KR0171048B1 - Method and apparatus for tuning the channel of a satellite broadcasting receiver - Google Patents

Abstract

The present invention relates to a channel selection method and a device thereof in a satellite broadcasting receiver. Particularly, a carrier frequency shift caused by cold and external environmental factors, such as frequency fluctuations due to air temperature change or phase synchronization error of the receiver itself, is received. In response to this, it is possible to maintain a clear reception state at all times.

The present invention is a phase-locked loop type tuning circuit composed of a local oscillator 20, a phase controller 21, a fine tuner 22, and a controller 26, and includes an integrating circuit 23 and an automatic microstructure 24. A channel tuning apparatus comprising an A / D converter 25; When the desired channel signal is inputted by discriminating the presence or absence of the input signal by the channel selection switch SW1, the controller 26 reads the frequency data of the desired channel from the memory and outputs it to the fine tuner 22 and at the same time the channel data A ) And the output value B and the reference value C of the A / D converter 25 are stored in respective places, and the output value B and the set reference value C of the A / D converter 25 stored at the place are stored. Is equal to the next channel input signal, and if the output value (B) is not equal to the reference value (C), the difference (D) and the channel data (A) and the difference (D) A first step of storing the sum value E and outputting the sum value E to the fine tuner 22 as data of the phase synchronization loop; If the channel signal is not input from the channel selection switch SW1, the controller 26 stores the digital input value F output from the A / D converter 25, and then stores the digital input value F and the first input signal of the first process. When the output value B of the A / D converter 25 is compared and the values are different, a routine of inputting the output value of the A / D converter 25 of the first step is performed. A channel tuning method comprising a second process of outputting loop information, characterized in that it is used in a satellite broadcasting receiver.

Description

Channel tuning method and apparatus thereof in satellite broadcasting receiver

1 is a block diagram of a satellite broadcasting receiver equipped with the present invention channel selecting apparatus.

2 is a flow chart showing a channel tuning control process in the present invention satellite broadcasting receiver.

3 is a block diagram of a satellite broadcasting receiver using a conventional PLL method.

4 is a block diagram of a satellite broadcast receiver using a conventional AFT scheme.

5 is a flowchart illustrating a channel tuning control process in a conventional satellite broadcasting receiver.

* Explanation of symbols for main parts of the drawings

22: local oscillator 21: phase controller

22: Fine tuner (FS) 23: Integrating circuit

24: automatic micro-tuner (AFT) 25: A / D converter

26: micom

The present invention relates to a channel selection method and a device thereof in a satellite broadcasting receiver. In particular, the present invention relates to a carrier frequency shift caused by internal and external environmental factors such as frequency fluctuations caused by satellite broadcasting receiver temperature changes or phase synchronization errors of the receiver itself. In response, it is possible to maintain a clear reception state at all times.

Tuning apparatus of the conventional satellite broadcasting receiver includes a satellite broadcasting receiver of a PLL (Phase Synchronous Loop) method as shown in FIG. 3, and an AFT (automatic fine tuning) system of a satellite broadcasting receiver as shown in FIG. Most widely known, the electronic phase locked loop (PLL) type satellite broadcasting receiver inputs an intermediate frequency signal from a parabolic antenna and a satellite frequency converter to the first intermediate frequency amplifier 1, and a bandpass filter (2). Is applied to the mixer (3).

At this time, when the tuning switch SW1 of the channel to be received is pressed, the phase synchronization loop information (data, clock enable) of the channel selected by the controller 11 is applied from the fine tuner 10 to generate a frequency generated by the local oscillator 9. Was performed to perform a series of phase-locked loop operations checked by the fine tuner 10 through the phase control unit 8 so that the frequency of the desired channel is generated in the local oscillator 9, but in this manner, the fine tuner ( In 10), since a constant channel frequency is managed by logic data, there is a disadvantage in that a clear reception state cannot be maintained when the first intermediate frequency changes due to the local oscillation frequency of the parabolic antenna and the satellite frequency converter. In addition, in the latter automatic satellite tuning (AFT) satellite broadcasting receiver, as shown in FIG. As in the synchronous loop method, in the operation of the local oscillator 9, the semi-fixed voltage of the selected channel is first applied to the local oscillator 9 through the amplification circuit 12, and the detected base band output is It was applied to the variable diode of the local oscillator 9 through the integrating circuit 13, the automatic fine tuner 14, and the amplifying circuit 12 to perform the tuning operation by tracking the center frequency shift. There was a problem in that the reception state of the screen due to the change in the operation temperature or the volume (Volume) caused by the influence of the inside of the receiver cannot be adequately coped with.

The present invention is conceived to solve the poor reception state of the satellite broadcasting receiver due to the frequency fluctuation due to environmental factors in view of the above problems of the conventional phase-locked loop or automatic fine-tuning method, the frequency of the initially selected channel When the input signal is demodulated and demodulated as bad as the input signal frequency is changed, the base band output is digitally converted to the automatic microtuning circuit and the A / D converter, and the digital signal is controlled to compare the reference value. It is an object of the present invention to provide a channel tuning method and apparatus therefor in a satellite broadcasting receiver capable of feeding back a minute to modify an initial oscillation frequency so that a clear reception state can be maintained at all times. It will be described in detail.

As shown in FIG. 1, the apparatus of the present invention filters a first intermediate frequency amplifier 1 that amplifies and outputs an input first intermediate frequency signal, and filters a signal that is amplified and output from the first intermediate frequency amplifier 1. The oscillation frequency corresponding to the difference is obtained by receiving the band pass filter 2 applied to (3) and the channel signal selected by the channel selection switch SW1, and comparing the feedback digital signal for the base band output with a reference level. A controller 26 for tuning to tune, a fine tuner 22 for fine-tuning the frequency changed by the control signal of the controller 26, and a predetermined oscillation to the mixer 3 by receiving the fine-tuned frequency. Local oscillator 20 for generating a frequency, a phase controller 21 for receiving the oscillation frequency generated by the local oscillator 20 and phase-adjusted it to the fine tuner 22, and the band pass filter 2 Filtered from A mixer (3) for receiving the first intermediate frequency signal and the predetermined oscillation frequency generated by the local oscillator (20) and mixing them to output a second intermediate frequency signal, and filtering the mixed signal from the mixer (3) A surface acoustic wave filter 4, a second intermediate frequency amplifier 5 for amplifying the filtered intermediate frequency signal, and a limiter circuit for limiting and outputting the amplitude of the amplified output second intermediate frequency signal to a constant level. And an FM demodulator (7) for receiving a second intermediate frequency signal level limited output from the limiter circuit (6) and demodulating the same to a base band, which is output from the FM demodulator (7). An integrated circuit 23 for receiving a base band out and integrating the feedback signal into an input signal, and an interpolator of a voice limiter whose local oscillation frequency is changed in a demodulated signal fed back through the integration circuit 23. The controller 26 converts the rear signal into a DC voltage so as to automatically maintain a constant local oscillation frequency as a control voltage, and a local oscillation frequency held constant by the automatic microtuner 24. A / D converter 25 for converting the digital signal to be recognized by a).

In addition, in the method of the present invention, as shown in FIG. 2, the first process of determining whether the channel signal selected by the channel selection switch SW1 is input, and if the channel signal is input, the controller 26 selects the desired channel. Reads the frequency data from the memory and outputs it to the fine tuner 22, stores channel data A, receives the output value B of the A / D converter 25, and outputs the output value B. And a second step of storing the set reference value C and comparing the output value B of the A / D converter 25 stored at the place with the set reference value C, and the comparison result A / D converter 25. If the output value (B) is equal to the set reference value (C), it returns to the mode for discriminating the next channel input signal. If the output value (B) and the reference value (C) are not equal, the output value (B) and the set reference value (C) After storing the difference value (D), the sum value (E) obtained by adding the channel data (A) and the difference value (D) is stored and the sum value thereof. A third process of outputting (E) to the fine tuner 22 as data of the phase-locked loop, and if the channel signal is not input from the channel selector switch SW1 as a result of the determination of the first process, the controller 26 Reads the digital signal converted and output from the / D converter 25 to store the digital input value F, and then the digital input value F thereof and the output value B of the A / D converter 25 in the second process. ) And the output value of the A / D converter 25 of the second process if the value of the digital input value F and the output value B of the A / D converter 25 is different. A process of inputting B) is performed, and if the values match, a fifth process of outputting corrected phase-locked loop information is performed.

Referring to Figures 1 and 2 the effects of the present invention configured as described above are as follows.

First, as shown in FIG. 2, when the user first selects a desired channel through the channel selection switch SW1, the controller 25 executes the program of the present invention as shown in FIG.

That is, as shown in FIG. 2, when a desired channel signal is input from the channel selection switch SW1, the controller 26 reads out channel frequency data corresponding to the channel from the memory shown in the controller 26. And output to the fine tuner 22.

At the same time, the channel data A corresponding to the selected channel is stored in the memory, and the microtuner 22 receiving the channel data drives the variable diode of the local oscillator 20 to generate a local oscillation frequency equal to the channel frequency. .

When the analog potential generated in this way is applied to the A / D converter 25, the A / D converter 25 generates n bits corresponding to the potential (that is, the higher the degree is), that is, digital data.

The digital data generated in this way is read by the controller 26, and the output value B of the newly input A / D converter 25 is stored in the memory in the controller 26, and the controller 26 then outputs the output value B. ) And the previously set reference value (C) data are compared with each other, if not matched with each other, the difference value (D) obtained by subtracting the reference value (C) from the output value (B) is calculated and stored, and the difference value (D) Stores the sum E obtained in addition to the channel data A and outputs the sum E to the fine tuner 22 as data of the phase-locked loop.

Accordingly, since the fine tuner 22 receives the corresponding digital logic signal corresponding to the difference changed by the internal and external influences, the fine tuner 22 is repeatedly operated according to the information of the modified phase synchronization loop to correct the fine oscillation frequency.

As described above, according to the present invention, the baseband output is fed back through an automatic micro-tuner and an A / D converter to digitalize the digital signal, and compares the digital signal with a set reference value to correspond to a change by a difference. By providing information, it is possible to maintain a clean reception state regardless of internal or external influences such as frequency fluctuations or error rates due to temperature changes.

Claims (2)

A first process of determining whether the channel signal selected by the channel selection switch SW1 is input, and if the channel signal is input as a result of the determination, the controller 26 reads frequency data of a desired channel from the memory and outputs the frequency data to the fine tuner 22. Simultaneously with storing the channel data (A), receiving the output value (B) of the A / D converter 25, and stores the output value (B) and the set reference value (C), A stored in the place The second process of comparing the output value B of the / D converter 25 and the set reference value C and the result of the comparison are the same as the output value B of the A / D converter 25 and the set reference value C. Return to the mode for discriminating the channel input signal, and if the output value B and the reference value C are not the same, the difference value D between the output value B and the set reference value C is stored, and then the channel data ( The sum value E obtained by adding A) and the difference value D is stored, and the sum value E is stored in the fine tuner 22 as data of the phase synchronization loop. If the channel signal is not input from the channel selection switch SW1, the controller 26 reads the digital signal converted from the A / D converter 25 and outputs the digital signal. A fourth process of storing the input value F and comparing the digital input value F thereof with the output value B of the A / D converter 25 in the second process; and the comparison result digital input value F ) And the output value B of the A / D converter 25 are different from each other, a routine for inputting the output value B of the A / D converter 25 of the second step is performed. And a fifth process of outputting the phase locked loop information. A first intermediate frequency amplifier 1 for amplifying and outputting an input first intermediate frequency signal, and a band pass filter 2 for filtering and applying the signal amplified and output from the first intermediate frequency amplifier 1 to the mixer 3; And a controller 26 for receiving the channel signal selected by the channel selection switch SW1 and controlling channel selection to correct the oscillation frequency corresponding to the difference by comparing the feedback digital signal for the baseband output with a reference level. A fine tuner 22 for fine-tuning the frequency changed by the control signal of the controller 26, a local oscillator 20 for receiving the fine-tuned frequency and generating a predetermined oscillation frequency in the mixer 3, and a local The phase controller 21 receives the oscillation frequency generated by the oscillator 20 and adjusts the phase thereof to the fine tuner 22, and the first intermediate frequency signal and the local oscillator filtered by the band pass filter 2. In 20) A mixer (3) for receiving a predetermined predetermined oscillation frequency and mixing the same, and outputting a second intermediate frequency signal, a surface acoustic wave filter (4) for filtering the mixed signal from the mixer (3), and a filtered output second A second intermediate frequency amplifier 5 for amplifying the intermediate frequency signal, a limiter circuit 6 for limiting and outputting the amplitude of the amplified output second intermediate frequency signal to a constant level, and a limited output in the limiter circuit 6; A satellite broadcasting receiver comprising an FM demodulator (7) for receiving a dual frequency signal level, demodulating the same, and outputting the demodulated signal to a base band. The intercarrier signal of the voice limiter whose local oscillation frequency is changed from the demodulation signal fed back through the integrating circuit 23 and the integrated circuit 23 for integrating The automatic fine tuner 24 automatically maintains a constant local oscillation frequency as a voltage, and the digital oscillator 24 can recognize the local oscillation frequency maintained constant by the automatic fine tuner 24 as a digital signal. A channel tuning apparatus in a satellite broadcasting receiver, characterized by comprising an A / D converter (25) for converting.