KR20020084719A - Apparatus of the channel equalizer for high definition television receiver by vestigial sideband and method using the same - Google Patents

Abstract

PURPOSE: A device and a method for channel equalizing of a vestigial sideband type high definition television are provided to remove the dynamic ghost while minimizing the reduction of SNR(Signal to Noise Ratio) by converting training/blind mode to training mode when dynamic ghost is not exist. CONSTITUTION: A channel equalizer of a vestigial sideband type high definition television includes a filter part(400) for filtering input signals of a channel equalizer for a predetermined time to output a channel equalized output signal, an error generating part(401) for outputting an error signal by comparing the equalized output signal with a reference signal generated when a tap position data is output, a mode decision part(402) for determining whether to convert a training mode between training/blind mode by the error signal and a segment error signal, and a coefficient update part(403) for updating all coefficients in a symbol clock with the output signal of the mode decision part and the input signal of the equalizer for the predetermined time.

Description

Apparatus of the channel equalizer for high definition television receiver by vestigial sideband and method using the same}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a channel equalizer of a high definition television receiver (hereinafter referred to as an HDTV) receiver and a method thereof, and more particularly to a training and blind mode. The present invention relates to an equalizer of a residual sideband type high definition television receiver capable of automatic conversion between a training mode and a training mode, and a method thereof.

In general, in a high speed digital communication system, the biggest factor that degrades the performance of the system is inter-symbol interference (hereinafter referred to as ISI). ISI is caused by the linear distortion of the channel, that is, multipath channel, non-ideal frequency response, group delay, and so on, and it adapts inside the receiver to recover the data sent from the transmitter without error. Install an adaptive equalizer to eliminate or reduce this ISI as much as possible. Thus, the adaptive equalizer is a kind of inverse filter.

Equalizer tap coefficients in a general adaptive equalizer to offset the distortion characteristics of the channel by transmitting a predetermined training sequence between the transmitting side and the receiving side during the initial training mode. While operating in the blind mode, the equalizer tap coefficient is adjusted to compensate for channel distortion by estimating the symbol sent from the transmitter using only the received signal. The training mode and the blind mode are operated alternately to estimate the channel inversely.

1 is a block diagram of a typical GA scheme residual sideband high definition television receiver.

Referring to FIG. 1, an antenna 100 that receives a signal, a tuner 101 that tunes only a desired channel from a signal received by the antenna 100, and a middle of a channel tuned by the tuner 101. An intermediate frequency filter and a synchronization detector 102 for filtering only an intermediate frequency (hereinafter referred to as IF) and detecting segment synchronization and field synchronization, and the intermediate frequency filter and a synchronization detector 102. NTSC interference that excludes channel interference from the channel information output from the intermediate frequency filter and the synchronization detector 102 and the timing information providing unit 103 that provides timing for processing an input signal according to the synchronization signal detected by Equalizer 105 for compensating for linear channel distortion of the signal output from NTSC interference cancellation filter 104, and phase estimation from the output of equalizer 105 A phase tracker 106, a trellis decoder 107 that decodes input data by performing a back trace after receiving a predetermined amount of data through the phase tracker 106, and the trellis decoder. A data deinterleaver 108 for deinterleaving the data output from 107 and a Reed Solomon decoder for reed solomon decoding the data through the data deinterleaver 108. Reed Solomon decoder (109) and a data derandomizer (110) for de-randomizing data through the Reed Solomon decoder (109).

2 is a block diagram showing a data frame of a residual side band specification by GA.

Referring to FIG. 2, one segment is composed of 832 symbols, the first 4 symbols of every segment are segment sync signals, and 828 symbols are data. One field is composed of 312 segments of data and one segment of field synchronization signal, and one frame is composed of two fields. In addition, 4 symbols constitute 1 byte in 8VSB, and 2 symbols constitute 1 byte in 16VSB.

The operation of the GA type residual sideband high definition television receiver having the above-described configuration will be described in detail.

The signal received from the antenna 100 is tuned to the desired channel by the tuner 101, and the intermediate frequency filter and the synchronization detector 102 obtain the intermediate frequency of the tuned channel, and then detect the segment synchronization signal and the field synchronization signal. . The timing information providing unit 103 provides timing information for processing input data according to the segment synchronization signal and the field synchronization signal obtained above, and the NTSC interference cancellation filter 104 detects interference of the input channel data. Will be filtered. In addition, the equalizer 105 compensates for channel distortion of the channel data through the NTSC interference cancellation filter 104, and the phase tracker 106 attempts phase tracking for phase error compensation and frequency error compensation. The data compensated for the phase and frequency errors are then deinterleaved by the deinterleaver 108 after being decoded by the lattice decoder 107 and decoded by the reed solomon decoder 109 and then decoded by the derandom decoder 110. Quantization is performed to restore the original data.

The HDTV with the residual sideband receiver having the above-mentioned functions provides high quality video and CD (Compact Disk) level sound quality. To realize this, high compression must be used. You need a complete recovery. One of the techniques for completely recovering such transmission data is a channel equalizer, and plays a particularly important role when compensating for distortion caused by a channel during digital transmission and reception.

As described above, the channel equalizer is a kind of inverse filter installed inside the receiver for the purpose of compensating for the linear channel distortion such as tilt and ghost. Distortion may be caused by incomplete elements in the transmission channel or in the receiving end. This distortion is caused by picture distortion and ghosting deterioration in analog televisions we use today, but in digital transmission systems, it is completely different from image or unrecoverable due to bit detection error.

3 is a block diagram showing a simplified structure of an equalizer according to the prior art.

Referring to FIG. 3, the filter unit 300 outputs a channel equalization output signal Y (n) by filtering the input signal x (n) of the equalizer at time 'n', and the equalization output signal y (n). And an error generator (301) outputting an error signal 'e' by comparing the reference signal r (n) generated according to the time point at which the tap position data is output, and the error signal 'e' and the time ' A coefficient update block 302 is formed to update all coefficients of the tap within a symbol clock by the input signal x (n) of the equalizer at n 'to form a feedback loop to the filter unit 300. .

It looks at the operation of the equalizer having the above configuration.

First, when a VSB receiver receives a symbol from a transmitter, a controller (not shown) obtains information on a data frame from a corresponding signal (field_sync, segment_sync, etc.) and controls channel equalization operation through the signal.

That is, while the data frame received signal is activated and the front end 700 symbol of the field sync signal of 828 symbols is received, the channel equalization operation is controlled in the training mode. While receiving, control to perform channel equalization in the blind mode. When switching from the training mode to the blind mode, the coefficient update is suppressed up to 256 symbols of the next segment, and the coefficient update resumes after a certain time even when switching from the blind mode to the training mode.

The filter unit 300 outputs the channel equalization output signal Y (n) by filtering the input signal x (n) of the equalizer at time 'n', and the error generator 301 outputs the equalization output signal y (n). ) And the reference signal r (n) generated according to the time point at which the tap position data is output, and outputs an error signal 'e'. The coefficient updater 302 outputs the error signal 'e' and the time 'n'. The coefficients of the taps are all updated within one symbol clock by the input signal x (n) of the equalizer and fed back to the filter unit 300.

On the other hand, the channel environment does not remain fixed but has a dynamic property that changes from time to time. In particular, if the ghost environment changes rapidly, if channel equalization is performed using only training trains that are periodically transmitted, the convergence state will be lost.

As described above, the conventional equalizer eliminates the possibility of divergence by simultaneously applying the training mode and the blind mode, but when the blind mode is applied, the reliability of the estimation error is deteriorated, resulting in a problem that the convergent SNR is deteriorated. .

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art, and an object of the present invention is to provide a channel equalization apparatus and a method for equalizing a residual sideband type high definition television receiver capable of minimizing attenuation of SNR while performing dynamic ghost removal. There is this.

1 is a block diagram showing the configuration of a typical GA VGA HDTV receiver;

2 is a block diagram illustrating a data frame structure of a residual sideband method according to the GA standard;

3 is a block diagram showing the structure of an equalizer according to the prior art;

4 is a block diagram showing an equalizer structure according to the present invention;

5 is a block diagram showing an operation mode of each SNR of the equalizer according to FIG. 4;

6 is a block diagram showing the structure of a mode determination unit according to FIG. 4;

7 is a block diagram showing the structure of the state machine part according to FIG. 6;

8 is a flow chart showing the algorithm of the equalizer according to FIG.

* Description of the main parts of the drawing

400 filter unit,

401: error generating unit,

402: mode determination unit,

403: Tap coefficient update unit.

In order to achieve the above object, the present invention provides an equalizer of a residual side waveband type high definition television receiver, comprising: a filter unit for filtering an input signal of the equalizer at a predetermined time and outputting a channel equalization output signal; An error generator which compares the equalization output signal with a reference signal generated according to a time point at which data of a tap position is output and outputs an error signal; A mode determination unit determining whether to switch between a training mode and a training and blind mode based on the error signal and the segment error signal; And a coefficient updater that updates the coefficients of the taps within one symbol clock using the output signal of the mode determiner and the input signal of the equalizer at the predetermined time to form a feedback loop to the filter.

In addition, to achieve the above object, the present invention provides a method for equalizing a residual sideband type high definition television receiver, comprising: a first step of proceeding to a training and blind mode; A second step of comparing a segment error with a magnitude of an error number in the training and blind modes; A third step of switching to a training mode when the segment error is greater than or equal to the number of errors in the blind mode; A fourth step of returning to the first step if the segment error is smaller than the number of errors in the blind mode in the second step; A fifth step of comparing the magnitude of the number of errors in the training mode with the segment error again after the third step; In the fifth step, if the segment error is greater than the number of errors in the training mode, returning to the first step and repeating a series of processes; And a seventh step of returning to the third step if the segment error is smaller than the number of errors in the training mode in the fifth step.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art may easily implement the technical idea of the present invention. .

4 is a block diagram illustrating an equalizer structure according to the present invention, and FIG. 5 is a block diagram illustrating an operation mode of each SNR of the equalizer according to FIG. 4.

Referring to FIG. 4, a filter unit 400 for filtering the input signal x (n) of the equalizer at time 'n' and outputting a channel equalization output signal y (n) and the equalization output signal y (n) An error generator 401 for comparing the generated reference signal r (n) with the time point at which the tap position data is output, and outputting an error signal e_pre (n), and the error signal e_pre (n) and the segment error signal. a mode decision unit 402 for determining whether to switch a training mode and a training and blind mode by seg_error, and an output signal e (n) of the mode decision unit 402 and an equalizer at the time 'n' And a coefficient updater 403 for updating all of the coefficients of the tap within one symbol clock by the input signal x (n) to form a feedback loop to the filter 400.

The operation of the equalizer having the above configuration will be described in detail.

First, the equation applied to the filter unit 400 is as follows.

Where x (n) is the equalizer input signal at time n, r (n) is the equalizer reference signal at time n, and C _j (n) is the j th tap of the forward filter at time n W _j (n) represents the j th tap coefficient of the feedback filter at time n.

In addition, the equation applied to the coefficient updater 403 is as follows.

Here, 2 ^/ denotes a step size, and e _k denotes an error at 'k' time. In addition, the range of m is defined as follows.

2 ^m-1 + 2 ^m-2 ≤ | e _k | <2 ^m-1 + 2 ^m

First, when a VSB receiver receives a symbol from a transmitter, a controller (not shown) obtains information on a data frame from a corresponding signal (field_sync, segment_sync, etc.), and controls channel equalization operation through the filter unit (not shown). 400 outputs the channel equalization output signal y (n) by filtering the input signal x (n) of the equalizer at time 'n', and the error generator 401 taps the equalization output signal y (n) and the tap. The error signal e_pre is output by comparing the reference signal r (n) generated in accordance with the time point at which the data of the position is output, and the mode determining unit 402 performs a training mode by the error signal e_pre (n) and the segment error signal seg_error. And whether to change the training and blind mode, and the coefficient updater 403 determines the output signal e (n) of the mode determiner 402 and the input signal x (n) of the equalizer at the time 'n'. Update all the coefficients of the tap within one symbol clock The feedback to the filter unit 400.

When an error occurs in any segment of one segment corresponding to 828 symbols, segment_error occurs. In the present invention, the segment_error is received as a feedback and used as an index of mode switching.

Therefore, it is important to apply 'e' indicating an error value.

The equalizer operates in a training mode and a blind mode in a default mode. The equalizer operates in a training mode in a field_sync section, and operates in a blind mode in the remaining sections.

That is, the error value 'e' is applied to equalization in all sections. However, in the case of the simple training mode, the error value 'e' is simply applied to the equalization only in the field synchronization section.

The above operation algorithm will be described with reference to the flowchart shown in FIG.

First, the process proceeds to training and blind mode (801). Subsequently, the segment error (eg segment_error) is compared with the magnitude of the error number TB-err in the training and blind mode (802). Here, when the segment error (segment_error) is greater than or equal to the error number TB-err in the blind mode, the training mode is switched (803). However, when the segment error (segment_error) is smaller than the number of errors TB-err in the blind mode, it returns to the initial training and blind mode 801. Subsequently, after the training mode, the segment error (segment_error) is compared with the magnitude of the error number (T-err) in the training mode (804). Here, if the segment error (segment_error) is greater than the number of errors (T-err) in the training mode, a series of processes proceeding to the first training and blind mode (801) is repeated. However, if the segment error (segment_error) is smaller than the number of errors (T-err) in the training mode, the process returns to the training mode 803 again, and the segment error (segment_error) and the error in the training mode again. The process of comparing the size of the number (T-err) (804) is repeated.

Therefore, the equalizer receives the feedback from the segment error value from the Forward Error Correction (FEC) stage, counts it, and switches to another mode when the threshold value is exceeded.

At power-on, it will run in training and blind mode with the specified value, and in poor SNR situations, it will dial into training mode. Thus, in the absence of dynamic ghosts as shown in FIG.

FIG. 6 is a block diagram illustrating a structure of a mode determination unit according to FIG. 4.

Referring to FIG. 6, a counter for outputting a field frame count (field_count) and a segment error frame count (segment_err_count) by using the field sync signal (field_sync), the segment error signal (segment_error), and the segment sync signal (segment_sync) as different inputs, respectively. A unit 601, the field frame number (field_count) and the segment error frame number (segment_err_count) are input; The field frame count (field_count) or the segment error frame count (segment_err_count) is controlled by a power-on reset (POR) signal to train the specified training and blind mode (t & b_init) and the specified training mode (t_init). A state t and a state machine 602 outputting each mode conversion state in comparison with the training and blind modes b & t and the output of the state machine 602 by the output of the state machine 602. A first multiplexer 603 for multiplexing the mode b & t and the training mode t, and the output of the first mux is inputted so that the field synchronizing signal field_sync is "1" or the state of the training and blind modes. The mode determination unit output signal (e) by multiplexing other inputs of "0" and the error signal e_pre (n) by the output of the training and blind mode unit 604 and the training and blind mode unit 604 which transmits (n)) as output And a second multiplexer.

The operation of the mode determination unit is as described above with reference to FIG. 8.

7 is a block diagram showing the structure of the state machine unit according to FIG.

Referring to FIG. 7, the designated training and blind unit 701 operating by the power-on reset signal POR and the training and blind unit 702 when the field frame count and the specified training and blind frame number are the same. ), The specified training mode 703 when the segment error frame number (segment_err_count) and the training and blind error frame number (t & b_error) are the same, and the field frame number (field_count) and the specified training frame number (t_init_count) are the same. If the training mode 704 and the segment error frame number segment_err_count and the training error frame number t_error are equal to each other, the training mode 704 and the training error frame number t_error are repeated.

According to the present invention made as described above, in the case where there is no dynamic ghost in the simultaneous application of the training and the blind mode, the mode can be switched to the training mode, thereby eliminating the dynamic ghost while minimizing the attenuation of the SNR. Learned through.

Although the technical idea of the present invention has been described in detail according to the above preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

The present invention made as described above has the effect of preventing the deterioration of the SNR simultaneously with the removal of the dynamic ghost in the equalization of the residual sideband band type high definition television receiver.

Claims (4)

In the equalizer of the residual sideband band type high definition television receiver, A filter unit for outputting a channel equalization output signal by filtering an input signal of the equalizer at a predetermined time; An error generator which compares the equalization output signal with a reference signal generated according to a time point at which data of a tap position is output and outputs an error signal; A mode determination unit determining whether to switch between a training mode and a training and blind mode based on the error signal and the segment error signal; And A coefficient updater for forming a feedback loop to the filter by updating both coefficients of the tap within one symbol clock using the output signal of the mode decision unit and the input signal of the equalizer at the predetermined time. Equalizer of the residual sideband-type high-definition television receiver comprising a. The method of claim 1, The mode determination unit, A counter unit for outputting the number of field frames and the number of segment error frames by using the field synchronizing signal, the segment error signal, and the segment synchronizing signal as different inputs; The field frame number and the segment error frame number are input. A state controlled by a power-on reset signal to output each mode conversion state by comparing the number of field frames or the number of segment error frames with a specified training and blind mode, a specified training mode and a training mode, and a training and blind mode. Machine part; A first multiplexer which multiplexes the training and blind modes and the training mode by an output of the state machine unit; A training and blind mode unit in which a field synchronizing signal transmits "1" or a state of training and blind mode by using an output of the first multiplexer as an input; And A second multiplexer configured to multiplex " 0 " and another input of an error signal by the output of the training and blind mode unit to output a mode decision unit output signal; Equalizer of the residual sideband-type high-definition television receiver comprising a. The method of claim 2, The state machine unit, A designated training and blind portion operated by the power-on reset signal; A training and blind unit when the field frame number and the designated training and blind frame number are the same; A designated training mode unit when the segment error frame number and the training and blind error frame number are the same; A training mode unit when the field frame number and the designated training frame number are the same; And When the segment error frame number and the training error frame number are the same, a loop form is repeated to the designated training and blind unit again. Equalizer of the residual sideband-type high-definition television receiver comprising a. In the equalization method of the residual sideband band type high definition television receiver, A first step of proceeding to training and blind mode; A second step of comparing a segment error with a magnitude of an error number in the training and blind modes; A third step of switching to a training mode when the segment error is greater than or equal to the number of errors in the blind mode; A fourth step of returning to the first step if the segment error is smaller than the number of errors in the blind mode in the second step; A fifth step of comparing the magnitude of the number of errors in the training mode with the segment error again after the third step; In the fifth step, if the segment error is greater than the number of errors in the training mode, returning to the first step and repeating a series of processes; And A seventh step of returning to the third step if the segment error is smaller than the number of errors in the training mode in the fifth step; Equalization method of the residual sideband band type high-definition television receiver comprising a.