Controlling various NMEA sentences and options
Measurement Frequency
By default, the RTK Surveyor outputs a solution or location 'fix' 4 times a second. This can be increased but
anything above 4Hz is not guaranteed to be stable. The Bluetooth buffer can quickly become overwhelmed and/or
if datalogging is enabled the system can become bogged down with SD write delays. Decreasing to 1Hz is
completely acceptable and will reduce the log sizes significantly.
Note: When in base mode, measurement frequency is set to 1Hz. This is because RTK transmission does not
benefit from faster updates, nor does logging of RAWX for PPP.
NMEA
From this menu you can control the output of various NMEA sentences. Disabling these sentences will reduce the
size of the log but will also reduce the data being sent to any Bluetooth attached device.
RAWX
RAWX sentences are needed for post processing and PPP or Precise Point Positioning. This is
disabled
by
default. When enabling RAWX you will also probably want to enable logging to an SD card.
SBAS
Satellite-based Augmentation System or SBAS is disabled by default. This is because there is a bug in u-blox's
v1.13 firmware for the ZED-F9P that causes the RTK status LED to stop functioning when SBAS is enabled. We
have found no major difference in lock times or accuracy with SBAS turned off but SBAS can be enabled if
desired. Enabling SBAS will cause the RTK LED to no longer illuminate, regardless of the RTK fix.
Configure Data Logging Menu
RTK Surveyor Data Logging Configuration Menu
Pressing 2 will enter the Data Logging Menu. This menu will report the status of the microSD card. While you can
enable logging, you cannot begin logging until a microSD card is inserted. Any FAT16 or FAT32 formatted microSD
card up to 32GB will work. We regularly use the SparkX brand 1GB cards but note that these log files can get very
large (>500MB) so plan accordingly.
Option 1 will enable/disable logging. If logging is enabled, NMEA data from the ZED-F9P will be recorded to
microSD. A log file is created at power on with the format
SFE_RTK_Surveyor_YYMMDD_HHMMSS.txt