JPH03254529A - Equalizer - Google Patents

Abstract

PURPOSE:To ensure a signal of quality of a prescribed level or over at all times by selecting either an inputted reference signal for transmission line equalization or a signal without error stored in a storage means according to the result of discrimination of an error presence discrimination means and applying equalization of the transmission line by the selected signal. CONSTITUTION:A reproduced VIT signal is inputted from a reproduction signal processing circuit 20 to an input terminal 30 of a signal (VIT) replacement circuit 22 including information of equalization of a transmission line. A VIT level detection circuit 32 compares an input signal level of the input terminal 30 with a level of a regular VIT signal and throws a switch 34 to a (b) contact when an error of a prescribed level or over exists. In other cases, the circuit 32 generates a switch control signal throwing a switch 34 to its (a) contact. A signal selected by the switch 34 is fed to the reproduction signal processing circuit 20 via an output terminal 38. As a result, even when an important error such as dropout exists in a reference signal for transmission line equalization, the transmission line equalization is implemented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an equalization device that performs transmission line equalization according to a reference signal for transmission line equalization.

[Prior Art] High-quality televised signals such as high-definition signals require a wide band, so during transmission, they are compressed and encoded on the transmitting side and decoded on the receiving side.

One of the compression methods is the MUSE method. The MUSE method digitally processes a high-definition signal to significantly compress its band, time-axis multiplexes the time-compressed digital audio signal, converts it into an analog signal, and transmits it through an analog transmission path.

FIG. 3 shows a transmission signal for one frame of the MUSE signal. The transmission signal for one frame of the MUSE signal is 1°12
It consists of five lines, and each line is transmitted sequentially. In Figure 3, Y is a luminance signal obtained by converting sample values into analogs, C is a color difference signal, and A is a digitalized audio signal.
Audio signal as value signal, HD signal for horizontal synchronization, FP
/VIT is a signal containing transmission path equalization information (WIT) and frame pulse (FP) for vertical synchronization, GO is a guard space, CON is a control signal, BL is empty data, and CP is a symbol indicating a clamp level. be. Third
The numerical values shown in the figure indicate the number of data in the digital format before converting the transmission signal to analog.

FIG. 4 shows details of the WIT signal. The VIT signal is shifted 32MH21 clocks every frame. The details of each symbol shown in Figure 3 are explained in detail in Chapter 3 of "Hi-Vision Technology" edited by NHK Broadcasting Technology Research Institute, published November 25, 1986, so no further explanation will be given here. omitted.

Since the transmission signal by the MUSE method, that is, the MUSE signal, is a sample value transmission, it is necessary on the receiving side to accurately resample the received signal without interference with adjacent sample points. will be carried out. FIG. 5 shows a system diagram of transmission line equalization. As shown in Figure 6, the frequency characteristics from the encoder's matching filter to the decoder's A/D conversion circuit are symmetrical at the point of 8.1 MHz (-6 dB), and within the transmission band. Then, on the decoder side, vI is set so that the phase characteristic becomes a straight line.
The frequency characteristics of the transmission path are corrected by the T signal.

[Problems to be Solved by the Invention] However, in addition to signal deterioration due to transmission distortion, dropouts may also occur in the transmission path. For example, in a recording/playback device that records high-definition signals on a magnetic tape, the recording head, magnetic tape, and electromagnetic conversion system between the magnetic tape and the playback can be thought of as a transmission path. - Stubble out occurs.

Transmission distortion can be corrected using the VIT signal as described above, but if a transmission error such as dropout occurs in the VIT signal, correct transmission path equalization cannot be performed, and therefore the image quality will deteriorate significantly. do.

Therefore, an object of the present invention is to provide an equalization device that solves these problems.

[Means for Solving the Problems] An equalizer according to the present invention is an equalizer that performs equalization using a reference signal for equalizing a transmission line, and is an equalizer that performs equalization using a reference signal for equalizing a transmission line, and eliminates errors in the input reference signal for equalizing a transmission line. a determination means for determining the presence or absence of the input transmission line equalization reference signal; a storage means for storing error-free signals among the input transmission line equalization reference signals; It is characterized by comprising a selection means for selecting one of the signals stored in the storage means, and an equalization means for performing transmission line equalization based on the signal selected by the selection means.

[Operation] With the above means, even if there is a serious error in the transmission line equalization reference signal, transmission line equalization can be performed using the preceding normal transmission line equalization reference signal. Therefore, it is possible to always ensure a signal with a quality higher than a certain level.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a circuit configuration block diagram of an embodiment in which the present invention is applied to a MUSE signal recording/reproducing device. 10 is MUSE
The recording signal processing circuit 12 is a signal input terminal, and converts the input MUSE signal inputted to the input terminal 10 into a recording format of a predetermined recording medium such as a magnetic tape. The output of the recording signal processing circuit 12 is amplified by a recording amplifier 14, and recorded on a recording medium by the recording head of an electromagnetic transducer system 16 consisting of a recording head, a recording medium, and a reproducing head.

The signal reproduced by the reproduction head of the electromagnetic conversion system 16 is amplified by the reproduction amplifier 18.

The reproduction signal processing circuit 20 converts the output signal of the reproduction amplifier 18 into the original MUSE signal. The reproduced VIT signal is supplied to the VIT signal replacement circuit 22, and as will be described in detail later, the VIT signal replacement circuit 22 directly passes the reproduced VIT signal to the reproduced signal processing circuit 20 if there is no problem (for example, dropout) in the reproduced VIT signal. If there is a problem, the normally reproduced VIT signal is output to the reproduced signal processing circuit 20.

The reproduced signal processing circuit 20 uses the VrT signal from the WIT signal replacement circuit 22 to perform transmission line equalization. The reproduced MUSE signal obtained by the reproduced signal processing circuit 20 is output to the output terminal 24.

FIG. 2 shows an example of the circuit configuration of the WIT signal replacement circuit 22. A reproduced VIT signal is input to the input terminal 30 from the reproduced signal processing circuit 20 . VIT level detection circuit 3
2 is a switch control that compares the input signal level of the input terminal 30 with the level of the regular WIT signal, and connects the switch 34 to the B contact if there is an error of more than a predetermined value, otherwise connects the switch 34 to the A contact. Generate a signal. The input signal of the input terminal 30 is supplied to the a contact of the switch 34, and the output signal of the switch 34 is delayed by two frames by a FIFO (first in, first out) memory 36 to the b contact of the switch 34. signal is supplied. The signal selected by switch 34 is output to output terminal 3.
8 to the reproduction signal processing circuit 20.

Therefore, firstly, there is always a normal W in the FIFO memory 36.
IT signal is supplied and secondly, the regenerated VfT
If the signal exceeds a predetermined value and differs from the normal level, the FI
The VIT signal from the previous two frames from the FO memory 36 is supplied to the reproduced signal processing circuit 20, and if the error from the normal level is within a predetermined value, the reproduced WIT signal from the reproduced signal processing circuit 20 is directly used as the reproduced signal. It is sent back to the processing circuit 20.

In FIG. 2, the abnormality of the reproduced WIT signal is determined based on the level difference from the normal level, but of course, other methods may be used to determine the abnormality.

Although the explanation was given using a recording/reproducing device equipped with an electromagnetic conversion system as an example,
The present invention can of course be applied to general transmission receiving devices, decoding devices, and playback devices that include other recording media and transmission media.

[Effects of the Invention] As can be easily understood from the above explanation, according to the present invention, transmission line equalization can be performed even if there is a serious error such as a dropout in the reference signal for transmission line equalization. Therefore, in the case of a high-definition MUSE signal, for example, the image quality does not deteriorate even in the event of such a serious error.

[Brief explanation of drawings]

FIG. 1 is a circuit configuration block diagram of an embodiment of the present invention, and FIG.
The figure is a circuit configuration block diagram of the WIT signal replacement circuit 22 in Figure 1, Figure 3 is the transmission signal for one frame of the digital MLISE signal, Figure 4 is a timing diagram of the WIT signal, and Figure 5 is the transmission path. The equalization system diagram, FIG. 6, is a distortion-free transmission characteristic diagram of the transmission line. 10: MLISE signal input terminal 122 Recording signal processing circuit 14: Recording amplifier 16: Electromagnetic conversion system 18:
Reproduction amplifier 20: Reproduction signal processing circuit 22: VIT signal replacement circuit 24: Output terminal 30: Input terminal 32
: VIT level detection circuit 34: Switch 36:
FIFO memory 38: Output terminal Figure 1 Figure 2 Figure 1 Frequency (MHz) Figure 6 480 Figure 4

Claims (1)

[Claims] An equalizer that performs equalization using a reference signal for transmission line equalization, which includes a determination means for determining the presence or absence of an error in the input reference signal for transmission line equalization, and a determination means for determining the presence or absence of an error in the input reference signal for transmission line equalization. a storage means for storing error-free signals; a selection means for selecting either the input transmission line equalization reference signal or the signal stored in the storage means according to the determination result of the determination means; 1. An equalization device comprising equalization means for performing transmission line equalization using a signal selected by a selection means.