KR100269435B1 - A high definition - digital vcr - Google Patents

Abstract

The present invention relates to a two-head high-definition digital BC.

This invention comprises a first head 202; Second head 204; A first analog-to-digital converter 206 for converting an analog signal input through the first head into digital; A second analog-to-digital converter 208 for converting an analog signal input through the second head into digital; A first adaptive equalizer 210 which receives an error value, updates the equalization coefficient, calculates an output of the first analog-digital converter with the equalization coefficient, and outputs a filtered value; A second adaptive equalizer 212 that receives the error value, updates the equalization coefficient, calculates an output of the second analog-digital converter with the equalization coefficient, and outputs a filtered value; A first determination unit 214 for determining an output of the first adaptive equalizer and outputting three levels of values; A second determination unit 216 for determining an output of the second adaptive equalizer and outputting three levels of values; A first error value calculator 218 which receives an output of the first determiner and an output of the first adaptive equalizer, respectively, and calculates an error value for calculating and providing an output to the first adaptive equalizer; A second error value calculator 220 which receives an output of the second determiner and an output of the second adaptive equalizer, respectively, and calculates an error value for providing to the second adaptive equalizer; A first Viterbi detector 222; Second Viterbi detector 224; And a coupling unit 226 which combines the outputs of the first Viterbi detector and the second Viterbi detector to provide a double speed.

Description

A High Definition-Digital VCR

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a high definition (HD) digital BD (DVCR), and more particularly to a two head type high definition digital BC.

In general, digital VSI has been made possible by the continuous development of high density magnetic recording technology, narrow track recording and reproducing technology, high density recording medium, high performance head, signal band compression technology, and miniaturization technology. DVCR) is for recording / reproducing SD (Standard Definition) baseband signal which is the current TV signal (SD-DVCR) and for recording / reproducing high definition (HD) baseband signal (HD-VCR) Separated by.

SD-DVCR, which is a system for compressing and encoding and recording and reproducing an SD baseband signal, has a head 102 for reading out a signal recorded on the magnetic tape 100 and an analog-to-digital converter, as shown in FIG. (ADC: 104), adaptive equalizer 106, Viterbi detector 108, decision unit (DEC: 110), error value calculation unit 112, phase detector 114, digital-analog converter (DAC: 116) And the voltage controlled oscillator (VCO) 118 to reproduce the data recorded on the magnetic tape 100. Although not shown in the drawing, an amplifier for amplifying the reproduced signal, an error decoding unit for error correction in the detected data, an MPEG decoder for restoring the compressed data to the original data, and the like are required for the reproduction unit of the SD-VCR. do.

Referring to FIG. 1, the signal reproduced through the head 102 is input to the analog-to-digital converter 104 via a reproduction amplifier (not shown), which is sampled by a sampling clock and then converted into 8-bit digital data. It is converted and input to adaptive equalizer 106.

The adaptive equalizer 106 is to reduce the inter-symbol interference (ISI) affecting the sampling instant during decoding, and is a general equalization scheme and a partial response using a linear equalizer or a decision feedback equalizer. In the general equalization method, the Nyquist evaluation is satisfied by using zero enhancement or least-square error method so that the intersymbol interference becomes "0" at the sampling time around, and the PR method approximates the reproduction waveform. By choosing the equalizer to be a partial response of, we can reduce the noise increase, which is a disadvantage of the general equalization method.

The determiner 110 determines the output of the adaptive equalizer to three values, the error value calculator 112 subtracts the determined value from the output of the equalizer to obtain an error value e, and the Viterbi detector 108 The output of the adaptive equalizer detects data according to the Viterbi maximum likelihood decoding algorithm.

The phase detector 114, the digital-to-analog converter 116, and the voltage controlled oscillator 118 constitute a PLL, which synchronizes the regeneration clock.

Here, the recording of SD DVCR is briefly described. The sound records PCM data without compression, and the 4: 2: 2 format video has a data rate of about 167 Mbps based on the effective pixels. ) And intra-field compression coding using variable length coding (VLC). The compressed video data, sound data, and subcodes are recorded and encoded on the magnetic tape by adding error correction coding, respectively. The additional data by error correction encoding and recording encoding results in a final recording data rate of about 41.85 Mbps.

And in a data recording format in a truck on a magnetic tape, the head is helical running from the bottom of the track to the top, where the inclination angle of the track is about 9.1668 degrees when the tape is running at 18.131 mm / sec. One screen of 525 / 60Hz, like the current TV, is recorded on 10 tracks, and one screen of 625 / 50Hz, like the current TV of Europe, is recorded on 12 trucks. Four types of data are recorded in the recording area in the center of the tape, and ITI (insert and track information), sound data, video data, and subcodes are sequentially recorded in each area in the order of progress of the magnetic head.

However, since the HD baseband signal requires at least twice the speed of the SD baseband signal, it is necessary to double the drum speed or use two heads when using the conventional SD-DVCR. However, the specific configuration is not yet known.

Accordingly, the present invention has been proposed in order to satisfy the above necessity, and an object thereof is to provide a high-definition DVD (HD-DVCR) capable of reproducing data recorded on a tape in a two-head method.

In order to achieve the above object, the present invention provides a digital BD for reproducing data of a high quality baseband signal recorded on a magnetic tape, comprising: a first head; a second head; A first analog-digital converter for converting the analog signal input through the first head into digital; A second analog-digital converter for converting an analog signal input through the second head into digital; A first adaptive equalizer that receives an error value, updates an equalization coefficient, sequentially receives the output of the first analog-to-digital converter according to a clock, and calculates the filtered value by calculating an updated equalization coefficient; A second adaptive equalizer which receives an error value, updates an equalization coefficient, sequentially receives the output of the second analog-to-digital converter according to a clock, and calculates the filtered value by calculating an updated equalization coefficient; A first determiner which determines an output of the first adaptive equalizer and outputs a value of three levels; A second determination unit which determines an output of the second adaptive equalizer and outputs a value of three levels; A first error value calculator configured to receive an output of the first determiner and an output of the first adaptive equalizer, respectively, and calculate an error value for providing the first adaptive equalizer to the first adaptive equalizer; A second error value calculator configured to receive an output of the second determiner and an output of the second adaptive equalizer, respectively, and calculate an error value for providing the second adaptive equalizer to the second adaptive equalizer; A first Viterbi detector receiving the output of the first adaptive equalizer and detecting the digital data; A second Viterbi detector receiving the output of the second adaptive equalizer and detecting the digital data; And a coupling unit coupling the output of the first Viterbi detector and the second Viterbi detector.

1 is a schematic diagram showing the configuration of a digital TV of general image quality;

Figure 2 is a block diagram showing a high-definition digital BC in accordance with the present invention.

* Explanation of symbols for main parts of the drawings

200: magnetic tape 202,204: head

206,208: analog-to-digital converter 210,212: adaptive equalizer

214, 216: determination unit 218, 220: error value calculation unit

222,224 Viterbi detector 226: coupling portion

230: PLL

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

Figure 2 is a block diagram showing a high-definition digital BC in accordance with the present invention. Referring to FIG. 2, the digital VSI for reproducing the high quality signal recorded on the magnetic tape 200 may include a first head 202, a second head 204, a first analog-to-digital converter (ADC) 206, A second analog-to-digital converter (ADC: 208), a first adaptive equalizer 210, a second adaptive equalizer 212, a first determiner (DEC: 214), a second determiner (DEC: 216), Composed of a first error value calculator 218, a second error value calculator 220, a first Viterbi detector 222, a second Viterbi detector 224, a coupling unit 226, and a PLL 230. do. The PLL 230 includes a digital phase detector 232, a digital-to-analog converter 234 (DAC), and a voltage controlled oscillator 236 (VCO).

Next, the operational effects of the digital VSI according to the present invention configured as described above are as follows.

First, in the operation of the recording and reproducing system in the digital VRS according to the present invention, recording encoding is performed at the time of recording and equalization processing at the time of reproduction.

The recording encoding is performed by error correcting and encoding scrambled video data, audio data, subcodes, and gaps in a track and dividing them by 24 bits, and adding 1 bit at the beginning of every 24 bits, and then I-NRZI (Interleaved Non Rerurn to Zero Inverse). That is, I-NRZI, which is one of recording encodings, belongs to PR4 (Partial Response Class4) developed in the data communication field, and corresponds to PR (1,0, -1). I-NRZI has a bandpass frequency characteristic, which is very close to that of a magnetic recorder.

As described above, the process of recording and reproducing by digital recording in digital VSI is represented by (1-D ² ), which can be decomposed into (1-D) and (1 + D). Here, (1-D) is replaced by the same as the regeneration system differential characteristic, and only (1 + D) is constituted by an analog delay circuit and an adder. After the reproduction decoder of (1 + D) has been identified, the ternary waveforms (1,0, -1) are identified as binary waveforms (1,0) to enable reproduction of the recording signal. Each transfer function becomes 1 / (1-D ² ) in the recording stage, and during playback, the tape, head, and amplifier become (1-D) due to their differential characteristics, and the playback decoder Is expressed. Therefore, when the playback process of the tape head and the playback decoder are combined, it becomes 1-D ² .

Referring to FIG. 2 again, data recorded and recorded in a baseband manner is reproduced and amplified by analog RF signals by the first head 202 and the second head 204, respectively, and then the analog-to-digital converters 210 and 212. The sample is sampled according to the clock and converted into digital data. The response of the sampled data channel is expressed by Equation 1 below.

1 + a ₁ ⋅D- (1 + a ₂ ) D ² + a ₃ ⋅D ³ + ..... + a _n ⋅D ⁿ

Where a ₁ to a _n represent perturbation from the ideal channel response, and D is a symbol delay. This data is input to the first and second adaptive equalizers 210 and 212 and calculated as shown in Equation 2 to obtain an equalized output value.

y (k) = X ^t (k) W (k) = W ^t (k) X (k)

Here, X is a filter input vector of Nx1, and W is a filter coefficient (ie, equalization coefficient) vector of Nx1. y is the filter output and t is the transpose of the vector.

When all a values of Equation 1 become 0 by the filter coefficient values, the overall channel response is close to the characteristic of 1-D ² .

The adaptive equalizers 210 and 212 need to adaptively change the equalization coefficients according to the state of the recording medium. In order to update the equalization coefficients, the output values of the adaptive equalizers 210 and 212 are determined by the decision units 214 and 216. 3 levels are determined, and the determined values and the output values of the adaptive equalizers 210 and 212 are input to the error value calculators 218 and 220 and calculated as shown in Equation 3 below to obtain an error value.

e (k) = d (k) -y (k)

The error values obtained by the error value calculating units 218 and 220 are fed back to the adaptive equalizers 210 and 212 and then calculated by the adaptive equalizers 210 and 212 as shown in Equation 4 to calculate a new equalization coefficient W. It is used to

W (k + 1) = W (k) + ue (k) X (k)

In this way, the adaptive equalizers 210 and 212 receive the error values e from the error value calculators 218 and 220 and compute them with a predetermined scaling constant u to update the equalization coefficients W. Accordingly, the overall channel response is reduced. The coefficient is automatically adjusted to be 1-D ² .

Viterbi detectors 222 and 224 decode the outputs of adaptive equalizers 210 and 212 into binary data (1,0) according to the Viterbi algorithm. That is, the Viterbi detectors 222 and 224 implement a PR polynomial, which is the output of the adaptive equalizers 210 and 212, in a trellis form and apply a maximum likelihood estimation method.

The combiner 226 is read by the first head 202 and decoded by the second head 204 and the data decoded by the first Viterbi detector 222 and decoded by the second Viterbi detector 224. The high quality data reproduced by combining the data is output to a decoding unit for error correction and source decoding. In this case, if the data reproduced by the first Viterbi detector 222 and the second Viterbi detector 224 is about 41.85 Mbps, the combined data rate is about 83.7 Mbps.

As described above, the high-definition digital video signal (HD-DVCR) of the present invention can process high-definition video signals with a simple configuration by reproducing high-definition data in a two-head method, and thus, realize a high-definition digital video signal at a low cost. It can be effective.

Claims (2)

A digital VSI for reproducing data of a high quality baseband signal recorded on a magnetic tape, First head 202; Second head 204; A first analog-to-digital converter (206) for converting the analog signal input through the first head into digital; A second analog-to-digital converter (208) for converting the analog signal input through the second head into digital; A first adaptive equalizer 210 which receives an error value, updates an equalization coefficient, sequentially receives the output of the first analog-to-digital converter according to a clock, and calculates the filtered value by calculating an updated equalization coefficient; A second adaptive equalizer 212 that receives an error value, updates an equalization coefficient, sequentially receives the output of the second analog-digital converter according to a clock, and calculates the filtered value by calculating an updated equalization coefficient; A first determiner 214 for determining an output of the first adaptive equalizer and outputting three levels of values; A second determination unit 216 for determining an output of the second adaptive equalizer and outputting three levels of values; A first error value calculator 218 for receiving an output of the first determiner and an output of the first adaptive equalizer, respectively, and calculating an error value for providing the first adaptive equalizer to the first adaptive equalizer; A second error value calculator 220 which receives an output of the second determiner and an output of the second adaptive equalizer, respectively, and calculates an error value to be provided to the second adaptive equalizer; A first Viterbi detector 222 which receives the output of the first adaptive equalizer and decodes the digital data according to a Viterbi algorithm; A second Viterbi detector 224 which receives the output of the second adaptive equalizer and detects the digital data according to the Viterbi algorithm; And And a coupling unit (226) for combining the outputs of the first Viterbi detector and the second Viterbi detector to output digital data at double speed. The first analog signal of claim 1, wherein the high-definition digital VSI is configured to receive the output clock of the second Viterbi detector 224 and the output of the second error value calculator 220 and output a phase-locked playback clock. And a phase-locked loop (PLL: 230) provided to the digital converter 206 and the second analog-to-digital converter 208, respectively.