GNSS Receiver Amplifier Interference Detection Before Nonlinear Saturation
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Solution Overview
Problem
Global navigation satellite system (GNSS) signals are prone to interference from high-level signals, which can degrade measurement accuracy and reliability, particularly due to the low signal levels of GNSS signals being overwhelmed by interference signals, leading to non-linear amplification and subsequent loss of measurement precision.
Innovation Solution
A high-linear amplifier stage is designed with a directional coupler and rectifier circuit to detect and manage excessive interference signals, maintaining linearity and preventing the amplifier from entering non-linear mode by using a directional coupler to separate incident and reflected signals and a rectifier circuit to detect signal levels, thereby extending the amplifier's linearity range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the amplifier gain is increased to amplify weak GNSS signals, then the signal level is improved, but interference signals cause non-linear amplification and measurement precision deteriorates
Solution Approach 1:
The patent applies preliminary action by detecting interference signal levels before they cause non-linear amplification. The detection circuit monitors the input signal level and generates an interference indicator signal in advance, allowing the system to take preventive measures (such as adjusting gain or alerting operators) before measurement precision deteriorates due to non-linear amplification of weak GNSS signals in the presence of strong interference.
2Reliability
If the amplifier operates in high-gain mode to detect weak signals, then signal detectability is improved, but the amplifier enters non-linear mode under high interference and reliability decreases
Solution Approach 1:
The patent implements feedback by using a detection circuit that continuously monitors the amplifier input signal level and generates an interference indicator signal. This feedback mechanism provides real-time information about interference conditions, allowing the system to adjust operating parameters or alert operators to maintain the amplifier in linear operation mode even when detecting weak signals, thereby ensuring reliability without sacrificing detectability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively alerts operators to impending interference thresholds, allowing for corrective actions to maintain linear amplification, thus ensuring accurate GNSS signal processing and measurement precision even in the presence of high interference levels.
Implementation Method 1
A high-linear amplifier stage is designed with a directional coupler and rectifier circuit to detect and manage excessive interference signals
Implementation Method 2
a rectifier circuit to detect signal levels
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A high-linear amplifier receives, from an input bandpass filter, input signals including weak process signals and strong interference signals, amplifies the input signals, and transmits the amplified signals to an output bandpass filter. The high-linear amplifier includes a transistor and a feedback circuit that stabilizes the operating current of the transistor. The operating current includes the direct-current and low-frequency output signal currents of the transistor. The feedback circuit includes an interference detector that rectifies a portion of the high-frequency output signals of the transistor and extends the linear range of the high-linear amplifier. An interference indicator unit alerts an operator to the presence of excessively high levels of interference before the high-linear amplifier enters the non-linear mode. Amplified signals rejected by the output bandpass filter are reflected back to the high-linear amplifier stage. A directional coupler prevents the reflected signals from disrupting the operation of the interference detector.