Digital Retro-Directive Antenna Array Without Phase Calculation
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Solution Overview
Problem
Existing communication systems face challenges in transmitting signals back towards a transmitting source in a precise manner without measuring the direction or calculating phase differences, especially for signals with unknown frequencies and in simultaneous multisignal communication scenarios, and require antennas to be positioned on a straight plane.
Innovation Solution
A digital retro-directive method and system that uses a plurality of antennas to transmit signals back towards a transmitting source in a substantially synchronous and precise angular direction by sampling and reconstructing signal samples without measuring direction or calculating phase differences, applicable to both narrow and wideband systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phased arrays are used to transmit signals back towards the transmitting source, then the signal transmission accuracy can be improved, but the device complexity increases due to the need for direction measurement and phase difference calculation
Solution Approach 1:
The patent applies time-reversal technique where the received signal is reversed in time and transmitted back through the same antenna array. This inversion approach automatically compensates for multipath effects and channel characteristics, eliminating the need for complex direction measurement and phase difference calculation while achieving precise signal transmission back to the source
Solution Approach 2:
The system uses the received signal itself as the basis for generating the transmitted signal. By capturing the signal characteristics including phase and amplitude information from the received signal and using these same characteristics for retransmission, the system achieves automatic adaptation without requiring external direction measurement or complex processing
2Measurement precision
If antennas are positioned close to one another to improve measurement accuracy at high frequencies, then the measurement precision can be improved, but the antennas may overheat during RF signal transmission
Solution Approach 1:
The patent replaces traditional phased array beamforming methods with digital signal processing techniques. Instead of relying on precise mechanical positioning and phase shifters that generate heat, the system uses digital time-reversal processing to achieve the same signal focusing effect, thereby eliminating the overheating problem associated with closely spaced antennas
3Device complexity
If heterodyne mixing is used to handle signals of known frequencies, then the signal processing can be simplified, but the system cannot handle simultaneous signals with unknown frequencies
Solution Approach 1:
The time-reversal system is universally applicable to signals with any frequency characteristics. By capturing the complete time-domain signal waveform and reversing it, the system automatically adapts to different frequency content, multiple simultaneous signals, and unknown frequency spectra without requiring frequency estimation or signal classification, thereby achieving both simplicity and versatility
4Measurement precision
If direction measurement is performed to determine the transmitting source location, then the signal transmission precision can be improved, but the system becomes vulnerable to accidental reflectors such as tower blocks and balconies
Solution Approach 1:
The system uses feedback from the received signal to automatically adjust the transmitted signal characteristics. By capturing the actual signal path including reflections and using this feedback information for time-reversal processing, the system adapts to the real propagation environment and eliminates errors caused by accidental reflectors, achieving reliable signal transmission without direction measurement
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
Enables simultaneous and precise transmission of signals from multiple antennas without the need for direction measurement or phase calculations, allowing for coherent reception at the transmitting source, independent of signal frequency and antenna positioning.
Implementation Method 1
a prior art method called 'heterodyning' or 'heterodyne mixing' is a phase conjugation method, according to which a signal received at each antenna is multiplied by means of a local oscillator, having a frequency which is two times of the frequency of the received signal
Implementation Method 2
The problem of transmitting RF signals back towards the transmitting source has been recognized in the prior art, and various systems have been developed to provide a solution, disclosing various time-reversal and phase-conjugation techniques
Data Source
Figure 1
Figure 2A~2D
Figure 3A~3B
AI summary
The present invention relates to a digital retro-directive system and method thereof for receiving incoming signals from a transmitting source by means of at least two antennas and transmitting outgoing signals back, substantially simultaneously, towards said transmitting source through said at least two antennas irrespective of the location of one antenna with respect to another and without calculating phase differences between said outgoing signals.