Emily Velsaco's Espressif ESP8266 Transmitter Is an Analog TV Station in Your Pocket
A short-range microcontroller-driven TV transmitter provides an easy way to test old TV sets.
Self-described "arts-and-crafts supervillain" Emily Velsaco has taken the closure of analog terrestrial TV stations personally — so built her own, short-range version using an Espressif ESP8266 microcontroller.
"Since there are no more analog TV stations on the air in this country, I have no way of testing sets I find it thrift stores any more," Velasco explains of the project. "So, I finally decided to try the code that Charles Lohr developed for tricking an [Espressif] ESP8266 into transmitting analog TV signals over the air with its RX pin."
Terrestrial television was, traditionally, an analog affair, transmitted over-the-air on radio waves to receivers built into everyone's TV sets. The birth of more bandwidth-efficient digital television led to most countries closing down their analog TV stations in order to use the spectrum for other services — with the United States having closed all but its lowest-power stations in June 2009 and all stations by 2022.
For modern TVs, which have replaced their analog receivers for digital decoders, that's not a problem — but Velasco is on the prowl for vintage sets, and sensibly unwilling to drag a VCR, 1980s microcomputer, or other source of RF video signal around to test potential acquisitions. Enter, then, the ESP8266.
"This is actually someone else's version of [Lohr's] code because he wrote his code to be compiled in the ESP8266 SDK [Software Development Kit] environment and I don't know how to use that," Velasco explains of the project. "This code compiles in the Arduino IDE and it does work!" That code uses an antenna connected to a general-purpose input/output (GPIO) pin on the ESP8266 to transmit a color TV signal — over a very short range, admittedly, but it works.
"If I get all this working where I want," Velasco muses, "I think I will package the ESP8266 in a little housing with a battery, and [an] on off switch and an antenna so I can easily take it with me to a store. I [also] need to see if I can learn how to use the [Espressif] SDK so that I can see the really nice demos that Charles wrote on a TV."
More details are available in Velasco's Mastodon thread; Lohr's original code is available on GitHub under the permissive MIT license.