: a determination unit that determines whether a fundamental wave and harmonics of a signal are included. The first extraction unit extracts a reception signal of a first frequency band that is centered on the first frequency and narrower than the predetermined frequency band;
The second extraction unit extracts a received signal in a second frequency band having a width narrower than the predetermined frequency band with the second frequency as a center.
The radio wave receiver according to claim 1. The first extraction unit generates the pseudo fundamental wave signal having the first frequency and receives the first frequency band including the frequency of the pseudo fundamental wave signal among the reception signals received by the antenna. Extract the signal,
The second extraction unit generates the pseudo second harmonic signal having the second frequency and includes the second frequency band including the frequency of the pseudo second harmonic signal among the reception signals received by the antenna. The received signal of
The radio wave receiver according to claim 2. A reception processing unit that processes the received signal by reducing the influence of harmonics of the received signal that is determined to be included in the predetermined frequency band by the determination unit;
The radio wave receiver according to any one of claims 1 to 3.

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