KR19990055568A - How to reduce initialization time of digital satellite set-top box - Google Patents

Abstract

The present invention reads and stores the frequency, Viterbi code, and symbol rate required for tuning in an internal EEPROM when the receiver is turned off, and tunes the received signal by reading information stored in the IPI when the system is powered on. The present invention relates to a method for shortening the initialization time of a digital satellite broadcasting set-top box, which enables the system operation and channel tuning to be performed quickly. Such an exemplary embodiment of the present invention is to tune to standby power when the set-top box is turned off while the digital satellite broadcasting set-top box is driven. Detecting and storing a frequency, a Viterbi code, and a symbol rate required for the EPIROM; When the main power is supplied to the receiver, the initialization time is shortened by sequentially tuning the received signal with the information stored in the EPROM.

Description

How to reduce initialization time of digital satellite set-top box

The present invention relates to a shortening of the initialization time of a digital satellite broadcasting (DBS) set-top box (STB), in particular the frequency, Viterbi code, necessary for tuning in the internal EEPROM (OFF) when the system off, A method of shortening the initialization time of a digital satellite broadcasting set-top box that reads and stores a symbol rate and the like, and tunes a received signal by reading the information stored in the EPROM when the system is powered on. It is about.

In general, satellite broadcasting refers to a broadcasting method of retransmitting a broadcasting signal through a repeater in space for the purpose of receiving satellite broadcasting directly in a general home.

With recent technology, direct reception is possible due to the installation of a small antenna and a receiver, and thus it is widely used.

The advantage of satellite broadcasting is that it can provide high quality uniform broadcasting in a large area with less output than terrestrial broadcasting, and it is possible to prevent geographical reception disturbance and ghost phenomenon, local broadcasting is impossible, high reliability is required, and large investment There is a disadvantage that it is necessary.

In Korea, Mugunghwa satellite has been launched, and Mugunghwa satellite is composed of surrounding and auxiliary satellites, and it functions to relay signals emitted from the ground by stopping at 116 degrees east of 36000KM at low altitude.

Each satellite is equipped with twelve communication repeaters and three broadcast repeaters.

Telecom repeater is called FIXED SATELLITE (FS) and BANDWIDTH is 36M 14W. It is mainly used for TV broadcasting and long distance telephone relay.

The broadcast repeater is called BROADCASTING SATELLITE (BS), and its bandwidth is 27M and its output is 120W.

As above, satellite broadcasting is called DBS (DIRECT BROADCASTING SERVICE), and since 1995, it has been providing digital services.

At present, NHK of Japan and STAR TV satellite broadcasting of Hong Kong are already being received in Korea.

Digital DBS broadcasting has been successfully conducted by DIRECT_TV in the United States since 1994, and in Europe, the DVB standard has been prepared.

Digital DBS can broadcast four or more television signals simultaneously to one repeater using digital compressed signals, while analog DBS can only transmit one television signal per repeater.

Digital DBS is composed of three parts. Transmitter converts TV signal into digital TV signal and transmits it to satellite. Transmitter compresses video and audio data signal into digital signal according to Empok2 standard, and then configures it into PACKET STREAM. Create a digital television signal stream.

Multiple digital television signal streams are multiplexed in a transport multiplexer (TRANSPORT MULTIPLEXER) to form a transport stream (TRANSPORTS STREAM: TS) packet, which is then sent to the channel encoder. .

In the channel encoder, channel coding is performed to correct an error occurring during transmission, and the coded signal undergoes a modulation process to be transmitted to the satellite.

TS packets sent to the channel encoder are first converted into a random data stream during the ENERGY DISPERSION process.

Modulation uses QPSK because the power of the satellite repeater is limited, so power EFFICIENCY takes precedence over spectrum.

The modulated signal is converted to the KU-BAND (14GHZ) band in the upconverter and then amplified sufficiently in the HIGH POWER AMPLIFER (HPA) to be launched to the satellite through the transmit antenna.

The satellite repeater receives the signal of 14GHZ, amplifies it, converts it into 12GHZ, and retransmits it to the ground.

This signal is received by the home antenna, amplified by the LNB, converted to a signal of 1GHZ, and sent through the cable to the tuner.

The signal selected by the tuner is QPSK demodulated, de-multiplexed after transmission error correction in the FEC decoder, restored to MPEG2 TS PACKET, and decoded into video, audio, and data signals by the MPEG2 decoder.

The channel portion is composed of a channel coding portion and a modulation part.

Channel coding uses the FEC (FORWARD ERROR CORRECTION) method to correct errors in transmission. The FEC encodes and transmits data along with the redundancy to enable error detection and correction at the receiving end.

FEC adopts Reed Solomon code as the inter code, and uses CONCARCHATED coding with convolution interleaving in between.

The modulation part consists of a data randomizer, a pulse sharpening filter, a vena modem, and the like.

The channel coding and modulation schemes follow the current DVB specification, and the FEC uses Reed Solomon codes that can correct up to 8 vat errors.

Reed Solomon codes are relatively simple and have high error correction.

Since the size of the input packet is 188 bytes, we use the SHOORTENED RD CODE, RS, which is made from the RS code.

The MPEG 2 transport is randomly encoded by Reed Solomon after 187 bytes except the sync byte in the energy differential unit is converted into an error protection packet. Here RS coding also applies to sync bytes.

The receiver channel part is largely composed of an output part and an input part, and the output part is composed of an antenna, an LNB and a cable, and an input part is a tuner and a QPSK demodulator. It consists of an FEC decoder.

The output of the channel portion becomes an MPEG transport stream, which is restored by the MPEG decoder and restored by the TV and data signals.

The set-top box, which is a general satellite broadcasting receiver having such an operation, has a problem in that initialization time is required because channel tuning is actually performed after performing frequency generation, bit rate code, and symbol rate detection required for channel tuning.

Therefore, the present invention has been proposed to solve all the problems of the general digital satellite broadcasting receiver as described above.

The present invention reads and stores the frequency, Viterbi code, and symbol rate necessary for tuning in an internal EEPROM when the system is turned off, and tunes the received signal by reading the information stored in the IPI ROM when the system is powered on. The purpose of the present invention is to provide a method for shortening the initialization time of a digital satellite broadcasting set-top box, which enables the system operation and channel tuning to be fast.

Method according to the present invention for achieving the above object,

Detecting a frequency, a Viterbi code, a symbol rate, and the like necessary for tuning to standby power when the receiver power is turned off while the digital satellite broadcasting receiver is driven;

When the main power is supplied to the receiver, the step of tuning the received signal with the information stored in the YPIROM is sequentially performed to shorten the initialization time.

1 is a system block diagram of a digital satellite broadcasting set-top box to which the present invention is applied;

2 is a flowchart illustrating a method for shortening the initialization time of a digital satellite broadcasting set-top box according to the present invention.

<Explanation of symbols for main parts of the drawings>

10: switching mode power supply

20: channel section

30: MPEG decoder unit

50: Output terminal part

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail.

1 is a block diagram of a digital satellite broadcasting receiver system to which the present invention is applied.

Here, 10 is a switching mode power supply to supply driving power to each end of the receiver system, and 20 is composed of a microcomputer 21, a front panel 22, and a satellite broadcasting channel decoder 23. A channel section for tuning the signal and demodulating the original digital broadcast signal, and 30 denotes an Y pyrom 31, a plurality of DRAMs 32, 35, 37, a central processing unit 33, an MPEG demultiplexer 34, The MPEG audio decoder 36, MPEG video decoder 38, and video encoder 39 are MPEG decoders for demodulating the digital broadcast signal obtained from the channel unit 20 into audio video data, and 40 is a high frequency modulation unit. .

In the figure, reference numeral 50 denotes a video and audio output terminal, 51 denotes a video output terminal, and 52 and 53 denote audio output terminals.

Referring to the accompanying drawings, a method for shortening the time for initializing a satellite broadcast set-top box according to the present invention with reference to the digital satellite broadcast receiver to which the present invention configured as described above is described.

First, the switching mode power supply 10 converts an external commercial AC power into a DC voltage, and then performs DC-DC conversion again to generate a plurality of DC voltages (including standby power and main power) to supply each stage of the system. do.

In this state, the channel unit 10 performs a demodulation process by receiving satellite signals through the antenna and the LNB sequentially.

In this case, the antenna concentrates the weak signals transmitted to the surface and delivers the signal to the LNB. At this time, the signal focused on the antenna is selected and transmitted to the LNB through a feed hole.

The LNB is composed of a low noise amplifier and a block down converter, the signal received from the antenna is amplified and down-converted at the LNB, attenuated through the cable, passed to the tuner, and then amplified and converted to IF, Filtering process

Since the gain of the LNB is very large, about 50db, the noise characteristic of the entire receiver is determined by the noise FIGUTE and the influence of the tuner is small. Therefore, the LNB uses a low noise amplifier with a very good noise FIGUTE characteristic. The frequency of the input signal of the LNB is very high at 12 GHz. When the signal is sent to the tuner through the cable, the loss and noise effect due to the cable are severe.

Therefore, in the down converter, it is lowered to 1020-1340MHz (L-BAND), which is a relatively low frequency band, and transmitted through the cable.

This down converter uses a 10,678 GHz local oscillator, the LONG TERM FREQUENCY DRIFT of the local oscillator up to 2 MHz.

The power required for the LNB is DC 18V, and the current consumption is 18MA.

Meanwhile, the tuner module is a module in which the analog parts of the tuner unit and the QPSK demodulator are implemented in one shield case.

To tune the desired channel from the RF input signal, the tuner uses a PLL and a mixer to demodulate the analog in phase (I) and quadrature (Q) signals. These I and Q signals are sampled by the analog-to-digital converter and passed to the QPSK demodulator.

The automatic gain control input adjusts the IF signal level appropriately for analog QPSK demodulation and analog-to-digital conversion. It adjusts the gain so that the level of the I and Q signals is 2VPP at 1K ohm load.

This automatic gain control signal is received from the QPSK demodulator, with a control input voltage ranging from 1-5V and a dynamic range of 50db.

On the other hand, the baseband filter combines a demodulator and a digital filter to perform pulse sharpening, in which only amplitude components are filtered and the demodulator filters phase.

The PLL offsets the frequency value by the AFC value obtained by the demodulator after the IF is programmed to 479.5 MHz.

The LONG TERM FREQUENCY DRIFT is calibrated up to 2 MHz by the microcomputer 21, and the analog signal demodulated by I and Q in the tuner module is sampled at a 6-bit symbol rate in the analog / digital converter and input to the demodulator.

The demodulator digitally performs carrier tracking (CT), symbol timing recovery (STR), and automatic gain control (AGC) using the input digital I and Q signals.

Looking at the function of the demodulator more as follows.

First, the demodulator DEPUNCTURING the input symbol stream. That is, during encoding, a PUNCTURING symbol is replaced with a null symbol and converted into a symbol stream having a rate of 1/2.

This converted stream is decoded using the Viterbi algorithm.

On the other hand, the main functions of the Reed Solomon decoder are sync word detection, deinterleaving, Reed Solomon decoding, and derandomization. The input module converts a bitterdy decoded serial input bit stream into a byte stream and finds a sync word.

The de-interleaving rearranges the received byte stream. During the decoding of the decoded codeword, the decoding data is delayed by the codeword length due to the operation of the error detection of the MPEG packet and the addition of the data fail which is the error signal, so that the error correction is made simultaneously with the codeword output.

And de-randomization is pseudo de-randomization.

In the output module, when an error that cannot be corrected by the Reed Solomon decoder occurs, the transport packet error bit is set to "1" to inform the MPEG decoder 30 of the next stage.

The decoded byte, the clock, the data fail, the data validity, and the data streams are transmitted to the MPEG demultiplexer 35 at the rear end to terminate the function of the channel decoder.

Here, the Reed Solomon decoder periodically detects the sync word in the input byte stream, initializes the pointer of the read / write of the de-interleave and periodically initializes the de-randomizer.

Meanwhile, the MPEG decoder 30 separates video and audio data from the MPEG demultiplexer 35 into respective data obtained from the channel decoder 23 as described above, and separates MPEG audio data from the MPEG audio decoder 36. Decoded video is outputted to the audio output terminals 52 and 53, and the separated video data is decoded by the MPEG video decoder 38 and then encoded by the video encoder 39 in a color format suitable for a broadcast method. It is outputted to 51.

The audio and video output in this way is output to the monitor and speaker of the TV actually connected.

Herein, the operation of the MPEG decoder 30 will be described in more detail as follows.

MPEG decoders include transport, audio, and video decoding. The transport block performs multiplexing of any legitimate MPEG transport stream, and MPEG video decoder 38 records MPEG2 MP / ML streams up to 15 Mbps. The digital video data is output in CCIR601 format having NTSC resolution, and the video decoder 38 can display an image of 4; 3 (16: 9) aspect ratio on a TV having a 16: 9 (4: 3) aspect ratio. .

The MPEG audio decoder 36 can decode the MPEG layer 1/2 stream, and the decoded digital audio data is 16-bit PCM audio having an MPEG standard sampling frequency of 16 KHz to 48 KHz, and the D / The A converter converts this PCM data into an analog audio signal.

On the other hand, video overlays and graphics are embedded in the MPEG video decoder 38.

The graphic information has 16 color information, and 4 pieces of TRANPATANCY are supported when the graphic information is combined with the video data.

When the power of the receiver is turned off while performing the operation in this way, the conventional operation is immediately terminated and turned off. However, in the present invention, the main power is supplied to the ypyrom 31 as the standby power supplied from the switching mode power supply 10. It enters the standby state after storing the tuning frequency, Viterbi code, and symbol rate before being turned off.

Then, when the receiver is powered on, the channel signal is directly tuned by reading the frequency, Viterbi code, symbol rate, etc. required for tuning stored in the EPROM 31, and the system operation and channel are analyzed by analyzing PSI information transmitted as the tuned signal. It will process the information needed for synchronization.

This shortens the initialization time of the digital satellite broadcasting receiver.

As described above, the present invention stores a frequency, a Viterbi code, a symbol rate, and the like necessary for tuning in a Y. pyrom in the system as a standby power supply when the power is turned off. By tuning the received signal, the initialization time of the receiver can be shortened.

Claims (1)

In the digital satellite broadcasting receiver for receiving and processing a signal transmitted through a satellite, Detecting a frequency, a Viterbi code, and a symbol rate required for tuning to standby power when the receiver power is turned off while the digital satellite broadcasting receiver is driven; When the main power is supplied to the receiver, the initializing time of the digital satellite broadcasting set-top box, characterized in that the initialization time is reduced by sequentially tuning the received signal with the information stored in the EPIROM.