CRAWDAD tools/collect/location/loctrace

Loctrace - a collection tool for 802.11-based positioning systems.

Loctrace is a research tool for 802.11-based positioning systems. Loctrace gathers data offered by Loclib and stores it in a file.

Lastmodified :

2007-12-05

Dataname :

tools/collect/location/loctrace

File :

loctrace-0.5.src.tar.gz, loctrace-0.5.tar.gz

Releasedate :

2007-09-14

Change :

the initial version.

References :

king-tools
The Loctrace website

Website :

http://www.informatik.uni-mannheim.de/pi4.data/content/projects/loclib/loctrace.html

Keyword :

802.11
GPS
location
signal strength

License :

This tool is released under the GNU General Public License.
Please respect our work and abide the license.

Output :

See "usage" for details.

Parameters :

See "usage" for details.

Usage :

To start the tracer just invoke

java -Djava.library.path=PATH_LOCLIB_JNI -cp loctrace-0.5.jar:locutil1-0.5.1.jar:loclib-0.7.5.jar:debug-disable-1.1.jar:hexdump-0.1.jar:libdbus-java-2.3.1.jar:unix-0.2.jar org.pi4.loctrace.wirelesslan.Tracer

Please replace the placeholder PATH_LOCLIB_JNI with the path to the loclib
native library according to your installation.

Example :

The data collected from Loclib is stored in a human-readable trace file
and contains lines that adhere to the following format:

t="Timestamp";pos="RealPosition",id="MACofScanDevice";degree="orientation";"MACofResponse1"="SignalStrengthValue","Frequency","Mode","Noise";...;"MACofResponseN"="SignalStrengthValue","Frequency","Mode","Noise"

- t: timestamp in milliseconds since midnight, January 1, 1970 UTC
- pos: the physical coordinate of the scanning network device
- id: MAC address of the network device used for scanning
- degree: direction of the user carrying the scanning device in degrees
(only set if a digital compass is available)
- MAC: MAC address of a responding peer (e.g. an access point or a device
in adhoc mode) with the corresponding values for signal strength in dBm,
the channel frequency, its mode (access point = 3, device in adhoc mode = 1)
and noise level in dBm.

Trace files generated by Tracer are a major building block for our overall
research process. These files can be used by Loceva to evaluate and emulate
different positioning algorithms and scenarios. Furthermore, the traces
can be displayed for visual inspection by tools of the Locana package.
Finally, these traces can be used as an offline fingerprint database during
normal operation of an 802.11-based positioning system.

Algorithm :

1. Overview

Loctrace mainly consists of one application. This application gathers
data offered by Loclib and stores it in a file.

2. Tracer

Loctrace contains only one application: Tracer. Tracer is used to collect
the data required to create fingerprint databases. To achieve this goal,
Tracer is build on top of Loclib and directly retrieves sensor-specific data
(e.g., the signal strength of access points within communication range in
an 802.11-based wireless network). It contains a graphical user interface
(GUI) to make the configuration process easy to handle (e.g., select
a scanning mode and the scanning device).

Various parameters such as the number of scans or the delay between
two consecutive scans are also configurable through the GUI. If the trace
process is started, a histogram pops up in the bottom part of Tracer showing
the access points within communication range and their corresponding signal
strength distributions.