WAAS GUS Signal Generator User Guide Rev 1
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Chapter 1
Introduction
The WAAS GUS Signal Generator is a high performance L1/L5 Signal Generator. It generates a modulated
Intermediate Frequency (IF) signal that is upconverted, amplified and transmitted to a Geo-stationary Earth Orbit
(GEO) satellite. The primary GUS interfaces to the Signal Generator are the Safety Computer (SC), Radio
Frequency Uplink (RFU) and Frequency Distribution Amplifier (FDA). The Signal Generator also provides, for L1:
• Coarse/Acquisition (C/A) codes with Pseudo Random Number (PRN) values of 120 to 158 inclusive
(selectable via the initialization command)
• 70 MHz Binary-Phase Shift Keyed (BPSK) modulated or Quadrature-Phase Shift Keyed (QPSK) modulated
IF output signal generation using the SBAS message with the selected 1023 bit PRN code
• In-phase (I) channel, I channel with dataless quadrature (Q) channel or I channel with independent data on
the Q channel
• User configurable 1227.6 MHz (default) or 1575.42 MHz (alternate) RF output signal carrying the
configured modulation for L1
• L5 codes with PRN values of 120 to 158 inclusive (selectable using the Initialization Command, see
• 70 MHz BPSK or QPSK modulated IF output signal generation using the SBAS message with the selected
10230 bit PRN code
• In-phase Manchester encoded (I) channel, I channel with dataless quadrature (Q) channel or I channel with
independent Manchester enclosed data on the Q channel
• User configurable 1176.45 MHz (default) or 1227.6 MHz (alternate) RF output signal carrying the
configured modulation for L5
The Signal Generator consists of the Baseband Signal Generator (BSG), IF Signal Generator (ISG) and the
Loopback Signal Generator (LSG).
shows an example of a system containing the Signal Generator and
Receivers.