JPS62202696A - Television signal generator - Google Patents

Abstract

PURPOSE:To generate a test television signal with simple constitution by accessing a memory storing a television signal according to a counter representing the position of an 1/2 horizontal line and the dot position. CONSTITUTION:A horizontal signal is converted into a signal selecting the kind of a television signal by a conversion memory 3 is correspondence to the position of a 1/2 horizontal line. Various television signal of 1/2 horizontal line are stored in a data storage memory 4, the television signal of 1/2 horizontal line is read from the data storage memory 4 by using the count content of a dot counter 1 and the selection signal converted by the conversion memory to use it as the test television signal.

Description

[Detailed Description of the Invention] [Summary] This is a television signal generator that digitally generates a television signal for incremental system testing. ,
A memory storing television signals such as equalized pulses and burst signals is provided, and the memory is accessed from this memory according to a line counter indicating the position of a 1/2 horizontal line and a dot counter indicating the position of a dot within the 1/2 horizontal line. ,
It sequentially outputs the stored television signals to form a composite video signal.

[Industrial application field]

The present invention relates to a television signal generating device that generates a television signal for testing, such as black burst, in the incremental system.

A general television system uses an increment system in which one frame consists of two fields. Various types of television signal generators are used to generate test television signals in such an incrace system, but it is desired that they be small and inexpensive.

[Conventional technology]

Conventional television signal generators generate composite video signals by multiplying the output of an original oscillator, analog modulation, etc., and have a large circuit scale because they are configured using analog processing. Also known is a configuration in which analog processing is replaced with digital processing, a digital-to-analog converter is provided on the output side, and an analog composite video signal is output. Also known is a configuration in which a television signal for testing is digitized, stored in a memory, and sequentially read out from the memory in accordance with a scanning line, using a memory with a capacity for one frame.

[Problem that the invention seeks to solve]

As mentioned above, television signal generators using analog processing have the disadvantage that the circuit size is large and that they are affected by temperature fluctuations, etc., and in order to compensate for this, the circuit size has to be further enlarged. In addition, in a configuration in which analog processing is simply replaced with digital processing, the influence of temperature fluctuations and the like is reduced, but the circuit scale cannot be reduced much. Also, the conventional TV signal generation VtW in which the digitized test TV signal is stored in the memory.
Since this method requires a memory with a capacity for one frame and stores an interlaced television signal in advance, it requires a large memory capacity and lacks flexibility.

An object of the present invention is to generate a test television signal with a simple configuration.

[Means for solving problems]

The television signal generator of the present invention stores only the type of digitized television signal corresponding to 1/2 horizontal line in a memory, and selects the data to be read out corresponding to the position of 1/2 horizontal line. This will be explained with reference to FIG. A dot counter 1 that counts dot positions within a 1/2 horizontal line, a line counter 2 that counts the position of a 1/2 horizontal line within a fixed period interval such as one frame period, and the output of this line counter 2. A conversion memory 3 that converts a signal into a signal for selecting the type of television signal such as a horizontal synchronization pulse, a vertical synchronization pulse, an equalization pulse, or a burst signal, and the output signals of this conversion memory 3 and the dot counter 1 as an address signal. , a data holding memory 4 for reading out digitized television signals, and the dot counter 1 and the line counter 2 are controlled by a control circuit 5 which operates according to a horizontal synchronizing signal HD, a vertical synchronizing signal VD and a clock signal CLK. Count control is performed by.

[Effect]

The dot counter 1 is, for example, a 455-base counter corresponding to the number of dots within a 1/2 horizontal line, and indicates the position of a dot within the 1/2 horizontal line. The line counter 2 indicates the position of a 1/2 horizontal line within a fixed periodic interval such as an l frame, and is, for example, a 1050-base counter.

The position of 1/2 horizontal line-in in the first field based on the count up to 525 of line counter 2 is, for example, an odd number is on the left side of the screen, an even number is on the right side, and corresponds to the position of the 1/2 horizontal line. The type of television signal such as horizontal synchronization pulse, vertical synchronization pulse, or burst signal is selected by the conversion memory 3 according to the count contents of the line counter 2 every 1/2 horizontal line. is converted into a signal that

The data holding memory 4 stores horizontal synchronization pulses, vertical synchronization pulses, and equalization pulses for 1/2 horizontal line.

It stores television signals such as burst signals, the type of television signal is selected by the selection signal from the conversion memory 3, and the television signal selected according to the count contents of the dot counter 1 is read out.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention, in which a control circuit 5 applies a dot counter 1 a horizontal synchronizing signal HD, a vertical synchronizing signal VD, and a dot clock signal synchronized with a clock signal CLK. This dot counter l is 1/2
For example, if the number of dots in a horizontal line is a 455-decimal counter, the count content of dot counter 1 indicates the position of a dot in a 1/2 horizontal line.

The line counter 2 counts the line clock signal from the control circuit 5, and is, for example, a 1050-decimal counter that measures 1/2 the number of horizontal lines in one frame.
The count content of line counter 2 is 1/2 of one screen.
It indicates the position of the horizontal line.

For example, as shown in FIG. 2, the horizontal line period is Hlo
, 5H is the 1/2 horizontal line period, the solid line is the first field that starts scanning from the top left edge of the screen, the dotted line is the second field that starts scanning from the top center of the screen, and each 1/2 horizontal line is numbered. If you add , the first field will be 1 to 525, the second field will be 526 to 1050, and in the first and second fields, the odd numbered 1/2 horizontal line will be on the left, and the even numbered 172 horizontal line will be on the right. It becomes the thing that is located. The count contents of the line counter 2 indicate the positions of these 1/2 horizontal lines.

The count contents of the line counter 2 are added to the conversion memory 3 and converted into a signal for selecting the type of television signal. If there are eight types of television signals, for example, the 11-bit count from the line counter 2 will be converted into a 3-bit selection signal. The data holding memory 4 is accessed based on the selection signal from the conversion memory 3 and the count contents of the dot counter 1.

This data holding memory 4 stores television signals for 1/2 horizontal line. For example, as shown in FIG. 3, if the horizontal line period is H, the horizontal synchronizing pulse is 0.075. H pulse width, equalization pulse is 0.04
The vertical synchronization pulse is stored as a television signal with a pulse width of 0.43H. Further, the black level signal is used as a part of the black burst signal (right half of the screen), etc. The color burst signal is a gate signal that gates a sine wave color burst signal inserted immediately after the horizontal synchronization pulse.

When the count content of the line counter 2 is "1", indicating the 172nd horizontal line at the start of scanning of the first field, the conversion memory 3 converts it into a selection signal for selecting a horizontal synchronization pulse, and adds it to the data holding memory 4. Further, when the count content of the line counter 2 becomes "2", the conversion memory 3 converts it into a selection signal for selecting a black level signal, for example, and adds it to the data holding memory 4. Similarly, when the line counter 2 indicates an odd numbered 172 horizontal line, the conversion memory 3 converts it into a selection signal for selecting a horizontal synchronizing pulse. Also, during the vertical retrace period, the count contents of the line counter 2 are converted by the conversion memory 3 into a selection signal for selecting a vertical synchronization pulse, an equalization pulse, and a horizontal synchronization pulse.

The selection signal converted by the conversion memory 3 and the count contents of the dot counter 1 are added to the data holding memory 4 as address signals. By the signal
The type of television signal shown in FIG. 3 is selected, and data is sequentially read out according to the count contents of the dot counter 1. Then, the type of television signal is switched every 1/2 horizontal line, and the television signal constituting one frame is repeatedly read out. The television signal read from the data holding memory 4 is converted into an analog signal and applied to the receiver.

Various types of television signals other than those shown in FIG. 3 can be stored in the data holding memory 4. For example, white level data may be included in the horizontal synchronization pulse stored data. , it is also possible to display vertical stripes on the left side of the screen. Furthermore, by changing the contents of the conversion memory 3 or by providing a plurality of conversion memories with different conversion contents and switching between them, it is also possible to switch and output television signals corresponding to 1/2 horizontal line.

〔Effect of the invention〕

As explained above, according to the present invention, the conversion memory 3 converts the type of television signal into a signal for selecting the type of television signal corresponding to the position of the 1/2 horizontal line, and the data holding memory 4 stores the 1/2
Various television signals for horizontal lines are stored, and the television signal for 1/2 horizontal line is read out from the data holding memory 4 based on the count contents of the dot counter 1 and the selection signal converted by the conversion memory 3, and then tested. This means that the data holding memory 4 only needs to have the capacity to store 1/2 horizontal line worth of TV signals for the number of types, compared to the conventional example that stores one frame worth of TV signals. This has the advantage of requiring only a very small capacity, making it possible to provide a small and inexpensive television signal generator.

Furthermore, since the type of TV signal corresponding to 1/2 horizontal line is selected by the conversion memory 3, the type of TV signal can be changed by changing the contents of the conversion memory 2, providing flexibility. Therefore, it is possible to provide a television signal generating device with a wide range of functions.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is an explanatory diagram of line numbers, and FIG. 3 is an explanatory diagram of stored data. 1 is a don't counter, 2 is a line counter, 3 is a conversion memory, 4 is a data holding memory, and 5 is a control circuit.

Claims (1)

[Scope of Claims] A dot counter (1) that counts positions within a 1/2 horizontal line; a line counter (2) that counts positions of a 1/2 horizontal line within a fixed periodic interval; a conversion memory (3) for converting the output signal of step 2) into a signal indicating the type of television signal; and digitizing the output signal of the dot counter (1) and the output signal of the conversion memory (3) as address signals. 1. A television signal generating device comprising: a data holding memory (4) from which a television signal is read.