KR19980047724A - Automatic setting of local oscillation frequency of low noise block of satellite broadcasting receiver - Google Patents

Abstract

A method for automatically setting a local oscillation frequency of a low noise block of a satellite broadcasting receiver, the method comprising: detecting a repeater with a signal from an antenna, and precisely adjusting the antenna direction in a direction in which an automatic gain control level value is maximum; And selecting the local oscillation frequency of the low noise block by determining the number of repeaters for which signals are detected for each low noise block type, and the receiver automatically sets some LNB local oscillation frequencies without the user setting the receiver. There is an effect that it is easy to install the antenna and LNB setup.

Description

Automatic setting of local oscillation frequency of low noise block of satellite broadcasting receiver

The present invention relates to a frequency setting method of a satellite broadcasting receiver, and more particularly, to a method for automatically setting a local oscillation frequency of a low noise block of a satellite broadcasting receiver.

FIG. 1 is a block diagram showing a configuration of a general satellite broadcasting reception system. The general satellite broadcasting reception system includes an antenna 11, a low noise block (LNB) 12, a microcomputer 13, a tuner 14, , Analog / digital (A / D) conversion unit 15, QPSK demodulation unit 16, preprocessing error correction (FEC) unit 17, transport demux unit 18, video decoder unit ( 19), an audio decoder 20, a digital / analog (D / A) converter 21, and an NTSC encoder 22.

The operation of the general satellite broadcasting reception system configured as described above will be briefly described as follows.

First, the satellite broadcast signal of the 11 to 12 GHz frequency band received by the antenna 11 is converted into a local oscillation frequency of the LNB 12 to be converted into a 950 to 2150 MHz frequency band signal and input to the receiver.

Here, the microcomputer 13 of the receiver transmits a repeater preset value having a different value for each repeater to a phase locked loop (PLL) (not shown) inside the tuner 14 to correspond to a channel to be tuned by the user. The repeater is switched to a constant frequency, the intermediate frequency (479.5 MHz).

The signal converted to the intermediate frequency is converted back to the baseband signal by the tuner 14 and then converted into a digital signal through the A / D converter 15 and the timing recovery and the carrier recovery are performed by the QPSK demodulator 16. .

After that, error correction is performed in the FEC unit 17, and the corrected signal is transport-decoded in the transport demux unit 18 to output an audio signal and a video signal.

The audio signal of the signal output from the transport demux unit 18 is input to the audio decoder unit 20 and decoded, and is converted into an analog signal by the D / A converter 21 and output as an audio signal.

In addition, the video signal among the signals output from the transport demux unit 18 is input to the video decoder unit 19, decoded, and encoded by the NTSC encoder unit 22 to be output as a video signal.

2 is a diagram showing the center frequency of the repeater output according to the center frequency and the local oscillation frequency of the low noise block of the general Mugunghwa satellite broadcast repeater, the signal input to the antenna 11 is the repeater center frequency of the 11 ~ 12GHz frequency band This signal shows the repeater center frequency after passing through the LNB 12 with local oscillation frequencies of 10/678 GHz and 10.75 GHz, respectively.

If the channel selected by the user is in the repeater 2, when the LNB 12 having a local oscillation frequency of 10.678 GHz is used, the output center frequency of the repeater 2 is 1068.66 MHz, and thus the microcomputer 13 of the receiver is an intermediate frequency (479.5 MHz). A value corresponding to 1068.66 MHz + an intermediate frequency (479.5 MHz) is set in the PLL (not shown) inside the tuner 14 so as to be converted to ().

On the other hand, when the LNB 12 having a local oscillation frequency of 10.75 GHz is used, the output center frequency of the repeater 2 is 996.66 MHz, so that the micom 13 of the receiver is switched to an intermediate frequency (479.5 MHz) of 996.6 MHz and an intermediate frequency (479.5 MHz). ) Is set to a PLL (not shown) inside the tuner 14.

However, the local oscillation frequency of LNB (12) is not defined in the Mugunghwa-ho satellite broadcasting standard. Therefore, domestic satellite broadcasting receiver manufacturers randomly select one of several LNB (12) local oscillation frequencies for each company. Repeater tuning frequency was set.

Therefore, a receiver configured to use an LNB 12 having a local oscillation frequency of 10.678 GHz and an LNB 12 having a local oscillation frequency of 10.75 GHz cannot watch the Mugunghwa Lake satellite broadcast. Receivers intended to use LNB 12 with local oscillation frequency and LNB 12 with local oscillation frequency of 10.678 GHz cannot be used in connection.

3 is a flowchart illustrating a method for setting LNB local oscillation frequency and antenna direction according to the prior art, and in the Japanese digital satellite broadcasting standard, it is possible to receive for the local oscillation frequencies of three LNBs 12. There is a specification that should be available.

First, as shown in FIG. 3, when the user enters the installation mode of the antenna 11 to set the local oscillation frequency and the antenna 11 direction (S31), the user directly uses the local portion of the LNB 12. The oscillation frequency is selected (S32).

If the user selects a local oscillation frequency of the LNB 12 and then selects a repeater that is considered to have a signal (S33), the microcomputer 13 sets the corresponding polarization and PLL control data and sets the AGC for the antenna direction. (Automatic Gain Control) level is detected and displayed on the screen (S35).

While adjusting the antenna 11, it is determined whether the AGC level displayed on the screen is the maximum (S36). When the maximum is reached, the antenna 11 direction setting is terminated, and when the AGC level does not change from the minimum value, the repeater is changed ( S37) The antenna 11 adjustment is repeated so that the signal level appears.

In other words, if the frequency specifications do not match between the LNB 12 and the receiver, the user must manually set some kinds of LNB 12 local oscillation frequencies and find a repeater with a signal several times.

The satellite broadcasting receiver according to the prior art should use an LNB operating at a specified local oscillation frequency, and an LNB using a different oscillation frequency cannot be used. Unexpected problems arise.

In addition, when the user directly sets the local oscillation frequency of the LNB to the receiver, and finds a repeater with a signal, a problem may occur that may be burdensome for a user without any knowledge.

The present invention has been made to solve the problems according to the prior art as described above Automatically set the local oscillation frequency of the LNB, automatic detection method of low noise block local oscillation frequency of the satellite broadcasting receiver for automatically detecting a repeater with a signal in the receiver The purpose is to provide.

1 is a block diagram showing the configuration of a general satellite broadcasting receiving system

FIG. 2 is a diagram showing the output center frequency of the repeater according to the center frequency of the general Mugunghwa satellite broadcast repeater and the local oscillation frequency of the low noise block.

3 is a flowchart for explaining a method for LNB local oscillation frequency setting and antenna direction setting according to the prior art;

4 is a flowchart illustrating a method for automatically setting a local oscillation frequency of a low noise block of a satellite broadcasting receiver according to the present invention.

Explanation of symbols on the main parts of the drawings

11 antenna 12 LNB

13: Micom 14: Tuner

15: A / D conversion unit 16: QPSK demodulation unit

17: FEC18: transport demux part

19: video decoder unit 20: audio decoder unit

21: D / A conversion section 22: NTSC encoder section

The low noise block local oscillation frequency automatic setting method of the satellite broadcasting receiver according to the present invention is characterized by precisely adjusting the direction of the antenna after finding a repeater with a signal, and setting all repeater preset frequencies determined by the LNB type. The LNB local oscillation frequency having a large number of repeaters for which a signal is detected is selected.

In addition, if the number of repeaters for which signals are detected is the same, the broadcast channel repeater information is extracted and the broadcast repeater is tuned for each LNB local oscillation frequency type to determine whether there is a signal, and then the LNB local oscillation frequency with a large number of repeaters for which signals are detected is determined. To choose.

Hereinafter, a method for automatically setting a low noise block local oscillation frequency of a satellite broadcasting receiver according to the present invention will be described with reference to the accompanying drawings.

4 is a flowchart illustrating a method for automatically setting a local oscillation frequency of a low noise block of a satellite broadcasting receiver according to the present invention, which will be described with reference to the general satellite broadcasting receiving system of FIG.

First, when the user enters the antenna installation mode (S41), the LNB 12 voltage and the repeater frequency to be tuned according to the LNB 12 local oscillation frequency and the repeater polarization are set to find the repeater in which the signal exists (S42). ).

The microcomputer 13 detects the AGC level value output from the QPSK demodulator 16 to the tuner 14 and outputs it to the screen (S43).

At this time, if the repeater tuned in step S42 has a signal, the AGC level value displayed on the screen may have any value, but if there is no signal or if the antenna direction is not adjusted, the AGC level value does not exist. You will have this minimum value.

Therefore, when the AGC level value output on the screen is detected to be greater than the threshold value that can determine that the signal is present (S44), since the frequency of the repeater is found, the frequency is fixed so that the direction can be finely adjusted.

If the AGC level value is smaller than the threshold value, the search is performed while converting the repeater selection frequency, the LNB 12 local oscillation frequency, and the polarization until the detected AGC level value is larger than the signal threshold value (S45).

That is, even if all the repeaters are searched for the LNB 12 local oscillation frequency and the polarization set initially, if the AGC level value is smaller than the threshold value, the polarization setting is converted.

Even if all the polarizations are searched for the LNB 12 local oscillation frequency and the repeater preset frequency set by changing the polarization setting, if the AGC level value is smaller than the threshold value, the local oscillation frequency and the polarization of the LNB having the different local oscillation frequency are different. The conversion is performed until the detected AGC level value is larger than the threshold value.

If the AGC level value detected in the step S44 is greater than the threshold value and the repeater is detected and the signal is found, the local oscillation frequency of the LNB is set to a different kind, and the station frequency of the repeater determined to be present is determined. Switching to the nearest repeater tuning frequency (S46) detects the AGC level value (S47).

Subsequently, AGC level values are detected for each type of local oscillation frequency of the LNB 12, and when a maximum value of the detected AGC level values is detected (S48), a direction setting end key is input (S49).

When the direction setting end key is input, while setting the repeater tuning frequencies determined for each local oscillation frequency type of the LNB 12 with the antenna direction precisely adjusted, the AGC level value is detected and stored after determining the presence or absence of a signal (S50). .

Here, it is determined whether the number of repeaters for which signals have been detected for each local oscillation frequency type of the LNB 12 is the same (S51). If the number of repeaters for which signals have been detected is different, the LNB having the greater number of repeaters for which signals have been detected is determined. (12) A local oscillation frequency is selected (S52).

On the other hand, if the number of repeaters whose signals are detected is the same, the received signal is decoded to extract the repeater number of the broadcast channel (S53), and then the broadcast repeater is tuned for each type of LNB 12 to determine the presence of a signal (S54). The larger number of LNB 12 local oscillation frequencies are selected (S55).

For example, if you are broadcasting on Mugunghwa-ho broadcast satellite repeaters 2 and 6 as shown in FIG. 2 and use the LNB 12 of local oscillation frequency of 10.678 GHz, the repeater frequency of the local oscillation frequency LNB 12 of 10.678 GHz In the case of detecting the signal, the signal is detected at 2 and 6 repeater frequencies in the step S50, and when the signal is detected at the repeater frequency of the local oscillation frequency LNB 12 of 10.75 GHz, the LNB of the local oscillation frequency of 10.678 GHz. Signals are detected at repeater frequencies 6 and 10, similar to repeater frequencies 2 and 6 in (12).

In this case, if the signal is decoded and the repeater number is extracted and tuned to the repeater frequencies 2 and 6 of the LNB 12 of the 10.678 GHz local oscillation frequency, the repeater signals 2 and 6 are detected, but the LNB of the 10.75 GHz local oscillation frequency is detected. When tuning to the repeater frequencies 2 and 6 of 12), the signal cannot be detected at the frequency corresponding to the repeater 2, and the signal is detected only at the frequency corresponding to the repeater 6 (S54).

Therefore, in step S54, the number of repeaters for which signals are detected is determined, and the number of repeaters for signals detected is determined by the LNB 12 having a 10.678 GHz local oscillation frequency.

If you are broadcasting on repeaters 2, 6 and 10 and use the LNB 12 with a local oscillation frequency of 10.678 GHz, three repeaters are used to detect the signal with the repeater frequency of the LNB 12 with a local oscillation frequency of 10.678 GHz. Although the signal is detected, when signal detection is used as the repeater frequency of the LNB 12 of the 10.75 GHz local oscillation frequency, the signal is detected only at the frequencies corresponding to the repeaters 6 and 10. Therefore, the local oscillation frequency of the LNB 12 is selected as 10.678 GHz.

The method for automatically setting a low noise block local oscillation frequency of the satellite broadcasting receiver according to the present invention has an effect of easily setting the antenna and the LNB setting of the receiver because the receiver is automatically set without the user setting some LNB local oscillation frequency. .

Claims (5)

A satellite broadcast receiver for receiving satellite broadcast signals through an antenna and a low noise block, Detecting a repeater with a signal from the antenna; Precisely adjusting the antenna direction in a direction in which an automatic gain control level value is maximum by setting a repeater closest to the repeater with a signal for each of the low noise block types; And determining the number of repeaters for which signals are detected for each type of low noise block, and selecting local oscillation frequency of the low noise block. The method of claim 1, Detecting a repeater with the signal A first step of setting local oscillation frequency and repeater polarization and repeater tuning frequency initial value of the low noise block; A second step of detecting an automatic gain control level value and determining that a signal exists when the detected automatic gain control level value is greater than a threshold value, thereby fixing the frequency of the repeater; If the detected automatic gain control level value is smaller than the threshold value, the second step is performed by converting and setting the repeater tuning frequency and the local oscillation frequency and polarization of the low noise block until the detected automatic gain control level value is larger than the signal threshold value. A method of automatically setting a local oscillation frequency of a low noise block of a satellite broadcasting receiver, characterized in that the third step is repeated. The method according to claim 1 and 2, Finely adjusting the antenna direction A first step of detecting an automatic gain control level value by switching to a station preset frequency of the repeater with the signal and the station preset frequency closest to each of the low noise block types; Low noise block of the satellite broadcasting receiver characterized in that it comprises a second step of detecting the automatic gain control level value for each type of local oscillation frequency of the low noise block, and when the maximum value of the detected automatic gain control level value is detected How to set local oscillation frequency automatically. The method of claim 1, Selecting a local oscillation frequency of the low noise block A first step of detecting automatic gain control level values and determining the presence or absence of a signal while setting all repeater tuning frequencies determined for each local oscillation frequency type of the low noise block; A second step of determining the number of repeaters for which signals are detected for each type of local oscillation frequency of the low noise block; And a third step of selecting a local oscillation frequency of a low noise block having a large number of repeaters for which a signal has been determined as a result of the determination. The method of claim 4, wherein In a third step of selecting a local oscillation frequency of the low noise block As a result of the determination, if the number of repeaters with the same signal is detected, decoding the received signal to extract the repeater number of the broadcast channel, and then tunes the broadcast repeater for each low-noise block type to determine whether there is a signal, and the low-noise block with the higher number of signal detection. A method of automatically setting a local oscillation frequency of a low noise block of a satellite broadcasting receiver characterized in that it selects a local oscillation frequency of.