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2, Doppler Navigation: analog versus digital systems
Since more than 20 years Doppler Navigation Systems have been used
efficiently for survey flying. Systems to be mentioned are:
1. Singer-Kearfott SKK — 1000/SKQ 601
2. Marconi CMA 712
3. Bendix DRA-12 /CPA-24
4. Decca Doppler Type 72
Doppler Navigation is an efficient and economic tool to solve
difficult survey navigation problems.
The weak links in a Doppler Navigation System are the compass
— providing the heading reference — and to some extent the
analog computer — providing navigation parameters such as
"distance to go" and "across distance",
The production of first three systems has been stopped; only
the Decca Doppler type 72 has been further developed into an
entirely solid-state-plug-in form; its Doppler output data can be
fed into the advanced airborne digital computer TANS 5447D,
together with heading information, attitude data and air data. This
allows & rigorous solution of the corrections of the Doppler output
data and heading data because of aircraft's angular movements.
See figure 8.
The system can be integrated with & twin &yro platform to provide a
better heading reference, thereby improving the overall accuracy of the
system. Navigation parameters displayed are the following:
. Present position (Latitude/Longitude, Naval or
U.T.M. Grid)
. Bearing/Distance and Heading to Steer with Time to Go.
to any one of the waypoints, destinations or targets
. Pitch and Roll corrections to allow full resolution into
navigation axes if all three doppler velocity components
are used
. Automatic Wind calculation
. Automatic reversion to Air Data and doppler failure
. Sea surface motion compensation. In addition, TANS
can display other information as selected, such as track
and ground speed, irue airspeed, drift angle, doppler along and
across and vertical velocities, etc.,as required. This inform-
ation can be checked in flight as required. The following ;
outputs to external equipment are also available
. X and Y drives to a pictorial display, for example, the
Automatic Chart Display
Analogue output of track error to a steering indicator
Digital outputs of: -
