Trimble Outdoors 5700 - Manual (Page 108)

8 Real-Time Kinematic (RTK) Surveying
9 2 5700 GPS Receiver User Guide
Appl
icatio
ns
8.2.2
Update Rate and Latency
The number of position fixes delivered by an RTK system per second
is called the update rate. The update rate determines how closely the
trajectory of the rover can be represented and the ease with which
position navigation can be accomplished. For the 5700 receiver, the
maximum update rate is 10 Hz.
Solution latency is the lag in time between when the position was
valid and when it is displayed. For precise navigation, you must have
prompt position estimates, not values from 2 seconds ago. Solution
latency is particularly important when guiding a moving vehicle. For
example, a vehicle traveling at 25 kilometers per hour moves at
approximately 7 meters per second. Thus, to navigate to within
1 meter, the solution latency must be less than
1
/
7
second (0.14 s).
Various factors contribute to latency, as shown in Figure 8.1. The
latency value can vary between 0.5 and 2 seconds.
Figure 8.1 Factors contributing to RTK latency
Collec
t
F
o
rm
at
dat
a
Sync
hronize
Comput
e
Di
s
p
lay
pos
it
ion
Time (seconds)
Reference receiver
Rover
Transmit data
ref
e
rence
dat
a
R
T
K
pos
it
ion
obs
ervat
ions
Coll
ec
t
observ
a
ti
ons
Latency
0
0 1
1