ZED-F9K-Integration manual
3.9.9.1 GPS-only date resolution
In circumstances where only GPS L1C/A signals are available and for receivers with earlier firmware
versions, the receiver establishes the date by assuming that all week numbers must be at least
as large as a reference rollover week number. This reference rollover week number is hard-coded
at compile time and is normally set a few weeks before the software is completed, but it can be
overridden by CFG-NAVSPG-WKNROLLOVER configuration item to any value the user wishes.
The following example illustrates how this works: Assume that the reference rollover week number
set in the firmware at compile time is 1524 (which corresponds to a week in calendar year 2009,
but would be transmitted by the satellites as 500). In this case, if the receiver sees transmissions
containing week numbers in the range of 500 ... 1023, these will be interpreted as week numbers
1524 ... 2047 (calendar year 2009 ... 2019), whereas transmissions with week numbers from 0 to
499 are interpreted as week numbers 2048 ... 2547 (calendar year 2019 ... 2028).
It is important to set the reference rollover week number appropriately when supplying u-
blox receivers with simulated signals, especially when the scenarios are in the past.
3.9.10 Time pulse
3.9.10.1 Introduction
u-blox receivers include a time pulse function providing clock pulses with configurable duration and
frequency. The time pulse function can be configured using the CFG-TP-* configuration group. The
UBX-TIM-TP message provides time information for the next pulse and the time source.
Figure 20: Time pulse
3.9.10.2 Recommendations
• The time pulse can be aligned to a wide variety of GNSS times or to variants of UTC derived
from them (see the chapter on time bases). However, it is strongly recommended that the
choice of time base is aligned with the available GNSS signals (so to produce GPS time or
UTC(USNO), ensure GPS signals are available, and for GLONASS time or UTC(SU) ensure
the presence GLONASS signals). This will involve coordinating the setting of CFG-SIGNAL-*
configuration group with the choice of time pulse time base.
• When using time pulse for precision timing applications it is recommended to calibrate the
antenna cable delay against a reference timing source.
•
To get the best timing accuracy with the antenna, a fixed and accurate position is needed.
UBX-20046189 - R01
3 Receiver functionality Page 57 of 105
C1-Public Early production information
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