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Ultrasonic multiple-access ranging system using spread spectrum and MEMS technology for indoor localization.

Segers L, Tiete J, Braeken A, Touhafi A - Sensors (Basel) (2014)

Bottom Line: Direct sequence and frequency hopping spread spectrum ultrasound signals have been proven to achieve a high level of accuracy.Results show that in a single-access environment, the direct sequence spread spectrum method offers slightly better accuracy and precision performance compared to the frequency hopping spread spectrum.When two senders are used, measurements point out that the frequency hopping spread spectrum is more robust to near-far effects than the direct sequence spread spectrum.

View Article: PubMed Central - PubMed

Affiliation: Department of Industrial Sciences and Technology (INDI), Vrije Universiteit Brussel, Pleinlaan 2, Elsene 1050, Belgium. laurent.segers@vub.ac.be.

ABSTRACT
Indoor localization of persons and objects poses a great engineering challenge. Previously developed localization systems demonstrate the use of wideband techniques in ultrasound ranging systems. Direct sequence and frequency hopping spread spectrum ultrasound signals have been proven to achieve a high level of accuracy. A novel ranging method using the frequency hopping spread spectrum with finite impulse response filtering will be investigated and compared against the direct sequence spread spectrum. In the first setup, distances are estimated in a single-access environment, while in the second setup, two senders and one receiver are used. During the experiments, the micro-electromechanical systems are used as ultrasonic sensors, while the senders were implemented using field programmable gate arrays. Results show that in a single-access environment, the direct sequence spread spectrum method offers slightly better accuracy and precision performance compared to the frequency hopping spread spectrum. When two senders are used, measurements point out that the frequency hopping spread spectrum is more robust to near-far effects than the direct sequence spread spectrum.

No MeSH data available.


DSSS (left) and FHSS (right) multiple-access ranging.
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f13-sensors-14-03172: DSSS (left) and FHSS (right) multiple-access ranging.

Mentions: In the case of two senders, one can define three zones of measurements. The zones are defined according to the distance between the mobile node and the receiver. The first zone concerns the distance range in which distances to both senders are successfully calculated. This zone ranges from 120 cm to 300 cm. The other zones range from 0 cm to 120cm and beyond 300 cm. The major difference between the first zone and the other zones is given in the distance ratio. In the former case, the ratio of both senders against the receiver is close to 100%, meaning that both signals arrive with similar strength at the receiver. The signal-to-noise ratio of both signals is thus sufficient to be measured well by the receiver. In the other case, the signal-to-noise ratio decreases and is even dominated by the signal of the closest node. The resulting distance measurements are shown in Figure 13. One can notice that the FHSS method has, on average, a more robust distance measurement than DSSS. This is especially the case in the third zone, where the FHSS method remains stable at a distance up to 460 cm. However, the overall accuracy and precision of the DSSS method are generally better than FHSS (Figure 14).


Ultrasonic multiple-access ranging system using spread spectrum and MEMS technology for indoor localization.

Segers L, Tiete J, Braeken A, Touhafi A - Sensors (Basel) (2014)

DSSS (left) and FHSS (right) multiple-access ranging.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3958221&req=5

f13-sensors-14-03172: DSSS (left) and FHSS (right) multiple-access ranging.
Mentions: In the case of two senders, one can define three zones of measurements. The zones are defined according to the distance between the mobile node and the receiver. The first zone concerns the distance range in which distances to both senders are successfully calculated. This zone ranges from 120 cm to 300 cm. The other zones range from 0 cm to 120cm and beyond 300 cm. The major difference between the first zone and the other zones is given in the distance ratio. In the former case, the ratio of both senders against the receiver is close to 100%, meaning that both signals arrive with similar strength at the receiver. The signal-to-noise ratio of both signals is thus sufficient to be measured well by the receiver. In the other case, the signal-to-noise ratio decreases and is even dominated by the signal of the closest node. The resulting distance measurements are shown in Figure 13. One can notice that the FHSS method has, on average, a more robust distance measurement than DSSS. This is especially the case in the third zone, where the FHSS method remains stable at a distance up to 460 cm. However, the overall accuracy and precision of the DSSS method are generally better than FHSS (Figure 14).

Bottom Line: Direct sequence and frequency hopping spread spectrum ultrasound signals have been proven to achieve a high level of accuracy.Results show that in a single-access environment, the direct sequence spread spectrum method offers slightly better accuracy and precision performance compared to the frequency hopping spread spectrum.When two senders are used, measurements point out that the frequency hopping spread spectrum is more robust to near-far effects than the direct sequence spread spectrum.

View Article: PubMed Central - PubMed

Affiliation: Department of Industrial Sciences and Technology (INDI), Vrije Universiteit Brussel, Pleinlaan 2, Elsene 1050, Belgium. laurent.segers@vub.ac.be.

ABSTRACT
Indoor localization of persons and objects poses a great engineering challenge. Previously developed localization systems demonstrate the use of wideband techniques in ultrasound ranging systems. Direct sequence and frequency hopping spread spectrum ultrasound signals have been proven to achieve a high level of accuracy. A novel ranging method using the frequency hopping spread spectrum with finite impulse response filtering will be investigated and compared against the direct sequence spread spectrum. In the first setup, distances are estimated in a single-access environment, while in the second setup, two senders and one receiver are used. During the experiments, the micro-electromechanical systems are used as ultrasonic sensors, while the senders were implemented using field programmable gate arrays. Results show that in a single-access environment, the direct sequence spread spectrum method offers slightly better accuracy and precision performance compared to the frequency hopping spread spectrum. When two senders are used, measurements point out that the frequency hopping spread spectrum is more robust to near-far effects than the direct sequence spread spectrum.

No MeSH data available.