Communication Device Interference Rejection Using Multi-Tone Envelope Detection
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Solution Overview
Problem
Low power wireless sensor networks and wireless body area networks face challenges in maintaining long operation times with limited energy resources while achieving reasonable performance, and existing radio receivers suffer from poor phase and frequency selectivity due to the use of envelope detectors, leading to vulnerability to interference.
Innovation Solution
The method involves up-converting baseband signals using at least two frequency tones to modulate the signal, allowing the receiver to preserve amplitude, frequency, and phase information, enabling improved interference rejection and relaxing filter requirements by using an envelope detector for down-conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If envelope detector is used for down-conversion to reduce power consumption, then power consumption is reduced, but phase and frequency selectivity deteriorates
Solution Approach 1:
The patent segments the down-conversion process into two stages: first using an envelope detector to reduce power consumption while extracting amplitude information, then using a second down-conversion stage with frequency-selective filtering to recover phase and frequency information. This segmentation allows each stage to optimize for its specific function without compromising the overall system performance.
Solution Approach 2:
The envelope detector performs preliminary down-conversion and amplitude extraction before the final frequency-selective filtering stage. This preliminary action reduces the complexity and power requirements of subsequent processing while preserving the necessary signal information for achieving good frequency selectivity in the second stage.
2Object-affected harmful factors
If front-end filter with narrow bandwidth is added to improve interference rejection, then interference rejection is improved, but device complexity increases
Solution Approach 1:
The patent extracts the frequency-selective filtering function from the traditional front-end filter position and relocates it to the baseband processing stage after envelope detection. This extraction allows the use of simpler, lower-frequency filters that are easier to implement while achieving the same interference rejection effectiveness, as the filtering now occurs at a frequency where narrow bandwidth filters are more readily available and less complex.
Data Source
AI summary
A communication device is disclosed. The device may be in particular a radio transmitter and a receiver that can operate with low power consumption and with improved interference rejection, therefore particularly suitable for use in low-power communication systems, such as wireless sensor networks and wireless body area networks. In one aspect, multiple frequency tones (carriers) are used to carry information from the transmitter, such that a RF signal having multiple radio frequency components is produced and transmitted. In the receiver, an envelope detector is still the RF down-converter. After down-converting intermodulation components are extracted containing amplitude, phase and frequency information of the multiple radio frequency components. This allows the desired signal (the baseband information) to be distinguished from the carriers and unwanted interference.