KR100379451B1 - Digital Television Transmission System and Operation Method - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital television transmission system and operation method including a plurality of modulation devices and controlling operation of the modulation device using a personal computer. As described above, the present invention provides a modulation unit for modulating a broadcast signal inputted by a digital television transmission system to enable error correction, a power amplifier for amplifying a signal output from the modulation unit at a predetermined amplification ratio, and a signal output from the power amplifier. A vector signal analyzer for calculating a filter coefficient value by correcting the nonlinear error of the control unit; and a control for controlling the modulator to maintain an optimal filter coefficient value by transferring the filter coefficient value output from the vector signal analyzer to the modulator. It consists of a system. In addition, in the digital television transmission system having the above configuration, the vector signal analyzer calculates a filter coefficient value and transmits the filter coefficient value to a modulator having an order set at a predetermined period, and the modulator outputs a control signal for notifying when the transmission operation is completed. Delivering to the control system, and converting the communication port set in the modulation period having the set order into the ports of the modulator having the next order.

Description

Digital Television Transmission System and Operation Method

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to digital television transmission systems and operational methods, and more particularly to digital television transmission systems and operational methods that maintain optimal transmission conditions.

Recently, thanks to the development of image processing technology, many technologies related to digital television have been proposed. However, such digital television technology has not been disclosed because of its technical protection and commercialization of the product.

Accordingly, the present invention is to provide a digital television transmission system and operation technology including a plurality of modulation devices.

An object of the present invention is to provide a digital television transmission system and operation method including a plurality of modulation devices and controlling the operation of the modulation device by using a personal computer.

Another object of the present invention is to provide a digital television transmission system and an operation method for modulating and outputting an input transport stream signal so that error correction is possible by providing an optimum digital filter coefficient obtained by correcting a nonlinear error to a modulator. .

According to an aspect of the present invention for achieving the above object, the digital television transmission system comprises a modulator comprising a plurality of modulators for modulating the broadcast signal input to enable error correction, and the signal output from the modulator A power amplifier for amplifying the signal at a predetermined amplification ratio, a vector signal analyzer for correcting a nonlinear error of a signal output from the power amplifier, and calculating a filter coefficient value, and a filter coefficient value output from the vector signal analyzer. And a control system for controlling the modulator to maintain an optimal filter coefficient value, wherein the control system controls the operation of the modulator.

According to another feature of the present invention for achieving the other object as described above,

In a digital television transmission system comprising a plurality of modulators, a vector signal analyzer and a control system for controlling the operation of the plurality of modulators, the vector signal analyzer calculates a filter coefficient value. Transmitting a control signal informing that the transmission operation is completed when the transmission operation is completed, and transmitting the control signal to the control system to the control system. Converting the communication port set in the following steps to the modulator port having the following sequence.

1 is a block diagram of a digital TV transmission system according to the present invention.

2 is a flowchart illustrating a method of operating a digital TV transmission system according to the present invention;

* Description of the symbols for the main parts of the drawings *

10 modulator 11 main modulator

12: sub modulator 20: switch

30: frequency adjuster 31: IF compensator & mixer

32: RF compensator 40; cooler

50: power amplifier 60: power synthesizer

70: power supply unit 80: vector signal analysis unit

100: transmitter 200; Control system

201: modem 202: telephone

203: personal computer

Hereinafter, a configuration and an operation according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings.

1 is a block diagram of a digital TV transmission system according to the present invention. Referring to FIG. 1, the digital TV transmission system of the present invention modulates a 19.39 Mbps Moving Picture Experts Group 2 (MPEG2) -Transport Stream modulated to allow error correction. And a switch 20 for switching the signal output from the modulator 10 according to a control signal of a control system to be described later, and a frequency of an intermediate frequency band passing through the switch 20 as a frequency of a radio frequency band. A frequency adjusting unit 30 for upward adjustment, a power amplifier 50 for amplifying the signal output from the frequency adjusting unit 30 at a predetermined amplification ratio, and a signal output from the power amplifier 50 are synthesized and transmitted to a transmission antenna. To the vector signal analyzer 80 and the vector signal analyzer 80 that correct the nonlinear error in the output signal of the power synthesizer 60 to calculate an optimal filter coefficient value. The control system 200 is configured to control the modulator 10 to maintain the optimum filter coefficient value by transferring the output filter coefficient value to the modulator. Here, reference numeral 40 denotes a cooler 40 for cooling the frequency regulator 30 and the power amplifier 50 when they are overheated.

As shown in FIG. 1, the control system 200 is connected to a communication modem 201, a telephone 202, and a personal computer 203.

Here, the 19.39 Mbps Moving Picture Experts Group2 (MPEG2) -Transport Stream transmitted from the studio minimizes the error occurrence rate by minimizing the interference at the radio end in the modulator 10 and allows the receiving end to correct the error at 8 VSB. (Vestigial Side Band) data processing. In addition, the IF signal received by the frequency adjusting unit 30 is upwardly adjusted to the RF signal and transmitted through the power amplifier 50 and the power combiner 60.

In the embodiment of the present invention, the modulator 10 includes two modulators, that is, the main modulator 11 and the sub modulator 12. In other words, in case a problem occurs in the primary modulator 11, which is an important equipment of the transmission system, a 19.39 Mbps Moving Picture Experts Group2 (MPEG2) -transport stream is simultaneously inputted to another identical sub-modulator 12. If a problem occurs in any one of the modulators, the modulator 10 immediately switches the switching mode to use one of the modulators, and continuously transmits the broadcast signal to the frequency adjuster 30. These two modulators 11 and 12 are connected to serial port terminals COM1 and COM2 of the personal computer 203, respectively, to exchange data with the control system 200. In addition, in order to compensate for the nonlinearity (Digital Filter Correction) generated by the high power amplifier (High Power Amplifier) 50, a signal constellation is input by inputting the output of the final stage to the vector signal analyzer 80. By correcting the nonlinear error by using an eye diagram and the like, the filtering coefficient values are transmitted to the modulator 10 at regular intervals so that the modulators 11 and 12 maintain optimal coefficient values at all times. However, two or more modulators may be configured.

Hereinafter, a method for operating a digital television transmission system according to an embodiment of the present invention will be described with reference to FIGS. 1 to 2.

In the embodiment of the present invention, as shown in FIG. 2, the primary modulator 11 and the secondary modulator 12 installed for redundancy are connected to the serial port terminals COM1 and COM2 of the personal computer 203, respectively. The control signal is exchanged between 203 and the two modulators 11 and 12 and the two control devices are controlled by automatically converting the communication port under the control of the control system 200.

When the personal computer 203 sends a control signal requesting a predetermined operation to the main modulator 11, the main modulator 11 completes the operation required by the control signal and the signal that the main modulator 11 has completed the predetermined operation. By transmitting the to the personal computer 203, the communication port is automatically converted to control the sub-modulator 12. In the same way, the sub-modulator 12 transmits a signal to the personal computer 203 that the predetermined operation has been completed, so that the personal computer 203 switches the communication port and then controls the main modulator 11. Therefore, two modulators 11 and 12 installed for redundancy can be controlled alternately without any additional device or human operation.

Thus, controlling the modulator from the personal computer 203 compensates for the nonlinearity of the power amplifier 50 provided in the digital television transmitter. That is, as shown in Figure 1, by outputting the output signal passed through the power synthesizer 60 to the vector signal analysis unit 80 by a method such as signal constellation (Signal Constellation), eye diagram (Eye Diagram) The computer 203 simulates and obtains an optimized digital filter coefficient value. Then, the personal computer 203 periodically transmits the obtained optimized coefficient value to the primary modulator 11 and the secondary modulator 12. However, the coefficient value is transmitted to the main modulator 11 which operates first. After receiving the count value, the main modulator 11 transmits the completion signal to the personal computer 203 after confirming that all the count values have been transmitted. The personal computer 203 converts the current port terminal COM1 setting into the port terminal COM2 in the following order, exchanges control signals with the sub-modulator 12, and determines that there is no abnormality in the connection. The value is also sent to the secondary modulator 12. When the sub-modulator 12 confirms that the transfer of the count value is completed, the sub-modulator 12 transmits the control request signal to the modulator control program built in the personal computer 203 again. The modulator control program controls the main modulator 11 again by converting the port terminals. In an embodiment of the present invention, such operation occurs continuously during nonlinear compensation of the periodic power amplifier 60 so that the main modulator 11 is controlled. Even if is not operated, the filter coefficient value of the sub modulator 12 has the same optimized coefficient information as the main modulator 11, not the initial coefficient value, even if the sub modulator 12 is switched. Therefore, it is possible to maintain the best transmission state as a transmission system for processing digital broadcast signals.

Another feature according to the present invention may be remotely connected to the personal computer 203 by a modem or a dedicated line to monitor the state of the modulator 10. In addition, when it is determined that the inspection of the modulator 10 is necessary, since the modulator 10 can be controlled by remote control without going directly to the transmitting station, the main modulator 11 and the sub modulator 12 are respectively checked. can do. In addition, the sub-modulator 12 can be operated at the same period as the main modulator 11, thereby improving the reliability as a broadcast equipment.

In the present invention, when updating the control program or transmitting data for a specific test and inspection, the primary modulator 11 is not operated. Instead, the control request signal is first transmitted to the sub-modulator 12 and operated by remote control at a remote location. Check for any abnormality. Therefore, it is possible to update the control program or perform necessary tests while continuously providing high quality digital broadcast signals.

According to the present invention as described above, it is possible to monitor or remotely control the necessary information by controlling two modulators installed for redundancy with only a simple software command without separate redundant external equipment or switching equipment.

In addition, all modulators can always maintain optimal coefficient values because the modulators that have periodically changed digital filter coefficient values are transmitted without operator intervention. Accordingly, even when one of the modulators cannot be used, the reliability as a broadcasting device can be improved by maintaining the same optimal transmission state as the modulators used in the prior art.

In addition, when checking the modulator for maintenance of the transmission system, it is possible to easily check the status and transmit data from a remote location by using a modem or a dedicated line, and operate by performing necessary tests applied to the sub-modulator before applying it to the main modulator. You can check the status in advance.

Claims (6)

A modulator comprising a plurality of modulators for modulating an input broadcast signal to enable error correction; A power amplifier for amplifying the signal output from the modulator at a predetermined amplification ratio; A vector signal analyzer for calculating a filter coefficient value by correcting a nonlinear error of the signal output from the power amplifier; And a control system for controlling the modulator to maintain an optimal filter coefficient value by transferring the filter coefficient value output from the vector signal analyzer to the modulator, wherein the control system controls the operation of the modulator. Digital television transmission system. The system of claim 1, wherein said control system comprises at least one communication modem, a terminal, and a personal computer. The digital television transmission system as claimed in claim 1, wherein a switch for switching the output signal of the modulation unit is further configured at an output end of the modulation unit. In a digital television transmission system having a plurality of modulators, a vector signal analyzer and a control system for controlling the operations of the plurality of modulators, a) calculating, by the vector signal analyzer, a filter coefficient value and transmitting the filter coefficient value to a modulator having a predetermined order; b) the modulator transmitting a control signal informing the control system of the completion of the transmission operation; and c) converting the communication port set in the modulation period having the set order into the ports of the modulator having the next order. 5. The method according to claim 4, wherein when the modulator consists of one main modulator and a plurality of sub modulators, a sub modulator having a set sequence with the main modulator is alternately controlled. 5. The method of claim 4, wherein the filter coefficient value is calculated by a vector signal analyzer correcting a nonlinear error of a signal output from the modulator.