Controlling a DATVExpress

Work is ongoing to introduce the capability to control a DATV Express exciter board from the Portsdown transmitter. The capability will be included in the core build once it is robust. In preparation, here are some details.

The Portsdown Software running on an RPi 3 will control a DATV Express board directly, without the need for any PC or other computer. There are some limitations on functionality, due to the state of development of the DATV Express server software, and also limitations in the RPi 3 hardware and Portsdown software. You cannot expect the full functionality that you would get using a Windows PC to control DATV Express.

Equipment Required

For a usable Portsdown and DATV Express transmitter, you will need a Raspberry Pi 3, a Waveshare touchscreen, a DATV Express board, suitable power supplies, and transmitter filters and linear amplifiers. Connect the DATV Express to the RPi 3 using a USB lead.

Capability

Using the touchscreen, the following capabilities can be controlled:

DVB-S H264 transmissions using the Pi Camera at Symbol Rates from 333 KS to 4 MS.

DVB-S MPEG-2 transmissions using the Pi Camera at Symbol Rates from 333 KS to 4 MS.

Carrier transmission.

Successful encoding from the Pi Camera has been demonstrated between 250 KS and 8 MS, but these symbol rates are only selectable from the Console interface.

The FileTS (playing a pre-recorded TS file) and PATERNAUDIO (test card) and Desktop modes do not function properly. Work is ongoing to improve this capability. Analogue Capture does work with some EasyCap dongles, but not with others. I have seen successful encoding at between 333 and 1000 KS, with one dongle, but only intermittent pictures with another.

All FEC modes are available, and using the Console any frequency can be selected.

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