JPH0787464A - Television reinforcing signal system - Google Patents

Abstract

PURPOSE:To obtain a television reinforcing signal system with less ghost disturbance than that of a conventional system by dividing a vertical time reinforcing signal into signal series of three phases or over, applying frequency multiplexing to them and sending the multiplexed signal while being multiplexed onto upper and lower non-picture portions. CONSTITUTION:A vertical time reinforcing signal of an interlace scanning form having 360 valid scanning lines per frame, for example (hereinafter a VT signal of 360i form) is divided into three phases signal series 1-3 in a frequency multiplex circuit 2 and they are frequency-multiplexed to obtain a signal of 120i form. In this case, the signal series 1 is multiplexed without modulation as a base band, and the signal series 2,3 are multiplexed through orthogonal amplitude modulation. Then the result is sent while being multiplexed on upper/lower non-picture part of 120i form. Since the frequency multiplex signal is not accompanied with compression of a time base, a ghost image of the VT signal is produced at the same position as that of a major signal even when ghost is produced in a transmission line. Thus, ghost disturbance almost the same degree as that of an existing receiver is obtained and the effect of ghost is reduced more than that of a conventional reinforcing signal system due to time division multiplexing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television enhancement signal system, and more particularly to a vertical time enhancement signal (VT signal) or a vertical enhancement signal (V signal) while maintaining compatibility with the current television system.
H signal) is transmitted.

[0002]

2. Description of the Related Art Standardization of a second-generation EDTV system for achieving a wide screen and high image quality while maintaining compatibility with the current television system is being promoted. As a widening method, the adoption of the letterbox method in which non-image areas are provided above and below the current screen is under consideration, and many methods of transmitting various reinforcing signals for high image quality using this non-image area have been proposed. There is.

As a candidate for the reinforcement signal to be multiplexed in the non-picture part,
A vertical time enhancement signal (VT) that improves the image quality in the moving region of an image.
Signal) is listed. Further, transmission of a signal (VH signal) for reinforcing the vertical resolution that is lowered when the letterbox processing is performed on the transmitting side is also considered. Hereinafter, in order to simplify the description, the case of the VT signal will be described.

The VT signal is generated by an SSKF (Symmetric ShortKernel Filter) using a progressive scanning type signal source (Reference 1: Morita et al .; "Letterbox-type evaluation noise", TV Technical Report Vol.16). No.7 pp.25
-32 BCS'92-5 (Jan. 1992)). At this time, the number of effective scanning lines per frame is 360 and the interlaced scanning mode (hereinafter,
For the main signal of 360i), a VT signal of the same form as 360i is created. On the other hand, since the upper and lower non-image portions have only 120 (hereinafter, referred to as 120i) scanning lines per frame, conventionally, as shown in FIG.
i-form VT signal (scan lines 1, 2, 3, ..., And a,
(B, c ...) is divided into 3 phases for each scanning line, and each is divided into 1
Time-axis compression to / 3, and one scan line (for example,
The VT signals for three scanning lines (for example, the scanning lines 1, 2, and 3) are time-axis-multiplexed with respect to the scanning line A) to form 120i.

[0005]

The above-mentioned conventional technique for time-division-multiplexing a three-phase VT signal sequence has a drawback in that the image quality is greatly deteriorated due to ghost interference in the transmission path. Hereinafter, this drawback will be described in detail.

[0006] In the current television transmission path, a broadcast wave is often reflected by a building or terrain, and ghost interference is often generated in which a broadcast signal is superimposed on a regular signal with a time delay.

In the conventional system in which the VT signal is time-axis-compressed to 1/3 and time-division-multiplexed, the VT signal is time-expanded three times and added to the main signal at the time of reproduction. On the other hand, the ghost of the VT signal is generated at the position three times away on the screen. In addition, 120 shown in FIG.
In the i-type signal, for example, the right end of the signal 1 on the scanning line A is delayed and superimposed on the left end of the signal 2, and a ghost having a large amplitude not only on the right side of the image but also on the left side of the image toward the screen. Will occur. Therefore, a ghost disturbance that is significantly larger than that of the current receiver will occur.

Devices for removing ghosts are already on the market, but at present they are still expensive. Further, in order to completely remove the ghost of the VT signal compressed by the 1/3 time axis, the signal processing of the ghost removing apparatus needs to have a time accuracy of three times, which is more efficient and expensive and economical. is not.

Therefore, it is an object of the present invention to provide a television augmented signaling system with less ghost interference than before.

[0010]

In order to achieve the above object, a VT signal is divided into n phases (n is an integer of 3 or more), frequency-multiplexed, and then transmitted by an upper and lower non-picture section.

[0011]

The operation of the present invention will be described with reference to FIG. 36
0i type VT signal (scanning lines 1, 2, 3, 4,
5, 6 ...) and three-phase signal series (scan lines 1, 4, ..., 2,
5 ..., 3, 6 ...), frequency-multiplex them,
120i type signal (scan line A = 1 + 2 + 3, B = 4 +
5 + 6, ...).

Since this frequency-multiplexed signal is not accompanied by companding on the time axis, even if a ghost occurs on the transmission line, a ghost image of the VT signal is produced at the same position as the main signal. Therefore, the ghost interference is almost the same as that of the current receiver, and the influence of the ghost can be reduced as compared with the conventional augmented signal system by time division multiplexing.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. For the sake of simplification of explanation, an example will be shown in which a reinforcement signal is assumed to be a VT signal and the VT signal divided into three phases is frequency-multiplexed.

FIG. 1 shows a block diagram of an embodiment of the present invention. In the figure, on the transmitting side, a wide image signal with an aspect ratio of 16: 9 is input to a reinforcement signal separation circuit 1 described later in a progressive scanning mode with 360 effective scanning lines (hereinafter, referred to as 360p), and 360i is input. The morphological main signal and the VT signal are separated. The VT signal is divided into three phases and frequency-multiplexed by a frequency multiplexing circuit 2 described later, and converted into a 120i form. By using the switch 3, the main signal of the form of 360i is arranged at the center of the current screen with an aspect ratio of 4: 3, and
The 20i type VT signal is arranged in the upper and lower non-image portions of the current screen and output, and is used as a transmission signal. The receiving side performs reverse processing and
Obtain a 60p wide image output. That is, after the main signal and the VT signal are separated by the switcher 4, the VT signal is converted into the 360i form by the frequency separation circuit 5 described later. Further, a reinforcement signal synthesizing circuit 6 described later combines the main signal and the VT signal to obtain a 360p type signal.

FIG. 4 shows an example of the operation of the frequency multiplexing circuit 2. In the figure, the VT signal sequence divided into three phases is
Shown as signals 1, 2, and 3, respectively.

First, in FIG. 4A, the signal 1 is multiplexed as it is without being modulated in the baseband, and the signals 2 and 3 are multiplexed by quadrature amplitude modulation (QAM). In order to effectively use the transmission band of 4.2 MHz of the current television system,
The bandwidth of signals 1, 2, and 3 is 1.4 MHz (=
4.2 / 3), and the carrier frequency of quadrature modulation is 2.8M.
It is preferable to set to Hz (= 4.2 × 2/3). However, this carrier frequency is the color subcarrier frequency (fsc =
3.58 MHz) and horizontal scanning frequency (fh = 15.75)
If it is set to be expressed by a simple integer ratio with respect to (kHz), it is convenient in terms of circuit and operation. 2.8MHz
As a value close to, for example, 7 / 9fsc or 11 / 14f
sc etc. are possible. In addition, S / N for orthogonal modulation / demodulation
If the deterioration (3 dB) is corrected in advance on the transmitting side and the amplitude (gain) of the modulated carrier wave is set to 141%, the S / N ratios of the signals 1, 2, and 3 on the receiver side can be made equal.

In FIG. 4B, the signals 1 and 2 are quadrature amplitude modulated (QAM) and multiplexed, and the signal 3 is vestigial sideband amplitude modulated (VSB modulated) and multiplexed. Compared with the method of FIG. 4A, band loss of the signals 1, 2, and 3 occurs by the bandwidth of the double sideband component in VSB. For example, if the carrier frequency of QAM is 1/3 fsc and the carrier frequency of VSB is fsc, the bandwidths of signals 1, 2, and 3 are 1.2 MHz, respectively. However, in this method, since no DC component is generated, the receiver is less likely to be out of synchronization, and the DC component can be removed on the receiver side, which makes it more resistant to DC fluctuations such as sag. In addition,
In order to make the S / N on the receiver side equal to that for baseband transmission, the modulation carrier amplitude of QAM and the gain of the double sideband component of VSB are set to 141%, and the gain of the single sideband component of VSB is set to 200%. And it is sufficient. Further, although it is a loss in terms of S / N, gain correction (also called VSB correction or Nyquist correction) at the time of VSB demodulation is performed on the transmission side in advance, and as shown by a dotted line or a broken line in FIG. If the signal is transmitted after being filtered, the correction on the receiving side becomes unnecessary and the hardware can be simplified.

Although the characteristics are not as good as those in FIGS. 4A and 4B, the following modified examples are also possible.

In FIG. 4C, as in the case of FIG. 4B, signals 1 and 2 are quadrature-modulated and multiplexed, and signal 3 is converted to V.
SB modulated and multiplexed. However, the signal 3 has the upper sideband extended to a high range, and the carrier frequency of VSB modulation is slightly lower than that of FIG. 4B, for example, 5/6 fsc. In this method, if the quadrature modulation component leaks as the lower sideband component of VSB, it becomes a low-frequency component of the signal 3 and becomes a large interference. Therefore, a sharper band separation filter than that in the case of FIG. 4B is required. Is. The bandwidths of the signals 1, 2, and 3 are the same as in the case of FIG.

In FIG. 4D, the signal 1 is VSB-modulated and multiplexed on the low frequency side, and the signals 2 and 3 are orthogonally modulated and multiplexed on the high frequency side. The carrier frequencies of quadrature modulation and VSB are, for example, 1/3 fsc and 5/6 f, respectively.
If sc, the bandwidths of the signals 1, 2, 3 are the same as in the case of FIG. For crosstalk between signals, see FIG.
It is the same as the case of (c).

In FIG. 4E, as in the case of FIG. 4D, the signal 1 is VSB modulated and multiplexed, and the signals 1 and 2 are orthogonally modulated and multiplexed. However, the signal 1 has the upper sideband extended to a high range, and the carrier frequency of VSB modulation is slightly lower than that in FIG. 4D, for example, 1/6 fsc. Crosstalk between signals is as small as in the case of FIG. However, since the carrier frequency of the signal 1 is low, there is a possibility that a harmonic wave and a fundamental wave are mixed at the time of demodulation to cause intermodulation distortion. Therefore, the signal is once converted to a high frequency and then demodulated, or complex signal processing (reference document 2: Ohnishi et al. “New frequency conversion method by complex signal processing” IEICE Technical Report CAS 88-45 (Aug. 198)
8)) etc. need to be used.

In FIGS. 4F and 4G, signals 1, 2, and 3 are all VSB-modulated and multiplexed. The carrier frequencies of the respective signals are, for example, 2 / 9fsc, 11 / 18fsc, and fsc in the case of FIG. 4 (f), and are, for example, 1 / 6fsc, 5 / 9f in the case of FIG. 4 (g).
With sc and 17/18 fsc, the signal bandwidth of each case is 0.8 MHz. Also, FIG.
In (h), all the signals 1, 2, and 3 are subjected to double sideband amplitude modulation (DSB modulation) and multiplexed. As the carrier frequency of each signal, for example, 7/36 fsc, 7/12
fsc and 35 / 36fsc, the signal bandwidth is 0.
It becomes 7MHz. These are remarkably smaller than the signal bandwidth that can be originally secured (1.4 MHz = 4.2 / 3), but are strong against the phase distortion (orthogonal distortion) of the transmission line.

The VSB modulation shown in FIGS. 4 (b) to 4 (g),
It is also possible to multiplex other signals or high-definition components of the same signal by quadrature modulation with respect to the DSB modulation of FIG. 4 (h).

FIG. 5 shows a configuration example of the reinforcement signal separation circuit 1 and the reinforcement signal synthesis circuit 6. Reinforcement signal separation circuit 1
Is composed of a vertical low-pass filter 7, a vertical high-pass filter 9, and a sequential-> interlaced scanning conversion circuit 8, 10. The reinforcement signal synthesizing circuit 6 is composed of interlace-to-sequential scan converting circuits 11 and 13, a vertical low-pass filter 12, a vertical high-pass filter 14, and an adder 15. This configuration is called SSKF, and for example, the filter characteristics described in Reference 1 may be used as they are.

FIG. 6 shows a configuration example of the frequency multiplexing circuit 2. In this configuration example, frequency multiplexing is performed in the form shown in FIG. The input VT signal is first filtered by the horizontal low-pass filter 16 into a predetermined band (for example, 1.4 MHz =
4.2 / 3) and then delay circuits 17 and 18
By 1H (H is horizontal scanning period = 63.5μ
(Seconds) each. The output of the delay circuit 18 is the signal 1 and is input to the adder 21 without being modulated in the baseband. The output of the delay circuit 17 is amplitude-modulated by the multiplier 19 on the carrier wave cos (2πft) to obtain the signal 2, which is input to the adder 21. Further, the output of the horizontal filter 16 is amplitude-modulated by the multiplier 20 on the carrier wave sin (2πft) to be a signal 3, which is input to the adder 21. However, f is a frequency (for example, 7 / 9fsc), and t is time. Further, as described above, in order to compensate for the S / N deterioration due to modulation / demodulation, carrier amplitude correction of 3 dB (141%) may be performed. The signal multiplexed by the adder 21 is ⅓ by using the memory 22 controlled by the control circuit 23.
Scanning line thinning (360i → 120i conversion) and position shift are performed, and the upper and lower non-image portions are arranged. The frequency-multiplexed VT signal is adjusted to a predetermined (standard) gain by the gain adjusting circuit 24 and then used as an output signal.

FIG. 7 shows a configuration example of the frequency separation circuit 5. In this configuration example, frequency-multiplexed signals are separated in the form shown in FIG. The input VT signal is
Using the memory 25 controlled by the control circuit 26, the position is shifted from the upper and lower non-image portions to the central portion, and three scanning lines are repeatedly output. After adjusting this signal to a predetermined (standard) gain by the gain adjusting circuit 27,
Input to the switch 30, the multiplier 28, and the multiplier 29. The multiplier 28 multiplies the carrier wave cos (2πft) to demodulate the signal 2, and the multiplier 29 calculates the carrier wave sin.
The signal 3 is demodulated by multiplying by (2πft), and is input to the switcher 30. The switcher 30 sequentially switches the three input signals for each scanning line, and outputs 120i → 3.
60i conversion is performed. Unwanted components (modulated signals 2 and 3 and harmonic components due to demodulation) included in this signal are removed by the horizontal low-pass filter 31 to be output signals.

Although the case where the VT signal is frequency-multiplexed has been described above as an example, the present invention is not limited to this, and other reinforcing signals (for example, the above-mentioned VH signal) are also applicable. Obviously, the same applies. Further, the present invention can be applied by using a signal obtained by multiplexing (for example, time-frequency multiplexing) a VT signal and a VH signal as one reinforcement signal.

Further, the present invention is not limited to the case where the reinforcing signal is divided into three phases, but generally n phases (n is 3).
It is clear that it can also be applied to the case of division into the above integers). For example, n = 2m + 1 (where m is a positive integer)
In case of 2m phase reinforcement signal sequence,
Quadrature amplitude modulation (QA) is performed on a total of 2m carriers having orthogonal phases for m different frequencies.
M), the remaining one-phase reinforcing signal sequence is frequency-multiplexed without modulation, or a carrier having a different frequency is subjected to vestigial sideband amplitude modulation (VSB) and frequency-multiplexed. ) Or (b), the transmission band can be used efficiently (without waste). When n = 2m (where m is an integer of 2 or more), the 2m-phase reinforcing signal sequence has a total of 2m carriers having phases orthogonal to each other for m different frequencies. If they are quadrature amplitude modulated (QAM) and multiplexed, the transmission band can be used efficiently.

[0029]

According to the present invention, since the time axis companding unlike the conventional reinforcement signal system is not performed, the ghost of the reinforcement signal is generated at the same position as the ghost of the main signal, which is similar to that of the existing receiver. It doesn't cause such a big ghost disturbance.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of a conventional example.

FIG. 3 is an operation explanatory diagram of the present invention.

FIG. 4 is an operation explanatory diagram of the embodiment of the present invention.

FIG. 5 is a configuration diagram of a circuit used in the present invention.

FIG. 6 is a configuration diagram of a circuit used in the present invention.

FIG. 7 is a configuration diagram of a circuit used in the present invention.

[Explanation of symbols]

1 ... Reinforcement signal separation circuit; 2 ... Frequency multiplex circuit; 3,4,30 ... Switcher; 5 ... Frequency separation circuit; 6 ... Reinforcement signal combination circuit; 7,9,1
2,14 ... Vertical filter; 8,10,11,13 ... Scan conversion circuit; 15,21
… Adder; 16,31… Horizontal filter; 17,18… Delay circuit; 19,2
0,28,29 ... Multiplier; 22,25 ... Memory; 23,26 ... Control circuit; 24,2
7 ... Gain adjustment circuit.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Norihiro Suzuki 1-280, Higashi Koikeku, Kokubunji, Tokyo Inside Central Research Laboratory, Hitachi, Ltd. (72) Kazuo Ishikura 1-280, Higashi Koikeku, Kokubunji, Tokyo Hitachi, Ltd. Central Research Laboratory

Claims (5)

[Claims] 1. A television reinforcement signal system for transmitting a reinforcement signal while maintaining compatibility with a current television, wherein the reinforcement signal is divided into n-phase (where n is an integer of 3 or more) signal sequences, and these are divided. A television-enhanced signal system characterized by frequency-multiplexed transmission. 2. The reinforcing signal according to claim 1, wherein at least either one or both of a signal for reinforcing the vertical temporal resolution (VT signal) and a signal for reinforcing the vertical resolution (VH signal) are included. Television reinforcement signal system characterized by. 3. In claim 1 and 2, when n = 2m + 1 (where m is a positive integer), for a 2m-phase reinforcing signal sequence, phases that are orthogonal to each other for each of m different frequencies. Of 2 m in total are subjected to quadrature amplitude modulation (QAM), and the remaining one-phase reinforcing signal sequence is frequency-multiplexed without modulation, or carriers having different frequencies are vestigial sideband amplitude modulated (QAM). V
A television-enhanced signaling system characterized by SB) and frequency multiplexing. 4. In claim 1 or 2, when n = 2m (where m is an integer of 2 or more), 2m-phase reinforcing signal sequences are orthogonal to each other for m different frequencies. A television-enhanced signaling system characterized by quadrature amplitude modulation (QAM) and frequency-multiplexing a total of 2 m carriers having phases. 5. The television reinforcement signal system according to claim 1, 2, 3, or 4, wherein the reinforcement signal is arranged and transmitted in an area displayed at the upper and lower portions of a current television screen.