JP2004328031A - Reception apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To directly correct a received signal subjected to the effect of variations in the amplitude due to multi-path distortion or the like. <P>SOLUTION: The reception apparatus is provided with: a demodulation means 3 for demodulating a modulation signal from a first wireless signal 101; a means 1 for detecting an amplitude level of a second wireless signal 100 modulated by means of a non-amplitude-modulation and transmitted from a sender of the first wireless signal 101; and a means 2A for correcting the amplitude of the first wireless signal 101 in accordance with the amplitude level of the second wireless signal 100. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a radio signal receiving device.
[0002]
[Prior art]
In multipath distortion due to reception of a wireless signal through a plurality of paths, the amplitude and phase of the received signal fluctuate as a result of adding delayed waves having different path lengths.
[0003]
Conventionally, effective measures have not always been taken against such amplitude fluctuations due to multipath distortion.
[0004]
As this kind of technology, for example, Patent Document 1 below is known. In Patent Document 1, a multipath detection signal that has detected a multipath is output to a variable local oscillation circuit, and the modulation of the modulated signal to be detected is corrected to be shallow. In this technique, although the detected signal causes distortion in the detected signal, generation of abnormal noise due to multipath distortion is suppressed.
[0005]
However, the technique of Patent Document 1 corrects the influence of multipath distortion by controlling the oscillation frequency of the variable local oscillation circuit, and does not directly correct the influence of amplitude fluctuation.
[0006]
[Patent Document 1]
JP-A-9-163322 (abstract)
[0007]
[Problems to be solved by the invention]
The present invention has been made in view of such problems of the related art. That is, an object of the present invention is to provide a technique for directly correcting a received signal affected by a change in amplitude due to multipath distortion or the like.
[0008]
[Means for Solving the Problems]
The present invention employs the following means in order to solve the above problems. That is, the present invention is a receiving apparatus, and a demodulation unit for demodulating a modulated signal from a first wireless signal;
Means for detecting the amplitude level of a second radio signal modulated by non-amplitude modulation and transmitted from the source of the first radio signal;
Means for correcting the amplitude of the first wireless signal according to the amplitude level of the second wireless signal.
[0009]
Here, the non-amplitude modulation is, for example, an angle modulation, and is a modulation method in which there is basically no change in the amplitude level or extremely small unless there is disturbance. Generally, angle modulation includes frequency modulation and phase modulation. Therefore, the second wireless signal is, for example, an angle-modulated wireless signal. As described above, the second radio signal may be a frequency-modulated radio signal or a phase-modulated radio signal.
[0010]
The receiving device detects the amplitude level of the second wireless signal modulated by the non-amplitude modulation. Then, the amplitude of the first wireless signal is corrected according to the detection result of the amplitude level. When the first wireless signal and the second wireless signal are wireless signals transmitted from the same transmission source, there is a high possibility that the amplitude will fluctuate due to the same disturbance. Here, the disturbance is, for example, a variation in amplitude due to multipath.
[0011]
As a result, by detecting a change in the amplitude level of the second wireless signal having no amplitude change, the change in the amplitude level of the first wireless signal can be corrected, and the modulated signal is demodulated from the corrected first wireless signal. it can. Note that demodulation is also referred to as detection.
[0012]
Preferably, the receiving device receives a reception signal including the first radio signal and the second radio signal,
Means for separating the first wireless signal and the second wireless signal from the received signal.
[0013]
Further, the first wireless signal and the second wireless signal may be the same wireless signal. For example, the receiving device detects the amplitude level of the angle-modulated wireless signal, corrects the amplitude level of the angle-modulated received signal based on the detection result, and converts the angle-modulated wireless signal into the angle-modulated signal. May be demodulated.
[0014]
Preferably, the demodulation means may demodulate a modulated signal from the amplitude-modulated first wireless signal.
[0015]
Preferably, the demodulation means may demodulate a modulated signal from the angle-modulated first wireless signal.
[0016]
Preferably, the demodulation means may demodulate a modulated signal from the frequency-modulated first wireless signal.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawing of FIG.
[0018]
<Structure>
FIG. 1 is a block diagram of a receiving apparatus according to the present embodiment. Here, an embodiment of the present invention will be described using a receiving apparatus for receiving analog television broadcasts as an example. In this analog television broadcast, video is amplitude-modulated and audio is frequency-modulated and broadcast.
[0019]
This receiving device includes an antenna 5 for receiving a high-frequency signal, a high-frequency tuner 6 for converting a high-frequency signal received by the antenna 5 to an intermediate frequency, and a band for band-limiting the received signal from the high-frequency tuner 6 converted to the intermediate frequency. A filter 7, an amplitude level detection unit 1 for detecting an amplitude level of a received signal 100 including a frequency-modulated voice-modulated signal among the band-limited received signals, A multipath correction unit 2A that performs multipath correction on the reception signal 101 including the modulated video modulation signal, a video detection unit 3 that detects a video signal from the reception signal 101 after the multipath correction, A multipath correction unit 2B that performs multipath correction on the received signal 100 including the modulated voice modulated signal, and a reception signal after multipath correction. And a frequency detecting unit 4 that the frequency detecting the audio signal from the 100.
[0020]
As shown in FIG. 1, a received signal received by the antenna 5 is converted to an intermediate frequency by the high frequency tuner 6 and A / D converted. Hereinafter, in this receiving device, the received signal is processed as digital data. Then, the A / D-converted reception signal is input to the bandpass filter 7. The bandpass filter 7 discriminates, for example, a video modulation signal (amplitude-modulated signal) and an audio modulation signal (frequency-modulated signal) of a television broadcast according to the frequency band. Since the technology related to the antenna 5, the high-frequency tuner 6, and the bandpass filter 7 is widely known, the detailed configuration is omitted in the present embodiment.
[0021]
FIG. 1 illustrates a reception signal 100 and a reception 101 as reception signals discriminated by the bandpass filter 7. Here, it is assumed that received signal 100 is a frequency-modulated signal including a voice-modulated signal. It is also assumed that received signal 101 is an amplitude-modulated signal including a video modulation signal.
[0022]
The amplitude level detector 1 detects the amplitude level of the received signal 100. It is well known that such amplitude level detection can be realized by, for example, an envelope detection circuit. In the case of a digital signal, for example, the same processing as that of envelope detection can be realized by integration calculation with respect to the absolute value of the signal. As described above, the received signal 100 is a frequency-modulated voice-modulated signal of the signal received from the antenna 5.
[0023]
An amplitude level of a frequency-modulated signal is originally constant. However, when a frequency-modulated signal is received by multipath, it undergoes amplitude and phase fluctuations. Therefore, the output of the amplitude level detection unit 1 is not constant with respect to the signal received by multipath. That is, the output of the amplitude level detector 1 indicates the degree of amplitude fluctuation of the frequency modulation signal affected by the multipath.
[0024]
The multipath correction unit 2A corrects the amplitude fluctuation of the reception signal 101 according to the output signal of the amplitude level detection unit 1. The multipath correction unit 2A is, for example, a multiplication circuit that multiplies the reception signal 101 by the inverse of the output of the amplitude level detection unit 1. That is, the multipath correction unit 2A divides the reception signal 101 by the output signal value of the amplitude level detection unit 1.
[0025]
As described above, the received signal 101 is an amplitude-modulated video modulated signal of the signal received from the antenna 5. That is, the reception signal 101 is a signal whose amplitude level changes according to the video modulation signal. However, there are cases where the amplitude of the received signal 101 fluctuates due to the influence of multipath in addition to the original amplitude modulation. In this case, since the received signal 101 is an amplitude-modulated signal, it is difficult to directly detect the degree of the change.
[0026]
On the other hand, the received signals 100 and 101 are both signals received from the same broadcasting station via the same path. Therefore, when the amplitude level of the received signal 101 fluctuates due to the influence of multipath, the amplitude level of the received signal 100 fluctuates similarly. Since the received signal 100 is a frequency-modulated signal, the received signal 100 is originally a signal having no fluctuation in amplitude level. Therefore, the fluctuation of the amplitude level of the received signal 100 is likely to be an amplitude fluctuation caused by disturbance such as multipath. Therefore, if a change in the amplitude level of the received signal 100 is obtained and corrected so as to cancel the change, the amplitude change caused by disturbance such as multipath can be suppressed.
[0027]
The video detector 3 demodulates the received signal 101 corrected by the multipath corrector 2A. Since the received signal 101 is an amplitude-modulated signal, this demodulation may be performed by a demodulation process on a normal amplitude-modulated wave, for example, by synchronous detection. However, the processing of the video detection unit 3 is not limited to synchronous detection.
[0028]
Similarly, the multipath correction unit 2B corrects the amplitude fluctuation of the reception signal 100 according to the output signal of the amplitude level detection unit 1. The configuration and operation of the multi-pass correction unit 2B are the same as those of the multi-pass correction unit 2A. However, the multipath correction unit 2B corrects the received signal 100 frequency-modulated by the audio signal.
[0029]
The frequency detector 4 demodulates the received signal 100 corrected by the multipath corrector 2B. The frequency detector 4 is a general FM detection module. As such an FM detection module, for example, a PLL (Phase Locked Loop) detection method or the like is known. However, the embodiment of the present invention is not limited by the configuration of the frequency detector 4.
[0030]
<Action>
As described above, in this receiving apparatus, the bandpass filter 7 discriminates the received signal into the received signals 100 and 101. Among them, the reception signal 100 is a frequency modulation signal which does not originally have a fluctuation in the amplitude level. Further, the reception signal 101 is an amplitude modulation signal.
[0031]
Then, the amplitude level detector 1 detects a change in the amplitude level of the received signal 100, and inputs the detection result to the multipath correctors 2A and 2B. Since the received signal 100 is originally a signal having no change in amplitude level (referred to as a non-amplitude modulated signal), the change in amplitude level indicates an amplitude change due to disturbance such as multipath.
[0032]
Then, the multipath correction unit 2A corrects the amplitude level of the reception signal 101 based on the fluctuation of the amplitude level of the reception signal 100. Further, the multipath correction unit 2B corrects the amplitude level of the received signal 100 itself based on the fluctuation of the amplitude level of the received signal 100.
[0033]
In this way, the amplitude level detector 1 detects the received amplitude level of the received signal 100 having no amplitude level fluctuation, and the detection result indicates the amplitude fluctuation due to a disturbance such as multipath. Therefore, the multipath correction units 2A and 2B can be configured with a simple configuration such as a multiplier. As described above, according to the present receiving apparatus, amplitude fluctuation of a received signal is detected, and the received signal is directly operated, whereby amplitude fluctuation due to the influence of multipath or the like can be corrected.
[0034]
<Modification>
In the above-described embodiment, the configuration of the receiving apparatus that corrects the amplitude fluctuation due to the influence of the multipath and the like in the reception of the analog television broadcast has been described. However, embodiments of the present invention are not limited to receiving analog television broadcasts.
[0035]
In the above embodiment, a frequency-modulated reception signal is used as a reception signal for detecting an amplitude level. However, in the embodiment of the present invention, the input signal to the amplitude level detector 1 is not limited to a frequency-modulated radio signal. That is, the present invention is applicable to reception of a signal including a radio signal modulated by a method other than frequency modulation, for example, a modulation method such as phase modulation.
[0036]
【The invention's effect】
As described above, according to the present invention, it is possible to directly correct a received signal affected by a fluctuation in amplitude due to multipath distortion or the like.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a receiving apparatus according to an embodiment of the present invention.
DESCRIPTION OF SYMBOLS 1 Amplitude level detection part 2A, 2B Multipath correction part 3 Video detection part 4 Frequency detection part 5 Antenna 6 High frequency tuner 7 Bandpass filter 100 Received signal (frequency-modulated received signal)
101 reception signal (amplitude modulated reception signal)

Claims (7)

Demodulating means for demodulating a modulated signal from the first wireless signal;
Means for detecting a signal level of a second wireless signal modulated by non-amplitude modulation and transmitted from a source of the first wireless signal;
Means for correcting the amplitude of the first wireless signal according to the amplitude level of the second wireless signal. Means for receiving a received signal including the first wireless signal and the second wireless signal;
The receiving device according to claim 1, further comprising: means for separating the first wireless signal and the second wireless signal from the received signal. The receiving device according to claim 1, wherein the demodulation unit demodulates a modulated signal from the amplitude-modulated first wireless signal. The receiving device according to claim 1, wherein the demodulation unit demodulates a modulated signal from the angle-modulated first wireless signal. The receiving device according to claim 1, wherein the demodulation unit demodulates a modulated signal from the frequency-modulated first wireless signal. The receiving device according to claim 1, wherein the second wireless signal is an angle-modulated signal. The receiving device according to claim 1, wherein the second wireless signal is a frequency-modulated signal.

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