Novatel SMART ANTENNA - Manual (Page 25)

Operation Chapter 3
SMART ANTENNA User Manual Rev 6 25
from the satellite down-link message. After sufficient satellites have been acquired, the receiver
enters Navigation mode. In "Search the Sky", the TTFF is typically less than 3 minutes.
4. Navigation Mode
The receiver is in Navigation mode whenever sufficient satellite information and measurement
data is available to produce a GPS fix. Navigation mode is entered from Acquisition or Dead-
Reckoning mode and exits to Dead-Reckoning or Fault mode.
In Navigation mode, a receiver configured as a roving unit operates in 2 sub-modes: Differential
and Stand-Alone Nav. Sub-mode transition occurs automatically depending on satellite data
availability. A receiver which is configured as a base station unit operates in Base Station Nav
mode only. The receiver reports its current navigation sub-mode on its host port.
a. Differential (Roving Unit Only)
The receiver operates in Differential mode when data from at least 4 satellites with
adequate geometry and differential corrections and/or measurements exist to compute
position, velocity and time outputs. This is the preferred navigation mode. Differential
data is supplied to the receiver through the differential input port. Differential data can be
received only on the COM2 (DGPS IN) serial data port.
b. Stand-Alone Nav (Roving Unit Only)
The receiver operates in Stand-Alone Nav mode when it has data from at least 4 satellites
with adequate geometry, but no differential corrections or measurements exist to compute
position, velocity and time outputs. This is the preferred navigation mode when
insufficient differential data is available to generate a differential GPS fix.
c. Base Station Nav (Base Station Unit Only)
The receiver operates in Base Station Nav mode once the time has been initialized and at
least 4 satellites with adequate geometry can be used for navigation purposes. Once in
this mode, only a change of configuration (rover mode requested) or a reset will cause the
unit to leave this navigation mode. In this mode, the unit will have the ability to transmit
the DGPS messages which are requested and allowed once its position is initialized. See
also Section 3.5, Configurable Parameters starting on Page 23 for position initialization
details.
Your receiver must be a BASE model to act as a base station. A list of models may be found in Appendix A
of the SUPERSTAR II Firmware Reference Manual, see Reference [6] on Page 12.
5. Dead-Reckoning Mode
The receiver enters Dead-Reckoning mode when it cannot remain in Navigation mode. The speed
and direction is assumed to be constant to allow the receiver to provide an estimated position.
6. Fault Mode
The receiver enters Fault mode during the period of time in which the receiver outputs are affected
by one or more critical system faults. This mode supersedes all others and remains active until the
next power-down/power-up cycle. Fault mode is entered from any mode except Initialization.