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SPAN-CPT User Manual Rev 8
Appendix C
Frequently Asked Questions
1. Why don’t I hear sound from the SPAN-CPT?
The SPAN-CPT does not make noise. Check that the multi-purpose I/O cable is connected properly.
Check the input power supply. A minimum of 12 V should be supplied to the system for stable
SPAN-CPT performance. The supply should also be able to output at least 16 W over the entire
operating temperature range.
SPAN-CPT performance. The supply should also be able to output at least 16 W over the entire
operating temperature range.
2. Why is the INS solution status ‘INS_INACTIVE’?
The INS alignment routine does not begin until the system has solved for time. This requires that an
antenna is attached and satellites are visible to the system. Verify that time is solved by checking the
time status in the header of any standard header SPAN log such as BESTPOS. When the time status
reaches FINESTEERING the inertial filter starts and the INS begins attempting to align.
antenna is attached and satellites are visible to the system. Verify that time is solved by checking the
time status in the header of any standard header SPAN log such as BESTPOS. When the time status
reaches FINESTEERING the inertial filter starts and the INS begins attempting to align.
3. How can I access the inertial solution?
The INS/GNSS solution is available from a number of specific logs dedicated to the inertial filter. The
INSPOS, INSPVA, INSVEL, INSSPD and INSATT logs are the most commonly used logs for
extracting the INS solution. These logs can be logged at any rate up to the rate of the IMU data (100
Hz). Further details on these logs are available in
INSPOS, INSPVA, INSVEL, INSSPD and INSATT logs are the most commonly used logs for
extracting the INS solution. These logs can be logged at any rate up to the rate of the IMU data (100
Hz). Further details on these logs are available in
(OM-20000144) .
4. Can I still access the GNSS-only solution while running SPAN?
The GNSS-only solution is still available when running SPAN. Logs such as PSRPOS and RTKPOS
are still available. The best available GNSS-only solution is available in the BESTGNSSPOS log.
Any non-INS logs should be logged at a maximum rate of 5 Hz when running SPAN. Only INS
specific logs (documented in the
are still available. The best available GNSS-only solution is available in the BESTGNSSPOS log.
Any non-INS logs should be logged at a maximum rate of 5 Hz when running SPAN. Only INS
specific logs (documented in the
(OM-20000144)
should be logged at rates higher than 5 Hz when running SPAN.
5. What will happen to the INS solution when I lose GNSS satellite visibility?
When GNSS tracking is interrupted, the INS solution bridges through the gaps with what is referred
to as free inertial navigation. The IMU measurements are used to propagate the solution. Errors in
the IMU measurements accumulate over time to degrade the solution accuracy. For example, after
one minute of GNSS outage, the horizontal position accuracy is approximately 8.4 m. The SPAN
solution continues to be computed for as long as the GNSS outage lasts, but the solution uncertainty
increases with time. This uncertainty can be monitored using the INSCOV log.
to as free inertial navigation. The IMU measurements are used to propagate the solution. Errors in
the IMU measurements accumulate over time to degrade the solution accuracy. For example, after
one minute of GNSS outage, the horizontal position accuracy is approximately 8.4 m. The SPAN
solution continues to be computed for as long as the GNSS outage lasts, but the solution uncertainty
increases with time. This uncertainty can be monitored using the INSCOV log.
6. All the accels measurements in my RAWIMUS logs are zero and the IMU status shows one or all
accels are failing. What is wrong?
Ensure a monotonic power supply on power up of your SPAN-CPT receiver. See Connect Power on
page 16 for more information.
page 16 for more information.
7. The SPAN-CPT will not start /power on?
The SPAN-CPT is connected to an incorrect power supply and the internal breaker has tripped. Shut
down and disconnect the SPAN-CPT and reconnect to an properly supported power supply. Reapply
power to the SPAN-CPT.
down and disconnect the SPAN-CPT and reconnect to an properly supported power supply. Reapply
power to the SPAN-CPT.