The RTK Facet is a fully enclosed, preprogrammed device. There are very few things to worry about or configure
but we will cover the basics.
Power/Setup Button
The RTK Facet has one button used for both Power and Setup for in-field configuration changes. Pressing and
holding the Power button will cause it to power on or off. Short pressing the button will cause the RTK Facet to
change modes.
This device can be used in four modes:
GNSS Positioning (~30cm accuracy) - also known as 'Rover'
GNSS Positioning with RTK (1.4cm accuracy) - also known as 'Rover with RTK Fix'
GNSS Base Station
GNSS Base Station NTRIP Server
At Power On the device will enter Rover or Base mode; whichever state the device was in at the last power down.
When the POWER/SETUP button is pressed momentarily, a menu is presented to change the RTK Facet to Rover
or Base mode. The display will indicate the change with a small car or flag icon.
In Rover mode the RTK Facet will receive L1 and L2 GNSS signals from the four constellations (GPS, GLONASS,
Galileo, and BeiDou) and calculate the position based on these signals. Similar to a standard grade GPS receiver,
the RTK Facet will output industry standard NMEA sentences at 4Hz and broadcast them over any paired
Bluetooth device. The end user will need to parse the NMEA sentences using commonly available mobile apps,
GIS products, or embedded devices (there are many open source libraries). Unlike standard grade GPS receivers
that have 2500m accuracy, the accuracy in this mode is approximately 300mm horizontal positional accuracy with
a good grade L1/L2 antenna.
When the device is in Rover mode and RTCM correction data is sent over Bluetooth or into the radio port, the
device will automatically enter Positioning with RTK mode. In this mode RTK Facet will receive L1/L2 signals
from the antenna and correction data from a base station. The receiver will quickly (within a second) obtain RTK
float, then fix. The NMEA sentences will have increased accuracy of 14mm horizontal and 10mm vertical accuracy.
The RTCM correction data is most easily obtained over the internet using a free app on your phone (see SW Maps
or Lefebure NTRIP) and sent over Bluetooth to the RTK Facet but RTCM can also be delivered over an external
cellular or radio link to a 2nd RTK Facet setup as a base station.
In Base mode the device will enter Base Station mode. This is used when the device is mounted to a fixed position
(like a tripod or roof). The RTK Facet will initiate a survey. After 60 to 120 seconds the survey will complete and the
RTK Facet will begin transmitting RTCM correction data out the radio port. A base is often used in conjunction with
a second RTK Facet (or RTK Surveyor) unit set to 'Rover' to obtain the 14mm accuracy. Said differently, the Base
sits still and sends correction data to the Rover so that the Rover can output a really accurate position. You’ll
create an RTK system without any other setup.
