KR100525848B1 - Single Frequency Network System of Digital Television Transmission using Studio-Transmitter Link for an Analog Broadcasting - Google Patents

Abstract

The present invention relates to a single frequency network system (SFN) of a digital TV transmitter using a station-station link (STL) for analog broadcasting. In particular, in an SFN system, the SFN transmitter is connected to an IF signal. An I / Q demodulator for demodulating baseband I and Q, a digital processor for compensating and delaying channel distortion of a signal output from the demodulator, and an I / Q modulator for distortion compensation and delayed signals through the digital processor Q demodulator, frequency upconverter for converting to desired frequency band, and HPA that amplifies output signal of high frequency converter to high output, and restores digital TV RF signal relayed by STL for analog broadcasting with digital signal processing technology Can be sent to each station after a delay of the desired time. It will have to implement the framework.

Description

Single Frequency Network System of Digital Television Transmission using Studio-Transmitter Link for an Analog Broadcasting}

The present invention relates to a single frequency network system of a digital TV transmitter using a station-station link (STL) for analog broadcasting, and more particularly, to a conventional station-station link network (STL or ST link: Studio to By using a transmitter link, the same IF (Intermediate Frequency) signal is provided to each transmitter, and it is recovered by using digital signal processing technology to construct the same frequency network without adding new facilities. The invention relates to operation, recovery and processing, flow control and transmission technology.

FIG. 1 is a schematic diagram of a typical single frequency network (SFN) system for digital broadcasting. The performance of the link network is to compress video and audio signals into MPEG-2 and AC-3, respectively, and combine them with data broadcasting data. A studio (1) for producing an MPEG transport stream and a transport stream produced in the studio (1) through a station-transmitter link (ST-link) (optical network by radio waves or dedicated lines). ST link (transmitter-station link) Transmitter (Tx) (2), each of which transmits a signal received from the line from the baseband back to the original MPEG transport stream. Receiver (Rx) 4, SFN transmitter 5 which modulates and transmits after performing frequency and time synchronization as a transmitter supporting SFN transmission, and simultaneously transmits the same frequency at various transmitting stations in the network. It has a form consisting of a GPS (Global Positioning System) receiver 6 for receiving a reference signal for transmitting and a transmitting antenna 7 for transmitting in accordance with the SFN frequency.

In addition, Fig. 2 shows a configuration diagram of a SFN system using a conventional digital link. In the performance studio 11, video and audio signals are compressed into MPEG-2 and AC-3, respectively, and then combined with data broadcasting data. Make it,

In general, ATSC type DTV transmitters use two groups of 312 packets to form a transmission frame. The classification of these packet groups is processed in the order of incoming regardless of the contents of the input packets. The transmitter stores each state through the state memory for lattice coding. If the initial value is also different, the same data will be different even if the same data is input. There is no guarantee that the same signal will be sent out last.

Therefore, in order to solve this problem, the data processing unit 13 performs data processing for synchronization. That is, an initial value of a state signal to be used for lattice encoding of the transmitter and the reference signal for each transmitter to start the frame configuration at the exact time point is prepared in advance in the form of a packet, and the data processor 13 creates such synchronization data. It plays a role.

In addition, the synchronization data inserter 14 functions to insert the reference signal and the additional packet data generated from the data processing section 13 onto the transport stream, and the ST link transmitting end 2 carries out the combined transport stream. Transmission is performed through a transmission station link (ST-link), where transmission paths are transmitted through radio waves, leased lines, and optical networks.

On the other hand, the ST link receiving end 4 of each transmitting station recovers the signal received from the circuit back to the original MPEG transport stream from the baseband, and the SFN transmitter 5 performs frequency and time synchronization as a transmitter supporting SFN transmission. Then modulate and transmit.

In this case, the synchronized data processing 51 in the SFN transmitter 5 analyzes the synchronization reference signal and the additional packet data to form a packet group at an accurate position, constructs a transmission frame, initializes a state memory, and drowns. The exciter 52 converts the VSB (Vestigial Side Band) modulated signal in the baseband to the output frequency, and the high power amplifier 53 outputs the signal output from the exciter 52. Amplify the signal to high power and transmit it to the SFN frequency through the transmission antenna (7).

On the other hand, the GPS receiver 6 receives a reference signal for simultaneously transmitting at the same frequency from several transmitting stations in the network.

That is, in the SFN system using the conventional digital link, the digital ST link transmitting and receiving terminals (2, 4) are used to transmit the TS signal with the synchronization information inserted to each transmitting station. Transmits at the same frequency.

The conventional SFN system using a digital link having such a configuration inserts synchronization information in a packet form into a TS output of a studio using a data MUX function to generate data identical to a parameter to be set differently for each transmitter.

The TS signal inserted with the synchronization signal is sent to each transmitting station using the existing digital STL, and each transmitter extracts and applies the corresponding transmitter parameter from the received TS signal and periodically initializes the output data from the synchronization information. Through the signals transmitted by each transmitter is set to the same and sent out.

However, the SFN system using the conventional digital link having such a configuration has an advantage that the STL for digital broadcasting can be used as it is, and the transmission protocol needs to be redefined.

That is, the synchronization concept of the packet concept should be inserted into the TS stream in the studio, and the transmitter should extract the information and control the individual transmitter accordingly. Therefore, the structure of the VSB transmitter of the STL transmitter and the VSB transmitter of the STL receiver is It is very complicated and difficult to operate.

The present invention has been made to solve the above-mentioned conventional problems, and recovers the digital TV RF signal relayed by the existing analog broadcasting STL by digital signal processing technology and transmits it to each transmission station after a delay of a desired time. To provide a single frequency network system of digital TV transmitter using the station-station link (STL) for analog broadcasting, that is, the system construction, operation, recovery and processing, flow control and transmission technology that can realize the same frequency network without additional. The purpose is.

The object of the present invention described above is to pass a studio for producing a TS stream, a DTV modulator for modulating the TS stream into an analog IF signal, and the analog 6 MHz (or 8 MHz) bandwidth to transmit to a transmission station in each region through a transmission antenna. A station-station (ST) link configured with an analog STL transmitter; An STL receiver that receives a signal from an ST link and converts it into an IF signal, an SFN transmitter that modulates and transmits after performing frequency and time synchronization, a GPS receiver that receives reference signals for simultaneous transmission at the same frequency from several transmitting stations in a network, and In the SFN system consisting of each transmitting station consisting of transmitting antennas to transmit in accordance with the SFN frequency, I / Q demodulator for demodulating the SFN transmitter to the baseband I, Q, and the signal output from the demodulator Digital processor for compensating and delaying channel distortion of the digital signal, I / Q modulator for modulating the signal passing through the digital processor, Frequency upconverter and frequency upconverter This can be achieved by configuring with HPA.

Therefore, since the digital TV RF signal relayed by the existing analog broadcasting STL can be restored by digital signal processing technology, it can be transmitted to each transmission station after a desired time delay, thereby realizing a DTV same frequency network without adding new equipment.

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

Figure 3 shows the configuration of the system of the present invention, Figure 4 shows a detailed configuration of the digital processor of the present invention.

According to this, a studio 11 for producing a TS stream, a DTV modulator 12 for modulating the TS stream into an analog IF signal, and an analog 6MHz (or 8MHz) bandwidth are passed through each region through a transmission antenna 3. An ST link configured with an analog STL transmitting end 2 for transmitting to a transmitting station of the apparatus; STL receiving stage 4 which receives the signal from ST link and converts it into IF signal, SFN transmitter 5 which modulates and transmits after performing frequency and time synchronization, and reference signal for simultaneously transmitting at the same frequency from several transmitting stations in the network. In the SFN system consisting of each transmitting station consisting of a GPS receiver 6 for receiving the transmission and the transmission antenna 7 for transmitting in accordance with the SFN frequency,

An I / Q demodulator (51) for demodulating the SFN transmitter (5) into baseband I / Q; A digital processor (52) for compensating and delaying channel distortion of a signal output from the I / Q demodulator (51); An I / Q modulator (53) for modulating a signal through the digital processor (52); A frequency upconverter 54 for converting the output signal of the I / Q modulator 53 into a desired frequency band, and an HPA 55 for amplifying the signal converted by the frequency upconverter 54 to a high output; It is characterized by consisting of).

At this time, the digital processor 52, as shown in Figure 4, the channel distortion compensation unit 521 for compensating for the channel distortion of the signal demodulated to the baseband by the I / Q demodulator 51, and the channel The symbol recovery unit 522 recovers the transmission symbol of the signal whose distortion is compensated by the distortion compensator 521, a delay unit 523 for delaying transmission timing synchronization by a time allocated to each transmitter, and the delay unit 523. It is characterized by consisting of a waveform shaping filter 524 for shaping the signal output through the DTV waveform again.

Referring to the operation and effect of the system of the present invention configured as described above are as follows.

First, the TS stream produced in the studio 11 of the performance studio is modulated into an analog IF signal through the DTV modulator 12.

This analog 6 MHz (or 8 MHz) bandwidth is transmitted as is through the analog STL transmitter stage 2 to the transmitters in each region. In each transmitter, the IF signal received through the I / Q demodulator 51 is converted into a baseband digital signal. After the conversion, the channel distortion is compensated by the channel distortion compensator 521 in the digital processor 52, the symbol is recovered through the symbol recovery unit 522, and then assigned to each transmitter through the delay unit 523. After the delayed by a predetermined time, the waveform shaping filter unit 524 performs a distortion compensation process to remove and compensate for noise and channel distortion, and then passes through the I / Q modulator 53 and the frequency up-converter 54. The frequency is converted into frequency and retransmitted through the HPA 55.

At this time, the essential requirements of a single frequency network are divided into the following three, the first is the frequency synchronization between the transmission frequency, the second is the transmission timing adjustment of each transmitter, and the third is the perfect identity of each transmission signal.

Therefore, in the present invention, the following technique is applied to this.

First, it is possible to synchronize all frequencies of the system using GPS to synchronize each transmission frequency, and secondly, it is possible to program in consideration of the distance to the performance station and the distance to the next transmission station in order to synchronize the transmission timing between each transmitter. A digital delay value is assigned. Third, the DTL modulation is already performed by the STL transmitter in order to ensure the sameness of each transmission signal, so that only the transmission timing and the frequency synchronization are matched on the SFN network.

That is, in the single frequency network system using the analog broadcast ST link, the present invention converts a TS stream produced by a performance station into an analog IF signal through a DTV modulator, and then transmits the analog broadcast signal as if it is distributed to each transmission station. It will be sent at the desired time.

In other words, in the case of the existing digital broadcasting relay line, the performance station transmits the TS signal directly through the STL transmitter, but in the present system, the TS stream produced in the studio 11 of the performance station is transmitted through the DTV modulator 12. The analog signal is first converted into an analog signal through an analog IF modulation process, and then the 6 MHz bandwidth of the analog signal is transferred to a transmission station of each region through a transmission / reception antenna 3 or a dedicated transmission / reception line of the analog STL transmission terminal 2.

In addition, the transmitter transmits the IF signal I / Q demodulator 51 received through the STL receiver 4 to convert the IF signal into a baseband digital signal, and then the channel distortion compensator 521 in the digital processor 52. The channel distortion is compensated for, the symbol recovery unit 522 is used to recover the symbol, and then the delay unit 523 delays the signal by the time allocated to each transmitter. After removing and compensating for noise and channel distortion through the I / Q modulator 53 and the frequency up-converter 54, the frequency is converted to a desired frequency and retransmitted through the high output amplifier 55.

Such a system of the present invention is applicable to a digital broadcasting transmission system based on most single frequency networks such as DAB, DVB-T, and ISDB-T in addition to the DTV transmitter for ATSC.

As described above, according to the present invention, first, a single frequency network can be configured using an existing analog ST link system without any additional burden, and secondly, there is a digital delay unit that can be adjusted for each transmitter to a desired time. Third, each transmitter transmits the signal received through the STL receiver, and the symbol recovery and distortion compensation function using digital signal processing is built in each transmitter to compensate for the low S / N of the analog relayed signal. Fourth, it can transmit with high S / N signal, fourthly, it doesn't need separate protocol for transmitter data synchronization, fifthly, it can guarantee frequency synchronization between transmission signals using GPS, and sixth MPEG input source is same Therefore, the frequency difference between each transmitter does not occur due to the frequency change of MPEG signal. There are advantages.

1 is a schematic diagram of a typical single frequency network (SFN) system.

2 is a block diagram of a SFN system using a conventional digital link.

3 is a schematic diagram of a system of the present invention;

Figure 4 is a detailed block diagram of a digital processor of the present invention.

Explanation of symbols on main parts of drawing

2: STL transmitting end 3,7: transmitting antenna

4: STL receiver 5: SFN transmitter

6: GPS receiver 11: studio

12: DTV modulator 13: data processing unit

14: synchronization data insertion unit 51: I / Q demodulation unit

52: digital processor 53: I / Q demodulator

54: frequency upconverter 55: HPA

521: channel distortion compensation unit 522: symbol recovery unit

523: delay unit 524: waveform shaping filter unit

Claims (2)

The studio 11 producing the TS stream, the DTV modulator 12 which modulates the TS stream into an analog IF signal, and the analog 6 MHz (or 8 MHz) bandwidth pass through the transmission antenna 3 to the transmitting stations in each region. A station-station (ST) link composed of an analog STL transmitter 2 for transmitting; STL receiving stage 4 which receives the signal from ST link and converts it into IF signal, SFN transmitter 5 which performs VSB modulation after performing frequency and time synchronization and transmits the same frequency simultaneously from several transmitting stations in the network. In the SFN system which consists of each transmitter which consists of the GPS receiver 6 which receives a signal, and the transmission antenna 7 which transmits according to SFN frequency, An I / Q demodulator (51) which demodulates the SFN transmitter (5) into baseband I / Q; A digital processor (52) for compensating and delaying channel distortion of a signal output from the I / Q demodulator (51); An I / Q modulator (53) for modulating the signal passing through the digital processor (52); A frequency upconverter 54 for converting the output signal of the I / Q modulator 53 into a desired frequency band, and an HPA 55 for amplifying the signal converted by the frequency upconverter 54 to a high output; Single frequency network system of a digital TV transmitter using a station-station link (STL) for analog broadcasting. The method according to claim 1, The digital processor 5 includes a channel distortion compensator 521 for compensating for channel distortion of a signal demodulated to the baseband by the I / Q demodulator 51 and a distortion in the channel distortion compensator 521. A symbol recovery unit 522 for recovering the transmission symbol of the compensated signal, a delay unit 523 for delaying transmission timing synchronization by a time allocated to each transmitter, and a signal output through the delay unit 523 A single frequency network system of a digital TV transmitter using a station-station link (STL) for analog broadcasting, comprising a waveform shaping filter unit 524 for shaping the waveform again.