OFDM Transmitter Synchronization with Radio Alimeter Sweep
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional aircraft communication systems face challenges due to the limited available frequency spectrum for wireless avionic communications, which can lead to interference with critical safety systems like radio altimeters, and require complex electrical wiring that adds weight to the aircraft.
Innovation Solution
The avionics system employs an enhanced Orthogonal Frequency Division Multiplex (OFDM) transmitter that synchronizes with the frequency sweep and periodicity of a radio altimeter's signal tone to selectively turn off sub-bands, allowing the use of the radio altimeter's bandwidth for communication without interfering with its operation, thereby sharing the spectrum effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If wireless communication systems are implemented in aircraft, then communication flexibility and weight reduction are improved, but interference with critical safety systems like radio altimeters occurs
Solution Approach 1:
The radio altimeter frequency spectrum is divided into multiple sub-bands. The OFDM communication system uses only specific sub-bands (e.g., lower and upper sub-bands) while leaving the middle sub-band clear for radio altimeter operations, thereby eliminating interference while maintaining wireless communication capability
Solution Approach 2:
The OFDM transmitter periodically switches between different sub-bands in synchronization with the radio altimeter's periodic frequency sweeping. When the altimeter sweeps through a sub-band, the transmitter temporarily stops using that sub-band, creating a periodic transmission pattern that avoids interference
2Quantity of substance
If the radio altimeter frequency spectrum is used for wireless communication, then available bandwidth is improved, but interference with radio altimeter operation occurs
Solution Approach 1:
Different sub-bands within the radio altimeter frequency spectrum are assigned different functions: lower and upper sub-bands are used for OFDM communication while the middle sub-band is reserved for radio altimeter operations. This local differentiation allows simultaneous use of the spectrum for both purposes without interference
Solution Approach 2:
The OFDM signal acts as an intermediary that adapts to the radio altimeter's frequency sweeping by dynamically adjusting which sub-bands are active. This intermediary mechanism enables coexistence of communication and altimeter functions within the same spectrum
3Reliability
If conventional electrical wiring systems are used, then system reliability is improved through redundancy, but aircraft weight increases
Solution Approach 1:
Physical electrical wiring and harnesses are replaced with wireless OFDM communication systems. This substitution eliminates the need for extensive wiring infrastructure while maintaining communication functionality, thereby reducing aircraft weight
Data Source
AI summary
An avionics system comprises a plurality of avionics components; at least one OFDM transmitter coupled to a respective one or more of the plurality of avionics components and configured to transmit a wireless OFDM signal comprising a plurality of sub-bands; at least one OFDM receiver coupled to a respective one or more of the plurality of avionics components and configured to receive the wireless OFDM signal transmitted by the OFDM transmitter; and a radio altimeter configured to transmit a signal tone that sweeps a frequency spectrum allocated to the radio altimeter at a predefined rate and periodicity. The at least one OFDM transmitter is configured to transmit the wireless OFDM signal in the frequency spectrum allocated to the radio altimeter and to sequentially turn off respective subsets of the plurality of sub-bands in synchronization with the predefined rate and periodicity of the signal tone frequency sweep.