JPH03297279A - Television signal transmitter and its receiver - Google Patents

Abstract

PURPOSE:To detect a crosstalk between a main signal and an additional signal by using a ghost elimination reference signal (GCR signal) for the additional signal so as to eliminate ghost of the additional signal. CONSTITUTION:A master signal is fed to a terminal 1a and fed to a master signal GCR signal insertion device 1, in which a GCR signal is inserted to the master signal. The master signal subjected to insertion of the GCR signal is amplitude-modulated and the result is fed to an adder circuit 6. An additional signal is fed to a terminal 2a and to a GCR' signal insertion device 2, in which the GCR' signal is inserted to the additional signal at a location where the effect of other signals than the GCR' is eliminated. The signal subjected to GCR' signal insertion is subjected to balance modulation by using a carrier whose phase differs from the carrier of the master signal by 900 deg., the band is limited by a band limit circuit 4 and the result is fed to an adder circuit 6, in which the signal is added to the master signal and the resulting signal is sent.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention converts an additional signal used for high definition and wide aspect into a television main signal by using orthogonal modulation of a video carrier wave. The present invention relates to a television signal transmitting device and a television signal receiving device that multiplex signals, transmit them, and receive them.

[Prior art] In recent years, in order to perform high-precision ghost removal, a reference signal for ghost removal is inserted into a television signal (main signal), and the receiving side uses this reference signal for ghost removal to remove ghosts. A technology has been developed to do so.

This ghost removal reference signal (OCR signal) is the 7th y-th
: As shown in I, 11th 3rd, It! In the 6th and 8th fields, the rising edge is sin (X) /X1
An OCR waveform with a falling edge characteristic of 2T is inserted,
In the second, fourth, fifth, and seventh fields, a 0-pedestal waveform whose setup is the same as the OCR waveform is an 8-field sequence in which the 0-pedestal waveform is repeatedly sent out every 8 fields as shown in the figure.

The OCR signal of this 8-field sequence is
The first, third, sixth, and eighth fields into which the OCR waveform has been inserted are subjected to addition processing, and the second, fourth, fifth, and seventh fields into which the O-pedestal waveform has been inserted are subjected to subtraction processing.

This arithmetic processing removes signals existing before and after the OCR signal (sync signal, color burst signal, previous line signal, etc.), leaving only the OCR waveform shown in FIG. 8A. This OCR waveform is differentiated and shown in Figure B.
n (X) /X waveform.

This differential waveform has flat frequency characteristics within the video signal band (see C# in FIG. 5).

The sin (X) /X waveform can be compared with a reference waveform for ghost removal (FIG. 8C) output from a generator provided on the receiving device (television receiver) side. Then, based on the comparison output, the filter coefficients of a transpersal filter (not shown) for ghost removal are controlled, and the ghost signal mixed into the television signal is removed.

On the other hand, recently, high definition while maintaining compatibility with current broadcasting,
Research is being conducted on a television signal transmitting and receiving device that achieves wide aspect and high picture quality.

One method is to multiplex an additional signal for high definition and wide aspect onto a main signal into which an OCR signal has been inserted, using orthogonal modulation of a video carrier wave.

Briefly, by adding an additional signal balanced modulated with a carrier wave whose phase differs from the video carrier wave by 90 degrees to the main signal amplitude-modulated with a video carrier wave, the receiver 1!1 converts the main signal and the additional 4s signal. This is a method of multiplexing so that the two can be separated.

[The invention attempts to solve 5! III By the way, when the additional signal is multiplexed onto the main signal using orthogonal modulation as described above, the main signal and the additional signal are detected by carrier waves having different phases on the receiving side. Therefore, when a ghost is detected, the state of the ghost is detected.

Therefore, the ghosts of both the main signal and the additional signal cannot be effectively removed using only the OCR signal for the main signal.

In addition, when detecting the main signal and additional signal using carrier waves with a 90° phase difference, crosstalk will occur between the main signal and the additional signal if the detection axis shifts; Talk cannot be detected either.

Therefore, this invention solves these problems, and makes it possible to effectively remove ghosts mixed in both the main signal and additional signals, and to detect crosstalk between the main signal and additional signals. This paper proposes an apparatus for transmitting and receiving television signals.

[Means for Solving the Problems] In order to solve the above-mentioned problems, in the present invention, as a transmitting device, the frequency band is added to the No. 43 band for additional signals for high definition and wide aspect. means for generating a reference signal for ghost removal for the additional signal limited to , and means for inserting the reference signal for ghost removal for the additional signal into the additional signal during a period in which the current reference signal for ghost removal is not superimposed. The present invention is characterized by comprising a means for multiplexing this additional signal onto a television signal as a main signal into which a current ghost removal reference signal has been inserted, using orthogonal modulation of a video carrier wave.

Further, as a receiving device for Television No. 43, a means for extracting a reference signal for ghost removal for the main signal and a reference signal for ghost removal for the additional signal, and a means for extracting the reference signal for ghost removal for the main signal, The present invention is characterized by comprising a ghost removing means for removing the ghost of the additional signal, and a ghost removing means for removing the ghost of the additional signal using the reference signal for ghost removal for the additional signal.

[Operation] In this configuration, on the transmitting side, a ghost removal reference signal OCR' for the additional signal is inserted into the additional signal for high definition and wide aspect.

The insertion period is a period in which the current ghost removal reference signal OCR is not superimposed. This additional signal is multiplexed using orthogonal modulation of the video carrier wave.

On the receiving side, a main signal ghost removal reference signal OCR and an additional signal ghost removal reference signal GCR' are extracted. Then, the ghost of the main signal is removed based on the main signal ghost removal reference signal OCR. Furthermore, the ghost of the additional signal is removed based on the additional signal ghost removal reference signal OCR'.

As a result, ghosts mixed into each image can be effectively removed.

Furthermore, when detecting the main signal, the additional signal has been converted to a double-side band signal and therefore becomes a component orthogonal to the video carrier wave, so the additional signal does not affect the synchronous detection of the main signal. Even when detecting the additional signal, the main signal is converted into a double-side band signal, so the main signal does not affect the synchronous detection of the additional signal.

The main signal ghost removal reference signal No. 4 OCR and the additional signal ghost removal reference signal 0CR- are inserted at different horizontal positions, so crosstalk and addition of the additional signal to the main signal due to misalignment of the detection axis Crosstalk between the main signal and the signal can be easily detected.

[Example] Next, an example of a television signal transmitting device and a receiving device according to the present invention will be described in detail with reference to FIG. 1 and subsequent figures.

FIG. 1 is a block diagram showing an example of a television signal transmitting device.

A main signal (NTSC signal or television signal of a system compatible with the current NTSC system) having a frequency band shown in the third diagram is supplied to the terminal 1a. This main signal is supplied to the OCR signal inserter 1, and a reference signal for ghost removal, that is, an OCR signal, is inserted into the main signal.

As shown in FIG. 5C, this OCR signal is a s in (X) /X bar whose frequency characteristic after the difference in rising edge is approximately flat within the television signal band.

The amplitude of the main signal into which the OCR signal has been inserted is changed by the amplitude changing circuit 5. Its frequency characteristics are shown in FIG. 3E. The amplitude modulated main signal is supplied to an adder circuit 6.

On the other hand, an additional signal (FIG. 3A) used for high definition and wide aspect is supplied to the terminal 2a.

This additional signal is fed to the 0CR=signal insertion N2,
An 0CR- signal for an additional signal for a predetermined period is inserted into this additional signal.

The GCR' signal for the additional signal is as shown in Figure 5.
The frequency characteristic after the difference in the rising edge is approximately flat within the additional signal band and O outside the band, which is 5 in(X)/X par.

The OCR' signal is inserted into a period in which the current ghost removal reference signal OCR is not superimposed, as shown in FIG. 6A. Strictly speaking, as shown in Figure 8, the OCR signal corresponds to the time just before the 2T pulse is obtained (approximately +45 uS delay time), so the GCR' signal also needs to correspond to this delay time. .

Therefore, as shown in FIG. 6A, the horizontal position is not adjacent to the OCR signal, and the position where the influence of signals other than the OCR' signal (video signal, synchronization signal, etc.) can be removed by, for example, 8-field sequence arithmetic processing. insert.

The additional signal into which the 0CR=signal has been inserted is supplied to the balanced modulation circuit 3, where it is balanced modulated (carrier suppression amplitude modulation) with a carrier wave whose phase differs by 90 degrees from the carrier wave of the main signal. The frequency band is as shown in FIG. 3B.

The balanced modulated additional signal is supplied to the band-limiting circuit 4, and is band-limited by an inverse Nyquist filter having characteristics that are symmetrical with respect to the Nyquist filter formed on the receiver side and the video carrier wave (third Figure C).

Thereafter, it is supplied to the adder circuit 6, where it is added to the main signal (FIG. 3F), and transmitted in that state. In the figure, the shaded area indicates an area where additional signals are multiplexed.

FIG. 2 shows a block diagram of a television signal receiving apparatus.

An input signal (television signal) having the frequency band shown in FIG. 3F is supplied to a pair of band limiting circuits 7.10.

One of the band limiting circuits 7 can be composed of a Nyquist filter, and this Nyquist filter allows the input signal to be
The frequency band is limited to . The band-limited signal is supplied to the synchronous detection circuit 18, and only the main signal is extracted by synchronous detection using a carrier wave having the same frequency and the same phase as the video carrier wave a.

Since the additional signal indicated by diagonal lines in FIG. 4A has been converted into a double-side band signal by the Nyquist filter, it is only a component orthogonal to the image carrier wave a. Therefore, this additional signal does not affect the synchronous detection of the main signal.

The other band-limiting circuit 10 has a band-pass filter configuration, whereby the input signal is band-limited, and as shown in FIG.
frequency band. The band-limited signal is supplied to the synchronous detection circuit 11, and is synchronously detected using a carrier wave having the same frequency as the video carrier wave a but having a phase different by 90°. Through this synchronous detection, only the 7JI signal indicated by diagonal lines is extracted.

Here, since the main signal is converted into a double-side band signal by the bandpass filter, only the component orthogonal to the additional signal carrier wave is present. Therefore, only the additional signal is extracted by synchronous detection, and the main signal has almost no influence on the additional signal during processing.

The main signal detected in the manner described above is supplied to the OCR extraction section 9, where an OCR signal is extracted. Similarly, the additional signal is supplied to the OCR' extractor 12, and the OCR= signal is extracted and separated.

The GCR4M signal is then supplied to the ghost removal device 13, where ghost processing of the main signal is performed based on the OCR signal. Similarly, the 0CR- signal is supplied to a ghost removal device 14, and ghost processing of the additional signal is performed based on the 0CR- signal.

Therefore, by detecting the main signal and the additional signal using carrier waves having different phases, even if the state of the ghost mixed in the main signal and the additional signal changes, the ghost can be reliably removed.

Furthermore, as mentioned above, the GCR signal and the GCR- signal are
As shown in FIG. 6A, they are inserted in horizontal positions that are not adjacent to each other. Therefore, as shown in FIG. 6B, the GCR′ for the main signal
It is possible to accurately detect the amount of signal crosstalk and the amount of OCR signal a-stoke with respect to the additional signal.

[Effects of the Invention] As explained above, in this invention, a reference signal for ghost removal corresponding to each of the main signal and additional signal is inserted, and each ghost is removed based on this reference signal. .

According to this, it becomes possible to remove ghosts from both the main signal and the additional signal.

Also, during the period when no GCR signal is inserted, GCR'(
By inserting the ' symbol, crosstalk between the main signal and the additional signal due to deviation of the detection axis can be detected, and crosstalk reduction measures can be taken effectively.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of the configuration of a transmitting device according to the invention, FIG. 2 is a block diagram showing an example of the configuration of a receiving device according to the invention, FIG. 3 is an explanatory diagram of signals on the transmitting device side, and FIG. An explanatory diagram of signals on the receiving device side, Fig. 5 is an explanatory diagram of a reference signal for ghost removal, Fig. 6 is a diagram showing an example of insertion of a reference signal for ghost removal, and Fig. 7 is an explanatory diagram of an 8-field sequence of an OCR signal. , FIG. 8 is an explanatory diagram of an OCR waveform. 1, 2 ・ 3 ・ 4 ・ 5 ・ 7, 10 ・ 8, 11 ・ 9, 12 ・ 13, 14 ・ Reference signal inserter Balanced modulation circuit Band-limiting circuit Amplitude modulation circuit Band-limiting circuit Synchronous detection circuit Reference signal extraction section Ghost removal device

Claims (2)

[Claims] (1) A means for generating a reference signal for ghost removal for an additional signal whose frequency band is limited to the additional signal band for high definition and wide aspect, and a current reference signal for ghost removal. means for inserting a reference signal for ghost removal for the additional signal into the additional signal during a period when the additional signal is not superimposed; 1. A television signal transmitting device comprising means for multiplexing a television signal as a main signal. (2) A television signal receiving device for receiving the signal according to claim 1, comprising means for extracting a main signal ghost removal reference signal and an additional signal ghost removal reference signal, and a main signal ghost removal reference signal. A television characterized by comprising: ghost removing means for removing the ghost of the main signal using a signal; and ghost removing means for removing the ghost of the additional signal using the reference signal for ghost removal for the additional signal. John signal receiving device.