KR101580663B1 - Method and appartatus for repeating signal of atsc dtv broadcasting - Google Patents

Abstract

The present invention relates to a signal relaying method and a signal relaying apparatus for ATSC DTV broadcasting, and more particularly, to a signal relaying method and a signal relaying apparatus for ATSC DTV broadcasting, which are capable of receiving a signal to be relayed, performing frequency down conversion on the received signal, Extracts a pilot signal from the first separation signal, performs an ICS (Interference Cancellation System) operation on the second separation signal to generate an interference cancellation signal, separates the extracted pilot signal, Channel interference by using the ICS type digital on-channel repeating method, which combines the interference cancellation signal and the merged signal to another device, and has the effect of expanding the coverage and supplementing the shadow area service, So that efficient transmission can be performed at the same time.

Description

TECHNICAL FIELD [0001] The present invention relates to a signal relaying method and a signal relaying method for ATSC DTV broadcasting,

The present invention relates to a signal relaying method and a signal relaying device for ATSC DTV broadcasting. Particularly, by separating and processing the received signals, the ICS type digital in-channel repeating method having the effect of expanding the coverage and supplementing the shadow area service, Method and a signal relay apparatus.

In a SFN (Single Frequency Network) network including a DTV (Digital TeleVision) system through an ATSC (Advanced Television System Committee) transmission method, a digital equal channel A digital on channel repeater (DOCR) is used. The DOCR technique corresponds to a technique of amplifying and transmitting a received signal at the same frequency without frequency conversion.

The configuration of the DTV broadcast signal transmission system transmitter of the ATSC transmission scheme is as shown in FIG. That is, the DTV broadcast signal transmission system transmitter of the ATSC transmission type performs pilot signal insertion, VSB modulation, RF conversion, and the like through a data processing unit such as a data randomizer and a channel encoder. The inserted pilot signal is used for the receiver to easily detect the received signal. The insertion of the pilot inserts a DC of about 17% of the maximum signal into the data symbol. That is, 1.25 magnitude DC is inserted into the data symbol of +7 ~ -7 size, and the signal of -5.25 ~ + 8.25 is generated and the total average transmission power is increased by about 0.3 dB.

Also, when constructing the SFN network, the main signal and the signal passed through the repeater must have the same frequency. However, as shown in FIG. 2, when the two signals have a deviation from each other, a ghost phenomenon occurs in the receiver, which makes it impossible to properly receive the signal.

In order to prevent such a phenomenon, there is a method of using a GPS (Global Positioning System) signal to maintain the frequency synchronization or a method of matching the frequency of the output signal by using the received main signal, but the cost of the repeater is increased There is a problem that the complexity of the system increases, or a delay time occurs in the relay system.

In addition, there is a problem that the output signal of the repeater flows into the input antenna and acts as an interference source, thereby deteriorating the quality. In order to solve such a problem, there has been proposed a method of installing an antenna so as to maintain the degree of isolation between input and output antennas, but there is a limitation in implementation due to limited space.

In order to improve the quality of a relay signal, an identical channel repeater using an ICS (Interference Cancellation System) algorithm including an interference cancellation function using DSP technology is widely used. In case of the ICS type digital on-channel repeater, the interference signal is fed back through the DSP algorithm in the repeater to eliminate the interference signal. In this process, since the reference signal inputted from the output signal and the feedback signal are compared with each other using the correlator to estimate the feedback signal, the pilot component having the DC component is lost. Therefore, there is a high probability that the pilot will not be located at the correct position due to the input signal and the frequency deviation in the system. Such a deviation has a problem that the reception performance is significantly lowered at the receiver.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems of the prior art and to provide a method and apparatus for simultaneously performing transmission and reception frequency matching and efficient transmission of a pilot signal while using an ICS type digital in- And to provide a signal relaying method and a signal relaying device for an ATSC DTV broadcast.

A method of relaying a signal for ATSC DTV broadcasting according to an embodiment of the present invention includes receiving a relaying target signal, performing frequency down conversion on the received signal, converting the down- Extracting a pilot signal from the first separation signal, performing an ICS (Interference Cancellation System) operation on the second separation signal to generate an interference cancellation signal, Merging the pilot signal and the interference cancellation signal, and transmitting the merged signal to another device.

According to another aspect of the present invention, there is provided a signal relay apparatus for an ATSC DTV broadcast, comprising: a signal receiver for receiving a relay target signal for an ATSC DTV broadcast; a frequency down converter for performing frequency down conversion on the received signal; A pilot signal extracting unit for extracting a pilot signal from the first separating signal, a second demultiplexing unit demultiplexing the second demultiplexing signal by an Interference Cancellation System (ICS) ) Operation to generate an interference cancellation signal, an adder for merging the extracted pilot signal and the interference cancellation signal, and a signal output unit for transmitting the merged signal to another apparatus.

According to the embodiment of the present invention, it is possible to transmit the pilot signal closely to the original signal while reducing the complexity and time delay of the system, so that the receiver can receive the DTV broadcast without any problem.

FIG. 1 is a diagram illustrating a configuration of a DTV broadcast signal transmission system transmitter of the ATSC transmission type.
2 is a graph showing the frequency ghost phenomenon of the prior art.
3 is a flowchart illustrating steps of a signal relaying method for an ATSC DTV broadcast according to an embodiment of the present invention.
4 is a block diagram illustrating a configuration of a signal relay apparatus for ATSC DTV broadcasting according to an embodiment of the present invention.
5 is a block diagram illustrating a configuration in which a local oscillator operates according to an embodiment of the present invention.
6 is a graph illustrating a frequency deviation correction at the time of relaying an ATSC DTV broadcast signal according to an embodiment of the present invention.
7 is a block diagram illustrating a configuration of a signal relay apparatus for ATSC DTV broadcasting according to another embodiment of the present invention.
8 is a block diagram showing a configuration of a pilot signal extracting unit according to an embodiment of the present invention.
9 is a diagram illustrating a concept of generating a signal by merging a first separation signal and a second separation signal according to an embodiment of the present invention.

Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings. Furthermore, the suffix "device" and "module" for the components used in the following description are given merely for ease of description in the present specification, It can be designed in hardware or software.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG.

Hereinafter, efficient frequency synchronization and pilot signal processing methods capable of reducing system complexity and maintaining frequency synchronization in an ICS type on-channel repeater will be described.

3 is a flowchart illustrating steps of a signal relaying method for an ATSC DTV broadcast according to an embodiment of the present invention. The following steps can be performed through the respective modules configured in the ATSC DTV signal repeater. The ATSC DTV signal relay device will be described in detail with reference to FIG.

First, the ATSC DTV signal relay device receives a relay target signal (S101).

According to the embodiment, the relaying object signal can receive the relaying object signal using a local oscillator built in the signal relaying device. The operation of the local oscillator will be described in detail below with reference to FIG.

Next, frequency down conversion is performed on the received signal (S102).

According to the embodiment, the ATSC DTV signal repeater can receive a relay signal through an RF (Radio Frequency) antenna, and therefore, for signal relay, an RF signal received at the RF receiver of the signal relay device is converted into an IF signal Down conversion.

Next, the down-converted signal is separated into a first separation signal and a second separation signal (S103).

Next, the pilot signal is extracted from the first separation signal. (S104).

That is, the pilot signal can be saved through the first separation signal. The extracting of the pilot signal may include a first step of generating a DC suppressed signal using the DC blocker of the signal relay device for the first separation signal, A third step of extracting the pilot signal by removing a DC suppressed signal from the signal to which the delay component is added, a third step of adding a delay component to the extracted pilot signal, a fourth step of removing the image component from the extracted pilot signal, And a fifth step of up-converting the signal from which the image component is removed to a frequency before the frequency down-conversion is performed. The DC blocker may be implemented using an IIR filter.

Next, an interference cancellation signal is generated by performing an ICS (Interference Cancellation System) operation on the second separation signal (S105).

Next, the extracted pilot signal and the interference cancellation signal are merged (S106), and the merged signal is transmitted to another apparatus (S107).

The relay device may include a pilot tone signal having the same position and magnitude as the pilot tone signal of the relaying target signal received by the signal relay device by merging the extracted pilot signal and the interference cancellation signal, The merged signal can be generated.

According to an embodiment, in transmitting a signal to the other apparatus, a local oscillator receiving the relay target signal may be used. This will be described in detail below with reference to FIG.

4 is a block diagram illustrating a configuration of a signal relay apparatus for ATSC DTV broadcasting according to an embodiment of the present invention.

The signal relaying apparatus for ATSC DTV broadcasting includes a signal receiving unit 101, a frequency down unit 102, a signal separating unit 103, a pilot signal extracting unit 104, an ICS algorithm unit 105, An adding section 106, and a signal output section 107. [

The signal receiving unit 101 receives a relay target signal for the ATSC DTV broadcast. According to an embodiment, the signal receiver may be configured as an RF antenna. The signal can also be received via a local oscillator.

The frequency downlink 102 may perform frequency down conversion on the received signal. That is, according to the embodiment, the RF signal received by the signal receiving unit 101 can be down-converted to an IF signal. Also, for example, when an IF signal 53.8 MHz is sampled at a sampling frequency of 43.04 MHz, an image signal is generated at 10.76 MHz and this image signal can be used during signal processing.

The signal separation unit 103 can separate the down-converted signal into a first separation signal and a second separation signal.

The pilot signal extracting unit 104 can extract the pilot signal from the first separation signal. The detailed configuration and operation of the pilot signal extracting unit 104 will be described in detail with reference to FIG.

The ICS algorithm unit 105 can generate an interference cancellation signal by performing an ICS operation on the second separation signal.

The adder 106 can combine the extracted pilot signal and the interference cancellation signal. Further, according to the embodiment, the adder 106 generates a merge signal including the pilot signal having the same position and size as the pilot signal of the relaying signal received by the signal repeater 100 through the merge can do.

The signal output unit 107 can perform a relay operation by transmitting the merged signal to another apparatus. The signal output unit 107 can output the merged signal using the local oscillator used by the signal receiving unit 101. [ That is, the same frequency can be maintained through this.

5 is a block diagram illustrating a configuration in which a local oscillator operates according to an embodiment of the present invention.

As shown in the figure, the local oscillator 108 can be configured to be connected to the signal input unit and the signal output unit at the same time. Accordingly, through the above-described configuration, the local oscillator 108 can adjust the frequency synchronization of the received relay target signal and the transmitted merged signal to coincide with each other. That is, it is possible to perform an operation of removing only the interference component as the original signal and retransmitting the received signal without demodulating the received signal. The PLL (Phase Lock Loop) block and the DSP (Digital Signal Processor) block in this figure are merely examples and do not perform operations essential to the present invention.

6 is a graph illustrating a frequency deviation correction at the time of relaying an ATSC DTV broadcast signal according to an embodiment of the present invention.

When frequency synchronization is performed through the local oscillator as shown in FIG. 5, a graph waveform as shown in the figure can be obtained. In other words, as shown in FIG. 6, when a deviation of + Δf occurs at the receiving end, -Δf is shifted again at the transmitting end, so that a repeater output signal having the same frequency as the main signal is transmitted . This makes it possible to satisfy the performance required by the receiver without using an automatic adjustment device for frequency matching of a complicated structure.

7 is a block diagram illustrating a configuration of a signal relay apparatus for ATSC DTV broadcasting according to another embodiment of the present invention.

The signal repeater for ATSC DTV broadcasting according to the embodiment of the present invention can be implemented as shown in FIG. 4, but it can be configured as shown in FIG. 7 including additional configurations. That is, as described above, since the pilot tone signal is lost while performing the ICS algorithm, the pilot tone signal can be output to a signal having the same size as that of the main signal at the correct position, thereby performing the steps and operations of the present invention can do. For this, as shown in FIG. 7, a signal down-converted to an IF signal at the RF receiving end sends a first separation signal to a separate path for extracting the pilot signal before performing the ICS algorithm, And the second separation signal is sent to the main path so that the filtering and the ICS algorithm can be performed.

8 is a block diagram showing a configuration of a pilot signal extracting unit according to an embodiment of the present invention.

According to the embodiment, the pilot signal extracting unit may include a delay unit 201, a DC blocker 202, and a DC pass filter 203. The DC blocker can be implemented using an IIR filter.

Firstly, for the first separation signal, a DC blocker 202 is used to generate a DC suppressed signal, and a delay element 201 is added to the generated DC suppressed signal through a delay unit 201. [ That is, a delay component is added to generate an original signal whose timing is matched.

Also, the DC suppressed signal is removed from the signal to which the delay component is added to extract the pilot signal. That is, if the DC suppressed signal is subtracted, only the DC tone component can be extracted.

The pilot signal thus extracted can maintain its original size and position. Also, an image component is removed from the extracted pilot signal through the DC pass filter 203. Next, the image-removed signal is up-converted to a frequency before the frequency down-conversion is performed. The image component may be removed using a Half Band Filter (HBF).

In addition, the gain of the pilot signal can be obtained to be about 20 dB through the configuration as shown in the figure, and gain of 60 dB or more can be ensured by taking the DC pass filter one step further while paying attention to the occurrence of overflow. As a result, in the next stage, only the pilot signal can be obtained without significantly affecting the SNR (Signal to Noise Ratio) of the entire signal even in the signal of the main path.

9 is a diagram illustrating a concept of generating a signal by merging a first separation signal and a second separation signal according to an embodiment of the present invention.

According to the embodiment of the present invention, the first separation signal and the second separation signal can be separately processed. Thus, the separately processed first separation signal may include a pilot signal as shown in the figure, and the second separation signal may include a signal from which interference is canceled. Therefore, by combining the first separation signal and the second separation signal, the lost pilot signal can be compensated for and recovered by applying the ICS algorithm.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the present invention.

100: ATSC DTV signal relay device
101:
102: frequency downward section
103:
104: Pilot signal extracting unit
105: ICS algorithm section
106:
107: Signal output section

Claims (14)

A method for relaying an ATSC DTV signal in a signal repeater,
Receiving a relay target signal;
Performing frequency down conversion on the received signal;
Separating the down-converted signal into a first separation signal and a second separation signal;
Extracting a pilot signal from the first separation signal;
Generating an interference cancellation signal by performing an ICS (Interference Cancellation System) operation on the second separation signal;
Merging the extracted pilot signal and the interference cancellation signal; And
And transmitting the merged signal to another device,
Wherein merging the extracted pilot signal and the interference cancellation signal comprises generating a merged signal including a pilot tone signal having the same position and magnitude as the pilot tone signal of the relayed signal received by the signal relay device Including,
Wherein the step of extracting the pilot signal comprises: generating a DC suppressed signal for the first separation signal using a DC blocker of the signal relay device; Adding a delay component to the generated DC suppressed signal; Removing the DC suppressed signal from the signal to which the delay component is added to extract the pilot signal; Removing an image component from the extracted pilot signal; And upconverting the signal from which the image component is removed to a frequency before the frequency down conversion is performed. The method according to claim 1,
Wherein the step of receiving the relay-
Receiving the relaying target signal using a local oscillator built in the signal relaying device,
Wherein the step of transmitting the merged signal to another device comprises:
And transmitting the merged signal to another device using a local oscillator that receives the relaying signal. 3. The method of claim 2,
The local oscillator comprises:
And adjusting the frequency synchronization of the received relay signal and the transmitted merged signal so that they match each other. delete The method according to claim 1,
Wherein performing the frequency down conversion comprises:
And downconverting the RF signal received at the RF receiving end of the signal repeater to an IF signal. delete The method according to claim 1,
The DC blocker includes:
Lt; RTI ID = 0.0 > IIR < / RTI > filter. A signal receiving unit for receiving a relay target signal for ATSC DTV broadcasting;
A frequency down converter for performing a frequency down conversion on the received signal;
A signal separator for separating the down-converted signal into a first separation signal and a second separation signal;
A pilot signal extracting unit for extracting a pilot signal from the first separation signal;
An ICS algorithm unit for performing an ICS (Interference Cancellation System) operation on the second separation signal to generate an interference cancellation signal;
An adder for merging the extracted pilot signal and the interference cancellation signal; And
And a signal output unit for transmitting the merged signal to another apparatus,
The adder generates a merging signal including a pilot signal having the same position and size as the pilot signal of the relaying target signal received by the signal repeater,
Wherein the pilot signal extracting unit includes a delay unit, a DC blocker, and a DC pass filter, and generates a DC suppressed signal using the DC blocker for the first separation signal, Extracting the pilot signal by adding a delay component to the generated DC suppressed signal, removing the DC suppressed signal from the signal to which the delay component is added, and extracting the image component from the extracted pilot signal through the DC pass filter, And upconverts the signal from which the image component is removed to a frequency before the frequency down conversion is performed. 9. The method of claim 8,
Wherein the signal receiver comprises:
Receiving the relaying target signal using a local oscillator,
Wherein the signal output section comprises:
And outputs the merged signal to the other apparatus using the local oscillator used by the signal receiving unit. 10. The method of claim 9,
The local oscillator comprises:
And adjusts the frequency synchronization of the received relay signal and the merged signal so that they match each other. delete 9. The method of claim 8,
The frequency down-
And down converts the RF signal received by the signal receiver into an IF signal. delete 9. The method of claim 8,
The DC blocker includes:
IIR filter of the ATSC DTV signal repeater.

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