EVK-F9T - User guide
UBX-21040453 - R01
Troubleshooting
Page 19 of 23
C1- Public
Before shutting down the receiver externally, check the status in MON-
HW in field ‘Real Time Clock
Status’. Do not shut down the receiver if the RTC is not calibrated.
The EVK-F9T does not meet the TTFF specification
Make sure the antenna has a good sky view. An obstructed view leads to prolonged startup times. In
a well-designed system, the average of the C/N0 ratio of high elevation satellites should be in the
range of 40 dBHz to about 50 dBHz. With a standard off-the-shelf active antenna, 47 dBHz should
easily be achieved. Low C/N0 values lead to a prolonged startup time.
The EVK-F9T does not preserve the configuration in case of reset
u-blox F9 GNSS technology uses a slightly different concept than most other GNSS receivers do.
Settings are initially stored to volatile memory. In order to save them permanently, sending a second
command is required. This allows testing the new settings and reverting to the old settings by
resetting the receiver if the new settings are not good. This provides safety, as it is no longer possible
to accidentally program a bad configuration (e.g. disabling the main communication port).
The EVK-F9T does not work properly when connected with a GNSS simulator
When using an EVK together with a GNSS simulator, pay attention to proper handling of the EVK. A
GNSS receiver is designed for real-life use, i.e. time is always moving forward. By using a GNSS
simulator, the user can change scenarios, which enables jumping backwards in time. This can have
serious side effects on the performance of GNSS receivers.
The solution is to configure the GPS week rollover to 1200, which corresponds to Jan 2003. Then,
issue the cold start command before every simulator test to avoid receiver confusion due to the time
jumps
.
Power save mode and USB
For communication in power save mode, use the RS232.
