International Global Navigation Satellite Systems Association
IGNSS Conference 2016
Colombo Theatres, Kensington Campus, UNSW Australia
6 – 8 December 2016
Interference Mitigation and Preserving Multi-GNSS
Performance
Kirk Burnell
NovAtel Inc., Canada
Phone: +1-403-295-4500, kirk.burnell@novatel.com
John Schleppe
NovAtel Inc., Canada
Phone: +1-403-295-4500, john.schleppe@novatel.com
Rod MacLeod
NovAtel Australia Pty Ltd, Australia
Phone: +61 2 8668 4073, rod.macleod@novatel.com
ABSTRACT
The PNT market’s thirst for performance is placing more emphases on
tracking every possible GNSS signal in increasingly difficult conditions.
Tracking additional signals requires increasing the RF bandwidth which can
leave the system more susceptible to interference. At the same time the
once-quiet neighbouring RF spectrum is being used for an increasing
number of applications. Working near these noisy neighbours is adding
constraints to system designers and integrators working with GNSS.
A series of tests were conducted to see if NovAtel’s OEM719 GNSS
receiver with its Interference Toolkit could mitigate the out of band
interference from a Globalstar transceiver on the GPSL1 band as effectively
as the combination of a cavity filter and the OEM628. Without any form of
mitigation or protection, both NovAtel receivers will lose lock on GPS L1
signals when the Globalstar transceiver is broadcasting in close proximity to
the GNSS antenna. However, using a cavity filter very effectively preserves
performance. The main disadvantages of the cavity filter besides size,
weight and cost are that to be effective the passband is often narrow and
doesn’t allow for full tracking of BeiDou or GLONASS L1 signals, and two
or more cavity filters need to be used together for multi-frequency
applications like RTK.
NovAtel’s Interference Toolkit was able to detect and mitigate the impact of
the Globalstar broadcasts on the OEM719’s GPSL1 tracking as effectively
as the cavity filter.
KEYWORDS: GNSS, interference, Globalstar, mitigation
