Transmitting and Receiving Corrections

Corrections can be transmitted from a base station to a rover station to improve position accuracy. The base station is the GNSS receiver that acts as the stationary reference. The stationary reference has a known position and transmits correction messages to the rover station. The rover station is the GNSS receiver that does not know its exact position and requires correction messages from a base station to calculate differential GNSS positions. An example of a differential setup is shown in Figure: Basic Differential Setup.

	Rover Setup		Base Setup
1	Mount and connect a GNSS antenna	1	Mount and connect a GNSS antenna
2	Connect a fused power supply (user supplied)	2	Connect a fused power supply (user supplied)
3	Connect a radio device to COM2 (user supplied)	3	Connect a radio device to COM2 (user supplied)
4	Connect a storage device to COM1 (user supplied)	4	Connect a computer to COM1 for setup and monitoring (user supplied)

To receive corrections, a data link between the base station and the rover station is required. The base and rover stations can both be NovAtel receivers, however NovAtel receivers will work with some other brands. Contact Customer Support for further details (refer to Customer Support for details).

The data link should support a rate of at least 19200 bits per second, but a rate of 115200 bits per second, with less than 4.0 s latency, is recommended.

Unlike the base/rover concept, SBAS and PPP corrections can be applied directly to a single receiver.

When the base and rover are set up, configure them as shown in the configuration examples in Base Station Configuration and Rover Station Configuration.

Defining Antenna and Base Antenna

The type of antenna for the receiver and/or the base receiver can be defined using the THISANTENNATYPE command and BASEANTENNATYPE command respectively.

The Phase Center Variation (PCV) and the Phase Center Offset (PCO) for each can also be specified using the THISANTENNAPCV command and THISANTENNAPCO command or the BASEANTENNAPCV command and BASEANTENNAPCO command.

Base Station Configuration

At the base station, enter the following commands:

serialconfig [port] baud [parity[databits[stopbits[handshaking[break]]]]]

interfacemode port rx_type tx_type [responses]

fix position latitude longitude height (enter your own lat, long and hgt values)

log port message [trigger [period]] (port = COM2 / refer to Figure: Basic Differential Setup)

saveconfig (optional)

The following sections are examples of base station configurations.

RTK Automated Correction Generation

fix position lat lon hgt (enter your own lat, lon, hgt)

generatertkcorrections rtcmv3 com2

RTCM V3

serialconfig com2 19200 N 8 1 N on

interfacemode com2 none rtcmv3 off

fix position lat lon hgt (enter your own lat, lon, hgt)

log com2 rtcm1004 ontime 1

log com2 rtcm1006 ontime 10

log com2 rtcm1019 ontime 120

saveconfig (optional)

RTCM V3 with GLONASS

serialconfig com2 19200 N 8 1 N on

interfacemode com2 none rtcmv3 off

fix position lat lon hgt (enter your own lat, lon, hgt)

log com2 rtcm1004 ontime 1

log com2 rtcm1012 ontime 1

log com2 rtcm1006 ontime 10

log com2 rtcm1033 ontime 10

log com2 rtcm1019 ontime 120

log com2 rtcm1020 ontime 120

saveconfig (optional)

NOVATELX

serialconfig com2 19200 N 8 1 N on

interfacemode com2 none novatelx off

fix position lat lon hgt (enter your own lat, lon, hgt)

log com2 novatelxobs ontime 1

saveconfig (optional)

For more information, refer to the FIX command, INTERFACEMODE command, SAVECONFIG command and SERIALCONFIG command.

Rover Station Configuration

At the rover station, enter the following commands:

serialconfig [port] baud [parity[databits[stopbits[handshaking[break]]]]]

interfacemode port rx_type tx_type [responses]

saveconfig (optional)

The following sections are examples of rover configurations, if COM2 was connected to the correction source.

RTK Automated Correction Detection

serialconfig com2 19200 N 8 1 N on

interfacemode com2 auto none off

saveconfig (optional)

RTCM V3 with GLONASS

serialconfig com2 19200 N 8 1 N on

interfacemode com2 rtcmv3 none off

saveconfig (optional)

NOVATELX

serialconfig com2 19200 N 8 1 N on

interfacemode com2 NOVATELX none off
saveconfig (optional)

For more information, refer to the INTERFACEMODE command, SAVECONFIG command and SERIALCONFIG command.