JP2013223185A - Receiver unit and reception method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a receiver unit and a reception method capable of reducing a plurality of unwanted waves.SOLUTION: The receiver unit includes: an antenna for receiving a radio wave including a wanted wave of a predetermined frequency and an unwanted wave having a different frequency, as a reception signal; a plurality of filter units, each including a notch filter in series connection with the antenna for attenuating mutually different frequency bands, and configured to be selectable of an on state to output the reception signal from the preceding stage to the subsequent stage through the notch filter, or an off state to output the reception signal to the subsequent stage not through the notch filter. The on/off state of the plurality of filter units are set according to the frequency of the wanted wave or the unwanted wave included in the reception signal.

Description

  Embodiments described herein relate generally to a receiving apparatus and a receiving method.

  Conventionally, in order to reduce unnecessary waves contained in radio waves, receiving devices including various filters have been used. Such a receiving apparatus has been proposed in which unnecessary waves are reduced by filters connected in parallel, and is configured to output a signal subjected to filter processing by each filter.

JP 06-097901 A

  However, in the conventional technique for reducing unnecessary waves using filters connected in parallel, the number of radio wave distributions and the number of parts related to filter processing increase with the increase of unnecessary waves, which complicates the device configuration. There was a problem.

  The receiving apparatus according to the embodiment includes an antenna, a plurality of filter units, and a signal processing unit. The antenna receives, as a received signal, a radio wave including a desired wave having a predetermined frequency and an unnecessary wave different from the frequency. The plurality of filter units are connected in series to the antenna and each have a notch filter for attenuating different frequency bands, and the received signal from the previous stage is output to the subsequent stage via the notch filter or the notch filter. It is possible to select whether the output is in the off state without going through the output. The signal processing unit performs predetermined signal processing including at least signal amplification on the reception signals that have passed through the plurality of filter units. Further, ON / OFF states of the plurality of filter units are set according to the frequencies of the desired wave and the unnecessary wave included in the received signal.

FIG. 1 is a diagram schematically illustrating a configuration of a receiving apparatus according to the first embodiment. FIG. 2 is a diagram schematically illustrating an example of radio waves (reception signals) according to the first embodiment. FIG. 3 is a diagram schematically illustrating the filter characteristics of each filter unit illustrated in FIG. 1. FIG. 4 is a diagram for explaining the operation of the receiving apparatus according to the first embodiment. FIG. 5 is a diagram schematically illustrating the configuration of the receiving apparatus according to the second embodiment. FIG. 6 is a diagram schematically showing a configuration of a conventional receiving apparatus. FIG. 7 is a diagram showing the filter characteristics of the band limiting filter shown in FIG. FIG. 8 is a diagram for explaining the operation of the conventional receiving apparatus.

  Hereinafter, embodiments of a receiving apparatus and a receiving method according to the present invention will be described in detail with reference to the accompanying drawings.

[First Embodiment]
FIG. 1 is a diagram schematically illustrating a configuration of a receiving device 1 according to the first embodiment. As shown in FIG. 1, the receiving device 1 includes an antenna 11, a plurality of filter units 12, an amplifier 13, a distributor 14, and signal processing units 15 and 16.

  The antenna 11 is an antenna element or the like, for example, receives an airwave in the air, and outputs it as a received signal to the filter unit 12. Note that the antenna 11 of the present embodiment receives radio waves including a desired wave having a predetermined frequency and an unnecessary wave having a different frequency.

  Here, FIG. 2 is a diagram schematically illustrating an example of radio waves (reception signals) according to the present embodiment, where the vertical axis represents the signal level and the horizontal axis represents the frequency. In the figure, a radio wave including two desired waves DS1 and DS2 and two unnecessary waves US1 and US2 is shown. The antenna 11 receives radio waves including these desired waves DS1 and DS2 and unnecessary waves US1 and US2. The intermodulation distortion wave IM shown in FIG. 2 is generated from unnecessary waves US1 and US2 due to the characteristics of the amplifier 13 (amplifiers 25 and 26) and the signal processing units 15 and 16 (signal processing units 31 and 32) described later. 2 signal third order intermodulation distortion wave.

  Returning to FIG. 1, the plurality of filter units 12 are connected in series, and the reception signal from the antenna 11 input to the first filter unit 12 is sequentially output to the subsequent filter unit 12. Yes.

  As shown in FIG. 1, each filter unit 12 includes a notch filter 121 and switch units 122 and 123 connected before and after the notch filter 121. By switching the switch units 122 and 123, the front antenna 11 or the reception signal input from the filter unit 12 can be selected to output to the subsequent stage via the notch filter 121. Hereinafter, the states of the switch units 122 and 123 that output the reception signal from the previous stage to the subsequent stage via the notch filter 121 are referred to as “on state”, and the switch that outputs the reception signal from the previous stage to the subsequent stage via the path 124. The states of the parts 122 and 123 are referred to as “off state”.

  The notch filter 121 mounted on each filter unit 12 has a filter characteristic for attenuating a predetermined amount of signal levels in different frequency bands. When a received signal is input due to the ON state of the switch units 122 and 123, this filter The received signal is filtered using the characteristics. Note that the filter characteristics of the notch filter 121 preferably have a steep skirt characteristic. For example, a superconducting filter may be used.

  Here, FIG. 3 is a diagram schematically showing the filter characteristics of each filter unit 12, where the vertical axis represents the signal level and the horizontal axis represents the frequency. In the figure, the structure provided with the four filter parts 12 is assumed, and the filter characteristic of the notch filter 121 which each of the filter parts 12 has is represented by the code | symbol 121a-121d. As shown in FIG. 3, the filter characteristics of each notch filter 121 are set in advance to attenuate different frequency bands to a predetermined level.

  Returning to FIG. 1, the amplifier 13 amplifies the signal level of the received signal that has passed through the filter unit 12 and outputs the amplified signal level to the distributor 14. The distributor 14 distributes power of the reception signal amplified by the amplifier 13 to the signal processing units 15 and 16 in the subsequent stage.

  The signal processing units 15 and 16 have high-frequency components (not shown) such as a high-frequency amplifier and a demodulator, and extract desired signals different from each other by performing predetermined signal processing on the received signal input from the distributor 14. And output to an external device (not shown) as an output signal.

  Hereinafter, the operation of the receiving apparatus 1 according to the present embodiment will be described. First, for comparison with the receiving apparatus 1 of the present embodiment, a conventional receiving apparatus will be described.

  FIG. 6 is a diagram schematically illustrating a configuration example of a conventional receiving device 2. As shown in the figure, the receiving device 2 includes an antenna 21, a distributor 22, band-limiting filters 23 and 24, amplifiers 25 and 26, distributors 27 and 28, switch units 29 and 30, and a signal. And processing units 31 and 32.

  The aerial line 21 receives a radio wave in the air and outputs it to the distributor 22 as a received signal. As with the aerial line 11, the aerial line 21 receives a radio wave including a desired wave having a predetermined frequency and an unnecessary wave different from the frequency.

  The distributor 22 distributes the power of the reception signal input from the antenna 21 to the subsequent band limiting filters 23 and 24. The band limiting filters 23 and 24 have filter characteristics that allow signals in different frequency bands to pass therethrough, and output the received signals after filtering to the amplifiers 25 and 26, respectively.

  Here, FIG. 7 is a diagram schematically showing the filter characteristics of the band limiting filters 23 and 24, where the vertical axis represents the signal level and the horizontal axis represents the frequency. As shown in the figure, the filter characteristic 231 of the band limiting filter 23 and the filter characteristic 241 of the band limiting filter 24 are set in advance so as to pass signals in different frequency bands.

  Returning to FIG. 6, the amplifiers 25 and 26 amplify the reception signals output from the band limiting filters 23 and 24, respectively, and output the amplified signals to the distributors 27 and 28. The distributors 27 and 28 distribute the power of the reception signals amplified by the amplifiers 25 and 26 to the switch units 29 and 30.

  The switch units 29 and 30 are connected to the distributor 27 or the distributor 28 so as to be switchable, and by this switching, the received signals distributed by the distributor 27 or the distributor 28 can be selected.

  The signal processing units 31 and 32 have high-frequency components (not shown) such as a high-frequency amplifier and a demodulator, and perform desired signal processing on the received signals input from the switch units 29 and 30 so that different desired waves are obtained. Is output to an external device (not shown) as an output signal.

  Here, a case where unnecessary waves are reduced from a radio wave including a plurality of desired waves and unnecessary waves using the conventional receiving device 2 will be described. For example, as shown in FIG. 2, when the receiving device 2 receives radio waves including desired waves DS1 and DS2 and unnecessary waves US1 and US2, the high frequencies of the amplifiers 25 and 26 and the signal processing units 31 and 32 are included. The intermodulation distortion wave IM is generated due to the distortion characteristics of the parts. Since the change in the signal level of the intermodulation distortion wave IM is proportional to the signal levels of the unnecessary waves US1 and US2, the larger the unnecessary waves US1 and US2, the larger the intermodulation distortion wave IM. Then, for example, as shown in FIG. 2, when the intermodulation distortion wave IM is on the same frequency as the desired wave DS2 and becomes larger than the signal level of the desired wave DS2, the SN ratio decreases, so the desired wave It becomes difficult to receive DS2.

  In such a case, in the conventional receiving device 2, as shown in FIG. 8, the signal characteristics of the two unnecessary waves US1 and US2 are attenuated by the filter characteristics 231 and 241 of the band limiting filters 23 and 24, respectively. Reduction of intermodulation distortion wave IM is realized.

  However, in the configuration of the conventional receiving device 2, the power of the received signal is distributed by the distributor 22 so that the received signal is output to each of the band limiting filters 23 and 24 connected in parallel. There is a problem that the reception sensitivity decreases with an increase, that is, an increase in unnecessary waves. Further, every time an unnecessary wave increases by one signal, a filter set (band limiting filter, amplifier, distributor, etc.) for reducing the unnecessary wave is required, and the number and combination of the switch units 29 and 30 also increase. Therefore, the conventional receiving apparatus 2 has a problem that the number of parts increases with the increase of unnecessary waves, and the apparatus configuration becomes complicated.

  Therefore, in the receiving device 1 of the present embodiment, in order to solve the problems of the conventional receiving device 2 described above, the filter unit 12 connected in series can be used to reduce (attenuate) unnecessary waves (intermodulation distortion waves). Do.

  Specifically, for example, when receiving the radio wave of FIG. 2, the receiving device 1 attenuates the frequency band in which two unnecessary waves US1 and US2 exist among the four filter characteristics shown in FIG. The switch sections 122 and 123 of the filter section 12 (notch filter 121) having 121c are turned on, and the switch section of the filter section 12 (notch filter 121) having filter characteristics 121b and 121d other than the filter characteristics 121a and 121c. 122 and 123 are turned off.

  As a result, as shown in FIG. 4, when the radio wave of FIG. The original signal level is maintained for the waves DS1 and DS2. Thereby, since the signal level of the intermodulation distortion wave IM can be reduced, the signal level of the desired wave DS2 can be relatively increased.

  As described above, in the receiving device 1 according to the present embodiment, by switching the on / off state of the filter units 12 connected in series, the signal level of the unwanted wave included in the radio wave is attenuated, and the desired wave is transmitted. A filter series that holds the signal level is realized. Therefore, compared with the configuration of the conventional receiving apparatus 2 that distributes the power of the received signal, the output power of the received signal can be held, so that a decrease in reception sensitivity can be suppressed. Further, even when unnecessary waves increase, it can be dealt with by turning on the filter unit 12 corresponding to the frequency band of the unnecessary wave or adding the filter unit 12 corresponding to this frequency band. Therefore, unnecessary waves (intermodulation distortion waves) can be reduced with a simpler configuration as compared with the configuration of the conventional receiver 2.

  In the receiving apparatus 1 of the above-described embodiment, the example in which the number of the filter units 12 is four has been described. However, the number is not particularly limited as long as the number is plural. In the above embodiment, the number of desired waves and unnecessary waves included in the radio wave is two. However, the number is not limited to this, and the number is not particularly limited. When a plurality of desired waves are included in the radio wave, it is assumed that each desired wave receiving unit (signal processing units 15 and 16) is provided.

[Second Embodiment]
Next, a second embodiment will be described. 2nd Embodiment demonstrates the structural example which can switch the ON / OFF state of the filter part 12 automatically. In addition, about the component similar to 1st Embodiment, the same code | symbol is provided and description is abbreviate | omitted.

  FIG. 5 is a diagram schematically illustrating a configuration of a receiving device 1A according to the second embodiment. As shown in the figure, the receiving apparatus 1A includes an antenna 11, a plurality of filter units 12, an amplifier 13, a distributor 14, signal processing units 15 and 16, a signal detection unit 17, and a filter control unit 18. And.

  The signal detection unit 17 detects the frequency and signal level of the desired wave and the unnecessary wave included in the reception signal received by the antenna 11 and outputs the detection result to the filter control unit 18. In addition, the detection method of a desired wave and an unnecessary wave shall not be ask | required in particular. For example, the frequency of the desired wave and the unnecessary wave may be set in advance, and the signal level of the frequency may be detected (measured), or the frequency and the signal level of the desired wave and the unnecessary wave may be set using a known technique. It is good also as a form to detect.

  The filter control unit 18 turns on each filter unit 12 based on the detection result output from the signal detection unit 17 and the desired wave and intermodulation distortion wave included in the output signals from the signal processing units 15 and 16. / Determine the off state. And the filter control part 18 implement | achieves the filter series which reduces an unnecessary wave and an intermodulation distortion wave by switching the switch parts 122 and 123 of each filter part 12 according to the determined on / off state.

  Specifically, the filter control unit 18 turns on the filter unit 12 having a filter characteristic for attenuating a frequency band in which an unnecessary wave exists based on the detection result of the signal detection unit 17 and the desired wave exists. The filter unit 12 corresponding to the frequency band is turned off. Note that the filter unit 12 other than the frequency band of the unwanted wave and the desired wave may be in either an on state or an off state.

  Further, the filter control unit 18 calculates the SN ratio of the desired wave and the intermodulation distortion wave included in the output signals from the signal processing units 15 and 16, and turns on / off the filter unit 12 that maximizes the SN ratio. A combination of states may be derived by feedback control. In addition, the calculation method of the SN ratio of the desired wave and the intermodulation distortion wave is not particularly limited, and a known technique may be used.

  Further, when the notch filter 121 of each filter unit 12 is an adaptive notch filter or the like whose filter characteristics (filter coefficient) can be adjusted, the filter coefficient is dynamically adjusted in addition to the on / off control described above. It is good also as a form.

  Specifically, the filter control unit 18 performs the ON / OFF control of each filter unit 12 based on the detection result from the signal detection unit 17, and then the desired wave and mutual signals included in the signals output from the signal processing units 15 and 16. The filter coefficient is optimized by calculating the S / N ratio of the modulated distortion wave and adjusting the filter coefficient that increases the S / N ratio by feedback control while reflecting it in the notch filter 121 in the ON state.

  The adjustment target of the filter coefficient is not particularly limited, and any of the filter coefficients that can be adjusted in the notch filter 121, such as the center frequency of the filter characteristic, the attenuation gradient (skirt characteristic), the intensity of the attenuation level, etc., is adjusted. Also good.

  As described above, according to the receiving device 1A of the second embodiment, by dynamically setting the on / off state of each filter unit 12 according to the received signal, it is possible to flexibly deal with the received signal. Since it becomes possible, the same effect as 1st Embodiment mentioned above can be show | played efficiently.

  As mentioned above, although embodiment of this invention was described, each said embodiment is shown as an example and is not intending limiting the range of invention. Each of the embodiments described above can be implemented in various other forms, and various omissions, replacements, changes, additions, and the like can be made without departing from the scope of the invention. Each of the above embodiments and modifications thereof 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 receiver 11 Antenna 12 Filter part 121 Notch filter 122, 123 Switch part 13 Amplifier 14 Divider 15, 16 Signal processing part 17 Signal detection part 18 Filter control part

Claims (4)

An antenna that receives a radio wave including a desired wave of a predetermined frequency and an unnecessary wave different from the frequency as a reception signal;
Each of the antennas has a notch filter connected in series to attenuate different frequency bands, and the received signal from the previous stage is output to the subsequent stage through the notch filter, or the latter stage without passing through the notch filter. A plurality of filter units configured to be able to select whether the output is in an off state,
A signal processing unit that performs predetermined signal processing including at least signal amplification on the received signals that have passed through the plurality of filter units;
The receiving device in which the on / off states of the plurality of filter units are set according to the frequencies of the desired wave and the unnecessary wave included in the received signal. A detection unit for detecting the desired wave and the unnecessary wave from the reception signal received by the antenna;
A filter control unit that controls an on / off state of the filter unit corresponding to a frequency band in which the desired wave and the unnecessary wave exist based on a detection result of the detection unit;
The receiving device according to claim 1, further comprising:   The filter control unit calculates an SN ratio between the desired wave included in the output signal of the signal processing unit and an intermodulation distortion wave generated by the plurality of unnecessary waves, and the filter unit based on the SN ratio The receiving apparatus according to claim 2, wherein a filter coefficient relating to each filter characteristic is adjusted. A receiving method executed by a receiving device,
Each of the reception devices has a notch filter that attenuates different frequency bands, and outputs a reception signal from the previous stage to the subsequent stage without outputting the received signal from the previous stage through the notch filter or without the notch filter. It is provided with a plurality of series-connected filter units configured to be selectable in an off state,
A receiving step of receiving, as the received signal, a radio wave including a desired wave of a predetermined frequency and an unnecessary wave different from the frequency;
A filter processing step of inputting the reception signal received in the reception step to the plurality of filter units in which an on / off state is set according to the frequency of the desired wave and the unnecessary wave included in the reception signal; ,
A signal processing step of performing predetermined signal processing including at least signal amplification on the received signal after the filtering step;
Including receiving method.

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