Product Manual

92
RTK Implementation
Setting the RTK position output mode allows you to choose
the position output that is right for your application.
Ashtech receivers offer two different RTK position output
modes:
• Time-tagged RTK mode, also called “Synchronized RTK”
mode.
• Fast RTK mode.
Key Terms and Expressions
Latency: Delay between the time (t0) for which an RTK
position is requested and the time (t1) when the rover starts
delivering that position. More precisely, t1 represents the
time when the rover outputs the position data’s first
character. Caution! At time t1, the rover will start delivering
the position it occupied at time t0, and not the position it is
occupying at time t1. This is true for the two output modes
presented in this section.
Epoch: Relevant to a particular time at which a full set of RTK
correction data is generated by the base. As this time of data
availability is cyclical, each occurrence of this particular time
is called an epoch.
Extrapolation: A process through which the rover can
continue to compute accurate positions by extrapolating the
RTK correction data last received from the base. Generally
speaking, in an extrapolation process, the rover tries to
predict with the best possible accuracy the most likely value
of a quantity in a very near future.