Spirent SimINERTIAL

Integrated GPS/Inertial Test

Introduction

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

scenarios.

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 user’s 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.

Spirent SimINERTIAL

Integrated GPS/Inertial Test

For more information, call your Spirent sales representative or

visit us on the web at www.spirent.com/ContactSpirent.

www.spirent.com

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

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

GPS RF

Ethernet UDP

Unit

Under

Test

1553B Instrumentation Bus

SimINERTIAL

/N Controller

with RS422 Data Interface

Spirent

GSS9000

C50r

SimGEN

Host

SimBARO

(RT)

Timing

Signal

Delta Data oV, o0

(variant speciﬁc)

GPS + Inertial Testing Example

Figure 1. Typical SimINERTIAL system conguration.

Supported Variants

EGIs

• Honeywell H-764G, SIGI and

NAV100

IMU

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

HG-9900

(as used in JDAM, for example)

• Northrop Grumman LN200

• AMRAAM-compliant

• NATO STANAG 4572

• AIS SilMUO2 and SiNAV02

IMU interfacing is via the supplied

RS422 card

Summary

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

simulations.

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

request.

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