KR100210402B1 - Initial channel selecting method of digital dbs receiver - Google Patents

Abstract

The present invention relates to an initial channel selection method for a digital DBS receiver, and more particularly, to an effective initial channel selection method when a viewer applies power for the first time after purchasing a digital DBS receiver, comprising: a repeater selection step (S1); Receiving a transport stream (S2); Determining whether the received transport stream is a normal information stream or noise (S3); A valid PID setting step (S4) after detection of a program related table and a program map table when the received transport stream is a normal information stream; Determining whether there is an actual service stream input in the set effective PID, and ending all initial channel selection processes according to a result of the determination (S5); Determining whether there is a valid PID in the detected program related table and program map table (S6); And if a valid PID does not exist as a result of determining that there is a valid PID in the detected program related table and program map table, the receiver selects another repeater and then proceeds to the transport stream receiving step (S2) According to the present invention as described above, when the viewer first applies power to the digital DBS receiver after purchasing the digital DBS receiver, the effective initial channel of the effective initial repeater is selected in the receiver itself.

Description

A method of choosing an initial channel for a digital DBS receiver (Digital Broadcasting Service Receiver)

The present invention relates to an initial channel selection method of a digital direct broadcast service (DBS) receiver. In particular, when power is first applied after purchasing a digital DBS receiver, And to select a valid channel that includes the actual service information in a valid initial repeater that performs the initial channel selection.

In general, DBS refers to a broadcasting system in which a broadcasting signal is retransmitted through a satellite repeater for direct reception in a general household, and as a result of recent developments in technology, direct reception is possible by installing a small antenna and a digital DBS receiver, have.

The DBS can not perform local broadcasting, requires a large investment with a high reliability requirement, and has a disadvantage in that it causes a problem of propagation menstruation. On the other hand, the DBS is capable of uniformly high-quality broadcasting in a large area with a small output compared to terrestrial broadcasting, Since it has the merit of reducing reception disturbance and ghost phenomenon, Korea has also started to provide a pilot broadcasting service on July 1, 1996 by using Mugunghwa satellite.

1 is a block diagram illustrating the overall configuration of a general digital DBS system. The general digital DBS system shown in FIG. 1 includes a service provider 1, a satellite repeater 2 and a subscriber 3 The service provider side 1 and the subscriber side 3 are connected through a public switched telephone network (PSTN).

The service provider side 1 comprises a transmitter 11 (Encoder Transmitter) for encoding, converting and multiplexing television signals into transport stream packets and then channel-coding the signals to transmit them to a satellite in a frequency band of 14 GHz, And a resource subscriber management system (hereinafter referred to as RSMS) 12 for collecting usage information of the subscriber. The transmitter 11 includes an MPEG-2 (Moving Picture Experts Group-2) encoder 11-1, a FEC (Forward Error Correction) encoder 11-2, a Quaternary Phase Shift Keying (QPSK) modulator 11-3, And a transmission antenna 11-4.

The satellite transponder 2 receives the transport stream from the transmitter 11, amplifies it, and retransmits it to the 12 GHz frequency band.

The subscriber 3 includes a receiving antenna 31, a low noise block-down converter (LNB) 32, a digital DBS receiver 33, and a television 34. The digital DBS receiver 33 includes a tuner 33-1 and a QPSK demodulator 33-2, an FEC decoder 33-3, and an MPEG-2 decoder 33-4.

The operation of the digital DBS system configured as above will be described below.

The MPEG-2 encoder 11-1 of the transmitter 11 converts video, audio, and data signals into digital signals according to the MPEG-2 standard, compresses the digital signals, and forms packet streams, Create a stream. Then, the plurality of digital television signal streams are multiplexed into transport stream packets and then sent to the FEC encoder 11-2. The FEC encoder 11-2 performs channel coding to correct an error generated in transmission. The QPSK modulator 11-3 performs a modulation process to transmit the channel-encoded signal to the satellite. The modulated signal is converted from an up-converter (not shown) to a ku-band (14 GHz), amplified sufficiently by a high power amplifier (HPA) .

The satellite is composed of at least one satellite transponder 2. The satellite transponder 2 receives and amplifies the 14 GHz uplink signal transmitted from the base station and converts it to 12 GHz and retransmits it to the ground again. The satellite repeater can be classified as follows according to the signal processing method and frequency conversion frequency. The satellite transponder includes a general transponder type satellite transponder which converts a received signal into a downlink frequency and transmits the converted signal to a downlink frequency according to a signal processing method, a reproduction satellite which converts the received signal into a baseband signal, It is divided into repeater. Also, the satellite transponder includes a single frequency transform satellite repeater for converting the received frequency to a direct downlink frequency according to the number of times of frequency conversion, a receiver for converting the received frequency to an intermediate frequency, And a dual frequency conversion type satellite repeater.

The 12 GHz band transport stream signal relayed from the satellite transponder 2 is received by the receiving antenna 31. The LNB 32 drops the received 12 GHz transport stream signal to an intermediate frequency signal of 1 GHz band, removes the noise, and sends the signal to the tuner 33-1 through a cable. The signal selected by the tuner 33-1 is demodulated in the QPSK demodulator 33-2, and the demodulated signal is restored to transmission error in the FEC decoder 33-3. The signal in which the transmission error is recovered is decoded into video, audio and data signals in the MPEG-2 decoder 33-4. The decoded signal is displayed to the viewer through the television 34.

Here, the digital DBS receiver tunes the carrier frequency of one repeater and the carrier frequency of the receiver in the manufacturing process, and when the viewer first supplies power after purchasing the receiver, the digital DBS receiver has the pre- And receives the relayed transport stream from the repeater.

However, when the digital DBS receiver selects a repeater having a carrier frequency tuned to a preset carrier frequency, it may not relay the actual service information to the selected repeater. Therefore, The first thing to do is to select a valid repeater.

The next task to be performed is to select a valid channel by the digital DBS receiver itself and to provide actual service information to the viewer when a valid channel including actual service information does not exist in a valid repeater selected by the digital DBS receiver .

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a digital DBS which enables a receiver to select a valid channel including actual service information in a valid initial relay when power is first applied after purchasing a digital DBS receiver. And an object of the present invention is to provide a method of selecting an initial channel of a receiver.

In order to achieve the above object, in the initial channel selection method of a digital DBS receiver according to the present invention, a carrier frequency of a repeater and a carrier frequency of the digital DBS receiver are tuned in a manufacturing step, The method comprising the steps of: when a power is first applied to a digital DBS receiver after receiving a relayed transport stream from a repeater having a pre-tuned carrier frequency,

A first step of the digital DBS receiver selecting a repeater having a carrier frequency equal to a preset carrier frequency;

A second step of receiving a transport stream from the selected repeater;

A third step of determining whether the received transport stream is a normal service information stream or noise;

If the received transport stream is a normal service information stream as a result of the determination in the third step, detects a program related table and a program map table of the received transport stream, A fourth step of setting a valid PID in the second step;

A fifth step of determining whether there is an input of a service stream in the set valid PID, and then terminating all initial channel selection processes when there is a service stream input as a result of the determination;

Determining whether there is another valid PID in addition to the valid PID set in the fourth step to the detected program related table and program map table, and then proceeding to the fourth step according to the determination result; And

If it is determined that the received transport stream is noise other than a normal service information stream, or if it is determined that the PID is not valid in the fourth step as a result of the determination in the third step, And if the other valid PID does not exist, the receiver selects another repeater other than the repeater selected in the first step and then proceeds to the second step.

According to the present invention, when the viewer first applies the power after purchasing the digital DBS receiver, it is possible to select a valid initial channel including a valid service information stream in the initial relay available in the receiver itself.

1 is a block diagram of a general digital DBS system,

2 is a block diagram illustrating a digital DBS receiver according to the present invention.

3 is a diagram illustrating a structure of a channel received in a digital DBS receiver,

4 is a diagram showing a structure of a program map table on a transport stream,

5 is a flowchart illustrating an initial channel selection method of a digital DBS receiver according to the present invention.

Description of the Related Art [0002]

20: Digital DBS receiver 21: Tuner

22: A / D converter 23: QPSK demodulator

24: channel decoder 25: transport stream demultiplexer

26: decryption unit 27: audio / video decoder

28: video memory 29: video encoder

30: D / A converter 31: RF modulator

32: remote controller 33: microcomputer

34: modem 35: smart card

36: memory 40: resource and subscriber management system

60: Public network

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

First, an overall configuration of a digital DBS receiver applied to the present invention will be described in order to facilitate understanding of the present invention.

2 is a block diagram of a digital DBS receiver applied to the present invention. The digital DBS receiver shown in FIG. 2 includes a tuner 21, an A / D converter 22, a QPSK demodulator 23, a channel decoder Video decoder 28, a video encoder 29, a D / A converter 30, a radio frequency (RF) receiver 24, a transport stream demultiplexer 25, a decryption unit 26, an audio / video decoder 27, (hereinafter referred to as RF) modulator 31, a remote controller 32, a microcomputer 33, a modem 34, a smart card 35 and a memory 36. The RSMS 40 ).

The tuner 21 selects a transport stream of a channel desired by the viewer from a satellite repeater (not shown) received at a receiving antenna (not shown).

The A / D converter 22 converts the selected analog signal into a digital signal.

The QPSK demodulator 23 receives the A / D-converted QPSK modulation signal and performs QPSK demodulation.

The channel decoder 24 receives the QPSK demodulated channel-encoded signal and performs channel decoding.

The transport stream demultiplexer 25 receives and demultiplexes the channel-decoded multiplexed stream to extract only audio / video data of a channel desired by the viewer.

The decryption unit 26 decrypts the data so that the subscriber can view the encrypted signal.

The audio / video decoder 27 receives and decodes the extracted audio / video data.

The video memory 28 is a data storage space necessary for the video decoding process.

The video encoder 29 encodes the decoded video data into an analog signal in order to receive and display the decoded video data.

There are the following two methods of encoding the video signal and outputting the video signal in the video encoder 29. One is to output the encoded video signal to a display device (not shown) in the form of a baseband video signal, and the other is to output the encoded video signal to the RF modulator 30.

The D / A converter 30 receives the decoded audio data as a digital signal, converts the decoded audio data into an analog signal, and outputs the analog signal in the following two ways. One is for outputting to the display device in the form of audio left / right (Audio - Right / Left) stereo, and the other is for outputting to the high frequency modulator 31.

The RF modulator 31 modulates the audio / video signal and outputs an RF signal.

The microcomputer 33 controls the entire system in accordance with a reception signal from the remote controller 32 and the modem 34 is for communication between the RSMS 40 and the DBS receiver 20.

The smart card 35 gives the right to decrypt the encrypted data so that only the subscriber having the reception right can receive the data, and stores and provides information about the pay-per-view.

The memory 36 stores a program of the microcomputer 33. The RSMS 40 controls subscriber access to the program and collects usage information of the subscriber. Is used when exchanging information on pay-per-view viewing of the Internet.

The digital DBS receiver receives a plurality of multiplexed channels from a satellite transponder, wherein the one channel is composed of a plurality of transport streams, and the one transport stream is a program service reference stream (ES) : Hereinafter referred to as a stream), a data service stream, and an RSMS data stream. Here, according to the specification SPEC of Hibiscus satellite, the program service stream and the data service stream can not coexist on the same channel. Also, the RSMS data stream is always present in all channels because the RSMS data stream contains information necessary for selecting an initially valid repeater. On the other hand, the program service stream is composed of a video signal and an audio signal including caption data.

The RSMS data stream is composed of service information (SI) and an RSMS message. The service information SI includes Program Specific Information (PSI) used for demultiplexing the received multiplexed transport stream, supplementary information (Program Guide Messages) for program guidance, ). The RSMS data stream is composed of an Entitlement Management Message (EMM), an Entitlement Control Message (ECM), and a Receiver Command Message (RCM).

The program designation information PSI includes a program association table (PAT), a conditional access table (CAT), and a program map table (PMT).

The additional information may include a network information table (NIT), a service description table (SDT), an event information table (EIT), and a time date table (TDT) do.

Table 1 below shows the configuration of channels input to the digital DBS receiver as described above.

Channel Configuration Channel 1 Transport stream Program service stream RSMS data stream A video signal including caption data Audio signal SI RSMS message PSI Additional Information PAT CAT PMT NIT SDT EIT TDT ECM EMM RCM Channel 2 Transport stream Data service stream RSMS data stream - SI RSMS message PSI Additional Information PAT CAT PMT NIT SDT EIT TDT ECM EMM RCM

Here, the program related table (PAT) provides a packet identifier (PID) value of program map table sections having program definitions for a service stream (program service stream or data service stream) And provides the PID values of the transport packet carrying the program guide message and receiver command message (RCM) components of the RSMS data stream. Table 2 below shows the program related table (PAT) according to the specifications (SPEC) of the Hibiscus satellites.

Program related table (PAT) program 0 PIN (PMM) The transport packet that transports the PMM member of the RSMS data stream. program 1 PID (RCM) The transport packet that transmits the RCM member of the RSMS data stream. program i PID (PMT) A transport packet that transmits a PMT member of an RSMS data stream

The condition access table (CAT) provides the PID of the transport packet to which the entitlement management message (EMM) of the RSMS data stream is to be sent.

The following Table 3 shows the condition access table (CAT) according to the specification (SPEC) of the Hibiscus satellites.

Conditional Access Table (CAT) CA system 1section 0x00 System Description CA system id PID (EMM) The transport packet that transports the PMM member of the RSMS data stream. CA system nsection 0x00

The program map table (PMT) defines a program by mapping program numbers to streams. In other words, the program map table (PMT) includes a plurality of program numbers. Up to three stream PIDs per program can be used, and the PID for a given program number is associated with a program related table (PAT ). Here, the program number means a unique number of each broadcasting station program (often called TV-channel = 12, ...). For example, if the program number is 1000, it means that the program is provided by KBS-1 1001 indicates that the program is provided by KBS-2, and when the program number is 1002, it indicates that the program is provided by MBC.

Table 4 below shows the program map table (PMT) according to the specifications (SPEC) of the Hibiscus satellites.

The program map table (PMT) INDEX PG # (program number) VPID (Video PID) APID (Aideo PID) 0 0 × × One One × × 2 1000 101 102 3 1001 × × 4 × × × 5 1002 501 502 6 a - - :::: N-1 i - -

3 is a diagram illustrating a structure of a channel received by the digital DBS receiver. One channel shown in FIG. 3 includes a plurality of transport streams, wherein one transport stream packet includes 4 bytes, A header 100, an adaptation field 200, and a payload 300 of 184 bytes.

The header 100 is composed of 8 bits of sync signal 110 (sync byte: defined as 00101111 for a synchronized signal of a satellite station), 1 bit of a transport error indicator 120, A 1 bit transmission priority 140, a 13 bits PID 150, a 2 bits transport scrambling control 160, a 2 bits transmission scrambling control 160, An adaptation field control 170 and a continuity counter 180 of 4 bits.

The adaptation field 200 includes an adaptation field length 210, a 1 discontinuity indicator 220, a 1-bit random access indicator 230, An elementary stream priority 240, 5 bits of flags 250, optional fields 260 and stuffing bytes 270.

FIG. 4 is a diagram showing a program map table (PMT) on the transport stream according to the structure of the transport stream packet shown in FIG. 3 and referring to the program map table (PMT) in Table 4. FIG.

On the other hand, when the viewer first applies power to the digital DBS receiver after purchasing the digital DBS receiver, the first thing the digital DBS receiver must do is to select an effective initial satellite repeater. The selection of the effective initial repeater means selecting a repeater relaying a transport stream including a service information stream to be provided to an actual viewer.

The next task of the digital DBS receiver is to find a valid channel that includes service information to be provided to the actual viewer at the selected valid repeater. FIG. 5 is a flowchart illustrating an initial channel selection method of a digital DBS receiver according to the present invention. The initial channel selection method shown in FIG. 5 is as follows.

First, the digital DBS receiver tunes the carrier frequency of a repeater and the carrier frequency of the receiver in the manufacturing process. When the viewer first supplies power after purchasing the receiver, the digital DBS receiver has the pre- And receives the relayed transport stream from the repeater. For example, in the case of the Hibiscus satellite, since one satellite has six satellite repeaters, the carrier frequency of one of the six repeaters and the carrier frequency of the receiver are tuned at the manufacturing stage. In the first step S1, the digital DBS receiver selects a repeater having the same carrier frequency as the preset carrier frequency.

And receives a transport stream from the selected repeater in a second step (S2).

In a third step S3, it is determined whether the received transport stream is a normal service information stream or noise.

That is, in step 3-1 (S3-1), the received transport stream is a QPSK modulated signal at the transmitter, and therefore, it is determined whether there is a QPSK carrier capable of demodulating the received transport stream.

If the QPSK carrier exists in step 3-2 (S3-2), the bit error rate of the received transport stream is checked in step 3-1 (S3-1). Here, the bit error rate is expressed as a ratio of the number of error bits in the total reception reproduction bit number, which indicates the error rate in the transmission path in bit units.

In step S3-3, it is determined whether the checked bit error rate exceeds a reference bit error rate. If the checked bit error rate exceeds the reference bit error rate, it means that the relayed transport stream from the selected repeater is noise, not actual service information stream. As a result, since the repeater selection is wrong, it is necessary to start searching for another repeater without having to determine whether the selected repeater inputs a service stream.

If the checked bit error rate does not exceed the reference bit error rate as a result of the determination in step S3-3 (S3-4) in step S3-4, the synchronization of the received transport stream It is judged whether or not the sync byte (sync byte) is a synchronous signal (sync signal according to the standard of the USSR satellite) (0010 1111). When the sync signal is a sync signal (00101111) for which the sync signal is defined, it means that the actual service information stream can be received according to the received sync.

If it is determined in the fourth step S4 that the synchronization signal of the received transport stream is a prescribed synchronization signal (e.g., 00101111) as a result of the determination in the step 3-4 (S3-4) Detects a program related table (PAT) and a program map table (PMT) in the port stream, and sets a valid PID in the detected program related table (PAT) and program map table (PMT). Here, the valid PID may be a PID even if a program number is present as shown in Table 4. If there is a program number but also a PID in the program number, the PID is referred to as a valid PID. (E.g., INDEX = 5, VPID = 501 in PG # = 1002, APID = 502)

That is, in step 4-1 (S4-1), the RSMS data stream is detected in the received transport stream.

In step 4-2 (S4-2), the program related table (PAT) and the program map table (PMT) of the detected RSMS data stream are detected. The reason why the program related table (PAT) and the program map table (PMT) are detected at the time of initial channel selection is basically that the same program related table (PAT) and program map table (PMT) This is because it is basic information used for movement to other satellite repeaters and other channels.

In step 4-3 (S4-3), the timer for valid PID setting is initialized (t? 0).

In step 4-4 (S4-4), a valid PID is set in the detected program related table (PAT) and program map table (PMT).

In step 4-5 (S4-5), it is determined whether the time (t) required to set the valid PID exceeds the reference time (T ₁ ) using the initialized timer. Here, the fact that the time t required for setting the valid PID exceeds the reference time T ₁ means that there is no valid PID in the detected program related table (PAT) and the program map table (PMT) The fact that the time t required for setting the valid PID does not exceed the reference time T ₁ means that there is a valid PID in the detected program related table PAT and the program map table PMT.

If the time t required for setting the valid PID does not exceed the reference time T _{1 as a} result of the determination in the step 4-5 (S4-5) in the fifth step S5, If it is determined that the service stream is input to the PID, and if the service stream is input to the set PID, all initial channel selection processes are terminated. That is, the digital DBS receiver has selected a valid channel in the first available valid repeater.

If the service stream is not input to the set PID as a result of the determination in the fifth step S5 in the sixth step S6, (Step S4-4) if another valid PID is present as a result of the determination. If it is determined that another valid PID exists, the process proceeds to step S4-4.

If the QPSK carrier does not exist as a result of the determination in the 3-1 step (S3-1) in the seventh step S7 and the check result in the step 3-3 (S3-3) If the bit error rate exceeds the reference bit error rate and the sync signal of the received transport stream is not a prescribed sync signal, that is 0010 1111, as a result of the determination in the step 3-4 (S3-4) As a result of the judgment in the step 4-5 (S4-5), when the time t required for setting the valid PID exceeds the reference time T ₁ , As a result of the determination, if another valid PID does not exist, the digital DBS receiver selects another repeater and then proceeds to the second step (S20).

That is, after the digital DBS receiver selects a valid repeater, it must again select a valid channel in the valid repeater.

Once the initial channel selection is performed, the repeater and the channel at the time when the viewer turns off the power are stored in the nonvolatile memory of the digital DBS receiver, so that it is not necessary to repeat the initial channel selection process again.

There is an effect that, when the viewer first applies power to the digital DBS receiver after purchasing the digital DBS receiver, the valid channel of the effective initial relay can be selected in the receiver itself.

Claims (3)

The digital broadcasting receiver is tuned for a carrier frequency of a repeater and a carrier frequency of the digital DBS receiver in a manufacturing stage. When a viewer applies power for the first time after purchasing the receiver, A method for initial channel selection in a digital DBS receiver receiving a port stream, A first step (Sl) of the digital DBS receiver selecting a repeater having a carrier frequency equal to a preset carrier frequency; A second step (S2) of receiving a transport stream from the selected repeater; A third step (S3) of determining whether the received transport stream is a normal service information stream or noise; If it is determined in the third step S3 that the received transport stream is a normal service information stream, a program related table and a program map table of the received transport stream are detected, A fourth step (S4) of setting a valid PID in the program map table; A fifth step (S5) of determining whether there is an input of a service stream in the set valid PID, and then terminating all initial channel selection processes when there is a service stream input as a result of the determination; It is determined whether there is another valid PID in addition to the valid PID set in the fourth step S4 in the detected program related table and program map table, Step S6; And If it is determined that the received transport stream is noise other than a normal service information stream as a result of the determination in the third step S3 or a valid PID can not be set in the fourth step S4, , The receiver selects another repeater other than the repeater selected in the first step S1 and then proceeds to the seventh step S7 to go to the second step S2 in the case where there is no other valid PID The method of claim 1, further comprising: 2. The method according to claim 1, wherein the third step (S3) A third step (S3-1) of determining whether a QPSK carrier exists in the received transport stream; A third-2 step (S3-2) of checking the bit error rate of the received transport stream when there is a QPSK carrier as a result of the determination in the step 3-1 (S3-1); (S3-3) of determining whether the checked bit error rate exceeds a reference bit error rate; And If the checked bit error rate does not exceed the reference bit error rate as a result of the judgment in the step 3-3 (S3-3), it is judged whether the synchronous signal of the received transport stream is a prescribed synchronous signal, And a step (S3-4) of determining the initial channel of the digital DBS receiver. The method according to claim 1, wherein the fourth step (S4) A fourth step (S4-1) of detecting an RSMS data stream in the received transport stream; A fourth step (S4-2) of detecting a program related table and a program map table among the detected RSMS data streams; Step 4-3 (S4-3) of initializing a timer for effective PID setting (t? 0); A fourth step (S4-4) of setting a valid PID in the detected program related table (PAT) and the program map table (PMT); And And a fourth step (S4-5) of determining whether a time required for setting the valid PID exceeds a reference time using the initialized timer. Way.