JPH03157090A - Television signal transmission system - Google Patents

Abstract

PURPOSE:To separate a chrominance carrier signal and a luminance signal completely at a reception section by sending a difference signal between a luminance signal obtained through color luminance separation and a luminance signal from a signal source to a receiver side and subtracting the luminance signal decoded from a television signal at the receiver side so as to decode the chrominance carrier signal. CONSTITUTION:Two color signal 51,52 are balance-modulated at a modulator 1 in a transmission section 100 and chrominance carrier signal C53 is obtained and the chrominance carrier signal C53 and a luminance signal Y50 are added by an adder 2 to obtain an NTSC signal 54. The NTSC signal 54 is inputted to a luminance signal separator 4, in which a separated luminance signal Yb56 is extracted by the chrominance luminance separate processing. Then an NTSC signal (Yb+C) 54 and a difference signal (Y-Yb) 55 are obtained by the processing in the transmission section 100 and sent to a reception section 101. The section 101 applies the same chrominance luminance separate processing as that of the transmission section to the signal and a received separated luminance signal 57 is obtained. Moreover, the decoded luminance signal 58 is subtracted from the NTSC signal 54 to obtain the decoded chrominance carrier signal 59 and it is separated into two decoded color signals 60,61 by the demodulator 5.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a television signal transmission system.

(Prior art) Current television signals are transmitted in a composite format in which the color signals ■ and Q are balanced modulated and added to the luminance signal, as shown in Document 1rNHK Color Television Textbook (top row (edited by Japan Broadcasting Corporation)). That is, as shown in FIG. 4, the two color signals 51 and 52 in the transmitter 104 are balanced-modulated in the modulator 1 to become a carrier color signal 53, and this carrier color signal 53 and the luminance signal 50 are The adder 2 adds the current television signal 54.The frequency spectrum of the television signal 54 is generally determined by the third The structure is as shown in Figure (a).In other words, the peak of the luminance signal is located at an integral multiple of the line frequency fH, and the subcarrier frequency (L, 3.58 MHz) is shifted by 1/2 fH from the peak. There is a peak of the color signal at the center. However, the carrier color signal is multiplexed only in the band of approximately 2 to 4.2 MHz. 105), the chrominance signal and the luminance signal are separated again.Generally, it is impossible to completely accurately separate the chrominance signal and the luminance signal, so conventionally they are separated using a simple method.For example, There is a method of separating the signal shown in FIG. 3(C) as a carrier color signal by filtering the television signal 54 with the characteristics shown in FIG. 3(b).

However, in the shaded area in FIG. 3(C), the carrier color signal and the luminance signal remain without being separated.

(Problems to be Solved by the Invention) The above-mentioned conventional technology has a drawback in that the carrier color signal and the luminance signal cannot be completely separated, as shown by the shaded area in FIG. 3(C).

SUMMARY OF THE INVENTION An object of the present invention is to provide a television signal transmission system that eliminates the drawbacks of the conventional system and allows complete separation of a carrier color signal and a luminance signal in a receiving section.

(Means for Solving the Problems) In the television signal transmission system of the first invention, on the transmitting side, a luminance signal and a color signal obtained from a signal source are converted into a television signal in a composite format, A luminance signal obtained by color-luminance separation of the television signal is used as a separated luminance signal, a difference signal between the luminance signal obtained from the signal source and the separated luminance signal is obtained, and the difference signal is combined with the composite format television signal. The signal is transmitted, and on the receiving side, a luminance signal obtained by color-luminance separation of the composite format television signal is used as a received separated luminance signal, and a signal obtained by adding the received separated luminance signal and the difference signal is restored. A luminance signal is obtained, and the difference between the composite format television signal and the restored luminance signal is demodulated to produce a restored chrominance signal.

Further, in the television signal transmission system of the second invention, on the transmitting side, the color signal and luminance signal obtained from the signal source are converted into a composite format television signal, and the composite format television signal is separated into color and luminance. The carrier color signal obtained by the above-described method is used as a separated carrier color signal, a difference signal between the modulation signal of the color signal obtained from the signal source and the separated carrier color signal is obtained, and the difference signal and the composite format television signal are calculated. On the receiving side, a carrier color signal obtained by color-luminance separation of the composite format television signal is used as a received separated carrier color signal, and a signal obtained by adding the received separated carrier color signal and the difference signal is obtained. The restored carrier chrominance signal is used as a restored carrier chrominance signal, the restored carrier chrominance signal is demodulated to obtain a restored chrominance signal, and the difference between the composite format television signal and the restored carrier chrominance signal is used as a restored luminance signal.

Note that on the transmitting side of the first or second aspect of the invention, band limiting processing may be performed on the differential signal transmitted to the receiving section.

The present invention relates to a method for more accurately separating a carrier color signal and a luminance signal in a receiving section in transmitting a television signal.

In the first invention, in addition to the composite format television signal, the receiving side receives a difference signal between a luminance signal obtained by subjecting the composite format television signal to color luminance separation and a signal source luminance signal. to be transmitted. On the receiving side, the luminance signal is restored by adding the luminance signal obtained by subjecting the composite format television signal to color/luminance separation in the same manner as on the transmitting side and the transmitted difference signal. Further, the carrier color signal is restored by subtracting the restored luminance signal from the composite television signal. Here, if the carrier color signal is C and the R degree signal is Y, then
A composite format television signal is Y+C.

The luminance signal obtained by color luminance separation in the transmitting section is
b, the difference signal to be transmitted is Y-Yb. If the luminance signal obtained by color luminance separation in the receiving section is Yb, the signal obtained by adding this and the difference signal Y-Yb is the luminance signal Y of the signal source, and the luminance signal can be obtained accurately. become. Further, by subtracting the obtained luminance signal Y from the composite television signal Y+C, the carrier color signal C can be obtained accurately.

In the second invention, in addition to the composite format television signal, a difference signal between a carrier color signal obtained by subjecting the composite format television signal to color luminance separation and a source carrier color signal is received. Transmit to the department. The receiving section restores the carrier color signal by adding the carrier color signal obtained by subjecting the composite television signal to color-luminance separation in the same way as the transmitter and the transmitted difference signal. Furthermore, the carrier color signal is restored by subtracting the restored carrier color signal from the composite format television signal. Similarly to the first invention, if the carrier color signal is C1 and the luminance signal is Y, then the composite format television signal is Y+C. If the carrier color signal obtained by color-luminance separation in the transmitting section is cb, the transmitted difference signal is C-Cb. If the carrier color signal obtained by color-luminance separation in the receiving section is Cb, this and the difference signal C-C
The signal obtained by addition with b is the source carrier color signal C, and the carrier color signal can be obtained accurately. Moreover, by subtracting the obtained carrier color signal C from the composite format television signal Y+C, the luminance signal Y can be obtained accurately.

In addition, as the difference signal transmitted in the first invention,
When transmitting Yb-Y instead of Y-Yb, the luminance signal Y is accurately restored by calculating the difference with the luminance signal Yb obtained in the receiving section.

Similarly, in the second invention, when transmitting Cb-C instead of C-Cb, the carrier signal C is accurately restored by calculating the difference with the carrier color signal Cb obtained in the receiving section. It is easy to understand what will happen.

Furthermore, the difference signal transmitted in the first or second invention is composed only of signal components in the frequency band on which the carrier color signal is multiplexed. Therefore, the signal band in which the carrier color signal is not multiplexed may not be transmitted. Furthermore, if the chrominance signal and the luminance signal do not need to be completely and accurately separated, the band of the differential signal to be transmitted may be made narrower. In this case, if the differential signal is multiplexed, for example, during the blanking period of the television signal,
There is no need to prepare a new transmission path for transmitting the differential signal.

(Example) Next, an example of the present invention will be described using the drawings. In the following explanation, it will be assumed that the composite format television signal is an NTSC signal as an example, but other methods such as a PAL signal may be used.

FIG. 1 is a block diagram showing the basic configuration of an embodiment of the first invention. In the transmitting section 100, first, the two color signals 51 and 52 are balanced-modulated in the modulator 1 to become a carrier color signal C53, and this carrier color signal 53 is converted into a luminance signal Y5.
0 is added by the adder 2 to obtain the NTSC signal 54. The NTSC signal 54 is input to the luminance signal separator 4,
For example, by conventional color and luminance separation processing, the separated luminance signal Y
b56 is extracted. Next, the difference between the source luminance signal Y50 and the separated luminance signal Yb56 is calculated by the subtracter 3 and output as a difference signal (Y-Yb) 55. This subtraction causes the separated luminance signal 56 to be subtracted from the luminance signal 50. The above processing in the transmitter 100 results in an NTSC signal (Y
b+C) 54 and a difference signal (Y-Yb) 55 are obtained and transmitted to the receiving section 101.

In the receiving section 101, first, the NTSC signal 54 is manually input to the luminance signal separator 4 and subjected to the same color and luminance separation processing as in the transmitting section to obtain a received separated luminance signal 57. Next, the received separated luminance signal 57 and the difference signal 55 are added together in an adder 2 and outputted as a restored luminance signal 58. Furthermore, NTSC signal 5
By subtracting the restored luminance signal 58 from 4, the restored carrier color signal 59 is obtained. The restored carrier color signal 59 is sent to the demodulator 5
is separated into two restored color signals 60 and 61.

FIG. 5 shows an example of the configuration of the luminance signal separator 4 used in the transmitting section 100 and the receiving section 101. That is, two line memories are used to generate the NTSC signal 54, a signal delayed by one line from the NTSC signal 54, and a signal obtained by delaying the NTSC signal 54 by one line.
Create a signal that is delayed by two lines, and for each
The comb-shaped filter 106 is configured by multiplying by /4.1/2 and -114 and adding them. Furthermore, the output of the comb filter 106 is passed through the bandpass filter 9 to separate the carrier color signal (
A received separated carrier color signal) 73 is obtained. A separated luminance signal (
A received separated luminance signal) 74 is obtained. Note that it is not necessary to use the same luminance signal separator 4 in the transmitting section and the receiving section, but if the same ones are not used, the restored luminance signal 58 and the restored carrier color signal 59 obtained in the receiving section will differ slightly. This will result in crosstalk.

Further, when calculating the difference between the luminance signal 50 and the separated luminance signal 56 in the transmitter 100, the separated luminance signal 56 may be subtracted from the luminance signal 50, or conversely, the separated luminance signal 56 may be subtracted from the luminance signal 50.
The luminance signal 50 may be subtracted from . However, the luminance signal 5
When the separated luminance signal 56 is subtracted from 0, a signal obtained by adding the received separated luminance signal 57 and the difference signal 55 is used as the restored luminance signal 58 in the receiving section, but when the luminance signal 50 is subtracted from the separated luminance signal 56 In order to do this, it is necessary to use a signal obtained by subtracting the difference signal 55 from the received separated luminance signal 57 as the restored luminance signal 58 in the receiving section.

Alternatively, the difference signal 55 that is the output of the transmitting section 100 may be subjected to band limiting processing before being transmitted to the receiving section. That is, the signal band of the difference signal 55 has the same bandwidth as the luminance signal 50, but in reality, the band of the carrier color signal is approximately 2 to 4.2 MHz, so the DC
The signal component of the difference signal 55 is not included in the signal band of ~2 MHz. Therefore, the required bandwidth of the differential signal 55 is 2.2
MHz would be fine. Therefore, the signal 1 of the difference signal 55
Even if the signal band is transmitted from DC to 2.2 MHz, it is possible to completely accurately separate the carrier color signal and the luminance signal in the receiving section. Furthermore, the signal energy of the carrier color signal is generally equal to the subcarrier frequency (-3,
The difference signal 55 does not necessarily need to cover the entire frequency band of the carrier chrominance signal, since the difference signal 55 tends to decrease as the frequency band becomes higher, centering around 58 MHz). Therefore, the signal band of the differential signal 55 may be further narrowed and transmitted.

FIG. 2 is a block diagram showing the basic configuration of an embodiment of the second invention. In the transmitter 102, first, the two color signals 51 and 52 are balanced-modulated in the modulator 1 to become a carrier color signal C53, and this carrier color signal 53 and a luminance signal Y5 are
0 is added by the adder 2 to obtain the NTSC signal 54. The NTSC signal 54 is input to the color signal separator 6, and is separated into a carrier color signal C by, for example, conventional color luminance separation processing.
b62 is extracted. Next, the difference between the carrier color signal 53 and the separated carrier color signal 62 is calculated by the subtracter 3 and output as a difference signal 63. This subtraction is such that the separated carrier color signal 62 is subtracted from the carrier color signal 53. The above transmitter 102
The NTSC signal 54 and the difference signal 63 are obtained through the processing at and transmitted to the receiving section 103.

In the receiving section 103, first, the NTSC signal 54 is input to the color signal separator 6, and subjected to the same color/luminance separation processing as in the transmitting section to obtain a received separated carrier color signal 64. Next, the received separated carrier color signal 64 and the difference signal 63 are added together in an adder 2 and outputted as a restored carrier color signal 65. Furthermore, by subtracting the restored carrier color signal 65 from the NTSC signal 54, a restored luminance signal 66 is obtained. The restored carrier color signal 65 is separated in the demodulator 5 into two restored color signals 67 and 68.

The configuration of the color signal separator 6 used in the transmitting section 102 and the receiving section 103 may be the same as that shown in FIG. Although it is not necessary to use the same components in the transmitting section and the receiving section, if the same components are not used, some crosstalk will occur between the restored luminance signal 66 and the restored carrier color signal 65 obtained in the receiving section. .

Furthermore, when calculating the difference between the carrier color signal 53 and the separated carrier color signal 62 in the transmitter 102, the separated carrier color signal 62 may be subtracted from the carrier color signal 53, or conversely, the carrier color signal 62 may be subtracted from the carrier color signal 53. The carrier color signal 53 may be subtracted. However, when the separated carrier color signal 62 is subtracted from the carrier color signal 53, the signal obtained by adding the received separated carrier color signal 64 and the difference signal 63 is used as the restored carrier color signal 65 in the receiving section.
When the carrier color signal 53 is subtracted from the separated carrier color signal 62, it is necessary to use a signal obtained by subtracting the difference signal 63 from the received separated carrier color signal 64 as the restored carrier color signal 65 in the receiving section.

Further, similarly to the embodiment of the first invention, the differential signal 63 output from the transmitting section 102 may be subjected to band limiting processing before being transmitted to the receiving section.

(Effects of the Invention) As described above, according to the present invention, it is possible to completely separate the carrier color signal and the luminance signal in the receiving section.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an embodiment of the first invention, FIG. 2 is a diagram showing the configuration of an embodiment of the second invention, and FIG. 3(a)
is a diagram showing the frequency spectrum of current television signals,
FIG. 3(b) is a diagram showing an example of filter characteristics for color signal separation, FIG. 3(C) is a diagram showing a carrier color signal extracted by the filter of FIG. 3(b), and FIG. is an explanatory diagram of a conventional system, and FIG. 5 is a block diagram of a color/luminance separator. In the figure, 1...Modulator, 2...Adder, 3...
- Subtractor, 4... Luminance signal separator, 5... Demodulator,
6... Color signal separator, 7... Color luminance separator, 8...
- Line memory, 9...Band-pass filter. Figure 3 Frequency

Claims (3)

[Claims] (1) On the transmitting side, the luminance signal and color signal obtained from the signal source are converted into a composite format television signal, and the luminance signal obtained by separating the composite format television signal into color and luminance is used as a separated luminance signal. Then, a difference signal between the luminance signal obtained from the signal source and the separated luminance signal is obtained, and the difference signal and the composite format television signal are transmitted, and on the receiving side, the composite format television signal is transmitted. A luminance signal obtained by color-luminance separation is a received separated luminance signal, a signal obtained by adding the received separated luminance signal and the difference signal is a restored luminance signal, and the composite format television signal and the restored luminance signal are A television signal transmission system characterized by demodulating the difference between the chrominance signal and the chrominance signal to obtain a restored color signal. (2) The transmitter converts the color signal and luminance signal obtained from the signal source into a composite format television signal, and separates and transmits the carrier color signal obtained by color and luminance separation of the composite format television signal. A color signal is obtained, a difference signal is obtained between a modulation signal of the color signal obtained from the signal source and the separated carrier color signal, the difference signal and the television signal in the composite format are transmitted, and the receiving side receives the television signal in the composite format. A carrier color signal obtained by color-luminance separation of a television signal of A television signal transmission method characterized in that a restored color signal is obtained by demodulating the composite carrier color signal, and a difference between the composite television signal and the restored carrier color signal is used as a restored luminance signal. (3) The television signal transmission system according to claim 1 or 2, wherein the transmission side performs band limiting processing on the difference signal transmitted to the reception section.