TV and Video related projects

This page contains information about TV and video related projects.
VHF/UHF spectrum analyser
Computer based TV test pattern generator
IVS monitor power supply
LCD monitor

VHF/UHF spectrum analyzer

This is a simple spectrum analyzer based on a TV tuner. Below is a photo of the setup:


The tuner unit and IF amplifier/filter is at the top left, the module to the right is the sweep signal generator which generates the 0-33V sweep voltage which tunes the tuner. The power supply is at the bottom. Below is a photo of the output of the spectrum analyzer on an oscilloscope for an aerial signal:



I did not use any IF-filtering in this design, the bandwidth is the bandwidth of the tuner output. Neither did I use a peak detector, the output on the scope is the actual IF signal. Furthermore as no signal processing is done on the output, the amplitude is expressed linearly on the scope and not logarithmically.
I am currently busy to build the above spectrum analyzer into a case. Below are a picture of the spectrum analyzer.


Currently only the sweep generator and IF output directly from the tuner is working. I have yet to design the IF filtering, peak detector and linear to logarithmic amplifier.

The three vertical gray wheels are used to control the tuning frequency and/or the sweep range. There are two tuning sources, the fixed source, as well as the sweep generator. The switch below the gray knobs selects which source is used for tuning. The two LEDs above the switch forms part of a window comparator which compares the tuning voltage of the sweep generator to the fixed tuning voltage.

The yellow knob adjusts the gain of the tuner. Currently it is not calibrated. The UHF/VHF slide switch selects the frequency band. The LOG/LIN switch selects the type of amplifier. The WIDE/NARROW switch selects the IF response. The MARKER switch puts a marker into the SCOPEY output which corresponds when the sweep generator frequency equals the fixed frequency. This signal is derived from the window comparator driving the LEDs.
 
Computer based TV test pattern generator


I have modified a Aquarius home computer to be used as a TV test pattern generator. Below is a picture of the setup.


I have basically build the cassette recorder, power supply and computer into one box. I have also added a composite video output. The Aquarius only had a RF output. The signal level of the composite output is adjustable from 0Vpp to about 2Vpp. I have written a simple program to generate some test patterns. Below is the main screen when the program is run:


Here I can select which pattern I would like to generate. The red, green, blue and white screens are mainly used for purity adjustments. Below is the color bar test pattern. The colorbar pattern is mainly used for color adjustments.


Below is the crosshatch pattern. The crosshatch pattern is used to adjust the convergence of a TV.


Using a home computer as a test pattern generator have several drawbacks. One being the process of loading the program from tape. The other drawback is the fact that the area used for graphics output is smaller than the TV screen. The cyan border around the above images cannot be used for graphical output. This is a problem with especially the crosshatch pattern, since one cannot see how the convergence operates on the edges of the screen.
I am currently in the process of designing a microprocessor based test pattern generator. It will possibly be based on a PIC16F84 since I have already used that device to generate a colorbar test pattern. I will also be using the AD724 composite encoder chip to generate the composite video signal.

I have recently build a new cover for the Aquarius based test pattern generation using 0.6mm galvanised sheet steel. Below is a top view with the cover removed:



The tape recorder and its power supply is to the left. The Aquarius motherboard is at the bottom right of the tape recorder. The Aquarius power supply is above the Aquarius motherboard on the left. The module in the expansion slot of the Aquarius is additional memory. Just above the memory module is the BNC video output as well as the RF output. The board left of the outputs is the video amplifier. Below is the test pattern generator from the front and from the back.








IVS monitor power supply

I have build this power supply unit for testing LCD monitors that are used with IVS on film cameras. It can supply power to two monitors. It has a voltage as well as a current meter, as well as several different output voltages. It also contains a video distribution amplifier. Below is a front view of the unit:



The left LCD display indicates the current output voltage to the monitor. Just below the LCD display is the voltage selector knob. The right LCD display indicates the output current in mAs. The monitor is connected to the power supply by one of the 4 pin Fischer sockets, which has the same pinout as the ARRI cameras. The switch below the mA meter selects which output is monitored. The LEDs indicates which output's current is monitored. Below is a view of the backpanel.



The 4mm Banana plugs gives a regulated 12V output which can be used to power a signal generator. The BNC connector is the video signal input, that is send to the distribution amplifier.

LCD video monitors


I have been responsible for the design of the electronics of the monitors below. These monitors were designed to be used as IVS monitors for the film industry. It has a 4 pin Fischer connector to connect directly to the IVS output socket of the ARRI cameras. There is also a cable available for the Moviecam  IVS socket. The monitor has two inputs. Line A is 4-pin Fischer, while Line B is the BNC connector on the back panel. The monitor has a signal indicator to indicate whether a valid video signal is present on the selected channel. Therefore, even if the camera's lens cap is still on and the image you receive is black, you will know if the IVS feed is working. The monitor also has a built-in color bar test signal generator which may be used to adjust the monitor's settings. These monitors has a wide power supply range of from about 9V to 35V.



Below the onboard colorbar test pattern of the monitor is activated.




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