EMTAC CRUX II BTGPS, Руководство пользователя

Страница: 13 / 34

13
narrow street and passageway,
protection film on glass,
heavy foliage,
large cliffs,
and other obstructions where the satellite signals may blocked, and, poor satellites
geometry situation. Initial state of the receiver, means latest status in memory of the
receiver, may mainly determine the time of TTFF. Position can be quickly fixed within
only 10 seconds from a hot-start state and needs 80 seconds typically from a
cold-start state. Or, might need at least 3 to 5 minutes from a completely restart-state,
for example, flying a distance over 500 kilometers from initial origin.
BTGPS uses the satellite signals to calculate an exact geodetic location through
triangulation method, contained in 10 meters CEP accurateness devoid of Selective
Availability (SA), which is good enough for general location awareness purposes. The
position data is then converted within the receiver to latitude and longitude
coordinates, which is usually provided in the geodetic datum on which GPS is based
(WGS 84). Position offsets of hundreds of meters or much more can result from using
the wrong datum.
In addition to datum used, there are number of positioning errors can occur, limiting
accuracy. The major errors including satellites orbiting error, poor satellites geometry,
multi-path signals, atmospheric delay and receiver clock timing.
The indication of GPS signal reception is described in section “Indication of BTGPS
operation” of Chapter 3.
Using optional external active antenna
*
Your BTGPS is optional equipped with an external active antenna(optional accessory)
for convenience usage when operating under certain environment situation, such
inside vehicle where satellite signals are blocked. Detailed operation is described in
Operation chapter. Make sure using the optional external antenna supplied by EMTAC.
Use of unqualified antenna will severely degrade positioning performance or even
damage the receiver. Read basic guidelines before using external active antenna
accessory.
*The external active antenna is an optional accessory which not included in the standard package.