IF Filter Array Switching for Multi-Waveform Tactical Radios
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Solution Overview
Problem
Current radio frequency transmitters and receivers for the Joint Tactical Radio System (JTRS) are limited by their small form factors and cost considerations, which restrict the number of filters and switches that can be used, preventing them from supporting multiple narrowband and wideband signal waveforms without exceeding physical dimensions.
Innovation Solution
A compact filter array is introduced, comprising at least one narrowband filter and one wideband filter, with switches that can be selectively inserted into signal paths in the intermediate frequency stage, allowing operation with multiple JTRS waveforms by using surface acoustic wave (SAW) filters and discrete matching elements in a system-in-package configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple filters and switches are added to support multiple narrowband and wideband waveforms, then waveform compatibility and functionality are improved, but the physical dimensions and form factor of the radio exceed military specifications
Solution Approach 1:
The patent combines multiple narrowband and wideband filters along with their associated switches and matching elements into a single integrated filter array package. This merging of previously discrete components into one compact unit enables the radio to support multiple waveforms while maintaining compliance with military form factor specifications.
Solution Approach 2:
The filter array is designed as a universal solution that can handle both narrowband and wideband waveforms through a single integrated structure. The array includes filters with different bandwidth characteristics (narrowband filters for waveforms like SINCGARS and wideband filters for waveforms like SRW) that can be selectively activated to support multiple waveform types without requiring separate filter banks for each waveform category.
2Adaptability or versatility
If the number of filters and switches is increased to support multiple waveforms, then signal path flexibility is improved, but device complexity and component count increase
Solution Approach 1:
The patent integrates multiple filters, switches, and matching elements into a single filter array package, reducing the overall device complexity despite the increased number of functional components. The integrated package consolidates what would otherwise be separate discrete components scattered throughout the radio, making the system easier to manage and install.
Solution Approach 2:
The filter array is segmented into multiple independent filter elements (narrowband filters and wideband filters) that can be independently selected and activated. This segmentation allows the radio to provide multiple signal paths for different waveforms while maintaining a organized, modular structure within the integrated package.
3Ease of manufacture
If discrete matching elements and switches are arrayed individually on the circuit board, then ease of manufacturing is improved, but the area occupied on the circuit board increases
Solution Approach 1:
The patent implements nesting by placing the entire filter array (including multiple filters, switches, and matching elements) into a single compact package that occupies minimal circuit board area. This nested structure allows the radio to maintain ease of manufacturing through standardized package installation while dramatically reducing the area required on the circuit board compared to individually mounted components.
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 solution enables radios to support a wide range of JTRS and other narrowband and wideband waveforms within the same physical dimensions, enhancing functionality and reducing parasitic inductance and capacitance, while maintaining a small form factor and supporting waveforms up to 30 MHz bandwidth.
Implementation Method 1
using surface acoustic wave (SAW) filters and discrete matching elements in a system-in-package configuration
Data Source
AI summary
A communications radio has an IF stage with an associated filter array. The array includes at least one narrowband filter whose passband is less than 3 MHz, at least one wideband filter whose passband is 3 MHz or greater, a first switch with a common pole connected to an input terminal of the array, a second switch with a common pole connected to an output terminal of the array, a third switch whose common pole is operatively connected to the input terminal, and a fourth switch whose common pole is operatively connected to the output terminal. The first and the second switches cooperate to insert a selected filter between the first and second terminals. The third and the fourth switches cooperate to insert the filter array into either a receive signal path when the radio is in a receive mode, or a transmit signal path when in a transmit mode.