SonTek, a Xylem brand
6 RiverSurveyor S5/M9 System Manual (February 2013)
2.2.2. Spread Spectrum (SS) Option
A PCM with the Spread Spectrum radio option provides remote communication between the
PCM and the SS Base radio connected to a PC. The operational range is about 2 km.
2.3. GPS Components – Optional
SonTek offers two GPS options integrated into the PCM. The first option provides RTK quality
data (±3 cm). RTK quality data requires additional hardware in the PCM as well as a separate
RTK Base Station (Figure 5). The Base Station provides RTK corrections to the GPS receiver
built into the PCM. The Differential GPS (DGPS) option does not require a Base Station, but
additional hardware is required for the PCM. Some general rules of thumb for connection times
for the various communications are:
• GPS Lock: Typically takes 5 minutes to turn from Red to Green (greater than 1-m ac-
curacy).
• Differential Lock: Typically takes up to about 5 minutes to turn from Red to flashing
Red/Green (sub-meter accuracy).
• RTK Lock: Typically takes up to about 10 minutes to turn from alternatively flashing
Red/Green to Green (±3 cm accuracy).
• BT/SS LED: Turns to Green as soon as connection is established between PC/Phone
and the system (assuming you are within range).
• Base Station Radio Link Established: Red light
Figure 5. Real-Time Kinematic (RTK) Base Station