Use With a DTX-1
As of Software Version 201710081, the Portsdown software can be used to transmit MPEG-2 or H264 encoded pictures with a DTX-1. This experimental capability is NOT compatible with the use of WaveShare touchscreen and must be controlled from the Console or an Official Raspberry Pi 7" touchscreen (often referred to as a "7 inch Element 14 touchscreen"). If you select DTX-1 as the output mode with a Waveshare touchscreen connected, the touchscreen will become unusable as soon as you got to transmit, as some of the pins used for the screen are the same as those used for sending signals to the DTX-1.
Additionally, the hardware shutdown button, hardware shutdown button LED, keyed streaming, hardware keyed transmit, Attenuator and signal generator functions are inoperative due to GPIO pin conflicts.
A summary of the pin connections used is here Summary of GPIO Connections.
Further details can be found in CQ-TV 248 page 25 and on the DTX-1 support site. http://www.dtx1.info/index.html
The settings on the DTX-1 under the DTX1 ADVANCED MENU SETTINGS must match those set on the Portsdown otherwise corrupt digital signals will be transmitted.
Thanks to Martin G8LCE for this information