KR20060126143A - Apparatus for receiving digital broadcasting - Google Patents

Abstract

A broadcasting receiver is provided to make it possible to extract a desired broadcasting signal from broadcasting even when strong neighboring channel signals are included in the broadcasting by using a digital SAW(Surface Acoustic Wave) and a digital self AGC(Automatic Gain Control). A tuner(10) selects the only specific channel which a user wants while receiving RF broadcasting. An analog SAW filter(20) filters neighboring channel signals and noise signals from the output signal of the tuner. An IF(Intermediate Frequency) amplifier(50) amplifies the intermediate frequency signal outputted from the analog SAW filter. An A/D converter(110) converts the analog signal, which is inputted from the IF amplifier, into a digital signal. A digital SAW filter(150) filters neighboring channel signals from the digital signal. A digital self AGC(170) compensates for digital gain loss of the digital signal.

Description

Broadcasting apparatus {Apparatus for receiving digital broadcasting}

1 is a structural diagram showing an embodiment of a conventional broadcast receiving apparatus

2 is a structural diagram showing an embodiment of a broadcast receiving apparatus according to the present invention;

3 is a conceptual diagram illustrating a waveform spectrum output by an A / D converter in a normal state without an adjacent signal and a waveform spectrum output by an A / D converter in a state in which a signal attenuated by a strong adjacent signal is received;

4 is a conceptual diagram illustrating a spectrum of a waveform passing through a digital SAW filter and a waveform passing through a digital self-gain control controller of a broadcast receiving apparatus according to the present invention.

<Description of Symbols for Main Parts of Drawing>

10 tuner 20 first SAW filter (analog SAW filter)

30: IF amplifier 40: second SAW filter

50: variable IF amplifier 100: digital signal processing unit

110: A / D converter 130: automatic gain controller

150: digital SAW filter 170: digital self gain controller

180: demodulator

The present invention relates to a broadcast receiving apparatus, and more particularly, to a broadcast receiving apparatus capable of extracting a broadcast signal even in the presence of strong adjacent channel interference and improving a response speed corresponding to a change in the size of the broadcast signal. .

The broadcast receiving apparatus includes a signal restoring unit for restoring a received broadcast, a decoding unit for decoding a received signal in a compressed form with respect to the restored signal, and a display unit for displaying the decoded signal on a screen for viewing by a viewer. Among them, the signal restoration unit restores the received broadcast according to the signal modulation scheme when transmitting from a broadcasting station. Broadcast signal transmission methods are largely divided into the American Advanced Television System Committee (ATSC) method and the European Digital Video Broadcasting (DVB) method. In a band-limited transmission system that receives such a broadcast, an analog surface acoustic wave (SAW) filter is used in a receiver to reduce interference of adjacent channels.

Referring to FIG. 1, an embodiment of a conventional digital broadcast receiver will be described. One embodiment of the conventional broadcast receiver shown in FIG. 1 includes a tuner 10, a first SAW filter 20, an IF amplifier 30, a second SAW filter 40, a variable IF amplifier 50, and an analog. A digital converter (A / D converter) 110, an automatic gain controller (AGC) 130, and a signal demodulator 180. When a band-limited broadcast signal is transmitted through a channel, an RF (Radio Frequency) signal input through an antenna is first input to the tuner 10, and the tuner 10 selects only a signal of a specific channel desired by the user. The channel signal is filtered, and the specific channel signal is converted into an intermediate frequency band and output. The first SAW filter 20 receives the output signal and filters the adjacent channel signal and the noise signal. The IF amplifier 30 restores and outputs the magnitude of the attenuated input signal when passing through the first SAW filter 20. Then, the output signal is filtered again for the remaining signals except for the desired signal in the second SAW filter 40. The variable IF amplifier 50 amplifies and outputs the signal output from the second SAW filter 40 according to the control signal to the automatic gain controller 130. The automatic gain controller 130 may determine the input signal gain and feed the result back to the variable IF amplifier 50 or the tuner 10. The output signal is input to the A / D converter 110 to convert from an analog signal to a digital signal. When the digital signal is output to the A / D converter 110, the digital signal is processed.

In the digital signal processing, the received signal converted to digital is shifted to the correct baseband by the carrier recovery unit and outputted, and a phase compensator for compensating for distortion caused by passing through the channel and a phase tracker caused by the tuner are removed. It is sequentially input to the channel decoding unit. Since the ATSC carries only data in the transmission signal, the timing recovery unit calculates the same symbol clock timing as used at the time of transmission so that the reception side can recover the transmission data.

In the structure of the receiver as shown in FIG. 1, the SAW filter, which is an analog device, most dictates the reception performance due to interference of an adjacent channel. Therefore, the performance of the broadcast receiver may vary depending on the SAW filter used when configuring the receiver. In particular, in order to minimize interference of adjacent channels with respect to a received signal, in the case of a terrestrial digital television receiver, two SAW filters, which are analog elements, are used in a cascade form as shown in FIG. 1. When using the cascade-type two-stage SAW filter, in-band loss occurs a lot in the received signal, and an IF amplifier must be added after the SAW filter in the receiver. However, when the IF amplifier is added to the broadcast receiver, there is a problem that the price of the broadcast receiver is a factor of increase.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a broadcast receiving apparatus capable of extracting a desired broadcast signal even when a strong adjacent channel signal exists and ensuring price competition of the broadcast receiving apparatus. It is.

In order to achieve the above object, the present invention provides a broadcast receiving apparatus capable of receiving a band-limited RF broadcast signal and demodulating and outputting the radio frequency signal, comprising: a tuner for selecting a signal of a specific channel desired by a user among the transmitted RF broadcasts; An analog SAW filter for filtering adjacent channel signals and noise signals among the signals output from the tuner; An IF amplifier for amplifying and outputting an intermediate frequency signal output from the analog SAW filter; An analog-digital signal (A / D) converter for converting an analog signal received from the amplifier into a digital signal and outputting the digital signal; A digital SAW filter for filtering an adjacent channel signal with respect to the output digital signal; And a digital self gain controller for compensating the digital gain loss of the digital signal output from the digital SAW filter.

The digital SAW filter can filter and output adjacent channel signals, so that there is no need to provide two-stage SAW filters in the analog region. The digital self-gain control controller can compensate for the attenuated signal when passing through the SAW filter to improve the performance of the receiver and to increase the auto gain control speed of the entire receiver.

A preferred embodiment of the broadcast receiving apparatus according to the present invention will be described with reference to FIG. 2 as follows. The broadcast receiving apparatus according to the present invention includes a tuner 10, an analog SAW filter 20, a variable IF amplifier 50, an analog-to-digital converter (A / D converter) 110, an automatic gain controller (Automatic Gain Control); AGC) 130, a digital SAW filter 150, a digital self-gain control controller 180 and a signal demodulator 180. Unlike the conventional broadcast receiver of FIG. 1, the IF receiver and the second SAW filter, which are analog elements, are removed in the broadcast receiver according to the present invention.

The tuner 10 selects and outputs the specific channel signal from the RF signals input through the antenna, and the analog SAW filter 20 receives the signal and first filters the adjacent channel signal and the noise signal. The variable IF amplifier 50 amplifies and outputs the magnitude of the signal output from the analog SAW filter 20 according to the control signal of the automatic gain controller 130. The output signal is input to the A / D converter 110 to convert from an analog signal to a digital signal. The automatic gain controller 130 that controls the magnitude of the signal input to the A / D converter 110 controls the signal through the output of the A / D converter 110. To this end, the automatic gain controller 130 determines the increase or decrease of the input signal gain using a detector circuit and feeds the result back to the variable IF amplifier 50 in the analog signal processing region. The received signal converted into a digital signal is input to the digital SAW filter. The digital SAW filter 150 removes and outputs the influence of the adjacent channel on the received signal and the CW noise existing in the vicinity. In the present invention, it is preferable that only one SAW filter exists in the analog signal processing region. Accordingly, the digital broadcast receiver according to the present invention reduces the number of IF amplifiers in the analog signal processing area to secure the price competitiveness of the entire broadcast receiver. In addition, the digital broadcast receiver according to the present invention shown in the embodiment of FIG. 2 includes a digital self-gain controller 170 behind the digital SAW filter. Accordingly, the digital self-gain gain controller 170 reduces the saturation of the IF amplifier appearing in the presence of a strong adjacent signal by performing automatic gain control on all signals present at the input of the A / D converter 110. Can be. The digital self-gain gain controller 170 can compensate for digital gain loss caused by a strong adjacent signal, and can also improve the speed of automatic gain control in all broadcast receivers.

The signal output from the digital self-gain gain controller 170 is input to the signal demodulator 180 to perform a signal demodulation process as in the prior art.

3 and 4 conceptually describe the change of the received signal waveform passed through the digital SAW filter and the digital self-gain control controller included in the digital broadcast receiver according to the present invention.

3 shows a signal waveform when a signal received by a digital broadcast receiver according to the present invention is input to a digital SAW filter. In FIG. 3, the digital SAW filter is indicated by a dotted line and the magnitude of the received signal waveform is indicated by a hatched line. In general, the magnitude (a) of a signal waveform in a steady state without adjacent signals is about several to several tens of dB greater than the magnitude (b) of a signal waveform in the presence of a strong neighbor signal.

FIG. 4 shows the magnitude (c) of the waveform that is output when the signal waveform of size b passes through the digital SAW filter and the adjacent signal is filtered in the presence of a strong neighbor signal, and the signal having the magnitude of c is digital self-automatically. Shows the magnitude (d) of the waveform output when the gain loss is compensated through the gain controller. That is, the signal size d may be compensated to be the signal size a of FIG. 3, and accordingly, the digital broadcast receiver according to the present invention may improve signal reception performance of several to several tens of dB.

The broadcast receiving apparatus according to the present invention can be applied to all systems for receiving a signal transmitted by being limited in bandwidth, and in particular, it can be applied to a terrestrial DTV system, a cable system and a DMB system. In addition, the broadcast transmission method that can be received by the broadcast receiving apparatus according to the present invention may be any one of the terrestrial DTV transmission methods 8-VSB, DVB-T, ISDB-T, and TDS-OFDM. The cable DTV transmission method may be any one of 16-VSB, 64 / 256QAM, and DVB-C, and the mobile DTV transmission method may be DMB or DVB-H.

Referring to the effects of the broadcast receiving apparatus according to the present invention described above is as follows.

First, according to the broadcast receiving apparatus according to the present invention, even when there is a strong adjacent channel signal by the digital SAW filter and the digital self-gain control controller, it is possible to extract the desired broadcast signal, and the broadcast apparatus is removed by removing the analog device. Price competition of the receiver can be secured.

Second, according to the broadcast receiving apparatus according to the present invention, the digital self-gain gain controller can not only improve the performance of the digital SAW filter but also improve the automatic gain control speed of the entire broadcast receiving apparatus.

Claims (2)

A broadcast receiving apparatus capable of receiving a band-limited RF broadcast signal and demodulating and outputting the same, A tuner for selecting a signal of a specific channel desired by a user among the transmitted RF broadcasts; An analog SAW filter for filtering adjacent channel signals and noise signals among the signals output from the tuner; An IF amplifier for amplifying and outputting an intermediate frequency signal output from the analog SAW filter; An analog-digital signal (A / D) converter for converting an analog signal received from the amplifier into a digital signal and outputting the digital signal; A digital SAW filter for filtering an adjacent channel signal with respect to the output digital signal; And And a digital self-gain controller for compensating for digital gain loss of the digital signal output from the digital SAW filter. The method of claim 1, The broadcast signal received by the broadcast receiving apparatus is a signal received by any one of a transmission method of a terrestrial digital television transmission method, a cable digital television transmission method, or a mobile digital television transmission method. .

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