The device contains an oscillator stabilized by a quartz resonator (DD1.1, DD1.2), frequency dividers (DD2 and DD3, DD5.1, DD5.2, DD4, DD1.3, DD1.4), horizontal synchronizing shapers (DD6.2) and quenching (DD5.3, VD1, VD2, R4) pulses, vertical sync pulses (DD7.2), gradation signals (R1-R3) and vertical (DD7.1) and horizontal (DD6.1) lines of the grid field, adders (VD3-VD8, R8, R9) and emitter follower (VT1).
is. 1 - Schematic diagram of the signal generator.
The generator generates a signal of a reference frequency of 500 kHz, which the divider DD2 reduces to horizontal (15625 Hz) at output 16. Element DD5.3 and diodes VD1, VD2 form horizontal quenching pulses (Fig. 2, a), trigger DD6.2 synchronizing (Fig. .2,6). A signal with a field frequency is obtained at the output of the DD1.4 element after dividing the horizontal frequency by serially connected dividers on the counter DD3 and elements DD5.1, DD5.2 (division ratio 26) and on the counter DD4 and elements DD1.3, DD1.4 (coefficient division 12). From the output of the trigger DD7.2, frame sync pulses are taken with a repetition rate of about 50.08 Hz (Fig. 2, c).
In the desired ratio with horizontal pulses, they are added in an adder on diodes VD6 - VD8 and resistors R8, R9 (Fig. 2, d). Through the emitter follower on the transistor VT1 and the level control - variable resistor R10 - the full video signal of the white field (with the buttons SB1, SB2 not pressed) is fed to the XP1 plug, which is connected to the video input of the TV.
To obtain the voltage of gradations of brightness, a shaper on resistors R1-R3 is used, which is a digital-to-analog converter. When you press the SB1 button, this voltage is added (through the VD5 diode) to the white field signal.
The pulses of the vertical and horizontal lines of the grid field signal, generated respectively by triggers DD7.1 and DD6.1, are added in an adder on diodes VD3, VD4 and resistor R6. The signal is turned on with the SB2 button.
The device is powered by a Krona battery (you can use a 7D-0.115 battery) and remains operational when its voltage drops to 6 V. MLT resistors, capacitors KT-1 (C1), KM-4. KM-5 or KM-b (C3-C5) and K50-6 (C2), P2K pushbutton switches (SB1, SB2 - with dependent fixation, SB3 - with independent).
Setting up the generator comes down to obtaining the desired brightness and width of the vertical lines by selecting the resistor R5 according to the image of the grid field on the TV screen. The percentage ratio of the amplitudes of the components of the video signal, if necessary, is set by selecting the resistor R9 according to the oscillogram in Fig. 2, d with a test signal of a white field.
Rice. 2 - Oscillograms of the signal generator.
P.S. To improve the reliability of the device, the input C of the DD7.1 trigger is recommended to be connected to a common wire through a 100 kΩ resistor.
Video signal generator on the microcontroller
Source: http://pic16f84.narod.ru
To generate a video signal, just one microcircuit and two resistors are enough - i.e. you can literally make a pocket video signal generator the size of a keychain. Such a device is useful to the telemaster. It can be used when mixing kinescope, adjusting color purity and linearity. The generator is connected to the TV's video input, usually a "tulip" or "SCART" connector.
The instrument generates six fields:
- text field of 17 lines;
- grid 8x6;
- grid 12x9;
- small chess field 8x6;
- large chess field 2x2;
- white field.Switching between fields is carried out by short-term (lasting less than 1 s) pressing the button S2. Holding this button pressed for a longer time (more than 1 s) turns off the generator (the microcontroller enters the "SLEEP" state). The generator is switched on by pressing the S1 button. The state of the device (on/off) is signaled by the LED.
Device Specifications:
- clock frequency - 12 MHz;
- supply voltage 3 - 5 V;
- current consumption in operating mode:
- at a supply voltage of 3V - about 5mA;
- at a supply voltage of 5V - about 12mA;
- frame rate - 50 Hz;
- number of lines per frame - 625All work on the formation of the video signal is performed by a program hardwired in the microcontroller. The two resistors, together with the TV's video input impedance, provide the necessary video signal voltage levels:
- 0 V - sync level;
- 0.3 V - black level;
- 0.7 V - gray level;
- 1 V - white levelRice. 1. Schematic diagram of the generator
To form a video signal, the zero bit of PORTA and the entire PORTB are used (this port operates in a shift mode). Despite the fact that the signal is taken only from its zero bit, the program uses it all. Therefore, all PORTB bits are configured as outputs. The first bit of PORTA is used to indicate the status of the generator. When the device is turned on, the LED is on. When the device is off, the LED is off. The third bit of PORTA is used to switch the generator operation modes and turn it off. A short press of the S2 button allows you to move from one field of the generator to another. By holding this button down for more than 1 s. the device turns off (the microcontroller enters the "SLEEP" state). To turn on the generator, you must perform a reset. This is done by pressing the S1 button. The supply voltage of the device can be selected within the range of 3 - 5 V. In this case, the resistor values must be selected accordingly.
3V - R5=456Ω and R6=228Ω
3.5V - R5=571Ω and R6=285Ω
4V - R5=684Ω and R6=342Ω
4.5V - R5 \u003d 802 Ohm and R6 \u003d 401 Ohm
5V - R5=900Ω and R6=450Ω
Here are the calculated values. In reality, you can install resistors from the standard range, for example, for 5V - 910Ohm and 470Ohm, and for 3V - 470Ohm and 240Ohm.
The probe-generator of the TV signal is assembled on the basis of the microcontroller of the pic12f629 series, and in terms of the totality of dimensions, current consumption, the cost of manufacturing the device and the functionality for the telemaster, it is simply irreplaceable. The supply voltage is 3 volts, i.e. two finger batteries. The current consumption in the generation mode is 11 milliamps, in sleep mode - only 3 microamps.
Schematic diagram of a TV signal generator
PCB drawing
This probe can generate five pictures, which is quite enough for checking and repairing horizontal and vertical scanning of the TV, adjusting the convergence and geometric distortion of the raster, color balance, and controlling the passage of signals through the TV circuits. With a short press on the button, it wakes up and starts generating the first picture, with subsequent clicks on it, the pictures switch in a circle. If the button is held for a long time, the moment the button is released, the generator goes into sleep mode. It also goes into sleep mode automatically if it is turned on for more than 5 minutes.
An archive is attached to the article, in which there is a circuit, a probe board, two firmware. The video shows that the picture on my TV is slightly non-linear - this is because the TV is 12 years old, or maybe something in the video input is not right.
In this article, we will present another device - the ANR-3126 television test signal generator, designed to assess image quality and eliminate existing distortions directly on the TV screen when displaying test signals in the SECAM standard received at the TV video input. Such a device is indispensable in assessing the image quality of black-and-white and color TVs, as well as television monitors, especially after repairs in the process of setting up basic parameters, such as linear image dimensions, horizontal and vertical image linearity, beam convergence quality, static and dynamic white balance, color correctness, trailing extensions, correct setting of color difference detectors, correct matrixing, etc.
Rice. 1. Measuring television generator
Structurally, the ANR-3126 generator (Fig. 1) is an external desktop module-attachment to a PC and is based on 12-bit digital-to-analog converters (DAC) with a clock frequency of 80 MHz, which ensures high quality of the generated signals. Communication with PC is carried out via USB 1.1 interface or parallel port operating in EPP mode.
The generator provides output on the analog output (channel "A") of one of the test television signals selected by the user, and on the other analog output (channel "B") - full sync mixture in accordance with GOST 7845-92. For synchronization with external devices, the output "Synchronization input / output" is intended, on which, after the start of generation, positive pulses with a line frequency and TTL level appear, synchronous with horizontal sync pulses at the analog outputs of the device.
The nominal amplitude of the signal at the analog outputs at a load of 75 Ohm or 1 MΩ in accordance with GOST 18471-83 and GOST 7845-92 is -0.3 ... + 0.7 V. The device allows you to smoothly adjust the amplitude of the video signal ranging from 0, 25 V to 1.5 V, the amplitude of the clock signals - in the range from 0 V to -0.5 V, as well as the "black" level in the range from 0 to 1 V, while the blanking level is 0 ± 0.01 V.
The AHP-3126 generator software is compatible with any Windows operating system - from Windows 98 to Windows XP. At the same time, the computer to which it is connected must have at least 10 MB of free disk space, at least 8 MB of RAM (excluding the memory required for the operation of the operating system itself), as well as USB 1.1 or LPT interfaces in EPP mode. Any Windows-compatible audio system is suitable for using sound messages while the program is running. In principle, the program will work fine on a computer with any processor of the Pentium family, but to speed up the process of loading data, it is more advisable to use a processor with a frequency of at least 400 MHz.
We will not dwell on the advantages of virtual instruments compared to stand-alone ones - they are well known: mobility, large screen with good resolution, unlimited resources for processing measurement results, etc.
The software (software) of the ANR-3126 generator provides simple, intuitive control of the device. So, to select the desired signal, it is enough to click the button with the symbolic picture of the corresponding signal with the mouse. At the same time, at the request of the user, it is possible to select the operating mode, in which exit from the program and disconnection from the computer via the interface does not lead to the disappearance of signals at the outputs of the device. To facilitate mastering the work with the device, the program is equipped with "pop-up hints" - brief text explanations on the use of each control element, as well as full-fledged help in the "Windows" style.
Rice. 2. The main window of the ANR-3126 program
The main window of the program is shown in Fig. 2. Its main element is a set of buttons with symbolic images of available standard test signals.
Generator control is reduced to selecting the required signal by clicking on the button with the image of the selected signal, loading it into the instrument's memory and starting generation using the "Load" and "Start" buttons. After that, a video signal is generated at the "Channel A" output, a standard sync mixture is supplied to the "Channel B" output, and sync pulses with a frequency of lines and a TTL level are fed to the synchronization output. At any time, the user can stop and restart the generation without restarting the signal.
The status bar of the main program window constantly displays information about the currently selected signal and the interface used to connect the instrument to the PC.
Software adjustment of the amplitude parameters of the signal is carried out using the "Control" panel. The user can adjust the amplitude of the video signal (white level) and clock pulses, as well as the black level. It is allowed to include and exclude a color subcarrier from the signal, as well as select the type of color synchronization from those provided for in GOST 7845-92.
Rice. 3. "Oscillogram Viewer" panel of ANR-3126 program
The "Oscillogram" of the resulting signal can be viewed in its entirety and line by line using the "Oscillogram Viewer" panel (Fig. 3). This function is especially convenient for visual observation of the results of adjustment of the amplitude parameters of the signal.
Using the waveform viewer panel pop-up menu commands, the test signals used in the program can be saved to the PC in numerical form or as images ("waveforms"). Numerical data is stored in a universal spreadsheet format "CSV", which can be processed in standard text (such as "Notepad") and spreadsheet (such as MS Excel) editors. In this case, the user, if necessary, can study the signal in much more detail than on the oscillogram in the standard program of the device. Waveform images can be saved in BMP bitmap format or in WMF or EMF vector formats. In addition, the user has the opportunity to print on a color or black-and-white printer the entire signal or a selected part of it.
The instrument software provides ample opportunities for customizing the user interface. The operator can change the colors of the chart elements, enable and disable the sounding of events, pop-up tips, configure connection, printing, and program operation parameters. You can load an arbitrary picture as the background of working panels, while the program, at the request of the user, can adjust the color scheme of the picture in accordance with the system color of the windows, or vice versa - correct the system color in accordance with the loaded picture. The special features of the working windows of the program are "minimizing" and "maximizing" (the window remains in place, but its height is reduced to the height of the title bar), "sticking" (windows move around the screen as a whole) and "floating panel" (the window is always displayed on top of other windows) - allow optimal use of desktop space.
All program and device settings are automatically saved when exiting the program and restored at the next start. In addition, you can save files with the most frequently used configurations, which allows you to simply load the desired file later instead of lengthy reconfiguration of settings. To check the reliability of the program, the program allows you to check the quality of the connection between the device and the computer via the selected interface at any time.
Now let's take a closer look at the test signals that are most often used in practice when setting up a TV after it has been repaired (in order of use). Before working with signals, the brightness, contrast and focus parameters should be set to normal and convenient for observation. At the same time, it must be borne in mind that before adjusting the image parameters on the TV screen, you need to be sure that all supply voltages in all TV units correspond to the nominal values, and frame and horizontal synchronization are stable.
Rice. 4. Black and white frame signal
The signal of a black and white frame around the contour of the visible part of the screen of white and black rectangles with white lines in the middle of the black rectangles (Fig. 4) is necessary to adjust the correct image size and is usually used at the beginning of the adjustment, since the image size is determined by the horizontal scanning parameters and the results of most other adjustments depend on this adjustment.
Rice. 5. Signal of a central white cross on a black background
The signal of the central white cross on a black background (Fig. 5) is designed to center the image relative to the geometric parameters of the TV screen. With the help of this signal, the image of the intersection of the vertical and horizontal lines of the cross is set at the geometric center of the screen during adjustment. The same signal is used to control and adjust the static convergence of beams. Correctly tuned convergence does not produce colored fringing on the white lines of the cross.
The black-and-white grid field signal is designed to adjust the linearity of the image vertically and horizontally, as well as for the subjective assessment of the focusing of the beam and the geometric distortions of the image. When setting up, the same size of grid cells is achieved horizontally and vertically along the edges of the image. The same signal can be used to check and, if necessary, eliminate pincushion and barrel distortion in the image. When adjusting the dynamic convergence of rays using this signal, the absence of color fringing on the grid lines at the edges of the image is achieved. Reticle field signal with dots and dot signal are for adjusting the focus of the image across the entire field.
Rice. 6. Black and white checkerboard signal
The black-and-white checkerboard signal (Fig. 6) is also designed to assess the geometric distortions of the image, its centering, the presence of dragging distortions at the boundaries of black and white squares, as well as to pre-check the white balance, the quality of the frequency detectors and color synchronization by the absence of color shades on black and white squares. By the presence of a pink color of white squares, a violation of the setting of the frequency color difference discriminator R-Y is determined, and a blue color - B-Y.
A signal of black and white vertical and horizontal stripes in descending order of brightness is needed to evaluate and adjust the dynamic white balance. With normal white balance adjustment, there is no color cast in the grayscale bands when the image brightness changes. The appearance of colored bands can also be caused by incorrect zeroing of the frequency detectors.
The white, black, red, green, and blue pure color field signals are designed to test and adjust the color purity of each color, as well as the blanking level. Reproduction of fields of auxiliary colors allows you to check the correct operation of the frequency discriminators and the matrixing scheme.
Rice. 7. Signal of the white and black halves of the screen vertically
The signals of the white (upper) and black (lower) halves of the screen vertically, as well as the white (left) and black (right) halves of the screen horizontally (Fig. 7) make it possible to check the centering of the image along both axes and the mutual influence of the brightness and color channels. These signals also check the quality of transient processes in lines and frames, the so-called dragging continuations and multi-loop.
Rice. 8. Signal of colored vertical bars
The signal of colored vertical stripes in the sequence of white, yellow, cyan, green, purple, red, blue and black (the brightness of the stripes decreases successively) (Fig. 8) allows you to check the correctness of the transmission of primary colors, the quality of the color rendering of the kinescope, as well as the correct adjustment of the detectors of color difference signals . If the matrixing circuit malfunctions, a given signal with different saturation may have color sequence distortions and even completely lose color at low saturation.
The signal of colored vertical stripes in the sequence of white, blue, yellow, cyan, red, green, magenta, black and white (maximum frequency differences) also allows you to check the correctness of the transmission of primary colors, as well as the quality of the transients of the color unit and kinescope.
Rice. 9. Signal of colored horizontal bars
The signal of colored horizontal stripes (Fig. 9) is designed to control and adjust color reproduction, brightness and contrast, as well as color tone and saturation throughout the frame field. Violation of the color rendering of individual colors indicates an insufficient width of the linear section of the corresponding frequency detector.
The "Rainbow" signal - a smooth color change from left to right - allows you to evaluate and, if necessary, adjust the zeros of the frequency detectors of color difference signals, as well as their linearity.
Rice. 10. Signal "Rainbow"
The signal from a set of groups of yellow-blue, magenta-green and red-cyan strokes is designed to evaluate and adjust the color clarity of the image.
Thus, in terms of its technical characteristics, variety of test signals and ease of control, the TV test signal generator ANR-3126 can successfully compete with similar devices. I would like to hope that this inexpensive, convenient and reliable device will appeal to specialists involved in the operational control of the equipment of television centers, as well as checking, configuring, repairing and maintaining the video paths of television equipment.
Publication date: 31.08.2004
Readers' opinions
- Natasch / 16.06.2012 - 10:32
Fiidnng this post solves a problem for me. Thanks! - EMEME / 07.12.2008 - 18:28
GUYS ARE VERY INTEREST-WHERE TO GET?????????
Schematic diagram and photo of a simple probe (test signal generator) designed to test and configure TVs.
The probe-generator of the TV signal is assembled on the basis of the microcontroller of the pic12f629 series, and in terms of the totality of dimensions, current consumption, the cost of manufacturing the device and the functionality for the telemaster, it is simply irreplaceable. The supply voltage is 3 volts, i.e. two finger batteries. The current consumption in the generation mode is 11 milliamps, in sleep mode - only 3 microamps.
Schematic diagram of a TV signal generator
PCB drawing
This probe can generate five pictures, which is quite enough for checking and repairing horizontal and vertical scanning of the TV, adjusting the convergence and geometric distortion of the raster, color balance, and controlling the passage of signals through the TV circuits. With a short press on the button, it wakes up and starts generating the first picture, with subsequent clicks on it, the pictures switch in a circle. If the button is held for a long time, the moment the button is released, the generator goes into sleep mode. It also goes into sleep mode automatically if it is turned on for more than 5 minutes.
An archive is attached to the article, in which there is a circuit, a probe board, two firmware. The video shows that the picture on my TV is slightly non-linear - this is because the TV is 12 years old, or maybe something in the video input is not right.