JP2010171488A5

JP2010171488A5 -

Info

Publication number: JP2010171488A5
Application number: JP2009009595A
Authority: JP
Filing date: 2009-01-20
Publication date: 2012-03-08
Anticipated expiration: 2029-01-20

Description

上記目的を達成するため、本願請求項１に記載の発明は、
受信信号を増幅するロウノイズアンプと、ロウノイズアンプで増幅された受信信号を増幅し中間周波数の信号に周波数変換して出力するＲＦ処理部と、中間周波数の受信信号をデジタル信号に変換した後に復調する復調部と、を備えたデジタル放送受信装置において、
前記復調部は、
受信信号の振幅レベルを検出する振幅検出回路と、
中間周波数の受信信号をデジタル信号に変換するＡＤ変換回路と、
該ＡＤ変換回路で変換された時間軸のデータを周波数軸のデータに変換するデータ変換回路と、
前記周波数軸のデータに基づいて、フェージングによるサブキャリアの周波数変動の大きさを検出する周波数変動検出手段と、
前記振幅検出回路の出力に応じて前記ＲＦ処理部の利得を制御する利得制御信号を生成して前記ＲＦ処理部へ出力する利得制御回路と、
前記周波数変動検出手段の出力および前記振幅検出回路の出力に応じて前記ロウノイズアンプの利得を切り替える利得切替え制御信号を生成して前記ロウノイズアンプへ出力する利得切替え制御回路と、
を備えることを特徴としている。 In order to achieve the above object, the invention described in claim 1 of the present application is
A low noise amplifier that amplifies the received signal, an RF processing unit that amplifies the received signal amplified by the low noise amplifier, converts the frequency to an intermediate frequency signal, and outputs the signal, and after converting the intermediate frequency received signal to a digital signal In a digital broadcast receiver comprising a demodulator for demodulating,
The demodulator
An amplitude detection circuit for detecting the amplitude level of the received signal;
An AD conversion circuit that converts a received signal of an intermediate frequency into a digital signal;
A data conversion circuit that converts time-axis data converted by the AD conversion circuit into frequency-axis data;
Based on the data on the frequency axis, frequency fluctuation detecting means for detecting the magnitude of the frequency fluctuation of the subcarrier due to fading;
A gain control circuit that generates a gain control signal for controlling the gain of the RF processing unit in accordance with the output of the amplitude detection circuit and outputs the gain control signal to the RF processing unit;
A gain switching control circuit for generating a gain switching control signal for switching the gain of the low noise amplifier according to the output of the frequency variation detecting means and the output of the amplitude detecting circuit and outputting the gain switching control signal to the low noise amplifier;
It is characterized by having.

請求項５に記載の発明は、請求項４に記載のデジタル放送受信装置において、
前記受信信号はマルチキャリア・デジタル変調方式で変調された信号であり、
前記利得切替え制御回路は、
パイロット信号の変動量が前記所定のレベル以下の場合、受信電力が−７０ｄＢｍ以下の時に前記ロウノイズアンプの利得を高い利得に切り替える一方、受信電力が−３０ｄＢｍ以上の時に前記ロウノイズアンプの利得を低い利得に切り替え、
パイロット信号の変動量が前記所定のレベルより大きい場合、受信電力が−７５ｄＢｍ以下の時に前記ロウノイズアンプの利得を高い利得に切り替える一方、受信電力が−２０ｄＢｍ以上の時に前記ロウノイズアンプの利得を低い利得に切り替えることを特徴としている。 According to a fifth aspect of the present invention, in the digital broadcast receiving apparatus according to the fourth aspect,
The received signal is a signal modulated by a multicarrier digital modulation method,
The gain switching control circuit includes:
When the fluctuation amount of the pilot signal is less than or equal to the predetermined level, the gain of the low noise amplifier is switched to a high gain when the reception power is −70 dBm or less, while the gain of the low noise amplifier is changed when the reception power is −30 dBm or more. Switch to lower gain,
When the fluctuation amount of the pilot signal is larger than the predetermined level , the gain of the low noise amplifier is switched to a high gain when the reception power is −75 dBm or less, while the gain of the low noise amplifier is changed when the reception power is −20 dBm or more. It is characterized by switching to a low gain.

復調部４は、図４に示すように、ＲＦ処理部３で所定の振幅レベルまで増幅された放送受信信号をデジタル信号に変換するＡＤ変換回路４１と、ＡＤ変換された受信データを高速フーリエ変換することで時間軸情報から周波数軸情報に変換するＦＦＴ４２、伝送路で生じた歪みを補正する波形等化回路４３、マルチキャリア・デジタル変調方式の一つであるＯＦＤＭ（直交周波数分割多重化方式）のような変調方式に対応した復調方式で受信データを復調する復調回路４４、受信データに含まれている誤り訂正符号に基づいて受信データの誤り訂正を行う誤り訂正回路４５を備える。 As shown in FIG. 4, the demodulator 4 includes an AD conversion circuit 41 that converts the broadcast reception signal amplified to a predetermined amplitude level by the RF processing unit 3 into a digital signal, and fast Fourier transform of the AD-converted reception data. FFT 42 that converts time axis information to frequency axis information, waveform equalization circuit 43 that corrects distortion generated in the transmission path, and OFDM (orthogonal frequency division multiplexing) that is one of the multicarrier digital modulation systems A demodulation circuit 44 that demodulates the received data by a demodulation method corresponding to the modulation method, and an error correction circuit 45 that performs error correction of the received data based on an error correction code included in the received data.

Claims

A low noise amplifier that amplifies the received signal, an RF processing unit that amplifies the received signal amplified by the low noise amplifier, converts the frequency to an intermediate frequency signal, and outputs the signal, and after converting the intermediate frequency received signal to a digital signal In a digital broadcast receiver comprising a demodulator for demodulating,
The demodulator
An amplitude detection circuit for detecting the amplitude level of the received signal;
An AD conversion circuit that converts a received signal of an intermediate frequency into a digital signal;
A data conversion circuit that converts time-axis data converted by the AD conversion circuit into frequency-axis data;
Based on the data on the frequency axis, frequency fluctuation detecting means for detecting the magnitude of the frequency fluctuation of the subcarrier due to fading;
A gain control circuit that generates a gain control signal for controlling the gain of the RF processing unit in accordance with the output of the amplitude detection circuit and outputs the gain control signal to the RF processing unit;
A gain switching control circuit that generates a gain switching control signal for switching the gain of the low noise amplifier in accordance with the output of the frequency fluctuation detecting means and the output of the amplitude detection circuit and outputs the gain switching control signal to the low noise amplifier. A digital broadcast receiver characterized by the above.

A reception power conversion circuit that converts received power based on the output of the amplitude detection circuit or the output of the gain control circuit; and the gain switching control circuit includes an output of the reception power conversion circuit and an output of the frequency fluctuation detection means The digital broadcast receiving apparatus according to claim 1, wherein the digital broadcast receiving apparatus is configured to generate the gain switching control signal according to the frequency.

The pilot signal detection circuit for detecting a pilot signal included in the received signal is provided, and the frequency fluctuation detecting means detects the magnitude of the frequency fluctuation based on a detection signal of the pilot signal detection circuit. 3. The digital broadcast receiver according to 1 or 2.

4. The digital broadcasting according to claim 3, wherein the frequency fluctuation detecting means includes a comparison circuit that compares the fluctuation amount of the pilot signal detected by the pilot signal detection circuit with a predetermined level set in advance. Receiver device.

The received signal is a signal modulated by a multicarrier digital modulation method,
The gain switching control circuit includes:
When the fluctuation amount of the pilot signal is less than or equal to the predetermined level, the gain of the low noise amplifier is switched to a high gain when the reception power is −70 dBm or less, while the gain of the low noise amplifier is changed when the reception power is −30 dBm or more. Switch to lower gain,
When the fluctuation amount of the pilot signal is larger than the predetermined level , the gain of the low noise amplifier is switched to a high gain when the reception power is −75 dBm or less, while the gain of the low noise amplifier is changed when the reception power is −20 dBm or more. The digital broadcast receiving apparatus according to claim 4, wherein the digital broadcast receiving apparatus is switched to a low gain.

A through path that supplies a received signal to the RF processing unit without passing through the low noise amplifier, and a switching unit that switches whether the received signal is supplied to an input terminal of the low noise amplifier or the through path. 6. The digital broadcast receiving apparatus according to claim 1, wherein the switching control circuit generates a signal for controlling the switching means.