TRANSFORMING THE WAY THE WORLD WORKS
TECHNICAL PUBLICATION
INTRODUCTION
A dominant error source on satellite
measurements is caused by a phenomenon
known as multipath. In the mid-1990s
Trimble introduced the patented Everest
TM
multipath rejection technology based on
advanced digital signal processing. Within the
satellite signal tracking loops, the reflected
multipath signals were processed and
ultimately rejected. This allowed sub-meter
DGPS positioning and faster more reliable
RTK initializations. With the introduction
of Maxwell
TM
7 Technology Trimble has
significantly improved the multipath
mitigation performance with a patent pending
technique known as Everest Plus. This
technical bulletin provides an overview of how
Trimble receivers provide this improvement.
WHAT IS GNSS MULTIPATH?
This is where a signal reflection is
Trimble Maxwell
TM
7 Technology -
Advanced Multipath Mitigation with Everest
TM
Plus
superimposed on the desired direct signal,
causing distortion. Reflective surfaces for
GNSS signals are all around us, and include:
metallic surfaces such as vehicles, buildings,
water, trees, fences and walls. Multipath
can introduce errors of many centimeters
in RTK positioning and decimeters or more
in autonomous, SBAS or DGPS positioning
modes.
