KR0138330B1 - Method for tuning digital voltage of broadcasting receiver - Google Patents

Abstract

Tuning data generation step of the present invention; Generating a pulse width modulated signal according to the generated tuning data; The digital tuning voltage method of a broadcast receiver comprising the step of intercepting a tuning drive voltage according to the generated pulse width modulation signal and integrating the intermitted voltage to generate a tuning voltage, wherein the tuning data generating step comprises the tuning voltage. Characterized in that the tuning data having a non-linear characteristic to compensate for the non-linear characteristics of the linear characteristics.

Therefore, in the present invention, by tuning and generating the tuning data nonlinearly so that the tuning voltage is generated linearly, the AFT lead-in range can be equalized over all channels and the occurrence of tuning errors can be reduced.

Description

Digital Voltage Tuning Method of Broadcast Receiver

1 is a block diagram of a broadcast receiver having a general analog AFT electronic tuner.

2 is a block diagram of a broadcast receiver having a general full digital tuner.

3 is a detailed circuit diagram of the tuning voltage driving circuit of FIGS. 1 and 2;

4 is a graph showing the relationship between the change in duty and the tuning voltage of a conventional pulse width modulated signal.

5 is a graph showing the relationship between the duty change and the tuning voltage of the pulse width modulated signal according to the present invention.

6 is an approximate graph showing the relationship between the duty change and the tuning voltage of the pulse width modulated signal of the preferred embodiment of the present invention.

7 is a flowchart showing a program for calculating a correction parameter according to the present invention.

8 is a flowchart for explaining a tuning operation performed by the correction parameter calculated according to the present invention.

The present invention relates to a digital voltage tuning method of a broadcast receiver, and more particularly, to a digital voltage tuning method of a broadcast receiver for improving nonlinear characteristics of a tuning voltage.

Electronic tuning devices for broadcast receivers such as VCRs and TVs include frequency synthesis and voltage synthesis. The voltage combining method selects a desired frequency by applying a voltage to the tuner. The principle is to tune the desired frequency by varying the capacitance of the variable capacitance diode according to the tuning voltage by using a variable capacitance diode in the tuning circuit of the LC resonance and applying a tuning voltage to both ends of the variable capacitance diode.

The generation of the tuning voltage increases or decreases the tuning data so as to approach the desired channel at the time of channel selection, and generates a pulse width modulated signal whose pulse width is varied by the tuning data. The tuning voltage is generated by integrating the interrupted and interrupted voltages.

However, the conventional tuning data increases linearly because the variable step is constant, but the corresponding tuning voltage has a nonlinear characteristic because the integral characteristic of the intermittent voltage is nonlinear and the characteristic of the variable capacitance diode is nonlinear. Therefore, since the tuning voltage has a non-linear characteristic, even if the tuning data is linearly changed, the tuning voltage is rapidly increased in a section in which the nonlinear curve has a large slope, thereby causing a tuning error during tuning.

An object of the present invention is to provide a digital voltage tuning method of a broadcast receiver that can improve the nonlinear characteristics of the tuning voltage to solve the problems of the prior art.

Another object of the present invention is to provide a digital voltage tuning method of a broadcast receiver capable of equally improving the automatic fine tuning inlet range for each channel.

The method of the present invention to achieve the above object is a tuning data generation step; Generating a pulse width modulated signal according to the generated tuning data; The digital voltage tuning method of a broadcast receiver comprising the step of intercepting the tuning drive voltage according to the generated pulse width modulation signal and integrating the intermitted voltage to generate a tuning voltage, wherein the tuning data generating step comprises the tuning voltage. And tuning data having a nonlinear characteristic that compensates the nonlinear characteristic of the linear characteristic.

The tuning data generating step includes obtaining each compensation parameter for each of a plurality of bands for a plurality of sections having different slopes of the nonlinear characteristic curve of the tuning voltage.

The calculating of the compensation parameter may include: checking a band; Calculating a frequency change per step of the checked band within a given resolution; Calculating an average pulse width change value of a pulse signal having a frequency given by the calculated frequency change value per step; Calculating an average step value within the given resolution by the calculated average pulse width change value; Checking a section of the tuning voltage nonlinear characteristic; Obtaining a pulse width change value and a step value of the first section according to a slope of the nonlinear characteristic curve of the first section, and feeding back the section checking process in the first section; Obtaining a pulse width change value and a step value of the second section according to the slope of the nonlinear characteristic curve of the second section, and feeding back to the section checking process in the second section; Obtaining a pulse width change value and a step value of the third section according to the slope of the nonlinear characteristic curve of the third section and feeding back to the band checking process in the third section; And repeating the process of calculating the frequency change value per step for the remaining bands, and then feeding back to the band checking process. If the last band is obtained, the pulse width change value and the step value of the third band are ended. It is equipped with a process.

The generating of the tuning data and the generating of the pulse width modulation signal may include: checking which band a desired channel frequency belongs to; Initializing the step and the number of times belonging to the first band; Generating a pulse width modulated signal according to the calculated pulse width change parameter; Checking the presence or absence of a video signal received by the tuning voltage generated by the pulse width modulation signal; If there is no check of the video signal, increasing the number of steps and the number of times, and feeding back to the pulse width modulation signal generating step until the increased step value becomes larger than the calculated step parameter of the first period; Initializing the number of times when the step value is larger than the calculated parameter; Repeating the same repetition process from the pulse width modulation signal generation process to the repetition process by the calculated parameters of the second section until there is no detection of the video signal and the step increased from the step parameter becomes larger; Repeating the same process for the third section as the repeating process for the number of times initialization process and the second section; Performing automatic fine tuning when a video signal is detected while repeatedly performing a variable pulse width modulation signal for each section; And performing a step larger than the step parameter of the third section or performing the automatic fine tuning process and performing a general device operation and terminating it.

Hereinafter, the present invention will be described in more detail with reference to a preferred embodiment of the present invention shown in the accompanying drawings.

First, prior to the description of the embodiment of the present invention will be described for the general electronic voltage tuning.

FIG. 1 is a block diagram of a broadcast receiver analogized to AFT (Auto Fine Tunning). The tuner 10 inputs a high frequency signal through an antenna or a coaxial cable and outputs an intermediate frequency signal when there is a broadcast frequency tuned by an applied tuning voltage VT. The demodulation circuit unit 20 inputs an intermediate frequency signal, demodulates and detects it, outputs a video signal, and outputs an AFT signal for fine tuning toward increasing the gain of the received signal. The AFT signal is applied to the AFT driver circuit 30 and output as an appropriate fine tuning signal, and the output fine tuning signal is applied to the tuner 10 through the AFT switching means 40. The sync detector 50 detects the sync signal in order to detect the presence or absence of the received video signal. The controller 60 generates an AFT on / off signal to control the switching of the AFT switching means 40, and when the desired channel is selected, the duty ratio is increased according to the tuning data while increasing the tuning data to tune the channel. Generates a pulse width modulation signal, but when the sink detection signal is supplied from the sink detector 50, it is recognized that the tuning is close, and the automatic fine tuning operation is performed by holding the duty ratio of the pulse width modulation signal at that time and turning on the AFT switching means. Control this to be done. The tuning voltage driving circuit 70 generates a tuning voltage VT whose voltage level is variable in response to the duty ratio of the pulse width modulation signal PWM.

This AFT analog method requires an AFT switch.

2 is a block diagram of a broadcast receiver whose tuning method is a full digital method. The difference from the scheme of FIG. 1 is that in order to digitally process the AFT, the control unit 60 inputs an analog AFT signal, converts it to digital, and generates a pulse width modulated signal corresponding to the AFT digital value so that the fine tuning is also digital. Is done by Therefore, the controller 60 varies the duty of the pulse width modulated signal until it becomes the center of the AFT voltage, and softly processes the fine tuning by holding the duty at this time. Therefore, the AFT switching means can be eliminated.

3 is a detailed circuit diagram of the tuning voltage driving circuit 70. As shown in FIG. That is, the tuning drive voltage of 33 V is intermittently switched by the pulse width modulated signal applied to the switching circuit 72, and the multi-step integrator 74 integrates the intermittent 33 V to generate the average tuning voltage VT. Therefore, the tuning voltage has a nonlinear characteristic curve as shown in FIG. This is due to the integral characteristic of the multistage integrator.

On the other hand, the duty ratio of the pulse width modulated signal is linearly changed by the tuning data. In general, the conventional tuning data setting method is as follows.

TABLE 1

In the low band,

Frequency change per step = band absolute reception frequency range / resolution

^{= (107.25-46.25) × 10 6/} 2 14

= 4 MHz

Here, the band frequency absolute reception range considers the upper and lower 2MHz for the AFT margin.

To set 50KHz per step PWM PWM

PWM = 50KHz / 4KHz = 12

Therefore, STEP

STEP = resolution / PWM = 1365

Therefore, for the high band and the UHF band in the same way as the low band, Table 2 shows the PWM and STEP.

TABLE 2

Therefore, conventionally, as described above, the increase in the tuning data is linear in each band, but the tuning voltage generated by the pulse width modulation signal generated by the linear tuning data has a non-linear characteristic as shown in FIG. Therefore, while the change width of the duty change S1 and S2 of the pulse width modulated signal is constant, the corresponding tuning voltage is V1 and You can see that there is a big difference with V2.

That is, in the related art, when the duty ratio of the pulse width modulation signal is increased by a certain step due to the integration characteristic of the tuning voltage driver circuit and the nonlinear characteristic of the variable capacitance diode of the tuner, the tuning voltage change is nonlinear, so that the AFT inlet range for each channel is different. There was a problem. In addition, in the high tuning voltage section, there was a problem of an error during tuning due to a sudden rise in voltage.

In order to solve such a conventional problem, the present invention allows linearly compensating for the nonlinear characteristics of the tuning voltage by varying the duty change of the pulse width modulated signal, as shown in FIG. We want to keep it constant.

In the preferred embodiment of the present invention, the correlation between the duty ratio change of the pulse width modulated signal and the tuning voltage is accurately analyzed in order to secure the AFT inlet range for each channel based on the approximated correction characteristics as shown in FIG. The correction parameter for generating the raw tuning data is calculated as follows.

1. Parameter setting of the VHF-LOW band

1) Average in the first section (0-C) PWM doubles and STEP increases by 1/2. This is because the slope of the first section is twice as large as the slope of the 0-D section of the tuning characteristics.

PWM = 12 × 2 = 24

STEP = average step x (7/32) x (12/24) = 149

2) Average in the second section (CB) Increase PWM and STEP by 1 times.

PWM = 12 × 1 = 12

STEP = average step x (10/17) x (12 x 12) = 472

3) Average in section 3 (BA) PWM doubles and STEP doubles.

PWM = 12 × (1/2) = 6

STEP = average step x (15/32) x (12/6) = 1280

2. VHF-HIGH band is set to parameter

1) Section 1

PWM = 5 × 2 = 10

STEP = average step × (7/32) × (5/10) = 358

2) Section 2

PWM = 5 × 1 = 5

STEP = average step x (10/32) x (5/5) = 1024

3) Section 3

PWM = 5 × (1/2) = 3

STEP = average step x (15/32) x (5/3) = 2559

3. UHF Band Parameter Setting

1) Section 1

PWM = 2 × 2 = 4

STEP = average step x (7/32) x (2/4) = 896

2) Section 2

PWM = 2 × 1 = 2

STEP = average step x (10/32) x (2 x 2) = 2560

3) Section 3

PWM = 2 × (1/2) = 1

STEP = average step × (15/32) × (2 × 1) = 7680

This is summarized in Table 3.

TABLE 3

General formula of the parameta acid formula of the present invention is as follows.

Frequency change per step = band absolute reception frequency range / resolution [KHz] (1)

Average PWM = 50KHz / Frequency change per step (2)

Average Step / Resolution / Average PWM (3)

PWM = average PWM × (Slope of Each Section) (4)

STEP = average step × (each section / PWM duty section) × (average PWM / PWM) (5)

7 shows a flowchart of a correction parameter calculation program according to the present invention.

The step of obtaining the compensation parameter is to first check the band for which to obtain the correction parameter (100A, 100B) and according to the band, 100 for the VHF-LOW band, 200 for the VHF-HIGH band, 300 for the UHF band, respectively. do. The detailed process of each band is as follows.

The frequency change value per step of the VHF-LOW band is obtained within the resolution given by Equation (1) (102), and the average pulse width change value ( PWM) is obtained by Equation (2) (104) and the calculated mean The average step value is obtained by equation (3) within the given resolution by PWM (106).

Check the slope (108) the first section Obtain PWM and STEP (L1), check the calculation of STEP (L3) (122) or feed back to 108. Then for the second segment Obtain PWM and STEP (L2) and feed back to (114, 116) 108. About the third section Obtain the PWM and STEP (L3) (118, 120) and finish because the STEP (L3) is calculated at 122.

Similarly, 200 is performed in the same process as 100 for the VHF-HIGH band and 300 is performed in the UHF band.

As described above with reference to FIG. 8, the tuning method in the state where the parameters for each section of each band are calculated is as follows.

Check which band the desired channel frequency belongs to (802), initialize the step and number belonging to the first band to 1 (804), and generate the pulse width modulated signal by the calculated pulse width change parameter ( 806). The presence or absence of the video signal received by the tuning voltage generated by the pulse width modulation signal is detected and checked (808). If the video signal is not checked, the step and the number of times are increased (810). The operation is repeatedly performed by feeding back to the pulse width modulation signal generation step until it is larger than the calculated step parameter of the first section (812). That is, steps 806 to 812 are processes for tuning the first section while increasing the steps.

If the step value is larger than the calculated STEP (L1) parameter, since the desired channel is not in the first section, the number of times is reset to 1 (814).

According to the calculated parameter of the second section, the same repetition process as that from the pulse width modulation signal generation process to the repetition process is repeated until there is no video signal detection and the step increased from the step parameter becomes larger (816). ).

If the step value is larger than the calculated STEP (L2) parameter, since there is no desired channel, the number of times is reset to 1 (818).

The same process as the repeating process for the second section is repeated for the third section (820).

When the video signal is detected in the process of repeatedly performing the variable pulse width modulation signal for each section, the signal is close to a desired channel. Now, after receiving the AFT signal and performing the automatic fine tuning by the received AFT data (822). Perform a general device operation and ends (1100).

If the step is larger than the step parameter in the third section, since there is no desired channel in the band, general device operation is performed (1100).

Similarly, in the VHF-HIGH band, the tuning operation is performed by the same process as step 800 (900), and the tuning operation is performed in the UHF band (1000).

As described above, in the present invention, by tuning and generating the tuning data nonlinearly so that the tuning voltage is generated linearly, the AFT inlet range can be equalized over all channels and the occurrence of tuning errors can be reduced.

Claims (4)

Tuning data generation step; Generating a pulse width modulated signal according to the generated tuning data; A digital voltage tuning method of a broadcast receiver, comprising the steps of: intercepting a tuning drive voltage by the generated pulse width modulation signal and integrating the intermitted voltage to generate a tuning voltage. And the tuning data generating step generates tuning data having a nonlinear characteristic for compensating the nonlinear characteristic of the tuning voltage with a linear characteristic. The method of claim 1, The tuning data generating step includes the step of obtaining each compensation parameter for a plurality of bands for a plurality of sections in which the slopes of the nonlinear characteristic curves of the tuning voltages are different from each other. The method of claim 2, The calculating of the compensation parameter may include: checking a band; Calculating a frequency change value per step of the checked band within a given resolution; Calculating an average pulse width change value of a pulse signal having a frequency given by the calculated frequency change value per step; Calculating an average step value within the given resolution by the calculated average pulse width change value; Checking a section of the tuning voltage nonlinear characteristic; Obtaining a pulse width change value and a step value of the first section according to the slope of the nonlinear characteristic curve of the first section, and feeding back to the section checking process in the first section; Obtaining a pulse width change value and a step value of the second section according to the slope of the nonlinear characteristic curve of the second section, and feeding back to the section checking process in the second section; Obtaining a pulse width change value and a step value of the third section according to the slope of the nonlinear characteristic curve of the third section and feeding back to the band checking process in the third section; And Repeating the process of calculating the frequency change value per step for the remaining bands to the band check process is repeated, and in the case of the last band after the pulse width change value and the step value of the third band is obtained Digital voltage tuning method of a broadcast receiver comprising a process. The method of claim 3, The generating of the tuning data and the generating of the pulse width modulation signal may include: checking which band a desired channel frequency belongs to; Initializing a step and a number belonging to the first band; Generating a pulse width modulated signal according to the calculated pulse width change parameter; Checking the presence or absence of a video signal received by the tuning voltage generated by the pulse width modulation signal; If there is no check of the video signal, increasing the number of steps and the number of times, and repeatedly feeding back to the pulse width modulation signal generating step until the increased step value becomes larger than the calculated step parameter of the first period; Initializing the number of times when the step value is larger than the calculated parameter; Repeating the same repetition process from the pulse width modulation signal generation process to the repetition process by the calculated parameters of the second section until no video signal is detected and an increased step is increased than the step parameter; Repeating the same process for the third section as the repeating process for the number of times initialization process and the second section; Performing automatic fine tuning when a video signal is detected in the process of repeatedly performing a variable pulse width modulation signal for each section; And And a step of making the step larger than the step parameter of the third section or performing the automatic fine tuning process and performing and terminating a general device operation.