Polyphase FFT Transceiver for Low-Detectability Broadband Radio
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Solution Overview
Problem
Existing broadband data transmission systems face challenges in ensuring secure and resilient transmission of RF signals, particularly in applications like police or military radio, where the signal should be difficult to detect and jam, while maintaining high transmission quality and resilience against perturbations.
Innovation Solution
The use of synthesis polyphase FFT filter banks in transmitter and receiver modules for broadband data transmission systems, employing cyclic shifted Kasami-sequences for spreading and de-spreading in the frequency domain, and Nyquist-filters for subcarriers to achieve orthogonal transmission and reception without interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional oscillators are used for frequency switching, then frequency hopping can be achieved, but signal loss occurs due to oscillator setting time
Solution Approach 1:
The patent replaces traditional mechanical oscillators with a digital signal processing approach using polyphase filter banks and FFT algorithms. This substitution eliminates the physical oscillator setting time by computing frequency transitions digitally, thereby preventing signal loss during frequency hopping while maintaining reliable continuous transmission.
2Difficulty of detecting and measuring
If spread spectrum techniques are used for security, then detection resistance improves, but transmission bandwidth increases
Solution Approach 1:
The patent segments the spread spectrum signal into multiple polyphase components that are processed through separate filter banks. This segmentation allows efficient frequency-domain spreading using cyclic shifted Kasami-sequences while managing bandwidth utilization through structured sub-channel allocation, thereby maintaining detection resistance without excessive bandwidth expansion.
3Productivity
If multiple users transmit simultaneously, then system capacity increases, but interference between users increases
Solution Approach 1:
The patent transitions from time-domain to frequency-domain processing using FFT-based polyphase filter banks. This dimensional change enables orthogonal frequency division multiplexing where multiple users transmit simultaneously on different frequency sub-channels, increasing system capacity while the orthogonality of the polyphase filters minimizes inter-user interference through frequency separation.
Data Source
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AI summary
A transmitter module (12) for a broadband data transmission system (10) for radio communications, comprising at least one polyphase FFT filter bank is described. The at least one polyphase FFT filter bank is established as a synthesis polyphase FFT filter bank (22), wherein the at least one polyphase FFT filter bank comprises several filter units (32), wherein the transmitter module (12) is configured to receive an input signal comprising a symbol sequence, and wherein the transmitter module (12) is configured to transmit a signal based on the received input signal. Moreover, a receiver module (14) for a broadband data transmission system (10) and a data transmission system (10) are described.