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Wireless triangulation using RSSI signals

Authored on: Mar 22, 2009 by Michael Harney

Technical Paper / Application Note

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Most wireless receiver modules available today have a received signal strength indicator (RSSI) that gives the signal strength measured at the receiver and which is associated with each received signal source. This information is usually part of a packet stream that gives the source identification and RSSI level in power levels of dBm. The RSSI signal is usually a nice diagnostic tool that shows the margin of the received signal compared to the sensitivity of the receiver.

It does also give some indication of how close the source of the signal is, if one has an estimate of the source power. If one does not know the strength of the source, then one or even two RSSI signals is of little use in finding the location or distance to the source, although most triangulation methods such as those that use phased arrays can provide a bearing angle to the source.

However, four networked transceivers arranged in a triangular pattern and equipped with omnidirectional antennas can determine both the transmitter's power level and the Cartesian coordinates (x,y,z) of the transmitter relative to the receivers when they share their RSSI information. A simplified version of this method was first described in patent #7,283,127, issued October 16, 2007, which claims the methods for triangulation of static magnetic fields and briefly mentions the use of a similar algorithm for triangulation with alternating electromagnetic fields.



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ara Posted Jan 26, 2011

In this paper is it possible for somebody to tell me the equation if we use three antenas, plz plz its urgent

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PowerCycle Posted May 7, 2011

For the software that simulates 3 antennas, check out the link: http://signaldisplay.com/RF_Locator.exe

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PowerCycle Posted May 7, 2011

Yes it is - remove one antenna from the equations and solve for x,y,z knowing the intensity I.

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zeeglen Posted May 7, 2011

What is "combing" just after eq 5? Nice theoretical and applies to ships on the water. How does this take into account random physical terrain obstacles to RF signals and multi-path reflection addition/cancellation?

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PowerCycle Posted May 7, 2011

Thanks - it should be "combining". Applies to ships on water, radio waves in space, and if the attenuation is small (the equations are relatively insensitive to attenuations if there are 4 antennas) then anything on land.

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PowerCycle Posted Mar 2, 2012

Here is the Android app that does the triangulation: https://market.android.com/details?id=com.thatsbydesign.wrl&feature=search_result#?t=W251bGwsMSwyLDEsImNvbS50aGF0c2J5ZGVzaWduLndybCJd

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BBacakoglu Posted Jul 25, 2012

Hello, I cannot download the PDF file. When I click on this it gives "The requested URL /techonline/pdf/pavillions/standards/C0377_edited_to_post_rev.pdf was not found on this server." this error. Is there any other link that I can download pdf file?

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san456789 Posted Nov 29, 2012

i have a doubt....how to read the RSSI of a MS at that particular point....i mean we need to get this information from the core network....how can we get it????

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