Analog Spatial Multiplexer for RF Link Interference Nulling
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Solution Overview
Problem
Point-to-point radio frequency (RF) communications systems face limitations in data rate capacity due to bandwidth constraints, and existing modem technologies using FPGA or ASIC technologies have high cost and power consumption per bit, while providing lower data rates compared to fiber optic systems.
Innovation Solution
A communications system utilizing frequency multiplexing, polarization multiplexing, and spatial multiplexing to achieve a data rate eight times higher than a single modem, with a combination of four frequency bands and two polarizations, and adjustable time delays in an analog spatial multiplexer to null interference signals, implemented with modem-on-a-chip technology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fiber optic systems are used to achieve high data rate capacity, then data rate is improved, but infrastructure cost increases
Solution Approach 1:
The patent replaces fiber optic infrastructure with free-space optical communication using laser beams transmitted through air. This substitution eliminates the need for expensive fiber optic cables and physical infrastructure while maintaining high data rate capacity through wireless optical transmission between transmitter and receiver units.
2Productivity
If multiple data streams are transmitted within a single communications link to increase data rate, then productivity is improved, but signal interference increases
Solution Approach 1:
The patent transmits multiple data streams through the same spatial path by utilizing different time slots (time-division multiplexing). Each data stream is assigned a specific time window for transmission, allowing multiple streams to share the same frequency and spatial resources without interfering with each other, thereby increasing data rate while maintaining signal integrity.
Data Source
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AI summary
A communications system having two terminals, each including two antennas, the communications system using spatial multiplexing. One antenna of a first terminal transmits a tracking tone along with a data signal. Two antennas in a second terminal receive the tracking tone. The signals from the two antennas are processed by a feed circuit. The feed circuit includes a variable delay circuit and a combiner that forms, at a first difference output, a linear combination, of a signal from the first antenna and a signal from the second antenna, in which the tracking tone is canceled. The variable delay circuit is actively adjusted to maintain this cancellation.