QPSKRF or Ugly mode
The F5OEO software has a QPSKRF or “ugly” test mode which directly generates a DATV signal on 437 MHz using the internal RPi clocks. This facility is available in the Portsdown transmitter as it is very useful for initial across the shack testing but has limited functionality and as its name implies, is not suitable for putting on air even if bandpass filters are used.
Image of UGLY mode spectrum
Ugly mode needs to be selected as the output mode using the console menu and has a number of functional limitations including:
- Only works on 437 MHz
- It will not work reliably above 333 Ksymbols
- Select the Desktop as the output as it may not work reliably with the internal test patterns
- Do not connect an aerial or piece of wire to the GPIO output pin (especially if you are using a plug top PSU) as there is a chance you will blow up your Rpi due to earth loops.
Receiving Ugly Mode
As Ugly mode only works up to 333Ks, you cannot receive it on a standard Satellite set top box and must use the MiniTiouner receiver.
Experience has shown it is enough just to lay a receive pick up loop close to the Rpi GPIO connector but it may require some playing with the coupling to eliminate multi-path and receiver overload before you get successful decodes.
MiniTioune needs to be set as follows:
- 00333 in the SR box
- 00437 in the Frequency box
- Tick DVB-S (not auto)
Details how to use the software are here.