Spectral Notch Modulation for Navigation and Communication
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Solution Overview
Problem
Current signaling systems face challenges in maximizing information throughput due to the need to convey overhead and control signals, which reduces the time available for primary communication signals, particularly in systems using time-of-arrival ranging signals for navigation and communication.
Innovation Solution
The method involves transforming a signal into the frequency domain using FFT, selectively nulling frequency bins to encode information, and transmitting the signal. This technique, known as spectral notch modulation, allows for additional information throughput without increasing signal bandwidth, power, or data rate, enabling simultaneous use of TOA ranging packets for both location and data communications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional overhead and control signals are transmitted to support computation of range and position, then navigation accuracy is improved, but the time available for primary communication signals is reduced
Solution Approach 1:
The patent combines navigation data and communication data into a single integrated message structure. The navigation support signals (range computation data, position coordinates, reference device identifiers) are merged with communication payloads, allowing both functions to be performed simultaneously within the same time frame rather than sequentially
Solution Approach 2:
The transmitted signal serves multiple functions simultaneously: it carries navigation ranging information for position determination, navigation support data for range computation, and communication information for data exchange. This multi-functionality eliminates the need for separate dedicated time slots for each function
2Measurement precision
If data fields are added to the TOA waveform to convey navigation support information, then navigation accuracy is improved, but transmitter and receiver hardware complexity increases
Solution Approach 1:
The patent modifies existing signal parameters (message packet structure, data fields, timing) to embed navigation support information rather than requiring new hardware components. By changing the parameter structure of existing waveforms and utilizing available signal bandwidth and time slots, the system achieves enhanced navigation capability without increasing hardware complexity
3Measurement precision
If the duration of TOA ranging signals is increased to include additional navigation messages, then navigation accuracy is improved, but the time available for other communications is reduced
Solution Approach 1:
The patent merges navigation messages and communication messages into a single integrated transmission. By combining these functions in one message packet rather than sending them separately, the total transmission time is reduced while still providing all necessary navigation information for accurate position determination
Data Source
AI summary
A spectral notch modulation technique for encoding information in a signal involves transforming the signal into the frequency domain via a fast Fourier transform (FFT) of length N, such that the signal is represented by N frequency bins, selectively nulling M of the N frequency bins, where nulled combinations of M frequency bins respectively correspond to encoded information bits, transforming the selectively nulled signal to the time domain via an inverse FFT, and transmitting the selectively nulled signal. At the receiving end, the signal is demodulated to recover the encoded information by transforming the signal into the frequency domain via a fast Fourier transform (FFT) of length N, identifying the set of M nulled frequency bins among the N frequency bins, and converting the set of M nulled frequency bins to corresponding information bits.