Degraded Navigation; Time Pulse; Introduction - u-blox ZED-F9P Integration Manual

ZED-F9P - Integration Manual
Figure 35: Flowchart of the Course Over Ground freezing

4.9.6 Degraded navigation

Degraded navigation describes all navigation modes which use less than four Satellite Vehicles (SV).
4.9.6.1 2D Navigation
If the receiver only has three SVs for calculating a position, the navigation algorithm uses a constant
altitude to compensate for the missing fourth SV. When an SV is lost after a successful 3D fix (min.
four SVs available), the altitude is kept constant at the last known value. This is called a 2D fix. u-
blox receivers do not calculate any navigation solution with less
u-blox receivers do not calculate any navigation solution with less than three SVs.

4.10 Time pulse

In addition to positioning and navigation applications, GNSS signals are widely used as low cost
precision time or frequency references used by remote or distributed wireless communication,
industrial, financial, and power distribution equipment. By capitalizing on atomic clocks which are
on-board positioning satellites, GNSS signals which contain embedded timing information can be
used to synchronize equipment, as well as provide UTC time. For wireless communication standards
that utilize Time Division Multiplex (TDM) and applications such as femtocell base stations, a
precision time reference is mandatory.

4.10.1 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, time source and the
quantization error of the output pin.
UBX-18010802 - R02 4 Receiver description Page 58 of 114
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