the "GPS Gyros" which use 2 or 3 GPS heads and then
do kinematic phase tracking to get absolute heading
even with no platform motion have come down dramatically in price,
enough so that using a DFer seems like a pretty marginal
approach. the GPS Gyros also have accelerometers and/or
IFOG gyros to allow for dead-reckoning for some period
of time when the GPS signal is obscured. Simrad, Furuno,
Leica, and i think Raymarine all have units of varying
degrees of sophistication (Furuno has two - the SC60
and the SC120 depending on certification needed). Leica
also integrates with their AIS unit, which will very likely
become the norm as well.
expect others to bring similar units to market this year
with the expected price pressures and feature improvements.
Clever heading ref from Taiyo, uses GPS and ADF
Threaded Mode
