JP2826567B2 - Digital signal magnetic recording / reproducing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a simple reproduction of a camera-integrated digital signal magnetic recording / reproducing apparatus.

2. Description of the Related Art In a broadcast digital video signal recording / reproducing apparatus (hereinafter abbreviated as digital VTR), an NTSC color video signal is sampled at a frequency 4fsc, which is four times the subcarrier frequency (fsc), and quantized to 8 bits. 100M to record
It is necessary to record data of bps or more. In this case, 1
Since the recording bit rate becomes too high in the channel, the recording is performed by dividing the recording bit rate into two channels in half.

FIGS. 3 and 4 show block diagrams of a recording circuit and a reproducing circuit of the digital VTR, respectively.

First, the recording circuit of FIG. 3 will be described. An analog video signal is input from an input terminal 15 and is converted into digital data by an A / D converter 16. At the time of reproduction, even if one channel becomes unreproducible due to clogging of the head at the time of reproduction, the data is shifted by 180 ° for each line as shown in FIG. It is divided into two channels of Ach and Bch by shifting. The distributed data is added with parity of an outer correction code in outer ECC encoders 18A and 18B, respectively, and written to the next shuffling memories 19A and 19B.
At this time, the video data is written to the shuffling memories 19A and 19B at an address different from the order in which they were input in time series, and the reading is performed in a fixed order. By recording the data on the tape with the order of the data changed in this way, when a burst error occurs during reproduction, the error is dispersed on the screen, and the error correction described later becomes easy. Next, data from the shuffling memories 19A and 19B are read out in units of blocks of a predetermined length,
In the ID adders 20A and 20B, a block number or the like indicating a position in one track at the time of recording on the tape is added to the block data. And the inner ECC encoder 2
In 1A, 21B, the parity of the inner correction code is added,
The modulators 22A and 22B convert the data after modulation into a data series convenient for magnetic recording and reproduction. And SY
In the NC adders 23A and 23B, a SYNC signal for indicating the start position of the block is added, and finally converted into serial bit data by the parallel / serial converters 24A and 24B, and then transmitted through the recording amplifiers 25A and 25B. Recording head 26A, 26B
Is recorded on the magnetic tape.

Next, the reproducing circuit of FIG. 4 will be described. The signal reproduced from the magnetic tape by the reproducing heads 27A and 27B is
Clocks synchronized with the reproduced signals are generated by the PLL circuits 29A and 29B via the reproduction amplifiers 28A and 28B, and the data detectors 30A and 30B
Is detected as digital data by the SYNC detector 31
A and 31B detect a SYNC signal in the reproduction signal. Then, based on the detected SYNC, a serial / parallel converter
The signal is converted into a word signal by 32A and 32B, and is returned to data before modulation in the next demodulators 33A and 33B. This signal is
In the ECC decoders 34A and 34B, error correction is performed by the inner correction parity added at the time of recording, and the ID detector
The ID is detected at 35A and 35B, and the error flag indicating the position of the subsequently corrected data and the error that could not be corrected are both stored in the deshuffling memory 36A according to the write address generated based on the ID information. , 36B
Is written to. Next, the deshuffling memories 36A and 36B
Data and error flags read from the same address as the write address from the outer EC
In the C decoders 37A and 37B, error correction is performed by an outer correction parity and an error flag added at the time of recording,
After the channels are mixed by the channel mixer 38, the corrected data and the error flag indicating the position of the error that could not be corrected are sent to the error corrector 39, where error correction processing is performed, and finally, the D / A converter 40 Is returned to an analog video signal and output from the output terminal 41.

By the way, for news coverage, a camera and VTR
A camera-integrated digital signal magnetic recording / reproducing apparatus (hereinafter abbreviated as a camcorder) is required. Generally, a camcorder only needs to have a recording function, and it is sufficient to have only a recording circuit. However, in a device for which reliability is particularly important, such as a broadcasting device, a function of checking whether or not data is correctly recorded at the time of recording is indispensable. Therefore, in the conventional camcorder, a simultaneous reproducing head is provided in addition to the recording head, and the recording state is monitored by the simultaneous reproducing head.

FIG. 6 shows the position of a head mounted on a rotary cylinder of a conventional camcorder. Where A1
A3, B1 and B3 are a pair of recording heads corresponding to each other and shifted by 180 °, and A2 and A4, and B2 and B4 are a pair of simultaneous reproducing heads corresponding to each other and shifted by 180 °. The recording head and the reproducing head are mounted at an angle difference of 90 ° from each other.
FIG. 7 shows trace positions when recording on a tape using the head shown in FIG. Simultaneous reproduction is performed by tracing the signal recorded by the recording head A1 with the simultaneous reproduction head A2 with a half track delay.

As the monitoring method, the following two methods have conventionally been used. The first method is to provide a complete reproduction circuit and monitor simultaneously reproduced images with a viewfinder or the like. The second method is to provide an RF signal reproduced from a simultaneous reproduction head without a reproduction circuit. This is a method of monitoring the envelope.

Problems to be Solved by the Invention Problems in the conventional example described above will be described. In the first method for checking the recording state, it is necessary to have a complete reproduction circuit as shown in FIG. 4 in the camcorder.
On the other hand, considering the mobility required most for the camcorder, small size, light weight and low power consumption are the most important factors for the camcorder. Therefore, this method has an advantage that the recording state can be surely monitored, but has a problem that mobility is reduced.

In the second method for confirming the recording state, the only circuit required in the camcorder is the recording circuit shown in FIG. 3, and although the mobility is excellent, the monitoring of the recording state can be reliably performed. There is a problem that can not be. That is, in the method of monitoring the envelope, although clogging of the recording head can be detected, for example, when there is an abnormality in the recording circuit, it cannot always be detected. This is a fatal problem for a broadcast camcorder that requires high reliability.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a simple reproduction processing apparatus for simultaneously checking recording errors during recording.

Means for Solving the Problems In order to achieve the above object, the present invention provides a channel switching means for switching and outputting a two-channel signal reproduced by a simultaneous reproduction means at a predetermined cycle, and a signal output by the channel switching means. Channel interpolating means for interpolating a signal of a channel which is not output by the channel switching means by using a signal of a certain channel.

Operation With the above means, the reproduced signal is switched alternately and periodically, and the signal of the non-reproduced channel is interpolated and output using the signal of the reproduced channel.

Embodiment An embodiment of the present invention is shown in FIG. In FIG. 1, 1
A, 1B, 2A, 2B, 5 to 10, 13, and 14 are the same as the corresponding blocks of the conventional example shown in FIG. Also,
Blocks corresponding to the inner ECC decoders 34A and 34B, the outer ECC decoders 37A and 37B, and the error rectifier 39 shown in FIG. It can be omitted. In the present invention, in order to greatly reduce the size of the reproduction circuit, a reproduction processing circuit for only one channel is incorporated. Then, in order to monitor the recording state of two channels by a reproduction circuit for one channel, channel switching means is introduced so that Ach and Bch are periodically switched.

In FIG. 1, 3 is a channel switch, 4 is a channel switch control signal generator, and 12 is a channel interpolator. The two-channel video signals reproduced via the reproduction amplifiers 2A and 2B are switched at a certain period by the channel switch 3 based on the switching control signal generated by the channel switching control signal generator 4.
At this time, if switching is performed in units of shuffling or less,
Since the samples to be interpolated are not uniformly distributed on the screen and effective interpolation cannot be performed, the channel is switched at an integral multiple of the shuffling unit. Channel switch 3
The signal of only one channel switched by the above is subjected to the same processing as in the conventional method, and is performed by the deshuffling memory 11.
The data read from is interpolated in the channel interpolator 12 for one channel that is not reproduced. Second
The figure shows an example of channel interpolation. Now, consider the case where only Ach is reproduced by the channel changeover switch 3. In the figure, a pixel with Bch surrounded by a solid frame is represented by X
(L, N). Channel interpolation is performed using 10 pixels of Ach surrounded by a dotted frame near the pixel X (L, N). N
In the case of a TSC color video signal, the interpolation values of the Y component and the C component in the pixel X (L, N) can be expressed as the following equation.

Therefore, the pixel X (L, N) can be interpolated using the following equation.

(L, N) = [(L, N)] _y + [(L, N)] The _c- channel interpolator 12 converts the data of the non-reproduced channel obtained by interpolation and the data of the reprocessed channel. An analog signal that is synthesized and D / A converted by the next D / A converter 13 is output from an output terminal.

As described above, by providing the minimum necessary simple reproduction processing circuit, it is possible to monitor simultaneously reproduced images with a viewfinder or the like during recording. The present invention can be applied not only to simultaneous playback but also to normal playback. In the present embodiment, only the case where recording is performed by dividing into two channels is described, but the same can be said for the case where recording is performed by dividing into two or more channels. Although only one type of interpolation filter is illustrated in this embodiment, other filter configurations are of course possible. Although the error correction circuit is omitted in this embodiment, for example, only an error detection circuit is provided,
If a plurality of interpolation filters are adaptively switched and used in accordance with the state of the error in the reproduction signal, more effective channel interpolation can be performed.

Effects of the Invention As described above, if the present invention is applied to a camcorder, it is possible to check with high reliability whether or not a video is correctly recorded by monitoring simultaneously reproduced images at the time of video recording. , Circuit size reduction,
The power consumption is reduced, the mobility required most for a camcorder is improved, the present invention can be enhanced, and the practical effect is great.

In this embodiment, only the case of the NTSC color video signal has been described. However, other television systems, for example, the PAL system,
Needless to say, the present invention can be similarly applied to a component-type video signal.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a layout diagram on a screen showing an example of channel interpolation in an embodiment of the present invention, and FIGS.
FIG. 5 is a block diagram of a recording and reproducing circuit of a VTR, FIG. 5 is a layout diagram of channels on a screen, FIG. 6 is a layout diagram of a recording head and a simultaneous reproducing head for performing simultaneous reproduction, FIG. FIG. 3 is a schematic diagram showing trace positions of a recording head and a simultaneous reproducing head when recording on a tape. 3 Channel switch, 4 Channel control signal generator, 12 Channel interpolator.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI G11B 27/36 G11B 27/36 A A

Claims (3)

(57) [Claims] 1. A recording means for dividing a digital signal into n (n.gtoreq.2) channels and recording it on a magnetic recording medium using a magnetic head, and at least a magnetic recording medium for reproducing a signal recorded by the recording means. A recording / reproducing apparatus including both of a reproducing unit having a head, a reproducing amplifier, and a reproducing data interpolator, or a reproducing apparatus including only the reproducing unit, wherein n is obtained by the magnetic head and the reproducing amplifier.
Channel switching means for sequentially selecting and outputting at least one channel signal from the channel signals at a predetermined cycle; and determining and interpolating data of a channel which is not selected based on a channel selection control signal obtained by the channel switching means. A digital signal magnetic recording / reproducing apparatus having channel interpolation means for performing the operation. 2. The digital signal magnetic recording / reproducing apparatus according to claim 1, wherein said reproducing means is a simultaneous reproducing means for performing reproduction with a predetermined time delay from a recording time. 3. A recording means for dividing a digital signal into two channels, shuffling each signal in a predetermined range and recording the signals on a recording medium, and a channel switching means for dividing the digital signals into two channels. 2. The digital signal magnetic recording / reproducing apparatus according to claim 1, wherein the reproducing signal of the channel is switched alternately at intervals of an integral multiple of the time corresponding to the shuffling range.