Integrated GPS/Inertial Test
The testing of an Inertial navigation sensor presents a
major challenge in its own right, even before considering
GPS integration. The linear and angular sensors are usually
characterized separately using centrifuges and angular rate
tables respectively. Some limited integrated navigation
testing can be performed using rate tables equipped with
a lever arm but establishing full operational performance
usually requires expensive and time-consuming eld test on
an appropriate moving vehicle platform.
To reduce the need for eld trials, operational performance of
an Integrated GPS/Inertial (IGI) system can be established in
the laboratory using a GPS RF Constellation simulator, such as
Spirent’s GSS9000 product, along with a real-time emulation
of the inertial sensor outputs that are coherently generated
to exactly match the simulated GPS vehicle trajectory. Typical
Inertial sensor performance regarding bias and drift, for
example, can be established using traditional techniques,
and then represented by a sensor error model driven by the
simulated motion with appropriate coefcients entered by the
user. It is often necessary to provide an altitude reference for
Inertial-only navigation, such as a pressure altitude input.
The key benet of this approach is that the stimuli to the
navigation algorithms, in the form of GPS pseudorange
measurements made by the GPS receiver under test and the
emulated linear delta- velocity and angular delta-theta inertial
sensor outputs, are under user control in the lab and are
extremely repeatable. This allows ne-tuning and debugging
of the navigation algorithms across a range of operational test
For hybrid navigation sensors that are fully integrated into
a single unit, (such as Northrop Grumman’s LN100 and
Honeywell’s H-764G) the manufacturer will often provide a
suitable test input port to accept the emulated sensor data
streams, bypassing the physical sensors in the unit under test.
For GPS/Inertial systems that have the Inertial Measurement
Unit (IMU) and GPS in physically separate units, all that is
required is to substitute the IMU with an inertial sensor stream
conforming to the IMU’s dened data output interface,
typically RS422 serial.
Spirent SimINERTIAL Inertial Test Systems
The GSS9000 GPS simulator range uses Spirent’s state-of-the-
art SimGEN
application and modeling software to dene
and control the test environment. This fully exible tool is
easy to use and is equipped with a comprehensive range of
trajectory generators as well as supporting true hardware-
in-the-loop applications via acceptance of external vehicle
motion data in real time.
SimINERTIAL is housed in a PC platform equipped with the
appropriate data interface card. The simulated motion data is
streamed from SimGEN
via Ethernet to SimINERTIAL, which
translates this simulated motion data into representative real-
time data streams at the data rate and with the data format
appropriate to the unit being tested.
SimINERTIAL is equipped with fully user-congurable sensor
error modeling and supports a range of popular Inertial
formats via a number of separately priced variants. All variants
adopt the same basic architecture as shown in Figure 1.
All SimINERTIAL solutions can also be equipped to deliver a
barometric altitude output via a MIL-STD-1553B card installed
in the SimINERTIAL controller PC.
Control and data monitoring of the unit-under-test would
normally be via the users own instrumentation interface.
Spirent’s SimINERTIAL architecture is also available in
congurations to support transfer alignment and multiple
sensor architectures.
SimINERTIAL testing
at Spirent’s facility.
Integrated GPS/Inertial Test
Contact Us
For more information, call your Spirent sales representative or
visit us on the web at www.spirent.com/ContactSpirent.
© 2018 Spirent Communications, Inc. All of the company names and/or brand names
and/or product names and/or logos referred to in this document, in particular the
name “Spirent” and its logo device, are either registered trademarks or trademarks
pending registration in accordance with relevant national laws. All rights reserved.
Specications subject to change without notice.
Americas 1-800-SPIRENT
+1-800-774-7368 | sales@spirent.com
US Government & Defense
info@spirentfederal.com | spirentfederal.com
Europe and the Middle East
+44 (0) 1293 767979 | emeainfo@spirent.com
Asia and the Pacic
+86-10-8518-2539 | salesasia@spirent.com
MCD00160 | Issue 1-06 | 05/19
Ethernet UDP
1553B Instrumentation Bus
/N Controller
with RS422 Data Interface
Delta Data oV, o0
(variant specific)
GPS + Inertial Testing Example
Figure 1. Typical SimINERTIAL system conguration.
Supported Variants
• Honeywell H-764G, SIGI and
Interfacing is via Honeywell’s
proprietary Inertial
Sensor Recorder Simulator ISRS2 card
• Northrop Grumman LN100G, LN250,
LN251 and LN260
EGIs interfacing is via the supplied
RS422 card
IMU Emulation
• Honeywell HG-1700, HG-1900 and
(as used in JDAM, for example)
Northrop Grumman LN200
• AIS SilMUO2 and SiNAV02
IMU interfacing is via the supplied
RS422 card
Spirent supports Integrated GPS
and Inertial performance testing by
combining its powerful and exible
GPS simulation systems with coherently
generated inertial sensor delta-theta
and delta-velocity data.
The SimINERTIAL architecture is
readily adapted to other inertial sensor
Please contact Spirent for more
detailed information to meet your
specied testing requirements.
Product Specications MS3008 and
MS3030 refer to the capabilities in this
information sheet and are available on
Performance gures and data in this
document are typical and must be
specically conrmed in writing by
Spirent Communications plc. before
they become applicable to any
particular order or contract.
The publication of information in this
document does not imply freedom
from patent or other rights of Spirent
Communications plc. or others.
For current product data, visit the
Spirent websites at www.spirent.com/
positioning or www.spirentfederal.com