Surveillance Signal Demodulation Using Multi-Band Under-Sampling
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Solution Overview
Problem
Existing surveillance communication systems for vehicles face challenges in efficiently demodulating signals across multiple non-overlapping frequency bands due to the need for high-bandwidth analog-to-digital converters and complex signal processing, which increases cost and complexity.
Innovation Solution
A receiver system that uses under-sampling techniques to down-convert radio-frequency signals to intermediate-frequency signals, sampling at a rate below the Nyquist rate, allowing signals from different frequency bands to fall within distinct Nyquist regions, thereby enabling demodulation using lower-cost, lower-bandwidth analog-to-digital converters and simplified processing circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional Nyquist-rate sampling is used to demodulate signals across multiple frequency bands, then signal demodulation accuracy is maintained, but ADC bandwidth and system cost increase significantly
Solution Approach 1:
The patent changes the sampling rate parameter from the traditional Nyquist rate (2× highest frequency) to a lower rate that still enables accurate demodulation of multiple frequency bands through intelligent signal processing, thereby reducing ADC bandwidth requirements while maintaining demodulation accuracy
Solution Approach 2:
The patent segments the frequency spectrum into multiple bands and processes each band separately through bandpass filtering before sampling, allowing lower sampling rates to be used for each individual band while collectively covering the full spectrum of interest
2Reliability
If multiple separate receiver chains are used for different frequency bands, then demodulation performance for each band is optimized, but system complexity and component count increase
Solution Approach 1:
The patent merges multiple frequency band processing functions into a single receiver chain by using a shared ADC and processing unit that handles multiple bands through time-multiplexed bandpass filtering and selective sampling, eliminating the need for separate receiver chains while maintaining demodulation performance
Solution Approach 2:
The patent creates a universal receiver architecture where a single ADC and processing system can demodulate signals from multiple frequency bands by dynamically configuring bandpass filters and sampling parameters, making the system multi-functional without requiring dedicated hardware for each band
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
This approach reduces the cost and complexity of the receiver system while maintaining effective demodulation of surveillance signals across multiple frequency bands, utilizing lower-speed ADCs and processing circuitry, and minimizing spurious frequency issues.
Implementation Method 1
a mixer configured to down-convert the received signals to intermediate-frequency (IF) signals based on a local oscillator signal
Implementation Method 2
at least one analog-to-digital converter (ADC) configured to sample the IF signals at a sampling rate, where a frequency band of the IF signals encoding the first message falls within a first Nyquist region, and a frequency band of the IF signals encoding the second message falls within a second Nyquist region
Data Source
AI summary
In some examples, a system includes a receiver configured to receive signals encoding first, second, and third messages in first, second, and third frequency bands. The system also includes a mixer configured to down-convert the received signals to intermediate-frequency (IF) signals based on a local oscillator signal. The system further includes at least one analog-to-digital converter configured to sample the IF signals at a sampling rate. A frequency band of the IF signals encoding the first message falls within a first Nyquist region, and a frequency band of the IF signals encoding the second message falls within a second Nyquist region. The first and second Nyquist regions are frequency ranges bounded by multiples of one-half of the sampling rate, and the second Nyquist region is different from the first Nyquist region. The system includes processing circuitry configured to determine data in the first, second, and third messages based on an output of the at least one analog-to-digital converter.