Kinematic Initialization Requirements; Performing A Kinematic Survey; System Setup - ashtech Z-Surveyor Operation And Reference Manual

Kinematic Initialization Requirements

A unique procedure to kinematic surveying is the initialization of the survey in order
to resolve the carrier phase ambiguities of all visible satellites. This is the very first
step in performing a kinematic survey.
Initializing the kinematic survey is done by one of two methods: 1) occupying a
known baseline (previously measured by GPS) with the base GPS system on one end
and a rover on the other, and 2) establishing a known baseline using the rapid static
survey method. The only difference between the two methods is the amount of time
required for the initialization. If more than one rover is being used in the survey, each
rover must be initialized. It is best that this baseline is not longer than 5 km. The
longer the baseline, the more chance of an initialization error.

Performing a Kinematic Survey

The kinematic method of GPS surveying is the most difficult due to the requirement
of maintaining the carrier phase ambiguities of at least four satellites at all times. The
advantage is high productivity.
A kinematic survey requires at least two GPS systems that collect data simultaneously
from a minimum of four common satellites over a specific time period. One system,
often referred to as the base, remains centered over a known point while the other
system(s), often referred to as rovers, move to unknown stations collecting short data
sets. In order to compute accurate baselines and establish accurate positions on the
unknown points, the data collected in the field is post-processed. This section
describes how to utilize the kinematic method of GPS surveying to collect the data
necessary for post-processing.

System Setup

Normally, when using the kinematic methods, the roving GPS systems utilize fixed
length pole and bipod systems or fixed length GPS tripods versus a standard tripod
and tribrach combination. There are three reasons for this. 1) These systems are
significantly easier and quicker to set up. Setup times are significant when
observation times are measured in seconds, as is true with a kinematic survey. 2)
Fixed length poles eliminate antenna height measuring errors. These errors become
more prominent when the number of set ups increases. 3) Fixed height poles result in
only one antenna height for the many points observed in a kinematic survey. As
mentioned earlier, only one antenna height is stored for each data file. In kinematic
surveying, one data file may contain data for many points. If different antenna heights
are measured at each point, they will not be stored. This means these antenna heights
will have to be manually recorded in the field and entered manually during the data
processing.
64 Z-Surveyor & Z-FX Operation Manual