JPH04319897A - Digital video signal transmission device - Google Patents

Abstract

PURPOSE:To always monitor the transmission quality by sending out a test signal even in the course of transmission of a digital video signal, and also, to execute the transmission of plural user data, as well. CONSTITUTION:A horizontal period detecting part 12 generates a signal <=1 for showing a specific horizontal scanning period of a vertical blanking period of a digital parallel video signal Sv1. A test signal generating part 13 generates a test signal St1 for evaluating a transmission quality by a digital sampling clock unit in the specific horizontal scanning period. A switching control part 14 generates a switching signal C1 by a digital sampling clock unit in the specific horizontal scanning period. A switching part 11 receives the digital parallel video signal Sv1, the test signal St1 and plural user data D11-D1n, selects one of them in accordance with the switching signal C1 and sends it out as a signal So.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital video signal transmission device, and more particularly to a digital video signal transmission device that can constantly monitor the transmission quality of digital signals.

0002

2. Description of the Related Art Conventionally, when a test signal is transmitted from a transmitting side to a receiving side in order to monitor the transmission quality of a digital signal, as shown in FIG.
is controlled according to the switching signal C1, and the digital video signal S
v and the test signal St, and on the receiving side, the test signal St is extracted from the received signal by controlling the gate circuit 32 with a switching signal C2 synchronized with the switching signal C1. are doing.

0003

As described above, conventionally, the digital video signal and the test signal are switched and sent out asynchronously, and the transmission quality is evaluated based on the sent out test signal. Therefore, there is a problem in that a test signal cannot be transmitted while transmitting a digital video signal.

SUMMARY OF THE INVENTION An object of the present invention is to provide a digital video signal transmission device that can transmit a test signal even when a digital video signal is being transmitted and can constantly monitor transmission quality.

[0005]

[Means for Solving the Problems] A digital video signal transmission device of the present invention includes a first horizontal period detection section that generates a signal indicating a specific horizontal scanning period of a vertical blanking period of a digital parallel video signal; a test signal generation unit that receives a digital sampling clock and a signal indicating the horizontal scanning period and generates a test signal for evaluating transmission quality in units of the digital sampling clock during the horizontal scanning period; and a signal indicating the horizontal scanning period. and a first switching control unit that receives the digital sampling clock and generates a first switching signal in units of the digital sampling clock during the horizontal scanning period; and a first switching section that receives each of the signals and selects and outputs one of them according to the first switching signal, on the transmitting side. a second horizontal period detection unit that generates a signal indicating a specific horizontal scanning period of the vertical blanking period of the received digital parallel video signal; a gate circuit that turns on and off in response to a signal indicating a horizontal scanning period from the second horizontal period detecting section, and a digital sampling synchronized with the signal indicating the horizontal scanning period from the second horizontal period detecting section and the received digital parallel video signal. a second switching control unit that receives a clock and generates a second switching signal in units of the digital sampling clock during the horizontal scanning period; and switches the received digital parallel video signal in accordance with the second switching signal. The receiving side includes a second switching section that extracts a test signal and a plurality of pieces of user data, and a test signal evaluation section that evaluates the extracted test signal.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention, in which the transmitting side includes a switching section 11 that selects one of a plurality of input signals according to a switching signal C1, and a switching section 11 that selects one of a plurality of input signals according to a switching signal C1, and a horizontal period detection unit 12 that generates a signal Sh1 indicating
It includes a test signal generation section 13 that generates a test signal St1 for evaluating transmission quality, and a switching control section 14 that generates a switching signal C1.

[0008] Here, the switching unit 11 receives the digital parallel video signal Sv1 and the plurality of user data D11 to
D1n is supplied, and one is selected according to the switching signal C1 and output as the signal So. Horizontal period detection unit 12
is supplied with a vertical synchronization signal V1 and a horizontal synchronization signal H1 synchronized with the video signal Sv1, and generates a signal Sh1 indicating a specific horizontal scanning period of the vertical blanking period. Also,
The test signal generation section 13 and the switching control section 14 are supplied with a digital sampling clock Sc1 and a signal Sh1, respectively.

Now, the test signal generating section 13 generates a signal Sh
1 and a digital sampling clock Sc1, test data is generated in units of digital sampling clocks during a specific horizontal scanning period of the vertical blanking period, and sent to the switching section 11 as a test signal St1. Similarly,
The switching control unit 14 generates a switching signal C1 in units of digital sampling clocks during a specific horizontal scanning period of the vertical blanking period, and sends it to the switching unit 11.

FIG. 2 is a diagram showing an example of the output signal So of the switching section 11, and is expressed by replacing the digital signal with an analog signal. The figure shows a case where a test signal and user data are superimposed on the tenth horizontal scanning period of the vertical blanking period.

Next, the receiving side will be explained.

The horizontal period detecting section 21 is supplied with a vertical synchronizing signal V2 and a horizontal synchronizing signal H2 synchronized with the signal So sent from the transmitting side, and detects a signal Sh2 indicating a specific horizontal scanning period of the vertical blanking period. and gate circuit 22
and sends it to the switching control unit 23. The gate circuit 22 is
The signal So sent from the transmitting side is turned on and off according to the signal Sh2, and the digital parallel video signal Sv1 of the transmitting side is
It is output as the same signal Sv2.

The switching control section 23 uses a digital sampling clock Sc2 synchronized with the signal Sh2 and the signal So.
is supplied, and generates a switching signal C2 in units of digital sampling clocks during a specific horizontal scanning period of the vertical blanking period. The switching unit 24 switches the signal S according to the switching signal C2.
o are sequentially switched, and the test signal and user data included in a specific horizontal scanning period of the vertical blanking period are changed to the test signal St2 and the user data D21 to D2, respectively.
n to a predetermined output terminal. Test signal evaluation section 2
5 evaluates the transmission quality by comparing the test signal St2 and the reference signal, and outputs the evaluation result.

In this embodiment, the test signal and user data are superimposed in one horizontal scanning period, but the same effect can be obtained by superimposing them using a plurality of horizontal scanning periods.

[0015]

As explained above, according to the present invention, on the transmitting side, a test signal for evaluating transmission quality and a plurality of User data is switched and transmitted in digital sampling clock units, and on the receiving side, the test signal and multiple user data that are superimposed on a specific horizontal scanning period of the vertical blanking period of the received digital parallel video signal are digitally sampled. By switching and extracting each clock, it is possible to send out a test signal and constantly monitor the transmission quality even during the transmission of a digital video signal. Furthermore, since a plurality of user data can be transmitted, it can be used for various purposes such as control signals.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a diagram showing an example of an output signal So of the switching section 11 shown in FIG. 1.

FIG. 3 is a block diagram showing an example of a conventional digital video signal transmission device.

[Explanation of symbols]

11, 23 Switching unit 12, 21 Horizontal period detection unit 13 Test signal generation unit 14, 24
Switching control section Sv1, Sv2 Digital parallel video signal S
c1, Sc2 Digital sampling clock Sh1, Sh2 Signal indicating a specific horizontal scanning period St1, St2 Test signal C1, C2 Switching signal

Claims (2)

[Claims] 1. A first horizontal period detection section that generates a signal indicating a specific horizontal scanning period of a vertical blanking period of a digital parallel video signal; a test signal generating section that generates a test signal for evaluating transmission quality in units of the digital sampling clock during the horizontal scanning period; a first switching control section that generates a first switching signal in digital sampling clock units; 1. A digital video signal transmission device, comprising: a first switching unit on a transmitting side that selects and outputs one of the signals. 2. The digital video signal transmission device according to claim 1, further comprising: a second horizontal period detection unit that generates a signal indicating a specific horizontal scanning period of the vertical blanking period of the received digital parallel video signal; a gate circuit that turns on and off the received digital parallel video signal according to a signal indicating a horizontal scanning period from the second horizontal period detection section, and outputs the received digital parallel video signal; a second switching control unit that receives a digital sampling clock synchronized with the received digital parallel video signal and the received digital parallel video signal, and generates a second switching signal in units of the digital sampling clock during the horizontal scanning period; The receiving side includes a second switching unit that switches the parallel video signal according to the second switching signal to extract a test signal and a plurality of user data, and a test signal evaluation unit that evaluates the extracted test signal. A digital video signal transmission device characterized by: