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GSS7725 Interference Generator User Manual
© Spirent Communications plc 2002-2017
3-1
Chapter 3: Introduction
Spirent designed the GSS7725 to test Satellite Navigation receiver equipment in a simulated
environment. The GSS7725 supports the playing of pre-canned IQ files that have been generated
by either Spirent equipment or a third-party software. The interference is output at RF and
optionally combined with the GNSS input from a Spirent signal generator. The output RF power of
the GSS7725 can be controlled independently from the output RF power from a Spirent GNSS
signal generator.
3.1 Phases of operation
This manual describes the operation of the GSS7725 in four separate phases:
Hardware Configuration
Describes the hardware interconnection of the GSS7725 and the interconnection to the software.
Scenario Definition
Guides you through defining the simulated interference environment.
Scenario Run-Time & Remote Control through SimGEN
Guides you through how to control the GSS7725 at run time while running a previously specified
interference scenario.
Remote control
Guides you through how to take direct control of the GSS7725
3.2 Nomenclature
SimGEN
and this document refer to various components using the Spirent nomenclature defined
below.
SimGEN
simulates one or more Vehicles, each Vehicle may have one or more Antennas mounted
on it. Each Antenna corresponds to an RF port, either on the front or rear panel of the signal
generator, or on the front panel of the GSS7725.
When you connect one (or more) GPS receivers to the RF output ports, the receiver functions as
though it is connected to the simulated antenna mounted on the simulated vehicle.
The dual-output, GSS9000-series and GSS8000-series signal generators have two RF ports on the
front panel, and can simulate two Vehicles, each with one antenna; or one Vehicle with two
separate antennas. Alternatively, the single output signal generators may operate in L1/L2 mode,
where the RF port produces an RF signal feeding a single antenna mounted on a single vehicle.
You can combine up to four units to allow multiple vehicles/multiple antennas or multiple L1/L2
vehicle/antenna combinations.
The GSS7727 has a single RF input and a single combined RF output. A single GSS7725 may
only be associated with one scenario antenna. Between scenarios, you can switch the GSS7725
between scenario antennas.
The collective name for the interference environment you require that incorporates the satellite
constellation, vehicle motion, atmospheric effects and antenna properties is a Scenario
.
