The ESP8266 is a $7 WiFi module that can be used to give any microcontroller access to a WiFi network. It is designed for creating Internet of Things (IoT) devices and has various features such as it’s ability to host it’s own web applications. The ESP8266 also has a I2S output with DMA support. By hooking up this I2S output pin to a short wire, YouTuber CNLohr has demonstrated that he is able to use the ESP to broadcast full color NTSC TV. This works in a similar way to how PiTX works, by using the pin to modulate a radio signal. CNLohrs code note only broadcasts color NTSC, but also provides a full web interface for controlling it.
In the first video CNLohr shows off his initial work at getting the NTSC output working and in the second video he shows color working. Later in the second video he also uses an RTL-SDR to check on the NTSC spectrum that is being output.
The PAL/NTSC analogue TV viewer TVSharp has recently been updated to version 1.2. This new version features an updated GUI as well as automatic frequency correction and automatic position correction. This may correct some of the scrolling and slanting problems seen in previous versions.
The rtl-sdr as a software defined radio actually does not have enough bandwidth to receive a PAL or NTSC signal properly. PAL and NTSC signals require more than double the 2MHz typical bandwidth of the rtl-sdr. But, a decent black and white signal can still be obtained by using some of the luminance part of the signal. As only part of the signal is sampled, resolution will be lost. Also, as sound is broadcast on a separate frequency, a second rtl-sdr dongle will be required to receive the matching audio.
On YouTube, users Superphish and ek6rc have posted videos showing TVSharp in action.
Analogue PAL TV with RTL SDR (RTL2832) and TVSharp