Signal Testing Apparatus for GNSS Receiver Verification
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Solution Overview
Problem
Current systems for verifying radio frequency (RF) signals from global navigation satellite systems (GNSS) are limited in testing and verifying signals while satellite vehicles (SVs) are on the ground, leading to inadequate pre-launch verification and costly post-launch issue resolution, especially in dynamic environments.
Innovation Solution
A signal testing apparatus that records and processes RF signals from a single SV, simulating a virtual constellation of signals, allowing real-time playback to receivers for position, velocity, and time (PVT) solution verification, enabling ground-based testing of GNSS signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If static tracking-only tests are used for pre-launch verification, then the testing process is simple and cost-effective, but the verification is inadequate and cannot reveal issues in dynamic environments
Solution Approach 1:
The patent creates a virtual copy of the satellite constellation environment by recording actual satellite signals and replaying them through a signal generator. This allows dynamic PVT solution testing without requiring actual satellites in orbit, resolving the contradiction between verification adequacy and system complexity by simulating the complex space environment through recorded signal copies
Solution Approach 2:
The system performs preliminary signal recording during periods when satellites are in orbit, storing the actual RF signals for later replay. This preliminary action enables comprehensive dynamic testing to be conducted on the ground before launch, allowing verification of PVT solutions in advance without requiring complex real-time space-based testing infrastructure
2Reliability
If actual receivers are used for pre-launch verification, then interoperability can be tested, but the cost and difficulty of fixing issues post-launch increases
Solution Approach 1:
The system enables preliminary interoperability testing by replaying recorded satellite signals through a signal generator to actual receivers on the ground. This allows detection and correction of interoperability issues before launch, avoiding the much higher costs of post-launch fixes while maintaining the benefit of testing with real receivers
3Measurement precision
If multiple orbiting GNSS SVs are required for PVT solution, then accurate positioning can be achieved, but ground-based testing becomes impossible
Solution Approach 1:
The patent records RF signals from multiple satellite vehicles and uses a signal generator to replay these recorded signals simultaneously. This creates a virtual multi-satellite environment that provides sufficient signal strength and geometric diversity for receivers to compute accurate PVT solutions while remaining entirely ground-based
Solution Approach 2:
The system combines multiple recorded satellite signals into a single test environment through the signal generator. By merging the recorded RF representations of multiple SVs, the system creates a composite signal environment that enables PVT solution computation without requiring physically separate orbiting satellites
Data Source
AI summary
A signal testing apparatus is provided. The signal testing apparatus generally comprises a recording device that is configured to receive a plurality of signals representative of a plurality of electromagnetic waves that correspond to a pre-defined period of time. The recording device is further configured to record a plurality of digital representations of the signals such that each digital representation corresponds to a separate signal. A processing device is coupled to the recording device, wherein the processing device is configured to introduce at least one operational parameter to each of the digital representations. A play-back assembly is coupled to the recording device and to the processing device, wherein the play-back device is configured to play each of the digital representations simultaneously in real-time to facilitate verification of each of the signals.