Digitally Tuned DRFM for Coherent RF Signal Replication
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Solution Overview
Problem
Current Digital Radio Frequency Memory (DRFM) systems lack efficient methods for capturing and retransmitting wideband coherent radio frequency signals, particularly in Electronic Warfare applications, where they are needed to create false targets and jam enemy radar effectively.
Innovation Solution
A digitally tuned digital radio frequency memory system that captures a portion of a radio frequency signal, converts it to a digital word, and retransmits it coherently using a track and hold circuit, digitizer, memory, and direct digital frequency synthesizer, with features like baseband modulation digitization and carrier frequency removal based on the Nyquist Theorem, and optional Doppler sampling for accurate signal replication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional up and down converters are used to capture and retransmit wideband coherent radio frequency signals, then the system can achieve signal replication, but the device complexity and cost increase significantly
Solution Approach 1:
The patent replaces traditional analog up and down converters with a digital signal processing system. The track and hold circuit captures the RF signal, the digitizer converts it to digital form, the memory stores the digital representation, and the direct digital frequency synthesizer retransmits it. This substitution of mechanical/analog conversion hardware with digital processing components reduces device complexity while maintaining signal replication accuracy.
Solution Approach 2:
The patent changes the operating parameters by using baseband modulation and carrier frequency removal based on the Nyquist Theorem. The digitizer is configured to digitize only the baseband modulation and remove the carrier frequency, allowing the system to operate at lower conversion rates while maintaining wideband coherent signal coverage. This parameter change enables simplified hardware implementation.
2Device complexity
If traditional DRFM systems are used, then the system structure is simpler, but the capability to provide wideband coherent jammer coverage is limited
Solution Approach 1:
The patent introduces dynamic frequency synthesis through the direct digital frequency synthesizer, which can generate signals across a wide frequency range. The system dynamically adjusts the retransmitted signal frequency based on the captured signal characteristics, enabling wideband coherent jammer coverage while maintaining a relatively simple overall system structure.
Solution Approach 2:
The patent creates a universal DRFM system that can handle multiple frequency bands and signal types through digital processing. The same basic architecture (track and hold, digitizer, memory, DDS) can capture and retransmit signals across different frequency ranges, providing multi-functional capability for various Electronic Warfare applications without requiring separate specialized hardware for each band.
3Measurement precision
If high conversion rate analog to digital converters are used, then the signal capture accuracy is improved, but the device complexity and cost increase
Solution Approach 1:
The patent applies partial action by using baseband modulation and carrier frequency removal to capture only the essential signal information. Instead of converting the entire RF signal at high rates, the system down-converts to baseband and captures the modulation characteristics, achieving sufficient accuracy with lower conversion rates and simpler hardware.
Solution Approach 2:
The patent changes the sampling parameter by using the Nyquist Theorem to determine the appropriate sampling rate for the baseband signal rather than the full RF signal. This parameter change allows the system to use lower conversion rate analog to digital converters while maintaining accurate signal capture, as the baseband signal requires fewer samples to represent the same information.
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
Enables the creation of realistic false targets and effective jamming by accurately capturing and retransmitting radio frequency signals, providing wideband coherent jammer coverage without the complexity and cost of traditional up and down converters, enhancing Electronic Warfare capabilities.
Implementation Method 1
a track and hold configured to track and hold the first radio frequency signal and to output a shaped signal
Implementation Method 2
a digitizer configured to convert the shaped signal to a digital word
Implementation Method 3
The digitizer may be further configured to remove a carrier frequency of the first radio frequency signal. The carrier frequency may be removed based on the Nyquist Theorem.
Implementation Method 4
a memory configured to store the digital word
Implementation Method 5
a direct digital frequency synthesizer configured to provide a sampling clock signal
Implementation Method 6
a Doppler direct digital frequency synthesizer configured to provide a Doppler sampling clock signal
Implementation Method 7
a digital to analog converter configured to convert the digital word to an intermediate frequency signal
Implementation Method 8
a multiplier configured to multiply the intermediate frequency signal to a Nyquist range
Data Source
AI summary
A digitally tuned digital radio frequency memory that captures a portion of a first radio frequency signal and retransmits the portion as a coherent radio frequency signal. The digitally tuned radio frequency memory may include a track and hold configured to track and hold the first radio frequency signal and to output a shaped signal; a digitizer configured to convert the shaped signal to a digital word; a memory configured to store the digital word; and a direct digital frequency synthesizer configured to provide a sampling clock signal, wherein the sampling clock signal is provided to the track and hold.