Monster Media 1993 #2/Image.iso/ham/aprs114.zip/README.FOX

Text File | 1993-04-01 | 2KB | 30 lines

                      USING APRS FOR DIRECTION FINDING

    APRS is an ideal tool for rapidly triangulating fixes to locate a hidden
transmitter or jammer.  APRS instantly plots vectors from all stations making
a signal report and the intersection of these lines of bearing indicates the
location of the jammer.  To see a sample, load the file named FOXDF.BK into
APRS and see the results of our DF on a constant carrier on our local 145.05
packet frequency.  The bearings from W3ADO and W3DTN were actual measured
beam headings.  The third bearing from N3BFO was added to the file to show
how great it would be if we had three stations reporting instead of just two.

     To accomplish this triangulation, each participating station simply
enters his bearing to the jammer into his own station's course by hooking
himself and using the INSert key to update his stations report.  As soon as
two or more stations are reporting a line of bearing to the jammer, everyone
can predict the intersection of the lines by pressing the (J)ammer key.  As
a further aid, the R key can be used to superimpose a set of range rings on
the screen for estimating distances for subjective analysis of signal
strnegths.  Even for stations not running APRS, their jammer bearings can be
quickly entered by any other APRS station using the alt-A key to add them to
the map in real time.

    Finally if a mobile fox-hunter is equiped with GPS or LORAN-C, his
movements will also be tracked so that he can be vectored into the jammer's
location.

    Eventually I want to add a signal strength contour display so that single
stations can report simply their relative signal strength on the jammer, and
intersecting circles from each station can also be used in the triangulation
process.  Feedback on this application of APRS is welcome.