BATC Video Source

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The BATC Video Source, based on a Raspberry Pi Zero or later models (but not the Raspberry Pi 4), was published in CQ-TV 270.

It was based on an earlier (now unsupported) version by G4EWJ described here: RPi Test Card.

The information below is provided to help advanced users to customise their VideoSource. Please refer to the original CQ-TV article for construction details.


All the files used to customise the display are in the folder /boot/testcard. This folder can be accessed directly on the card if you log in by SSH on a network-connected Raspberry Pi (not a Pi Zero on its own), or as the boot volume if you read the card on a Windows PC. The files are owned by root, so the use of sudo is required to edit them by ssh.

On start-up, if the previous banner text on the second and third slides include the text "BATC" or "IO90LU", the callsign.txt and locator.txt files are read and the banners are changed to "callsign at locator". This enables all the callsigns on the card to be initialised simply by setting the callsign.txt file correctly.

Also on start-up, the text in "callsign.txt" is convereted to an image and superimposed on the Test Card F used in the first slide. The same text is also stored for use as a camera caption.

Inserting New Images

Additional image files without a banner should be 720x576 .jpg files, and those for use with a banner should be 640x480. Each image needs to be accompanied by a text file named in sequence like tcdata10.txt and containing:


The number in the filename determines the sequence that the card is displayed in; for example the card specified in tcdata10.txt will be displayed in the 10th button push after the first card.

The first line must be tcprog.
The second line is the filename of the .jpg image to be displayed, without the .jpg extension.
The third line is the x displacement of the bottom left of the card.  This should be 40 for cards with a banner and 0 for cards filling the screen.
The fourth line is the y displacement of the bottom left of the card.  This should be 52 for cards with a banner and 0 for cards filling the screen.
The fifth line is the text for the "bubbles".  A maximum of 5 characters.  Some special characters such as "-/P-" can be displayed (try it).
The sixth line is the text for the scrolling banner.

Be careful to edit the file in a true text editor. Microsoft Word and Wordpad introduce special characters that will cause the file to not work. Use Notepad, or Notepad++.

Current Consumption

Current consumption of a Raspberry Pi Zero running the test card is about 150 mA, which increaes to 190 mA if the camera is selected.


Assembly of Video Source projects are covered in this topic.

Using an EBay £9 tripod ( with its 1/4" UNC mounting thread) to finish the project (M0YDH)
The video source shown fitted in a diecast box (M0YDH)