JP2004364175A - Receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To receive a desired wave without lowering the receiving sensitivity of the desired wave by preventing the interference of an interference wave from an adjacent band by a simple configuration. <P>SOLUTION: A receiver 10 receives one of a plurality of signal waves having the same contents with different frequencies as a desired wave, and determines which the interference wave is located between at a side where it is higher in frequency than the desired wave and at a side where it is lower in frequency than the desired wave to select a signal wave of a frequency most apart from the frequency of the interference wave as the desired wave when a detected level value is not lower than a prescribed level value. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a receiver capable of removing interference caused by an interfering wave from an adjacent band and accurately receiving a desired radio wave (a desired wave).
[0002]
[Prior art]
Generally, when a receiver receives a desired radio wave (desired wave) satisfactorily, it is necessary to remove interference caused by an interfering wave from an adjacent band. Therefore, the receiver is provided with various filters. , So as to remove the interfering waves.
[0003]
In order to reduce interference of an interfering wave, there is a variable band receiving channel filter that rejects an interfering wave, detects a predetermined amount of interference, and adjusts the band of the variable band receiving channel filter. (For example, see Patent Document 1).
[0004]
Furthermore, a filter (interference wave component removal filter) is provided which has an attenuation band near a boundary of a frequency band allocated to a wireless communication system based on the FDMA (frequency division multiple access) method. There is a filter in which an interference wave component removing filter is inserted between an antenna device and a low noise amplifier (for example, see Patent Document 2).
[0005]
[Patent Document 1]
Japanese Patent No. 2663716 (pages 3 to 4, FIGS. 1 to 5)
[Patent Document 2]
JP-A-6-132838 (paragraphs (0006) to (0008), FIGS. 1 to 3)
[0006]
[Problems to be solved by the invention]
However, since the conventional receiver is configured as described above, if the frequency of the desired wave is high and the frequency difference with the adjacent interfering wave is small, a predetermined amount of interference is detected and the variable band received channel is detected. When trying to adjust the band of the filter, there has been a problem that the desired wave itself is attenuated and the receiving sensitivity is reduced.
[0007]
Further, in the conventional receiver, since the frequency relationship between the desired wave and the interference wave is detected and the switch is controlled, the circuit configuration becomes complicated and the circuit scale increases. There were challenges.
[0008]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has a simple configuration and is capable of removing interference of an interfering wave from an adjacent band and receiving the desired wave without reducing reception sensitivity. The aim is to obtain a receiver that can.
[0009]
[Means for Solving the Problems]
A receiver according to the present invention receives and outputs one of a plurality of signal waves having the same content having different frequencies as a desired wave, and an interference wave with respect to the desired wave is located on a higher frequency side than the desired wave. And a selecting means for selecting a signal wave having a frequency farthest from the frequency of the interfering wave as the desired wave in accordance with the result of the determination.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described.
Embodiment 1 FIG.
Here, a receiver that receives a satellite (satellite) digital radio broadcast will be described as an example of the receiver. In FIG. 1, in the US SIRIUS radio broadcast, which is one of the satellite digital radio broadcasts, a radio broadcast signal (signal wave) is transmitted in the order of satellite wave 1 and satellite wave 2, and satellite wave 1 and satellite wave 2 are transmitted. Are broadcasting the same radio broadcast program contents. These satellite waves 1 and 2 are sequentially arranged on the frequency axis. In SIRIUS radio broadcasting, terrestrial waves are positioned in a band between satellite waves 1 and 2 in order to cope with reception interference in buildings and the like.
[0011]
In FIG. 1, XM radio broadcasting is allocated adjacent to SIRIUS radio broadcasting on the higher frequency side than SIRIUS radio broadcasting. In this XM radio broadcasting, satellite wave 1A, satellite wave 2A, terrestrial wave A, terrestrial wave A Bands are allocated in the order of the wave B, the satellite wave 2B, and the satellite wave 1B. As described later, the terrestrial waves A and B may act as interference waves for SIRIUS radio broadcasting (here, SIRIUS). The satellite wave is the desired wave and the XM terrestrial wave is the interfering wave).
[0012]
For example, when receiving the SIRIUS satellite wave, if the level of the XM terrestrial wave is large, in a receiver, particularly, in a low noise amplifier (LNA) or a frequency converter (D / C: Down Converter). As a result, as shown in FIG. 2, the SIRIUS satellite wave is disturbed by the XM terrestrial wave, and the reception state of the SIRIUS satellite wave deteriorates. Therefore, in order to properly receive the above-mentioned SIRIUS satellite waves, it is particularly necessary to prevent interference with XM terrestrial waves.
[0013]
By the way, in order to cope with the disturbance caused by the XM terrestrial wave, an LPF having a filter characteristic (low-pass filter (LPF) characteristic) indicated by a symbol A in FIG. Even if an attempt is made to cut, if the frequency difference between the SIRIUS satellite wave and the XM ground wave (interference wave) is small with respect to the signal frequency, it is difficult to obtain an LPF having steep characteristics (between the SIRIUS satellite wave and the interference wave). Therefore, it is difficult to obtain a filter having a sufficient attenuation ratio in the above case).
[0014]
Similarly, even when a filter having a filter characteristic (BEF (Band Enable Filter) characteristic) indicated by reference character E in FIG. 3 is used, a sufficient attenuation ratio can be obtained between the SIRIUS satellite wave and the interfering wave. Then, the attenuation of the SIRIUS satellite wave also inevitably increases, and the receiving sensitivity deteriorates.
[0015]
In addition, in FIG. 3, when a BPF having a filter characteristic (band-pass filter (BPF)) indicated by reference symbol B is used, if a sufficient attenuation ratio is obtained between the SIRIUS satellite wave and the interfering wave, the SIRIUS As a result, the satellite wave is also attenuated, so that the receiving sensitivity is reduced.
[0016]
By the way, in the SIRIUS radio broadcasting, considering that the satellite wave 1 and the satellite wave 2 transmit the same radio broadcast program contents, it is sufficient if either the satellite wave 1 or 2 can be received. Therefore, in FIG. 3, if a BPF having a filter characteristic (BPF characteristic) indicated by a symbol C is used, the satellite wave 1 distant from the XM terrestrial wave can be satisfactorily received.
[0017]
On the other hand, if a BPF having the BPF characteristic indicated by the symbol D is used, the satellite wave 2 can be received, but it is not separated from the XM terrestrial wave and is affected by the XM terrestrial wave. Then, in order to remove the influence of the interfering wave (XM ground wave) using the BPF having the BPF characteristic indicated by the symbol D, a BPF having a high Q value is required.
[0018]
In FIG. 1, the XM radio broadcast is located on the higher frequency side than the SIRIUS radio broadcast, but other radio broadcasts may be located on the higher frequency side lower than the SIRIUS radio broadcast. In this case, as will be described later, a satellite wave with the least interference of an interfering wave is selected.
[0019]
In the above description, the interference of the interfering wave when receiving the satellite wave was described, but not limited to the satellite wave, when receiving a radio wave such as a radio broadcast, a plurality of signal waves transmit the same content, Even when receiving a desired wave in which these signal waves are sequentially arranged on the frequency axis, it is sufficient to receive the signal wave with the least interference of the interfering wave.
[0020]
Here, with reference to FIG. 4, the receiver 10 includes a BPF unit 11, and radio waves (for example, SIRIUS satellite waves (satellite waves 1 and 2)) received by an antenna (ANT) 12 will be described later. After being filtered by the BPF unit 11 and amplified by the low noise amplifier (LNA) 13, it is converted to a low frequency signal by the frequency converter (D / C) 14. Thereafter, this low frequency signal is The signal is converted into a digital signal by an A / D converter (ADC) 15, demodulated by a demodulation / signal processing unit (DEM) 16, and subjected to signal processing described later.
[0021]
The signal (demodulated signal) demodulated by the DEM 16 is converted into an analog signal by a D / A converter (DAC) 17, amplified by an amplifier (AMP) 18, and output from a speaker (SP) 19 as voice or sound. You.
[0022]
FIG. 5 is a detailed block diagram of the receiver shown in FIG. In FIG. 5, the receiver 10 includes a level detector 21 and a microcomputer (microcomputer) 22, and the DEM 16 includes a first and second carrier-to-noise ratio (C / N) determiner as a signal processing function. 16a and 16b are provided.
[0023]
The above-described BPF unit 11 includes first to fourth switch (SW) units 31 to 34, and also includes first and second BPFs 41 and 42. In the illustrated example, the first and second BPFs 41 and 42 have BPF characteristics indicated by reference numerals C and D in FIG. 3, respectively, and the first to fourth BPFs are controlled by the microcomputer 22 as described later. Are controlled to be switched.
[0024]
Next, the operation will be described.
FIG. 6 is a flowchart for explaining the operation of the receiver shown in FIG. When the receiver 10 is turned on, the microcomputer 22 controls the switching of the first and fourth SW units 31 and 34 to directly connect the first and fourth SW units 31 and 34 (by connecting the bypass path 51). Form). As a result, the antenna 12 is directly connected to the LNA 13 by the first and fourth SW units 31 and 34. The level detector 21 detects the level of the output (low-frequency signal) of the D / C 14 as an input level, and this input level (detection level) is given to the microcomputer 22.
[0025]
The microcomputer 22 determines whether the detection level is higher than a predetermined level (step ST1). If the input level is lower than the predetermined level, the interference of the interference wave is small (no interference wave). ) (Step ST2), and the bypass path 51 is selected while maintaining the state where the first and fourth SW sections 31 and 34 are directly connected (step ST3).
[0026]
When the bypass path 51 is selected, the satellite waves 1 and 2 shown in FIG. 1 are received, and the DEM 16 performs demodulation and signal processing based on the low-frequency signals corresponding to the satellite waves 1 and 2. Then, a demodulated signal is transmitted.
[0027]
On the other hand, in step ST1, when the input level becomes equal to or higher than the predetermined level, the microcomputer 22 determines that there is interference of an interfering wave. On the other hand, the first and second C / N determination units 16a and 16b measure C / N values corresponding to the satellite waves 1 and 2, respectively, to obtain first and second C / N values, These first and second C / N values are given to the microcomputer 22. Here, measuring the C / N value corresponding to the satellite waves 1 and 2 means determining the reception sensitivity.
[0028]
The microcomputer 22 checks whether or not the first C / N value ≒ the second C / N value (step ST4). If YES, the process returns to step ST1, and if NO, the process proceeds to step ST5. In step ST5, it is checked whether or not the first C / N value <the second C / N value. If the first C / N value <the second C / N value is not satisfied (the first C / N value). If N value ≧ the second value), it is determined that the interference wave is on the higher frequency side than the satellite wave 2 of the SIRIUS radio broadcast wave (step ST6). Then, the microcomputer 22 controls the switching of the first and fourth SW units 31 and 34 so that the first and fourth SW units 31 and 34 are switched to the second SW unit 32 and the third SW unit 33, respectively. At the same time (step ST7), the second SW unit 32 and the third SW unit 33 are switch-controlled to connect the second SW unit 32 and the third SW unit 33 to the first BPF 41 (step ST7). ST8).
[0029]
As described above, since the first BPF 41 has the BPF characteristic of code C shown in FIG. 3, the satellite wave 1 is selected by the first BPF 41 for the SIRIUS radio broadcast wave received by the antenna 12 ( Filtering), and the result is supplied to the LNA 13. As a result, the satellite wave 1 distant from the interfering wave is selected, and the desired wave can be received without lowering the receiving sensitivity by avoiding interference due to the interfering wave. Since the satellite wave 1 is far from the interfering wave, it is not necessary to increase the Q value of the first BPF 41, and the first BPF 41 does not become expensive.
[0030]
In step ST5, if the first C / N value is smaller than the second C / N value, the microcomputer 22 determines that the interfering wave is on the lower frequency side than the satellite wave 1 of the SIRIUS radio broadcast wave. (Step ST9). Then, the microcomputer 22 controls the switching of the first and fourth SW units 31 and 34 so that the first and fourth SW units 31 and 34 are switched to the second SW unit 32 and the third SW unit 33, respectively. At the same time as the connection (step ST10), the second SW unit 32 and the third SW unit 33 are switch-controlled to connect the second SW unit 32 and the third SW unit 33 to the second BPF 42 (step ST10). ST11).
[0031]
As described above, since the second BPF 42 has the BPF characteristic of the code D shown in FIG. 3, the satellite wave 2 is selected by the second BPF 41 from the SIRIUS radio broadcast wave received by the antenna 12 ( Filtering), and the result is supplied to the LNA 13. As a result, the satellite wave 2 distant from the interfering wave is selected, and the desired wave can be received without lowering the receiving sensitivity by avoiding interference due to the interfering wave. Since the satellite wave 2 is far from the interfering wave, it is not necessary to increase the Q value of the second BPF 42, and the second BPF 42 does not become expensive. As is apparent from the above description, the level detection unit 21, the first and second C / N determination units 16a and 16b, and the microcomputer 22 function as the determination unit, and the microcomputer 22 and the BPF unit 11 function as the selection unit. Will do. When the first C / N value is substantially equal to the second C / N value, it is determined that the interference wave is a SIRIUS terrestrial wave, and in this case, the filtering need not be performed.
[0032]
As described above, according to the first embodiment, when receiving a broadcast wave including a plurality of signal waves having the same broadcast content, the interference wave is positioned on the higher frequency side with respect to the broadcast wave or Whether it is located on the lower side is determined according to the level value of the low-frequency signal and the C / N value for each signal wave, and a BPF that allows a signal wave distant from the interference wave to pass is selected according to the determination result. As a result, the desired wave can be received with a simple configuration without lowering the reception sensitivity of the desired wave.
[0033]
Embodiment 2 FIG.
FIG. 7 is a configuration diagram showing a receiver according to Embodiment 2 of the present invention. Components that are the same as those shown in FIG. 5 are given the same reference numerals. In the second embodiment shown in FIG. 7, first and second bit error rate (BER) determination units 16c and 16d are used instead of the first and second C / N determination units 16a and 16b shown in FIG. Are used, the first and second BER determination units 16c and 16d measure BER corresponding to the satellite waves 1 and 2, respectively, obtain first and second BER values, and obtain first and second BER values. The BER value of 2 is given to the microcomputer 22. Here, measuring the BER value corresponding to the satellite waves 1 and 2 means determining the reception sensitivity.
[0034]
Then, the receiver 10 shown in FIG. 7 operates as described with reference to FIGS. 5 and 6, but at this time, the microcomputer 22 sets the first to second values in accordance with the first and second BER values. By controlling the switching of the fourth SW units 31 to 34, a signal wave (satellite wave 1 or 2) separated from the interference wave is received. Here, the level detection unit 21, the first and second BER determination units 16c and 16d, and the microcomputer 22 function as a determination unit.
[0035]
As described above, according to the second embodiment, when receiving a broadcast wave including a plurality of signal waves having the same broadcast content, the interfering wave is positioned on the higher frequency side with respect to the broadcast wave or Whether to be located on the lower side is determined according to the level value of the low-frequency signal and the BER value of each signal wave, and a BPF that allows a signal wave distant from the interfering wave to pass is selected according to the determination result. Therefore, the effect that the desired wave can be received with a simple configuration without lowering the reception sensitivity of the desired wave can be obtained.
[0036]
Embodiment 3 FIG.
FIG. 8 is a configuration diagram showing a receiver according to Embodiment 3 of the present invention, and the same components as those shown in FIG. 5 are denoted by the same reference numerals. In the third embodiment shown in FIG. 8, a level detecting section 61 is used instead of the level detecting section 21 shown in FIG. 5, and this level detecting section 61 receives a radio wave received by the antenna 12 (reception level). Intensity) is detected and given to the microcomputer 22 as a reception level value (input level).
[0037]
The microcomputer 22 determines whether or not the reception level value is higher than the predetermined level value. If the reception level value is lower than the predetermined level value, the process proceeds to step ST2 described with reference to FIG. If it is equal to or more than the predetermined level value, the process proceeds to step ST4 described in FIG. The subsequent operation is the same as the operation described with reference to FIGS. 5 and 6, and a description thereof will be omitted.
[0038]
In FIG. 8, the first and second BER determination units 16c and 16d described in FIG. 7 may be used instead of the first and second C / N determination units 16a and 16b.
[0039]
As described above, also in the third embodiment, the same effects as in the first embodiment can be obtained.
[0040]
Embodiment 4 FIG.
FIG. 9 is a configuration diagram showing a receiver according to Embodiment 4 of the present invention. The same components as those shown in FIG. 5 are denoted by the same reference numerals. In the fourth embodiment shown in FIG. 9, a filter unit 62 is provided in place of the BPF unit 11, and the filter unit 62 includes the above-described first to fourth SW units 31 to 34, and includes the first and fourth SW units 31 to 34. An HPF 71 and an LPF 72 are provided instead of the two BPFs 41 and 42, respectively. The HPF 71 has, for example, a filter characteristic (HPF characteristic) indicated by a symbol G in FIG. 10 and allows passage of radio waves having a higher frequency than the satellite wave 2 and attenuates to a frequency slightly lower than the frequency of the satellite wave 2. The point is located. On the other hand, the LPF 72 has, for example, a filter characteristic (LPF characteristic) indicated by a symbol F in FIG. 10, allows passage of radio waves having a lower frequency than the satellite wave 1, and has a frequency slightly higher than the frequency of the satellite wave 1. The attenuation point is located at.
[0041]
In the receiver 10 illustrated in FIG. 9, as described with reference to FIGS. 5 and 6, when it is determined that the interfering wave is located on the higher frequency side than the broadcast wave, the microcomputer 12 sets the first to fourth SWs. The switching control of the units 31 to 34 connects the antenna 12 to the LNA 13 via the LPF 72. As a result, the satellite wave 1 located at a position distant from the interference wave is selectively received, so that interference by the interference wave can be prevented.
[0042]
On the other hand, if it is determined that the interfering wave is located on the lower frequency side than the broadcast wave, the microcomputer 12 controls the switching of the first to fourth SW units 31 to 34 to connect the antenna 12 to the LNA 13 via the HPF 71. I do. As a result, the satellite wave 2 located at a position distant from the interference wave is selectively received, so that interference by the interference wave can be prevented.
[0043]
As described above, according to the fourth embodiment, when receiving a broadcast wave including a plurality of signal waves having the same broadcast content, the interfering wave is positioned on the higher frequency side with respect to the broadcast wave or Whether it is located on the lower side is determined according to the level value of the low-frequency signal and the C / N value for each signal wave, and a filter that allows the signal wave distant from the interference wave to pass is selected according to the determination result. As a result, the desired wave can be received with a simple configuration without lowering the reception sensitivity of the desired wave.
[0044]
【The invention's effect】
As described above, according to the present invention, one of a plurality of signal waves having the same contents having different frequencies is received and output as a desired wave, and an interference wave for the desired wave has a higher frequency than the desired wave. A determination means for determining whether the signal is located on the lower side or on the lower side, and a signal wave having a frequency farthest from the frequency of the interfering wave is selected as the desired wave according to the determination result. With such a configuration, there is an effect that interference of an interfering wave from an adjacent band can be prevented and the desired wave can be received without lowering the receiving sensitivity.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an example of an arrangement on a frequency axis of a plurality of satellite digital radio broadcasts.
FIG. 2 is a diagram illustrating an example in which a desired wave receives interference of an interfering wave.
FIG. 3 is a diagram illustrating an example of a characteristic of a filter used for preventing interference of an interfering wave.
FIG. 4 is a configuration diagram showing a receiver according to Embodiment 1 of the present invention.
FIG. 5 is a block diagram showing the receiver shown in FIG. 4 in detail.
6 is a flowchart for explaining the operation of the receiver shown in FIG.
FIG. 7 is a configuration diagram illustrating a receiver according to a second embodiment of the present invention.
FIG. 8 is a configuration diagram showing a receiver according to Embodiment 3 of the present invention.
FIG. 9 is a configuration diagram showing a receiver according to Embodiment 4 of the present invention.
10 is a diagram illustrating an example of characteristics of a high-pass filter and a low-pass filter used in the receiver illustrated in FIG.
[Explanation of symbols]
Reference Signs List 10 receiver, 11 BPF unit, 12 antenna (ANT), 13 low noise amplifier (LNA), 14 frequency converter (D / C), 15 A / D converter (ADC), 16 demodulation / signal processing unit (DEM) , 16a, 16b Carrier-to-noise ratio (C / N) determination unit, 16c, 16d Bit error rate (BER) determination unit, 17 D / A converter (DAC), 18 amplifier (AMP), 19 speaker (SP), 21 , 61 level detector, 22 microcomputer (microcomputer), 31-34 switch (SW), 41, 42 band pass filter (BPF), 51 bypass path, 62 filter, 71 high pass filter (HPF), 72 low pass filter (LPF).

Claims (6)

In a receiver for receiving and outputting one of a plurality of signal waves having the same content having different frequencies as a desired wave,
Determination means for determining whether the interference wave for the desired wave is located on the higher or lower side of the frequency than the desired wave,
A receiver for selecting a signal wave having a frequency farthest from the frequency of the interference wave as the desired wave in accordance with a result of the determination by the determiner. A determining unit that detects an input level related to the received radio wave and obtains a detection level value;
A receiving sensitivity determining unit that obtains a receiving sensitivity value by obtaining a receiving sensitivity for each signal wave;
When the detection level value is equal to or higher than a predetermined level value, an interference wave determination for determining whether an interference wave is located on a higher or lower frequency side than a desired wave in accordance with the reception sensitivity value. The receiver according to claim 1, further comprising a unit. 3. The receiver according to claim 2, wherein the reception sensitivity determining section obtains a C / N value as a reception sensitivity value by obtaining a C / N for each signal wave. 3. The receiver according to claim 2, wherein the reception sensitivity determination unit obtains a bit error rate value as a reception sensitivity value by obtaining a bit error rate for each signal wave. A selection means provided for each signal wave, and a band-pass filter that allows the signal wave to pass therethrough;
5. The control method according to claim 1, further comprising: switching control means for performing switching control on a band-pass filter corresponding to a signal wave having a frequency farthest from the frequency of the interfering wave according to a result of the determination by the determining means. The receiver according to any one of the preceding claims. Selecting means, a high-pass filter and a low-pass filter,
When the determination result by the determination means indicates that the interference wave is located on the higher frequency side than the desired wave, the switching control is performed on the low-pass filter, and the determination result by the determination means is that the interference wave is greater than the desired wave. 5. The reception apparatus according to claim 1, further comprising: a switching control unit configured to perform switching control on the high-pass filter when the signal indicates that the frequency is positioned on a lower side. 6. Machine.

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