Ultrasonic Data Communication Using Frequency Ratio Encoding
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Solution Overview
Problem
Current ultrasonic positioning systems face limitations in data rate due to bandwidth inefficiencies caused by Doppler shifts, which restrict the number of objects or persons that can be tracked and the accuracy of movement tracking in acoustic data communications, especially in environments like air and water.
Innovation Solution
Encoding data as the ratio of pairs of frequencies, which remains invariant under Doppler shifting, allowing for more efficient use of bandwidth and eliminating the need for large guard bands, enabling higher data rates without additional bandwidth requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional FSK or MFSK modulation schemes are used in ultrasonic communication systems, then robustness to Doppler shifts is achieved, but bandwidth efficiency deteriorates significantly
Solution Approach 1:
The invention changes the fundamental parameter of data encoding from absolute frequency values to frequency ratios. By encoding data as ratios of frequencies (e.g., f1/f2), the system maintains robustness to Doppler shifts while dramatically improving bandwidth efficiency, as the ratio remains constant even when both frequencies are shifted by the same Doppler amount.
Solution Approach 2:
Instead of using frequency values directly as the encoding parameter (conventional approach), the invention inverts the approach by using the ratio of frequencies. This inversion transforms the problem from one where Doppler shifts cause errors to one where the ratio remains invariant under Doppler shifts, resolving the contradiction between robustness and bandwidth efficiency.
2Reliability
If frequency spacing is increased to accommodate maximum Doppler shifts with guard bands, then reliability under varying motion conditions is improved, but data rate deteriorates
Solution Approach 1:
The invention changes the encoding parameter from absolute frequency to frequency ratio, which eliminates the need for large guard bands. Since the ratio f1/f2 remains constant under Doppler shifts, frequencies can be spaced much closer together, increasing the number of distinguishable frequency pairs per unit bandwidth and thus increasing data rate while maintaining reliability.
Solution Approach 2:
The system dynamically adapts to Doppler shifts by using ratio-based encoding, which automatically compensates for frequency changes due to motion. This dynamic invariance allows the system to maintain accurate data transmission under varying motion conditions without requiring conservative frequency spacing, thereby improving data rate.
3Productivity
If multiple frequency pairs are used to increase data rate, then productivity is improved, but the complexity of managing frequency spacing and avoiding overlap increases
Solution Approach 1:
By using frequency ratios instead of absolute frequencies, the invention simplifies frequency management. The ratio f1/f2 provides a natural ordering and spacing mechanism that inherently avoids overlap, even when multiple frequency pairs are used to increase data rate. This reduces the complexity of frequency allocation and management compared to conventional approaches.
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 approach significantly increases data transmission efficiency, allowing for higher data rates and improved tracking accuracy of multiple objects or persons in ultrasonic communication systems, even under conditions of relative movement between transmitters and receivers.
Implementation Method 1
Wherever a transmitter and receiver are moving towards or away from each other the frequency of the signal perceived at the receiver differs from that transmitted by the transmitter as a result of the differing distance that each wavefront must travel between the two. This is known as the Doppler effect.
Data Source
AI summary
Data communication apparatus comprising transmission means adapted to transmit data as the ratio of pairs of frequencies between objects that are moving relative to one another. It is particularly applicable to acoustic data communications at ultrasound frequencies in air.