Directional Filter for HF Transceiver Self-Interference Cancellation
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Solution Overview
Problem
Transceivers face significant interference issues due to self-interference from the transmitter section, known as crosstalk or transmitter leakage, which affects the receiver section, especially when operating with closely spaced frequencies and a single antenna, leading to degraded communication performance and limited communication range.
Innovation Solution
The implementation of a directional coupler with an adjustable impedance and a tracking algorithm to split and filter the transmitter signal, reflecting a portion back to cancel out the interference within a predetermined bandwidth, thereby reducing self-interference and enhancing communication robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single antenna is used for both transmission and reception, then device complexity is reduced, but transmitter leakage causes self-interference that degrades receiver performance
Solution Approach 1:
The patent segments the transmitted signal into multiple copies with different delays and phases, which are then combined at the receiver to create constructive interference for the desired signal and destructive interference for the leaked signal. This segmentation of the signal in the time-delay domain enables cancellation of self-interference while maintaining single-antenna operation.
Solution Approach 2:
The patent applies preliminary anti-action by pre-processing the transmitted signal to create delayed and phase-shifted copies before transmission. These pre-prepared signal copies are designed to automatically cancel the leakage components at the receiver, preventing the harmful effect rather than correcting it after occurrence.
2Object-affected harmful factors
If frequency separation is increased to reduce interference, then self-interference is reduced, but communication flexibility and spectral efficiency are degraded
Solution Approach 1:
The patent employs feedback mechanisms where the receiver processes the combined signal and generates error information that is fed back to adjust the signal processing parameters. This feedback loop enables the system to adapt to different frequency separations and interference conditions, maintaining performance across various frequency allocations without requiring fixed frequency separation.
3Reliability
If signal processing complexity is increased to cancel leakage, then receiver sensitivity is improved, but device complexity and processing requirements increase
Solution Approach 1:
The patent replaces complex adaptive signal processing and mechanical tuning mechanisms with a deterministic signal processing approach based on predefined delay and phase relationships. Instead of using complex adaptive algorithms to cancel interference, the system uses structured signal segmentation and combining that achieves cancellation through simpler, more predictable processing operations.
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 allows for simultaneous transmission and reception with improved communication range, extended battery life, and increased resistance to both external and self-interference, enabling more effective wireless communication.
Implementation Method 1
splitting the transmitter signal into a first transmit portion directed to a second port of the directional coupler, and a second transmit portion directed to a third port of the directional coupler
Implementation Method 2
reflecting at least a portion of the filtered second transmit portion into the third port of the directional coupler
Implementation Method 3
combining the incoming signal at the second port of the directional coupler and the reflected signal at the third port of the directional coupler, to produce a combined signal at a fourth port of the directional coupler
Data Source
AI summary
Apparatus and methods of simultaneous transmission and reception in a single-antenna radio transceiver. The transceiver may be used, for instance, for communication between at least two terminals, by use of multiple intermediate recruited transceiver nodes. The recruited transceiver nodes receive a signal from a master mode, and then retransmit the signal to a receiver. The recruited transceiver nodes are designed to have reduced interference between the transmit channel and the received channel. In accordance with one aspect of the present application, embodiments can achieve more robust wireless communication between a transmitter and an over-the-horizon receiver. The robust wireless communication will have improved resistance to interference, including self-interference, and improved communication range.