KR100210127B1 - Adaptive equalizer updating variable weights for a digital vcr - Google Patents

Abstract

The present invention relates to an equalizer for sampling and equalizing a magnetic signal recorded at a high density on a magnetic tape or the like, wherein the magnetic channel unit 51 processes a signal read from a head of a rotating drum head of a digital VSI and a magnetic channel unit ( 51) an analog / digital converter 52 for converting and outputting an analog signal processed in 51) into a digital signal, and a transversal for maintaining the characteristic of the output signal to be 1-D even if the channel characteristic is changed by receiving the digital signal. A filter 53, a three-level detector 54 for detecting three output levels of the transverse filter 53, a delayer 55 for delaying the level detection signal by one bit and outputting the delayed signal; Input the output values of the 3-2 level generator 56, the transversal filter 53, and the 3-level detector 54, corresponding to 1 if the output bit value of the signal is 1 or -1, or 0 if the output bit value is 0. Receive and subtract the signal An adder 57 which feeds back to the transversal filter 53 and a difference signal output from the subtractor 57 and outputs a weight update control signal to the transversal filter 53 under the control of the control unit 59; By providing the variable weight update digital VSI adaptive equalizer including the weight update signal generator 58, there is an effect of improving reproduction equalization characteristics in the equalizer.

Description

Adjustable Weight Update Digital VSI Adaptive Equalizer

The present invention relates to an equalizer circuit for sampling and equalizing a magnetic signal recorded at a high density on a magnetic tape or the like in a digital video cassette recorder (DVCR). Adaptive weight update digital VSI adapts to equalize the number of processing taps inside the equalizer while reducing the number of processing taps inside the equalizer, by updating the weight of one or more symbols rather than updating the weight for each symbol to improve the characteristics. Relates to a type equalizer.

Currently, the DVCR under development is a kind of digital TV which converts and reproduces an analog signal reproduced from a magnetic recording medium such as a magnetic tape to a digital signal, unlike a conventional analog VCR, and is input from various signal sources. By digitizing the video signal and connecting it to various information devices such as a dedicated editor, workstation, or personal computer (PC), it is not possible to perform various editing and advanced functions that were impossible in the analog VCR. Of course, as a video and audio recording and reproducing device that enables high quality recording and playback, it is a broadcasting satellite (BS), high definition TV (HDTV), cable TV (CATV) and set-top box ( Set Top Box) is also used as the backbone for the next generation of multimedia devices. It is one of the expected roles.

The configuration of the entire circuit for recording and reproducing the magnetic signal recorded on the magnetic tape in such a DVCR can be classified into a recording system and a reproduction system as shown in FIG. Referring to each part of the recorder and playback system of the DVCR shown in FIG. 1, first, in the recorder for recording a signal on a digital tape, an analog video signal and an audio signal When received through the terminal, the analog / digital converters (1, 1 ') convert the analog video signal and the audio signal into digital signals, respectively, and then convert the timing of the signal input from the timing conversion circuit (2, 2'). . Here, a time interval is secured to the original signal so that the audio signal, the error correction parity, the synchronization signal SYNC for identifying the recording data, the identification signal ID, and the like can be inserted. The video signal then causes adjacent pixels to be scattered on the tape by shuffling in the shuffle circuit 3. This shuffling has a function of distributing relatively large errors (burst errors) caused by tape scratches, dust adhered to the tape, and the like on the screen. In the following external call parity insertion circuit 4, external call parity for correcting such a burst error is added. Analog audio signals are analog-digital converted as well, and four channels of audio signals are mixed and shuffled. Then, external code parity is inserted and mixed with the video signals in the video / audio signal mixer / splitter 5.

The mixed signal is further divided into two channels, and the synchronization signal SYNC and the identification signal ID are added to the synchronization and identification code insertion circuits 6 and 6 ', followed by the internal call parity insertion circuits 7 and 7'. In order to correct a random error, internal parity parity is inserted. Thereafter, coding (channel coding) suitable for the magnetic recording reproduction system is performed in the coding circuits 8 and 8 ', and parallel signals are converted into serial signals in the parallel-to-serial conversion circuits 9 and 9' and recorded. Recorded amplifiers of amplifying circuits 10 and 10 'are amplified to a predetermined size for recording and recorded as serial digital signals on tape through rotating transformers 11 and 11' and recording heads 12 and 12 '. Will be.

On the other hand, in the reproducing system, the magnetic signals recorded on the tape are converted into voltage by the reproducing heads 13 and 13 'and the rotating transformers 14 and 14', thereby regenerating the reproducing amplifiers of the reproducing amplifier circuits 15 and 15 '. After amplification at, the amplitude and phase distortion of the magnetic recorder are corrected in the reproduction equalizing circuits 16 and 16 ′.

An equalized signal is generated by a clock synchronized with a reproduction signal in a phase-locked loop (PLL) circuit of the phase loop locking circuits 18 and 18 ', and the clock is used as a trigger. The symbol 0 or 1 is determined corresponding to the level of the reproduction signal equalized by the code detection circuits 18 and 18 '. The determined signal is converted into a parallel signal by the serial-parallel conversion circuits 19 and 19 ', decoded by the decoding circuits 20 and 20', and then by the internal call error correction circuits 21 and 21 '. Random error is corrected.

Subsequently, jitter by the tape or the head is removed in the time axis correction circuits 22 and 22 '. Thereafter, in the video / audio signal mixer / splitter 23, the signals of the two channels are mixed and separated into a video signal and an audio signal again.

Thereafter, after the burst error is corrected in the external call error correcting circuit 24 and the deshuffling is performed in the deshuffle circuit 25, the error is corrected in the error correcting circuit 26. In this case, after the pixel which cannot be corrected is replaced with an interpolation from a neighboring pixel or a pixel before one field / 1 frame, the synchronization signal SYNC, the black burst signal, etc. are generated in the timing conversion circuit 27. Is added. Thereafter, the digital / analog converter 29 converts the digital signal into an analog signal and finally outputs an analog video signal.

Likewise, in the audio signal, a burst error is corrected in the external call error correction circuit 24 ', deshuffled in the deshuffle circuit 25', and then a sample whose error correction cannot be corrected in the error correction circuit 26 'is followed. The sample is interpolated into four channels, divided into four channels, and then converted into an analog audio signal and output.

The equalization circuit used in the recording and reproducing system of the digital video is a circuit for correcting and outputting the amplified video and audio signals by the distortion of the amplitude and phase of the magnetic recording system. Using the clock as a trigger signal, the code detection circuit determines the symbol 0 or 1 for the input signal corresponding to the level of the signal equalized by the equalizer, respectively. Since the signal determined in this way is processed and recorded and reproduced by a subsequent circuit, processing in the equalizer is very important. In the DVCR, an adaptive equalizer is used to adjust the level of the input signal to fit the digital processing of the signal well. The correct decision is made to produce the corresponding symbol (0, 1).

In general, an analog equalizer is used to implement a reproduction equalizer in a reproduction system as described above in a DVCR. As shown in FIG. 2, the head is read from the magnetic channel section 41 and amplified. When the received signal is inputted from the trnsversal filter 42 and the reproduction characteristic of the input signal is maintained at 1-D, the delayed signal is delayed to 1 + D with respect to the signal and outputted as 3-D. When the level detector 44 generates signals of 0 and 1 corresponding to the level of the signal, the 3-2 level generator 45 generates two levels of signals output from the 3-level detector 44. To level. In other words, when the level of the signal to be output is 1 and -1 when the level of the output signal is 1, and when it is 0, the corresponding level is output as 2 levels.

However, in such an analog-type interleaved non-return to zero inverse (I-NRZI) equalizer, the weight is updated at every symbol of the input signal, thereby making it possible to equalize the variable input signal. There was a problem that the corrected equalization could not be achieved.

The present invention relates to an equalizer for equalizing a recording or reproducing signal in the configuration of an entire circuit for recording and reproducing a magnetic signal recorded on a magnetic tape in a DVCR. Variable weight update to allow equalization of the taps used inside the equalizer as much as possible, by updating the weight of one or more symbols instead of updating the weight for each symbol to improve the characteristics of the adaptive equalizer. Its purpose is to provide a digital VSI adaptive equalizer.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block circuit diagram showing an entire circuit of a recording system and a reproduction system in a digital VSI.

2 is an overall block circuit diagram of an analog equalizer used in a conventional digital BC.

3 is an overall block circuit diagram of a variable weight update digital BS adaptive equalizer in accordance with the present invention.

* Explanation of symbols for main parts of the drawings

1, 1 ': analog / digital converter 2, 2', 27, 27 ': timing conversion circuit

3,3 ': shuffle circuit 4, 4': external parity insertion circuit

5, 23: Video / audio signal mixing / splitter 6, 6 ': Synchronization signal and identification code insertion circuit

7, 7 ': internal call parity insertion circuit 8, 8': coding circuit

9, 9 ': parallel-to-serial conversion circuit 10, 10': recording amplifier circuit

11, 11 ', 14, 14': Rotary transformer 12, 12 ': Record head

13, 13 ': Reproduction head 15, 15': Regeneration amplifier circuit

16, 16 ': Regenerative light circuit 17, 17': Phase loop lock (PLL) circuit

18, 18 ': code detection circuit 19, 19': parallel-serial conversion circuit

20, 20 ': Decoding circuit 21, 21': Internal call error correction circuit

22, 22 ': time base correction circuit 24, 24': external call error correction circuit

25, 25: deshuffle circuit 26, 26 ': error correction circuit

28: synchronization signal and burst signal insertion circuit 29, 29 ': digital / analog conversion circuit

41, 51: magnetic channel part 42, 53: transversal filter

43, 55: delay 44, 54: 3-level detector

45, 56: 3-2 level generator 52: analog / digital converter

57: subtractor 58: weight update signal generator

581: weight update unit 582: signal control unit

59: control unit 591: microcomputer

592 memory

In order to achieve the above object, the present invention, the magnetic channel unit for sending a signal read out from the head provided on the rotary drum head of the DVCR to the signal processing system, and is connected to the magnetic channel unit and output from the magnetic channel unit An analog / digital converter for converting an analog signal into a digital signal and outputting the digital signal; and a transversal for maintaining the characteristic of the output signal to be 1-D even if the channel characteristic is changed by receiving the digital signal output from the analog / digital converter. A three-level detector connected to the filter, the three filters connected to the transversal filter, and detecting three levels of a signal processed by the transversal filter; and one bit at 1 + D for the signal output from the three-level detector. Delayed output and the bit value outputted with respect to the signal outputted from the delayed The 3-2 level generator outputs the corresponding surface 1 and outputs 0 if 0, and the corresponding output of 1 if -1. The output value of the transverse filter and the output value of the three-level detector are respectively inputted. A weight update signal generator and a weight update signal generator for receiving a difference signal outputted from the subtractor and a weight update signal generator for outputting a weight update control signal to the transverse filter And a control unit for sending an update time adjustment signal of the weight.

According to the present invention configured as described above, when a plurality of heads are provided on a rotating drum of a DVCR, a signal is read and sent to a magnetic channel unit, and the magnetic channel unit is then sent to an analog / digital converter, where the analog signal is converted into a digital signal. When input to the transversal filter, the transversal filter equalizes the waveform of the input digital signal and outputs it. This signal is output by determining the output level of {1, 0, -1} by comparing the output level of this signal in a three-level detector.

Then, the delayer outputs the signal with a delay of 1 + D, and the 3-2 level generator outputs the output signal of these three levels as two level signals. That is, if the output bit value is 1, 1 is outputted correspondingly, 0 is outputted 0, and -1, 1 is outputted correspondingly.

The subtractor receives respective signals output from the transversal filter and the 3-level detector, subtracts the two values, feeds back the difference signal to the transversal filter, and the weight update signal generator By receiving a signal from the subtractor and sending a signal for adjusting the update of the weight to the transversal filter, equalization is performed to the same signal as the original signal as a whole.

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

The present invention for achieving the above object is, as shown in Figure 3, the magnetic channel unit 51 for transmitting a signal read out from the head provided on the rotary drum of the DVCR to the signal processing system and the magnetic channel unit ( And an analog / digital converter 52 for converting an analog signal output from the magnetic channel unit 51 into a digital signal and outputting the digital signal, and the digital signal output from the analog / digital converter 52. Transversal filter 53 for maintaining the characteristic of the output signal is 1-D even if the channel characteristics change, and the signal that is processed and output from the transversal filter 53 connected to the transversal filter 53 A three-level detector 54 for detecting three levels, a delayer 55 for delaying one bit by 1 + D with respect to the signal output from the three-level detector 54, and the delayer ( On 55) And a 3-2 level generator 56 for correspondingly outputting 1 if the output bit value is 1 and outputting 0 if 0 is output, and 1 for -1 if the bit value is 1, and the transverse filter 53. A subtractor 57 for receiving the output value of the output signal and the output value of the three-level detector 54 and subtracting the two signal values to feed back to the transverse filter 53, and the difference signal output from the subtractor 57. A control unit 59 for receiving a weight update signal generator 58 for outputting a weight update control signal to the transverse filter 53 and a weight update time control signal for the weight update signal generator 58. It was configured to include.

The weight update signal generator 58 is a difference signal and an analog / digital converter obtained by subtracting two signals output from the transverse filter 53 and the three-level detector 54 from the subtractor 57. A signal control unit 582 and a signal sent from the signal control unit 582 to receive the signals sampled at 52 together and add the respective signals according to the control signal sent from the control unit 59; Accordingly, a weight update unit 581 which transmits a weight update signal to the transversal filter 53 is included.

In addition, the control unit 59 is connected to the signal control unit 582 of the weight update signal generation unit 58, when the signal is input from the subtractor 57 to the signal control unit 582, the signal control unit ( The microcomputer 591 provides a control signal for adjusting the weight update to 582, and a time adjustment value, which is an initial value for adjusting the weight update, is stored in the microcomputer 591 at the request of the microcomputer 591. The memory 592 provides a memory 592 weight update adjustment value to the microcomputer 591.

According to the present invention configured as described above, when a plurality of heads are provided on a rotating drum head of a DVCR, the signals are read and sent to the magnetic channel unit 51, and the magnetic channel unit 51 transmits a weak playback signal to a preamplifier (Fig. After amplification to a predetermined size through a non-display), it is sent to the analog / digital converter 52, and the analog signal is converted into a digital signal and input to the transverse filter 53.

At this time, the transmission coefficient h (t) of the signal output from the magnetic channel unit 51 becomes h (t) = 1/1 + (2t / Tw ₅₀ ) ² depending on the transmission characteristics on the transmission path. , Tw ₅₀ is the waveform width at the position corresponding to half the maximum value of the independent waveform.)

In addition, the analog-to-digital converter 52 samples h (t), which is a signal output from the magnetic channel unit 51, in a symbol unit and sends the signal to the transverse filter 53.

The transversal filter 53 is an adaptive equalizer capable of maintaining a constant characteristic of an output signal even if a channel characteristic is changed with respect to an input digital signal by applying a wave equalizer. The output (y) is modified so that the characteristic of the signal (x), which is passed through the magnetic channel unit 51 and sampled by the analog / digital converter 52, becomes 1-D. The signal is then output by comparing the output level in the three-level detector 54 to determine the output level of {1, 0, -1}.

The signal is then sent to the delay unit 55, and the value determined by the three-level detector 54 and the previously determined value are added and delayed by one bit as a whole. Then, the signal is input from the 3-2 level generator 56. If the bit value outputted for the signal is 1, the corresponding output is 1; if the bit value is 0, 0 is output;

On the other hand, the subtractor 57 receives the respective signals output from the transversal filter 53 and the three-level detector 54, subtracts the two values, and subtracts the signal difference e (k) from the transformer. The weight update signal generator 58 subtracts two signals output from the transverse filter 53 and the three-level detector 54 from the subtractor 57 while feeding back to the versatile filter 53. When the difference signal e (k) is sent to the signal adjusting unit 581 of the weight update signal generating unit 58, the signal that is sampled by the signal adjusting unit 582 and the analog / digital converter 52 is received. Receives (x (k)) together and outputs each signal (x (k), e (k)) to the weight update unit 581, and in the weight update unit 581, x (k) and e (k) A signal is received and processed to send a weight update signal w (2k + 1) = w (2k) + μe (2k) .x (2k) to the transversal filter 53. Switch is adapted to adjust the number of taps in the equalizer stage of beoseol filter 53.

In this case, the control unit 59 stores the time adjustment value for initializing the weight update, and the microcomputer 591 subtracts the transversal filter 53 and the three-level detector from the subtractor 57. When the difference signal e (k) obtained by subtracting two signals output from 54 is sent to the signal controller 582 of the weight update signal generator 58, the difference signal e (k) is detected and immediately updated in the memory 592. The adjustment value is taken and provided to the signal control unit 582 of the weight update unit 581.

Therefore, the signal adjusting unit 582 of the weight update signal generating unit 58 receives the weight update time adjustment value provided from the microcomputer 591 of the control unit 59 together and performs a predetermined process to perform the weight update unit. The control signal w (2k + 1) = w (2k) + μe (2k) x (2k)) is sent to 581, finally being delayed by the time adjusted by the weight update unit 581 ( That is, since the weight is updated), the weight is fed back to the transverse filter 53 so that the adjusted signal is updated, so that the weight can be better adapted to real-time processing according to the hardware characteristics of the entire equalizer.

According to the present invention, the subtractor 57 receives the respective signals output from the transversal filter 53 and the three-level detector 54, subtracts the two values, and subtracts the signal difference from the transformer. The weight update signal generator 58 adds two signals output from the transversal filter 53 and the three-level detector 54 in the weight update signal generator 58. The difference signal e (k) is sent to the signal adjusting unit 581 of the weight update signal generating unit 58, and this signal from the signal adjusting unit 582 and the signal sampled by the analog / digital converter 52 ( x (k)) is input together and the respective signals are summed and output to the weight update unit 581, whereby the weight update unit 581 weight update signal w (2k + 1) = w (2k + 1) + (e) k (x) x (2k)) is fed back to the transversal filter 53 to tap in the equalization step. By adjusting the number, the equalization of the reproduction signal can be adapted more efficiently, thereby improving the characteristics of the reproduction equalization in the entire equalizer circuit.

Claims (3)

In the circuit for equalizing the reproduction signal in the DVCR with a digital adaptive equalizer, a magnetic channel section 51 for sending a signal read out from a head provided in a plurality of heads on a rotating drum of the DVCR to a signal processing system, and the magnetic channel. An analog / digital converter 52 connected to the unit 51 and converting an analog signal output from the magnetic channel unit 51 into a digital signal and outputting the digital signal; and a digital signal output from the analog / digital converter 52. Transversal filter 53 for maintaining the characteristics of the output signal is 1-D even if the channel characteristics are changed to the input, and is connected to the transversal filter 53 to process and output from the transversal filter 53 A three-level detector 54 for detecting three levels of the signal, and a delayer 55 for outputting the signal output from the three-level detector 54 with a delay of 1 bit at 1 + D. A 3-2 level generator 56 for correspondingly outputting 1 when the bit value outputted from the delayer 55 is 1, outputting 0 when 0, and correspondingly outputting 1 when -1; A subtractor 57 which receives the output value of the transverse filter 53 and the output value of the three-level detector 54 and subtracts the two signal values and feeds them back to the transverse filter 53; A weight update signal generator 58 for receiving a difference signal output from the signal 57 and outputting a weight update control signal to the transverse filter 53, and adjusting the update time of the weight to the weight update signal generator 58 And a control unit (59) for sending a signal. The difference update signal (e) of claim 1, wherein the weight update signal generator (58) subtracts two signals output from the transverse filter (53) and the three-level detector (54) by the subtractor (57). (k)) and a signal control unit 582 that receives the signals sampled from the analog / digital converter 52 together and adds each signal according to a control signal sent from the control unit 59, and the signal control unit. And a weight update unit 581 for transmitting a weight update signal to the transversal filter according to the signal sent from the unit 582. The signal controller of claim 1, wherein the controller 59 is connected to the signal controller 582 of the weight update signal generator 58 so that a signal is input from the adder 57 to the signal controller 582. The microcomputer 591 which provides a control signal to the signal control unit 582 and a time adjustment value which is an initial value for adjusting the weight update are stored in the microcomputer 591, and at the request of the microcomputer 591. And a memory (592) for providing a memory (592) weight update adjustment value to the microcomputer (591).