Data Collection for Post Processing

Some operations, such as aerial measurement systems, do not require real-time information from SPAN. These operations are able to generate the position, velocity or attitude solution post-mission in order to generate a more robust and accurate solution than is possible in real-time.

In order to generate a solution in post-processing, data must be simultaneously collected at a base station and each rover. The following logs must be collected in order to successfully post process data.

From a base:

LOG VERSIONB ONCE
LOG RXCONFIGB ONCE
LOG RXSTATUSB ONCHANGED
LOG THISANTENNATYPEB ONCE
LOG RANGECMPB ONTIME 1
LOG RANGECMPB_1 ONTIME 1
LOG GPSEPHEMB ONNEW
LOG GLOEPHEMERISB ONNEW (if using GLONASS)
LOG GALINAVEPHEMERISB ONNEW (if using Galileo)
LOG GALFNAVEPHEMERISB ONNEW (if using Galileo)
LOG BDSEPHEMERISB ONNEW (if using BeiDou)
LOG QZSSEPHEMERISB ONNEW (if using QZSS)

From a rover:

LOG VERSIONB ONCE
LOG RXCONFIGB ONCE
LOG RXSTATUSB ONCHANGED
LOG THISANTENNATYPEB ONCE
LOG HEADING2B ONNEW
LOG INSCONFIGB ONCHANGED
LOG RANGECMPB ONTIME 1
LOG GPSEPHEMB ONNEW
LOG GLOEPHEMERISB ONNEW (if using GLONASS)
LOG GALINAVEPHEMERISB ONNEW (if using Galileo)
LOG GALFNAVEPHEMERISB ONNEW (if using Galileo)
LOG BDSEPHEMERISB ONNEW (if using BeiDou)
LOG QZSSEPHEMERISB ONNEW (if using QZSS)
LOG RAWIMUSXB ONNEW
LOG TIMEB ONTIME 1
LOG BESTPOSB ONTIME 1
LOG BESTGNSSPOSB ONTIME 1
LOG INSPVAXB ONTIME 1
LOG INSUPDATESTATUSB ONCHANGED
LOG DMICONFIGB ONCHANGED (if using a DMI sensor)
LOG RAWDMIB ONNEW (if using a DMI sensor)

Post processing is performed using Waypoint Inertial Explorer. Visit our web site at novatel.com/products/waypoint-software for details.

The highest rate that you should request GNSS logs (RANGE, BESTPOS, RTKPOS, PSRPOS, and so on) while in INS operation is 5 Hz. If the receiver is not running INS (no IMU is attached), GNSS logs can be requested at rates up to 20 Hz.

The choice between ONNEW and ONCHANGED is dependent on the type of data collection and user preferences. The ONNEW trigger can result in larger files with duplicate logs that are ignored by Inertial Explorer’s converter. The ONCHANGED trigger is preferable to avoid duplicates and minimize file size. However, if the ONCHANGED log request is made before the logging file is opened the log will not be triggered until a value has changed. This may cause issues in short surveys, as slow changing logs (such as RAWEPHEMB) may not be logged during the data collection period. For this reason, ONNEW is suggested for short surveys.

No RAWDMIB logs will be decoded without the presence of a DMICONFIGB log. As such, users may consider logging this ONTIME at a coarse rate to ensure it is saved to file (e.g. LOG DMICONFIGB ONTIME 300).