JPS6388992A - Television signal transmission system - Google Patents

Abstract

PURPOSE:To widen the transmission band of I, Q signals by making the band zone of luminance signals larger than a standard band width, and making the frequency spectrum of carrier chrominance signals of I, Q signals of chrominance signals asymmetric vertically while centering arround respective chrominance subcarriers. CONSTITUTION:Chrominance signals of R, G, B from a camera are inputted respectively to input ends 1-3, and converted to signals Y (luminance signal), I (broad band chrominance signal), Q (narrow band chrominance signal) by a matrix circuit 4. Band zone of Y signals is enlarged to a standard band zone or above. Further, the frequency spectrum of carrier chrominance signals of I, Q signals are made asymmetric vertically while centering arround respective chrominance subcarriers. High frequency component of I signals is transmitted by the lower side wave zone of the carrier chrominance signal and high frequency component of Q signals is transmitted by the upper side wave zone of the carrier chrominance signal.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a color television signal transmission system, and more particularly to a wideband transmission system compatible with the standard NTSC system.

(Prior art) The prior art of this invention is the standard NTSC system itself, which is a well-known technology, for example, literature, Broadcasting Technology Volume 2 Broadcasting System, pages 132 to 153, Japan Broadcasting Corporation published by Japan Broadcasting Publishing Association, January 2, 1982.
It is described in detail in the first printing issued on the 0th.

(Problems to be Solved by the Invention) In the conventional standard NTSC system, the transmission bandwidth is 4.
2M) Iz, so even if the transmission bandwidth of the NTSC signal could be transmitted in a band wider than 4.2MHz, the band of the ■ signal in the color signal would be 1.5MHz2,Q. The signal band cannot be greater than 0.5 MIIz.

Therefore, an object of the present invention is to eliminate this drawback and to widen the transmission band of the Q signal and furthermore the transmission band of the I signal if the transmission bandwidth of the NTSC system can be wider than 4.2 FIHz. The aim is to provide a transmission method that makes it possible.

(Means for Solving the Problems) In order to achieve this object, the television transmission system of the present invention has the advantage that the brightness (Y) Regarding signals, the bandwidth is expanded beyond the standard bandwidth, and
Regarding the I signal and Q signal of the color signal, ■ The frequency spectrum of the carrier color signal of the signal and the Q signal is vertically asymmetrical with respect to the color subcarrier, respectively, and ■ The high frequency component of the signal is the lower wave of the carrier color signal. By transmitting the high-frequency components of the Q signal through the upper sideband of its carrier color signal,
High-frequency components of each signal and Q signal without crosstalk.
Moreover, it is intended to be transmitted while maintaining consistency with the standard NTSC system.

Furthermore, in addition to the above-mentioned transmission processing, the television transmission system of the present invention can convert the high-frequency components of the above-mentioned (1) signal to the lower sideband of its carrier color signal, if there is further surplus in the wide bandwidth. At the same time, the upper sideband of the chrominance signal, which carries the signal in a frequency range higher than the band used for transmitting the high-frequency component of the Q signal, is also used for transmission.

(Examples) The present invention will be described in detail below by way of examples with reference to the accompanying drawings.

FIG. 1(c) shows a transmission signal frequency spectrum according to the first embodiment of the present invention, and in this case, the transmission bandwidth is shown as approximately 5 MHz. Of course, this bandwidth is not limited to this, and can be made narrower or wider depending on the required luminance signal resolution or Q signal resolution.

FIG. 1(a) shows a circuit configuration block diagram of a television signal transmitting side encoder for obtaining a transmission signal having the frequency spectrum shown in FIG. 1(c).

In Figure 1(a), red (R), green (G) from the camera are shown.
), blue (B) color signals are input to the input terminals 1, 2, and 3, respectively, and the matrix circuit 4, which is the same as the conventional standard NTSC system, outputs Y (luminance signal), ■ (broadband chrominance signal), and Q (narrowband chrominance signal). color signal). Y signal is delay circuit 5
and is applied to one input of the adder 13. The delay time of the delay circuit 5 is equal to the delay time of the color signal system LPF (low pass filter) 6, 7, modulator 8゜9, BPF (band pass filter) 10.11, adder 12, and Y This eliminates the delay time difference between the signal and the color signal.

The I and Q signals of the output of the matrix circuit 4 are each L
Applied to PF6 and PF7. In this example, Fig. 1(c)
LPF 6.
The cutoff frequency of 7 is set to 5 MHz. Of course, these bandwidths can be varied as needed.

LPF 6. The outputs of 7 are applied to modulators 8 and 9, respectively. The color subcarrier (f sc 3.58MHz) generated by the color subcarrier oscillator 16 is applied to the modulator, and the phase of the color subcarrier applied to the signal modulator is as follows.
The phase is shifted by a phase shifter 15 so as to be delayed by 90 degrees with respect to the phase of the color subcarrier applied to the Q signal modulator. This color subcarrier is exactly the same as in the conventional NTSC system.

The outputs of the modulators 8.9 are then respectively applied to the inputs of the BPFI sails 11. The passband of BPFIO is shown in Figure 1(c).
1 signal modulated wave spectrum can be obtained. That is, in this case, if the color subcarrier frequency is fsc, then f
sc 1.5M1lz to f sc +0.5MHz
up to. Also, the passband width of BPFII is f sc
From 0.5MHz to Esc+1.5MHz. The output signals of the BPPIo, 11 are added in an adder 12, and then the output thereof is further added with the Y signal in an adder 13, and becomes a transmission signal at an output end 17 via an LPF 14.

Although the LPF 14 does not necessarily need to be included in the encoder, if the cutoff frequency of the LPF 14 is set to 4.2 MH2, the signal spectrum will be the same as that of a conventional NTSC signal. Since the burst signal, synchronization signal addition, etc. are completely the same as those of the conventional NTSC encoder, their explanation will be omitted.

Next, a receiving side decoder for demodulating the television signal of this embodiment will be explained.

The television transmission signal processed by the encoder shown in FIG. 1(a) is applied to the input end 18 of the circuit configuration block diagram of the receiving side decoder shown in FIG. 1(b) via a transmission path.

This input signal is first applied to a delay circuit 20 via a color subcarrier trap 19. This signal is a Y signal, and the output of the delay circuit 20 is applied to the matrix circuit 21. The delay circuit 20 is for eliminating the time difference with the color signal at the input of the matrix circuit 21. Meanwhile, the input television transmission signal is also applied to the BPF 22.23 for demodulating the color signal.

The passband characteristics of BPF22.23 are the same as those of BPFIo and 11 of the transmitting encoder. B.P.
The output signal of F22.23 is applied to synchronous detectors 24 and 25, and T and Q signals are demodulated from the carrier color signal.

The color subcarrier generated by the color subcarrier oscillator 29 (f sc'3.58M1lz) is applied to the M detector 24+ 20, but the phase of the color subcarrier applied to the synchronous detector 24 is shifted. 28, the phase is delayed by 90° from the phase of the color subcarrier applied to the synchronous detector 25. The outputs of the synchronous detectors 24 and 25 are each LPF 26.
27 to the matrix circuit 21. LP
The cutoff frequency of F26 and 27 is 1.5MHz in this example.
and the output terminals 30, 31, 32 of the matrix circuit 21
demodulated R, G, and B signals are obtained respectively.

In the demodulation of transmitted television signals, conventional NTSC
In the second method, YC separation is performed using a comb filter in order to remove cross-color interference, but this can of course be applied to this embodiment as well.

Next, an embodiment will be described in which the transmission bandwidth of I and Q signals is widened to 1.5 MHz or more.

The basic configurations of the transmitting side encoder and the receiving side decoder are the same as those shown in FIGS. 1(a) and 1(b), respectively.

First, a second embodiment will be described in which the bandwidth of the signal is expanded to 1.5 MHz or more. In the encoder shown in FIG. 1(a), the cutoff frequency of the LPF 6 is set to 1.5 MHz or higher, for example, 2.4 MIIz. In this case, the band of the Q signal remains at 1.5 Mtlz. The output of the LPF 6 is balanced modulated by the balanced modulator 8 and then band limited by the BPFIO, but the passband of the BPFIO is fsc-2,4-
Hz to Esc+0.5MHz. The other points on the encoder side are I and Q signals of 1.5MHz each.
This is the same as when transmitting in the 0.5MHz and 0.5MHz bands. FIG. 2 shows the frequency spectrum of the television signal in the second embodiment. In this embodiment, the cutoff frequency of the LPF 14 shown in FIG. 1(a) is 6 M)lz.

In the decoder, the BPF220 passband should be determined according to the signal spectrum in Figure 2, and the passband is the same as the BPFIO passband in this case, fsc2.4MH.
z to fsc10.5MHz. Also Lr'
The cutoff frequency of F26 is also 2.4MIIz.

Next, a third example will be shown. In this case too, the bandwidth of the ■ signal is 2.4MIIz, and the bandwidth of the Q signal is l, 5MHz.
However, the difference from the second embodiment is that the passbands of the BPFIO shown in FIG. 1(a) and the BPF 22 shown in FIG. 1(b) are changed. That is, the passband of BPFIO and 22 is f IC-1,5M) Iz to E sc +
up to 0.5MHz and f8. +1.5 MIIz to f s
c+ Up to 2.4MHz. FIG. 3(a) shows this passband spectrum characteristic, and FIG. 3(b) shows the spectrum of the television signal in the third embodiment. Naturally, the passband width of LPF6 and LPF26 is also 2.4M.
)lz.

Next, as a fourth example, the Q signal band is set to 1.5MHz.
An example of making it wider is shown below. In this case, the corresponding first
Figure (a) The cutoff frequency of the LPF7 shown is 1.5Mtlz
The above shall apply. Here, this cutoff frequency will be explained as 2.4 MHz.

With the expansion of the passband of the LPF 7 shown in FIG. 1(a), the passband of BPFII is also changed from fsc 0.5MHz to rsc÷2.4MlI2. On the other hand, on the decoder side, the passband of BPF23 is set to BPFII as shown in Figure 1(b).
At the same time, the passband of LPF27 is also 2.4.
Let it be MH2. As for (2) signals, the transmission bandwidth is, of course, limited to 1.5 MH2.

(Effects of the Invention) As explained above, by using the transmission method of the present invention, N
When transmitting TSC signals in a bandwidth wider than the standard bandwidth, each transmission band for luminance signals, It is possible to transmit color television signals that can be expanded without difficulty, have no crosstalk between signals, and maintain compatibility with the standard NTSC system.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIGS. 1(a) and 1(b) show circuit configuration block diagrams of a transmitting side encoder and a receiving side decoder, respectively, in the transmission system of the present invention, and FIG. Fig. 2 shows the frequency spectrum of the transmission signal in the second embodiment; Fig. 3 shows the frequency spectrum of the transmission signal in the third embodiment; and Fig. 3 shows the frequency spectrum of the transmission signal in the third embodiment. (b) shows the transmission frequency spectrum. 1, 2.3.18... Input terminal 4.21... Matrix circuit 5.20... Delay circuit 6.7.14.26.2
7...LPF8.9...Modulator 10.1
1.22.23...BPF12, 13...Adder
15.28... Phase shifter 16, 29... Color printing carrier wave oscillator 17, 30.31.32... Output end 19... Color subcarrier trap 24, 25... Demodulator

Claims (1)

[Claims] 1. In a color television signal transmission system, NT
When transmitting SC signals with a wider bandwidth than the standard bandwidth, the bandwidth of the luminance signal is expanded beyond the standard bandwidth, and the frequency spectra of the carrier color signals of the I and Q signals are expanded, respectively. The feature is that the color subcarrier is vertically asymmetrical, and the high-frequency components of the I signal are transmitted by the lower sideband of the carrier color signal, and the high-frequency components of the Q signal are transmitted by the upper sideband of the carrier color signal. Television signal transmission system. 2. In the color television signal transmission system, NT
When transmitting SC signals with a wider bandwidth than the standard bandwidth, the bandwidth of the luminance signal is expanded beyond the standard bandwidth, and the frequency spectra of the carrier color signals of the I and Q signals are expanded, respectively. The color subcarrier is vertically asymmetrical with respect to the center, and the high-frequency components of the Q signal are transmitted by the upper sideband of the carrier color signal, and the high-frequency components of the I signal are transmitted by the lower sideband of the carrier color signal and the Q signal. A television signal transmission system characterized in that transmission is performed using an upper sideband of an I signal carrier color signal in a frequency range higher than the band used for transmitting high frequency components.