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SPAN-CPT Operation Chapter 3
SPAN-CPT User Manual Rev 8 33
To store data from a SPAN-CPT, connect a computer. The computer should be equipped with a data
storage device such as a Compact Flash Card, CD or USB stick.
3.7 Data Collection for Post-Processing
Some operations such as aerial measurement systems do not require real time information from
SPAN-CPT. 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:
• RANGECMPB ONTIME 1
• RAWEPHEMB ONCHANGED
• GLOEPHEMERISB ONCHANGED (if using GLONASS)
From a rover:
• RANGECMPB ONTIME 1
• RAWEPHEMB ONCHANGED
• GLOEPHEMERISB ONCHANGED (if using GLONASS)
• RAWIMUSXB ONNEW
• IMUTOANTOFFSETSB ONCHANGED
• VEHICLEBODYROTATIONB ONCHANGED
Post-processing is performed through the Waypoint Inertial Explorer
®
software package available from
the NovAtel Waypoint Products Group. Visit our Web site at www.novatel.com/products/software/
waypoint-products/ for details.
Logging Restriction
Logging excessive amounts of high rate data can overload the system. When configuring
the output for SPAN, NovAtel recommends that only one high rate (>50 Hz) message be
configured for output at a time. It is possible to log more than one message at high rates,
but doing so could have negative impacts on the system. Also, if logging 100 Hz data,
always use the binary format and, if possible, the short header binary format (available on
most INS logs).
For optimal performance, log only one high rate output at a time. These logs could be:
• Raw data for post processing
RAWIMUXSB ONNEW (100 Hz)
- RAWIMU logs are not valid with the ONTIME trigger. The raw IMU observations
contained in these logs are sequential changes in velocity and rotation. As
such, you can only use them for navigation if they are logged at their full rate.
See details of these logs in the SPAN on OEM6 Firmware Reference Manual
(OM-20000144).
• Real time INS solution
INSPVASB ONTIME 0.01 (maximum rate equals the IMU rate)
- Other possible INS solution logs available at high rates are: INSPOSSB,
INSVELSB and INSATTSB
The highest rate to request GNSS logs (RANGE, BESTPOS, RTKPOS, PSRPOS and so
on) while in INS operation is 5 Hz. If the receiver is not running INS, GNSS logs can be
requested at rates up to 20 Hz.