At 12:59 06 November 2018, John Wells wrote:
I'd like to be able to take NMEA stream from the Softrf for NON-FLARM
contacts. I'm happy to write software or whip up a little micro to merge
this with the NMEA output from FLARM and present them on my xcsoar radar.

depending your skillset, it might be easier to review/adapt Xcsoar. I
believe XCSoar uses the data from the first device with that kind of data.
That is certainly the case for GPS.
So you might have to modify the code so that "FLARM" data is accepted from
several device. (flarm between quote because all traffic device are seen as
flarm if using the flarm protocol)

But I expect the Softrf antenna will negatively impact my flarm tx/rx and
vice versa.

If the SoftRF doesn't transmit and the antenna are not close there won't be
interference.

If the softRF transmit on the same or close by frequency as FLarm then we
might have provlem if they both transmit exactly at the same time.

--
Xtophe