KR20050003064A - Broadcasting receive apparatus having automatic-fine-tuning function - Google Patents

Abstract

PURPOSE: A broadcasting receiver having an AFT(Automatic Fine Tuning) function is provided to prevent the current broadcasting picture from being affected by the AFT function and minimize transient effect due to the AFT function in the event of channel switching by executing the AFT function through a sub-tuner while the main tuner receives a broadcasting signal and tuning the main tuner in response to the tuning result value of the sub-tuner. CONSTITUTION: A broadcasting receiver having an AFT function includes a main tuner(110), a sub-tuner(115), a video processor(130), an AFT comparator(141), and a tuner controller(143). The main tuner and sub-tuner transform RF(Radio Frequency) signals of a tuned channel into intermediate frequency signals and output the intermediate frequency signals. The video processor demodulates the broadcasting signal tuned by the main tuner to transmit the demodulated signal to an image output device(150), and detects a voltage corresponding to the frequency of the intermediate frequency signal input from the sub-tuner. The AFT comparator compares the detected voltage to a predetermined reference voltage. The tuner controller controls the oscillating frequency of the sub-tuner in response to the comparison result, compares the oscillating frequencies of the main tuner and the sub-tuner to each other, and adjusts the oscillating frequency of the main tuner into the oscillating frequency of the sub-tuner.

Description

Broadcast receiver with automatic fine tuning function {BROADCASTING RECEIVE APPARATUS HAVING AUTOMATIC-FINE-TUNING FUNCTION}

The present invention relates to a broadcast receiving apparatus having an automatic fine tuning (AFT) function, and more particularly, a tuning result of a sub tuner by performing a fine tuning function through a sub tuner during broadcast reception through a main tuner. The present invention relates to a broadcast receiver having an automatic fine tuning function for tuning the main tuner according to the present invention.

In general, in a broadcast receiver having a built-in tuner, a broadcast signal of a desired channel is tuned among a plurality of broadcast signals received through an antenna, and the video of the broadcast signal (in the case of the NTSC system) is 45.75 MHz, and audio is transmitted. Frequency conversion to 41.25MHz intermediate frequency signal.

However, when a broadcast station transmits a broadcast signal, a change may occur in a carrier frequency of the broadcast signal, and a change may occur in an oscillation frequency for converting a broadcast signal selected by the tuner into an intermediate frequency signal. In this case, there was a problem that the screen distortion is caused by the change of the intermediate frequency.

Accordingly, conventionally, the AFT circuit is employed in the broadcast receiving apparatus so that the fluctuation of the frequency during broadcast reception can be corrected.

However, according to the related art, since the oscillation frequency of the tuner is adjusted by the AFT function during the broadcast reception, it adversely affects the broadcast reception screen. In particular, when the reception channel is switched, a transient phenomenon caused by the AFT function appears on the screen.

The present invention has been proposed to solve such a conventional problem, by performing a fine tuning function through the sub-tuner during broadcast reception through the main tuner to tune the main tuner according to the tuning result of the sub-tuner, the AFT of the sub-tuner The purpose of the present invention is to keep the output of the main tuner during broadcast reception unchanged so that the current broadcast reception screen is not affected by the AFT function and to minimize the transient phenomenon caused by the AFT function when switching the reception channel.

In order to achieve the above object, a broadcast receiving apparatus having an automatic fine tuning function according to the present invention includes oscillating an RF signal of a channel tuned according to channel information from among RF type broadcast signals received through an antenna from each oscillator. A main tuner and a sub tuner for converting and outputting an intermediate frequency signal by a frequency, respectively, and demodulating the broadcast signal selected by the main tuner to the image output device, and transmitting the image signal to a frequency of an intermediate frequency signal input from the sub tuner. An image processor for detecting and outputting a corresponding voltage, an AFT comparator for comparing the detected AFT voltage with a preset reference voltage, and an AFT function for variably adjusting the oscillation frequency of the sub-tuner according to the AFT comparison value; The oscillation frequency of the main tuner is compared by comparing the oscillation frequencies of the main tuner and the sub tuner. And a tuner controller for adjusting the frequency by the oscillation frequency value of the sub tuner.

1 is a block diagram of a broadcast receiving apparatus having an automatic fine tuning function according to the present invention;

2 is a flowchart illustrating an automatic fine tuning process according to the present invention.

<Explanation of symbols for the main parts of the drawings>

110: main tuner 115: sub tuner

120: SAW filter 130: image processor

140: Micom 141: AFT comparator

143: tuner controller 150: video output device

There may be a plurality of embodiments of the present invention. Hereinafter, preferred embodiments will be described in detail with reference to the accompanying drawings. This embodiment allows for a better understanding of the objects, features and advantages of the present invention.

As shown in the block diagram of FIG. 1, the broadcast receiving apparatus having the automatic fine tuning function according to the present invention includes the RF of the channel tuned according to the channel information of the microcomputer 140 among the RF-type broadcast signals received through the antenna. Intermediate frequency signals output from the main tuner 110 and the sub tuner 115 and the main tuner 110 and the sub tuner 115 to convert the signal into an intermediate frequency signal by the oscillation frequency from each oscillator, respectively. Is inputted through a preamplifier (not shown) to obtain the required frequency characteristics SAW (Surface Acoustic Wave) filter 120 and the image output device by demodulating the broadcast signal tuned in the main tuner 110 An image processor 130 which transmits to the 150 and detects a voltage corresponding to the frequency of the intermediate frequency signal input from the sub tuner 115 and outputs the voltage to the microcomputer 140 through a dedicated AFT line; The sub-tuner 115 according to the output values of the AFT comparator 141 and the AFT comparator 141 in the microcomputer 140, which compares the AFT voltage of the image processor 130 with a preset reference voltage and outputs them to the tuner controller 143. Performs an AFT function to variably adjust the oscillation frequency of the main tuner 110, and compares the oscillation frequencies of the main tuner 110 and the sub tuner 115, and if the oscillation frequencies do not match, the oscillation frequency of the main tuner 110 is changed to the sub tuner 115. It comprises a tuner controller 143 in the microcomputer 140 to adjust the oscillation frequency value of.

The automatic fine tuning process by the broadcast receiving apparatus having the automatic fine tuning function configured as described above will be described with reference to FIGS. 1 and 2.

First, when the channel information to be received from the microcomputer 140 is supplied to the main tuner 110 and the sub tuner 115, the main tuner 110 and the sub tuner 115 tune the broadcast signal of the desired channel among the broadcast signals of the RF type received through the antenna. The RF signal is converted into an intermediate frequency signal by the oscillation frequency from the oscillator and output.

The intermediate frequency signal output from the main tuner 110 and the sub tuner 115 is amplified to a certain size by a preamplifier (not shown), and the amplified intermediate frequency signal is provided with the required frequency characteristics through the SAW filter 120. Get

The image processor 130 demodulates the broadcast signal tuned in the main tuner 110 and transmits the image signal to the image output device 150, and detects a voltage corresponding to the frequency of the intermediate frequency signal input from the sub tuner 115. The microcomputer 140 outputs the microcomputer 140 through the dedicated AFT line (S201).

The AFT comparator 141 in the microcomputer 140 outputs the AFT voltage of the image processor 130 to the tuner controller 143 by comparing the reference voltage with the reference voltage, and the tuner controller 143 performs the sub according to the output value of the AFT comparator 141. An AFT function for variably adjusting the oscillation frequency of the tuner 115 is performed. Thus, even if the carrier frequency of the input RF signal is fluctuated or the oscillation frequency is changed, the sub tuner 115 readjusts the oscillation frequency according to the frequency change of the intermediate frequency signal and always outputs an intermediate frequency signal of a predetermined frequency (S203).

In addition, the tuner controller 143 in the microcomputer 140 compares the oscillation frequencies of the main tuner 110 and the sub-tuner 115, and if the compared oscillation frequencies do not match, the oscillation frequency of the main tuner 110 is sub-tuner. Adjust to the oscillation frequency value at 115 (S205 to S209).

Subsequently, the main tuner 110 converts the RF signal of the tuned channel into an intermediate frequency signal by an adjusted oscillation frequency, that is, an oscillation frequency corresponding to the oscillation frequency of the sub-tuner 115, and outputs the main tuner 110. The output of the input signal is input to the image processor 130 through the preamplifier and the SAW filter 120, and is then delivered to the image output device 150 after image demodulation.

In the above description, but limited to one embodiment of the present invention, it is obvious that the technology of the present invention can be easily modified by those skilled in the art. Such modified embodiments should be included in the technical spirit described in the claims of the present invention.

As described above, according to the present invention, the output of the main tuner being broadcasted does not change even during the AFT of the sub-tuner so that the current broadcast reception screen is not affected by the AFT function. It has the effect of minimizing transients.

Claims (1)

A main tuner and a sub tuner for converting an RF signal of a channel selected according to channel information among RF signals received through an antenna into an intermediate frequency signal by an oscillation frequency from each oscillator and outputting the intermediate frequency signal; An image processor for demodulating the broadcast signal selected by the main tuner and transmitting the image signal to a video output device, and detecting and outputting a voltage corresponding to a frequency of an intermediate frequency signal input from the sub tuner; An AFT comparator configured to compare the detected AFT voltage with a preset reference voltage and output the same; Perform an AFT function to variably adjust the oscillation frequency of the sub-tuner according to the AFT comparison value, and adjust the oscillation frequency of the main tuner to the oscillation frequency value of the sub-tuner by comparing the oscillation frequencies of the main tuner and the sub-tuner. Tuner controller Broadcast receiving apparatus having an automatic fine tuning function comprising a.