OFDM Radar Signal Discrimination Circuit
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional radar detectors used in 802.11a wireless devices struggle to differentiate between OFDM signals and radar signals, leading to false detections due to similar pulse width and repetition rate characteristics.
Innovation Solution
A circuit and method utilizing first and second bandpass filters with non-overlapping passbands, a multiplier, and a power level comparator to distinguish between OFDM signals and radar signals based on their respective bandwidths, where the OFDM signal has a larger instantaneous bandwidth and the radar signal has a narrower bandwidth, generating an indicating signal if the power product exceeds a threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional radar detection methods are used to monitor the frequency band, then radar signals can be detected, but false detections occur due to inability to differentiate between OFDM signals and radar signals
Solution Approach 1:
The patent changes the detection parameter from pulse width and repetition rate to instantaneous bandwidth. By measuring the bandwidth occupied by the signal and comparing it against threshold values, the system can reliably distinguish between OFDM signals (narrow bandwidth) and radar signals (wide bandwidth), eliminating false detections while maintaining high detection accuracy
Solution Approach 2:
The patent applies different detection criteria to different signal characteristics. Instead of using a single detection method, it specifically targets the bandwidth parameter which has distinct local quality differences between OFDM and radar signals, allowing precise differentiation at the local signal property level
2Object-affected harmful factors
If the transmitter constantly monitors the frequency band for radar signals, then radar interference can be avoided, but transmission time is lost due to false detections causing unnecessary frequency changes
Solution Approach 1:
The patent implements a feedback mechanism where the detected signal type (OFDM or radar) feeds back to the transmission control logic. This feedback allows the system to make informed decisions about whether to switch frequencies or maintain current transmission, preventing unnecessary frequency changes and reducing transmission time loss while still protecting against radar interference
Data Source
AI summary
A radar detector determines whether an input signal is an orthogonally frequency division multiplexed (OFDM) signal or a radar signal by applying at least first and second bandpass filtering operations having substantially non-overlapping passbands to the input signal, each filtering operation having a passband of width substantially less than a relatively large instantaneous bandwidth characteristic of an OFDM signal and substantially greater than a relatively small instantaneous bandwidth characteristic of a radar signal. The detector multiplies power levels of output signals of the first and second filtering operations to form a power product signal and compares the power level of the power product signal with a threshold level and providing an indicating signal in a first state if the power level of the power product signal exceeds the threshold level and otherwise providing said indicating signal in a second state.