JPS6131677B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for testing or adjusting a receiving device that is capable of receiving a display signal multiplexed with a television signal and then displaying a display image together with the television image. The present invention provides a device that generates a test signal suitable for

Recently, systems have been developed that multiplex and transmit various information signals during the vertical retrace period of television signals. During the scanning period, display signals such as character images are multiplexed and transmitted, received by the receiver, stored in memory sequentially), and reproduced in synchronization with the scanning of the cathode ray tube to project the character image on the screen. A system has been proposed.

However, in television receivers, the passband of the VIF circuit is limited, so the high-frequency components of the binary signal of the received character signal are attenuated or subjected to phase distortion, resulting in considerable waveform distortion. is customary. For this reason, an equalization circuit is generally provided to compensate for the amplitude and phase distortion of the received display signal before it is supplied to a processing circuit such as a memory, and this equalization circuit compensates for the waveform distortion. It is designed to be added to the processing circuit from the beginning.

Therefore, when manufacturing and using a display information receiving device, it is necessary to appropriately adjust the equalization circuit and determine the compensation state so as to optimize the signal waveform.

One method for evaluating the degree of waveform distortion of a received character signal is to use an eye pattern. This involves applying a random binary received signal to an oscilloscope, and by superimposing multiple waveforms on the screen, a so-called eye pattern is projected, and the eye aperture ratio is observed. . The larger the eye aperture ratio, the more faithfully the binary signal waveform is transmitted.
The smaller the value, the more waveform distortion. Therefore, by using this eye pattern, it is possible to immediately judge the state of waveform distortion, and by adjusting the equalization circuit to maximize the eye aperture ratio, it is possible to obtain the best reception condition, which is convenient. It is.

Therefore, the present invention makes it possible to easily perform adjustment using such an eye pattern in a display information receiver using a television receiver.
Moreover, it is an object of the present invention to provide a test and adjustment device that can easily adjust the television receiver itself using color bars and the like.

Therefore, in the present invention, a display test signal is created and sent out during the vertical retrace period of the television signal as necessary, and a pseudo-random signal is generated during the majority of horizontal scanning periods during the vertical scanning period. Create and mix these to create an RF signal as a test signal for display.
It is characterized by being modulated and supplied.

EMBODIMENT OF THE INVENTION Hereinafter, the present invention will be described in detail with reference to the drawings showing one embodiment thereof. First, Figure 1 shows the overall configuration, where 1 indicates a horizontal synchronizing pulse H, a vertical synchronizing pulse V, a color subcarrier _SC , and a burst flag.
It is a common synchronous board that generates BF etc. 2 is for display signal creation and pseudo random signal (Pseudo
A clock generation circuit that generates a clock signal for generating random noise (hereinafter abbreviated as PN signal).
Based on the horizontal synchronization pulse from the synchronization board 1 and the color subcarrier, a clock signal of, for example, 8/5 _SC is created which has the same phase every H and is synchronized with the color subcarrier. In addition, 3 is a line counter that also creates line counting signals for display signal creation and PN signal creation, and based on the horizontal and vertical synchronization pulses from the synchronization board 1, a predetermined horizontal scanning period during the vertical retrace period. For example, a count output for creating a display signal is generated at the 20th H and 283rd H (hereinafter, only the 20th H will be explained), and during the majority of horizontal scanning periods during the vertical scanning period, for example, at the 22nd to 262nd H. On the 284th to 524th H (hereinafter, only the 22nd to 262nd H will be explained)
Generates count output for creating PN signal.

Then, the display signal generation circuit 4 generates a second signal based on these clock signals and the 20th H count output.
A display signal as shown in Figure A is created. The configuration of the display signal generation circuit 4 itself may be of a publicly known type; for example, as shown in the document IPD22-1 "Simplified Kanji Generator for Teletext Broadcasting" by the Image Display Study Group of the Television Society, various types of memory may be used. A device controlled by a microprocessor may be used. This display signal is the 20th H during the vertical retrace period.
A control code signal consisting of a 16-bit pilot signal (clock line signal CR, 8-bit framing code signal FC, 4-bit program code signal PC, 8-bit line number code signal LN, etc.) It consists of a bit display signal.

On the other hand, in the PN signal generation circuit 5, the second
Create a PN signal as shown in Figure B. This PN
As the signal generation circuit 5, for example, a configuration as shown in FIG. 3 which combines a shift register and an exclusive OR gate may be used, and it generates a PN signal of 292 bits in each horizontal scanning period of 22nd to 262nd H. occurs.

Then, the horizontal and vertical synchronization pulses and burst flags from the synchronization board 1, the display signal A from the display signal creation circuit 4, and the PN signal B from the PN signal creation circuit 5 are mixed in a mixing circuit 6, and a second Create a display test signal as shown in Figure C. The characteristics of this signal are
The PN signal B whose phase is synchronized with the majority of horizontal scanning periods during the vertical scanning period is created. By superimposing a PN signal over a long period of time in this way, when testing a receiver, you can immediately display an eye pattern by simply extracting the signal from each part of the receiver's circuit, such as the output side of the equalizer circuit, and applying it to the oscilloscope. It has the advantage of being able to perform tests easily. If you try to display an eye pattern in a state where the signal exists only for a short period of time (such as a display signal only), it is necessary to apply brightness modulation to the oscilloscope or use a memory scope. However, by sending the PN signal for a long period of time, this disadvantage has been eliminated, and the eye pattern can be easily displayed and tested by simply supplying the signal to a general oscilloscope. It became possible to do it. In addition, when adjusting the receiver, it is sufficient to display the eye pattern in this manner and adjust the waveform compensation circuit etc. so as to maximize the eye aperture ratio.

Such a display test signal is outputted as an RF signal by modulating the RF carrier wave of an arbitrary channel created by the RF oscillation circuit 8 in addition to the modulation circuit 7.

Furthermore, this device is equipped with a color bar signal creation circuit 9 and a monoscot pattern creation circuit 10 for other tests of the receiver, each of which has a synchronous board 1.
Based on the horizontal and vertical synchronizing signals, color subcarriers, burst flags, etc. from the above, color bar signals and monoscot pattern signals as general test signals may be created by known means. And those signals are also modulated by the modulation circuits 11 and 1, respectively.
In addition to 2, RF created with RF oscillation circuits 13 and 14
Modulates the carrier wave and outputs it as an RF signal. Of course, it is created using RF oscillation circuits 8, 13, and 14.
The RF carrier waves are set to different channel frequencies.

By adding mixing circuits 15 and 16 to these color bar signals and monoscot pattern signals so as to superimpose the display signal as shown in FIG. It can be implemented.

Then, the RF signals of these display test signals, other color bar signals, and monoscot pattern signal test signals are added to the RF mixing circuit 17, mixed, and supplied to the receiver under test via a common cable 18. .

FIG. 4 shows an example of a receiver under test that is tested or adjusted using such a signal. here,
19 is a tuner, 20 is a VIF circuit, 21 is a video detection circuit, 22 is a video/chroma circuit, and 23 is a picture tube, which are almost the same as those in a normal color television receiver. On the other hand, 24 is a waveform compensation circuit that compensates the waveform of the received binary signal, and compensates the waveform by adjusting the phase using, for example, an active delay equalization circuit having a quadratic interval configuration as shown in FIG. Just use something. And 25
is an information processing circuit that uses this waveform-compensated binary signal to store and process a display signal and other multiplexed signals to generate a video signal for display. Here, the output signal of the waveform compensation circuit 24 is taken out and added to one input of the oscilloscope 26, and a clock signal synchronized with the PN signal supplied via the cable 27 is added as a reference time input signal and delayed. By sweeping, an eye pattern can be displayed. Therefore, the waveform compensation circuit may be adjusted to maximize the aperture ratio of the eye pattern.

In addition, in the signals shown in FIG. 2B above, if code signals with predetermined waveforms of the clock line signal CR and the flemming code signal FC are sent out prior to the PN signal in each horizontal scanning period, the signals shown in FIG. A band amplifier circuit 28 extracts a component of a predetermined frequency, that is, a clock frequency, from the received signal,
Further, a gate circuit 29 extracts only the predetermined code signals CR and FC, excites a resonant circuit 30 such as a ringing oscillation circuit, and the output is waveform-shaped by a waveform shaping circuit 31 to obtain a reference time for the oscilloscope 26. A signal may also be generated. In this case, the cable 27 becomes unnecessary.

In this way, by using this device, by switching the reception channel in the receiver under test, it is possible to receive the test signal and easily display the eye pattern. It is also possible to receive general test signals such as signals, making it easy to test and adjust the receiver.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a test adjustment device according to an embodiment of the present invention, FIG. 2 A, B, and C are waveform diagrams of various parts of the device, and FIGS. 3, 4, 5, and 6. is a circuit diagram of a part of the same device. 1...Synchronization board, 2...Clock generation circuit, 3...
...Line counter, 4...Character signal generation circuit, 5
...PN signal generation circuit, 6...Mixing circuit, 7...
Variation circuit, 8... RF oscillation circuit, 9... Color bar signal creation circuit, 10... Monoscot pattern creation circuit, 11, 12... Modulation circuit, 13, 14...
RF oscillation circuit, 15, 16...Mixed circuit, 17...
...RF mixing circuit, 18...cable.

Claims (1)

[Claims] 1. A common synchronization board that generates horizontal synchronization pulses, vertical synchronization pulses, color subcarriers, and burst flags, and a common synchronization board that generates display signals and pseudorandom signals based on signals from this synchronization board. A clock generation circuit and a line counter that generate a clock signal and a line count signal, and a display signal that generates a display signal based on the clock signal and line count signal and outputs it during a predetermined horizontal scanning period during a vertical retrace period. a pseudo-random signal generating circuit that generates a pseudo-random signal based on the line count signal of the clock signal and outputs it during the majority of horizontal scanning periods during the vertical scanning period; and a synchronous pulse and burst from the synchronous disk. a flag, a mixing circuit that mixes the display signal from the display signal creation circuit and the pseudorandom signal from the pseudorandom signal creation circuit to create a display test signal, and a synchronization pulse and color subcarrier from the synchronization board. and a test signal generation circuit that generates a test signal such as a color bar signal based on the burst flag; a modulation circuit that modulates RF carrier waves of different channels with the display test signal and the test signal; A test adjustment device characterized by comprising an RF mixing circuit that mixes channel modulation signals and supplies the mixture to a receiver under test via a common cable. 2. The test adjustment device according to claim 1, characterized in that the display signal is also mixed with the test signal.