Summary of the technology
The Research Group of Electronic Engineering Applied to Intelligent Spaces and Transportation (GEINTRA) of Alcalá University has developed a procedure to estimate the arrival instant of acoustic signals for localization systems based on a non-coherent and capable DFT-S-DMT * modulation to compensate the Doppler effect, for its application in acoustic localization systems.
GEINTRA seeks companies from the Information and Communication Technologies (ICT) sector to sign technical cooperation agreements, commercial agreements with technical assistance and patent licensing agreements.
* Discrete multi-tone modulation, widening by discrete Fourier transform
Description of the technology
This invention presents a procedure to estimate the arrival instant of acoustic signals for localization systems based on a non-coherent DFT-S-DMT modulation capable of compensating the Doppler effect.
The locating system contemplated is formed by a number N. (N≥ 1) of positioning structures composed by a set of at least 3 emitting beacons. These transmit, simultaneously or multiplexed in time, sequences modulated in DFT-S-DMT to position a moving element within the coverage area of the LPS by hyperbolic multilateration (without synchronism between beacons and mobile element) or spherical (with synchronism between beacons and mobile element). Also in the localization system of the invention, synchronism between beacons of the same LPS is necessary, such synchronization being unnecessary between beacons of different LPS.
Zadoff-Chu sequences for the estimation of arrival time are used in this invention; However, any other type of sequences with good correlation properties could be used.
In order to minimize the peak-to-average power ratio (PAPR) of the DMT modulated signal, this invention employs DFT-S-DMT. Each of the beacons of the acoustic localization system transmits the Zadoff-Chu sequences in the frequency domain through a DMT modulator. These transformations together constitute the DFT-S-DMT modulation, which retains the advantages of multi-carrier modulations, being able to adjust the bandwidth of the transmitted signal to the transducer bandwidth, as well as to realize signal equalization in the domain of the frequency efficiently.
Given the ideal periodic self-correlation of Zadoff-Chu sequences an odd prime number, this type of sequences has a constant power spectral density, thereby reducing the PAPR of the transmitted signal. Therefore, the DFT-S-DMT modulation maintains the advantages of OFDM for acoustic location systems, while minimizing the PAPR (thus minimizing the consumption of the beacons) and allows non-coherent detection of the arrival time.
Finally, Doppler displacement, estimated by correlation, can be compensated by re-sampling the input signal or by means of minimum variance filters, thus allowing an increase in the robustness of the system when using mobile devices.
Intellectual property status
Patent already applied for
Patent application number : P201500540
Where : Spanish Patent and Trademark Office
Current development status
Desired business relationship
Commercial agreement with technical assistance
Universidad de Alcalá-OTRI
Research & Technology Organization