EVK-M91 - User guide
9 Troubleshooting
My application (e.g. u-center) does not receive all messages
When using UART, make sure the baud rate is sufficient. If the baud rate is insufficient, GNSS
receivers based on u-blox M9 GNSS technology will skip excessive messages. Some serial port cards/
adapters (e.g. USB to RS232 converter) frequently generate errors. If a communication error occurs
while u-center receives a message, the message will be discarded.
My application (e.g. u-center) loses the connection to the GNSS receiver
u-blox M9 positioning technology and u-center have an autobauding feature. If frequent
communication errors occur (e.g. due to problems with the serial port), the connection may be lost.
This happens because u-center and the GNSS receiver both autonomously try to adjust the baud
rate. Do not enable the u-center autobauding feature if the GNSS receiver has the autobauding flag
enabled.
Some COM ports are not shown in the port list of my application (e.g. u-center)
Only the COM ports that are available on your computer will show up in the COM port drop down list.
If a COM port is gray, another application running on this computer is using it.
EVK-M91 does not work properly when connected to a GNSS simulator
When using EVK-M91 together with a GNSS simulator, please pay attention to proper handling of
the EVK. A GNSS receiver is designed for real-life use, i.e., time is always moving forward. When using
a GNSS simulator scenarios, the scenario time can be in the past resulting in the receiver to jump
backwards in time. This can have serious side effects on the performance of GNSS receivers.
The solution is to configure the GPS week rollover value to a week number preceding the date in
GNSS simulator scenario. For example, setting the GPS week number to 1200 (corresponding to Jan
2003) allows running simulator scenarios taking place after this date. Please refer to
for
how to set the GPS week number with u-center GNSS evaluation software. In addition, always issue
a Cold start command before every simulator test to avoid receiver confusion due to the time jumps.
UBX-19056858 - R02
9 Troubleshooting
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