JPS604387A - Picture signal transmitting device - Google Patents

Abstract

PURPOSE:To transmit two television signals through 1-channel band width by transmitting the output wave of an oscillator intersecting each other at right angles by composing two modulated waves which are modulated in terms of amplitude with an analog picture signal and fetching the output wave by dividing the wave into two at the receiving side. CONSTITUTION:The output of an oscillator OSC is divided into two parts by a 90-degree hybrid circuit H-1 and carriers, whose phases are different by 90 deg. from each other, are supplied to amplitude modulating circuits AM-1 and AM-2. The amplitude modulating circuits AM-1 and AM-2 modulate an analog picture signal supplied to terminals 1 and 2 in terms of amplitude and supply the modulated analog picture signals to another hybrid circuit H-2. The two amplitude-modulated carriers composed at the hybrid circuit H-2 are frequency-converted by the output wave of a transmitting local oscillator T-LOC at a frequency converter CON and fetched to the outside. At the receiving side, the composed wave is divided into two parts, the 1st and 2nd outputs, and fetched as two separate analog signals.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to an image signal transmission device, and more particularly to an image signal transmission device with improved analog image transmission efficiency.

(bl) Prior Art and Problems Analog modulation and digital modulation are used to transmit image signals. - The former is divided into nine types: the 2-way modulation system and the frequency modulation system.

Amplitude modulation methods include double sideband modulation (DSB), single sideband modulation (SSB), and vestigial sideband modulation (VSB).
The vestigial sideband modulation (VSB) method is mainly used because of the ease of circuit configuration and the fact that it is within the transmission band.

On the other hand, the frequency modulation method is the amplitude modulation method (compared to the amplitude modulation method, which requires a wider transmission band, but is resistant to interference in the transmission path, so it is used for transmission in the microwave band.

Furthermore, digital modulation systems are inherently more resistant to interference than analog modulation systems, but have a wider transmission band. However, it is possible to compress bandwidth and is seen as promising for long-distance lines.

As mentioned above, in the transmission band, the vestigial sideband modulation (VSB) method is optimal from the point of view of ease of circuit configuration, but when transmitting television signals using this method, approximately 6 Pi'
There was a problem in transmitting the ITV signal in the transmission band of l'H2 and effectively utilizing the transmission band. The overall object of the present invention is to provide a 1IiIi image signal transmission device that can effectively utilize the transmission band when transmitting analog image signals.

(d) Structure of the Invention The object of the above invention is to provide an amplitude modulation circuit that amplitude modulates a carrier wave whose phase is 90 degrees with first and second analog signals, and a a modulating section comprising a combining means for combining outputs; a dividing means for dividing the output from the combining means into first and second outputs and further dividing the second output into two; and a first output from the dividing means. A carrier wave regeneration circuit that uses the output to regenerate carrier waves whose phases are stacked by 90 degrees, and a second output divided into two using the output from the carrier wave regeneration circuit, and a second output that is divided into two by phase detection. and second
This is achieved by providing an image transmission device characterized by including a phase detection circuit that extracts an analog image signal.

(e) Embodiment of the Invention Fig. 1 is a block connection diagram of an embodiment of the invention, and Fig. 1(a) shows the modulation section of the image signal transmission device, and Fig. 1(b) shows the modulation section of the image signal transmission device.
shows the detection section of the image signal transmission device.

In the figure, O8C is an oscillator, T-LOC is a transmitting local oscillator,
R-LOC is a receiving local oscillator, H-1 to H-4 are hybrid circuits, AM-1 and AM-2 are amplitude modulation circuits, CON is a frequency converter, AMP-1 to AMP-4
is an amplifier, MIX is a mixer, DET-1 and DET-2
are phase detection circuits, LPF-1 and LPF-I H are low-frequency wave transducers, G is a gate circuit, PLLFi phase
DL is a phase adjustment circuit, HD is a horizontal synchronization signal detection circuit, and 1 to 6 are terminals.

Among these blocks, the image signal transmission device modulation section shown in FIG. 1(a) is connected as follows.

The input terminal of the hybrid circuit H-1 is connected to the output terminal of the oscillator O8C through the outputs ψM of (1) and (2) (the child is oscillation 1) and the hybrid circuit H-1 through the modulation circuits AM-1 and AM-2'. -2, (1) and (2) input terminals 2 and the output terminal of the hybrid circuit H-2 are connected to the terminal 3 via the frequency converter CON and the amplifier AMP-1, and the amplitude modulation circuit AM
-1 and AM-2 to terminals 1 and 2, another input terminal of the frequency converter CON to the transmitting local oscillator T-
Each is connected to the LOC.

Next, the first group (shown in (b)) of the image signal transmission device detection section is connected as follows.

The input terminal of the amplifier AMP-2 is connected to the terminal 4 via the mixer MIX, and the output terminal of (1) is connected to the no-brid circuit (-
The output terminal of (2) is connected to the input terminal of gate circuit G (
Connect (1) of hybrid circuit H-3 to the input terminal of (1).
The output terminals of (2) and (2) are phase detection circuits DET-1 and D
ET-2, low-frequency E waveforms LPF-1 and LPF'-2, amplifiers AMP-3 and AMp-4 to terminals 5 and 6, and terminal 6 is connected to the gate via the horizontal synchronization signal detection circuit HD. A gate circuit G is connected to the input terminal (2) of the circuit G.

The IB power end is a phase lock loop circuit PLL.

The (2) input terminal of the mixer MIX is connected via the phase adjustment circuit DL and the hybrid H-4'e to the (2) input terminals of the phase detection circuits DET-1 and DET-2, and the (2) input terminal of the mixer MIX is connected to the receiving local oscillator R-LOC. Each is connected to the output terminal.

FIG. 2 is a diagram for explaining a block connection diagram of one embodiment of the present invention shown in FIG. 1, and the numbers shown on the left side of FIG. Since the waveforms are shown, the operation of the image signal transmission apparatus shown in FIG. 1 will be described in detail with reference to FIG.

The operation of the modulation section shown in FIG.
Since it is divided into two parts by 1, it is divided into two parts: -1 for amplitude modulation circuit and AM-
The phases of the carrier waves added to 2 are 90 degrees apart from each other.

On the other hand, analog image signals are applied to terminals 1 and 2.
, which amplitude modulates the carrier wave. When this carrier wave is amplitude modulated by 100% or more, its phase is reversed by 180 degrees (see Figure 2). 2 (see Figure 2 ■).

This composite wave is transmitted by the frequency converter CON to the transmitting local oscillator T-
The frequency is converted by the output wave of LOC, and the amplifier AMP-
After being increased in width to the required level in step 1, it is connected to the outside through terminal 3.

Next, the operation of the detection section shown in FIG. 1(b) is as follows.

The received signal applied to terminal 4 is mixed with the output signal of the receiving local oscillator R-LOC by the mixer MIX and converted into an intermediate frequency signal, and this converted signal is raised to the required level by the amplifier AMP-2. (See Figure 2 ■) 0 The amplified received signal is divided into first and second outputs,
Further, the second output is divided into two by a hybrid circuit H-3. This two-split received signal and a carrier wave whose phase differs by 90 degrees from a carrier wave regeneration circuit CR, which will be described later, are transmitted to phase detection circuits DET-1 and DET-2, respectively.
added to. Here, only the received signal component that is in phase with this carrier wave is detected, and the received signal components that have other phase relationships are not detected, so that the two analog image signals can be completely separated.

High frequency components of the separated image signals are removed by low-frequency wave generators LPF-1 and LPF-2, respectively, and amplified by high-frequency amplifiers AMP-3 and AMP-4 to the required level, and then sent from terminals 5 and 6. It is deposited outside (see Figure 2 ■ and ■).

On the other hand, in order to extract a horizontal synchronizing signal (part a in FIG. 2) from the increased image signal outputted to the terminal 6, a part of the output image signal is applied to the horizontal synchronizing signal detection circuit HD. At this point, the horizontal synchronizing signal included in the image signal is extracted and applied to the gate circuit G. Therefore, the gate circuit G repeats ON-OFF by this horizontal synchronization signal, and only the horizontal synchronization signal component of the first output wave of the amplifier AMP-2 added to the gate circuit G is extracted (the second Figure ■Diagnosis).

Then, the voltage controlled oscillator is controlled so that the phase of the output wave of the voltage controlled oscillator (not shown) included in the phase lock loop circuit PLL0 is synchronized with the phase of the extracted horizontal synchronization signal component. . The phase of the output signal of the voltage controlled oscillator is rotated by a phase adjustment circuit DL, divided into two by a 90-degree hybrid circuit H-4, and applied as a carrier wave to phase detection circuits DET-1 and DET-2.

The reason why the horizontal synchronization signal is extracted from the analog image signal is that since this signal has a constant frequency, a carrier wave for the phase detection circuit is created based on this signal.

Although the first and second analog image signals are extracted through the above operation, amplitude modulation can be performed directly in the high frequency section instead of in the intermediate frequency section. Further, although the analog image signal obtained at terminal 6 is used to detect the horizontal synchronization signal, it is also possible to completely synthesize the image signals of both terminals 5 and 6 for detection.

As a method for detecting this signal, it may be extracted using a bandpass filter, or a method using a commonly used differentiating circuit may be used.

(f) As described in detail, according to the present invention, the output waves of orthogonal oscillators are amplitude-modulated using analog image signals, and then the two modulated waves are combined and transmitted. By dividing the synthesized modulated wave into two and using a phase detection circuit to fully synthesize the original image signal, it is possible to transmit two television signals in a band where only one television signal could previously be transmitted. frequency can be used effectively.

[Brief explanation of the drawing]

FIG. 1 is a block connection diagram of an embodiment of the present invention, in which FIG. 1(a) shows the modulation section of the image signal transmission device, FIG. 11(b) shows the detection section of the image signal transmission device, and FIG. 2 shows the detection section of the image signal transmission device. 1A and 1B are diagrams for explaining the operation of the block connection diagram shown in FIG. 1, respectively. In the figure, O20 is an oscillator, T-LOG is a transmitting local oscillator,
H-1 to H-4 are hybrid circuits, AM-1 and AM
-2 is an amplitude modulation circuit, CON is a frequency converter, MIX is a mixer, DET-1 and DET-2 are phase detection circuits, L
PF-1 and LPF'-2 are low-frequency P wave generators, G is a gate circuit, PLL is a phase lock loop circuit, DL is a phase adjustment circuit, HD is a horizontal synchronization signal detection circuit, j to 6 are Aiko Each is shown below. ￥-1 ￥-1 αυ hair 2 呵

Claims (1)

[Claims] a modulation unit comprising an amplitude f-tai circuit that amplitude-modulates carrier waves whose phases differ by 90 degrees using first and second analog image signals; and a synthesizing means that synthesizes the outputs from the amplitude modulation circuit; The output from the combining means is divided into first and second outputs, and the second output is further divided into two by using a dividing means and the first output from the dividing means to generate carrier waves whose phases differ by 90 degrees from each other. a phase detection circuit that increases the first and second analog image signals by performing phase detection on a second output divided into two using a carrier wave regeneration circuit and an output from the carrier wave regeneration circuit; Including fr: An image signal transmission device characterized by: