how do i get HDOP ?

[bsimmo]

I have this setup, (agps3 and agps3threaded) and can get lat, long, alt and the demo give ones.
I see hdop in the list, but cannot get it, it just returns n/a

e.g.
agps_thread.data_stream.lat
works fine
agps_thread.data_stream.hdop

returns n/a

cgps, nmea and gpsmon are all giving me hdop in the stream
(ublox mk8030)