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#1
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non-directional navigation beacon location techique question
I'm trying to find the location of a low frequency mavigation beacon.
Two techniques come to mind. 1) Using the null of a loop antenna, find a vector to the beacon using a compass. Note the location where the vector was found on a GPS. Do this from multiple locations and the beacon is where the lines intersect. Since there will be error in both the compass (2 degrees using a Garmin GPS) and some error in finding the null, the result will be more of a locus of points where the beacon could be located rather than the beacon itself. 2) Again from various locations, find the direction of the unknown beacon and a known beacon (about 40 miles apart). Use a turntable of sorts to find the number of degrees between the known and unknown beacon. [Note, this will not require a compass, just an angular measurement) Given the angle difference between the two beacons, a vector can be drawn from a well known (via gps) location. Again, where these vectors intersect is the location of the unknown beacon. Throw into the mix one more reference. It should be possible to find a spot where both beacons null at the same time. The the unknown beacon is along a line between your location and the known beacon. This would be a line that should be quite accurate. This should be doable from two locations, i.e one where the known beacon is the closer of the two, and the opposite situation. Comments, besides get a life? |
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#3
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#4
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This particular beacon is somewhere around Area 12 on the Nevada Test
Site. It is not published. There are three unpublished NDB in the general area. 209Khz AEC located at Basecamp (near route 6 east of Warm Springs) http://www.lazygranch.com/sound/beac...ecamp209_2.wav 278Khz XSD located at the north end of the Tonopah Test Range www.lazygranch.com/sound/beacons/xsd278.wav 414Khz PYD somewhere near Area 12 on the Nevada Test Site www.lazygranch.com/sound/beacons/pyd414.wav Needless to say, these are not FCC licensed. |
#5
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One more though comes to mind. Would it make sense to use a narrow band
filter (say a CW filter) on the beacon when determining the null since the S meter will be used to determine the minimum signal strength. |
#6
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One more though comes to mind. Would it make sense to use a narrow band
filter (say a CW filter) on the beacon when determining the null since the S meter will be used to determine the minimum signal strength. |
#7
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I have a Bendix 555 marine RDF, but the null is no where near as good
as using a loop with a Welbrook amp. Further, you really don't know the bearing any better than a compass reading. That is, you can get the RDF to point at the source (via a null), but that information needs to be associated with a compass reading. Essentially, this is method one that I listed. |
#8
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#9
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1) Using the null of a loop antenna, find a vector to the beacon using
a compass. Note the location where the vector was found on a GPS. Do this from multiple locations and the beacon is where the lines intersect. Since there will be error in both the compass (2 degrees using a Garmin GPS) and some error in finding the null, the result will be more of a locus of points where the beacon could be located rather than the beacon itself. I have posted a law-of-cosines calculation example several times where coordinates of an intersection point are determined from two GPS locations with a bearing from each location...to the intersection point. I can find one of those in my files and post it later if that is needed. But it could been done graphically with 'Scratch-Plot' because one of the newer features of 'Scratch-Plot' is a plot by azimuth and distance. Just set-up a scale of UTM coordinates, plot each GPS location in UTM coordinates, plot a line from each location with an azimuth direction and a dummy-distance so that the lines intersect, mouse-click a point at the intersection of the lines, and check the coordinates of the mouse-click point immediately in the help file or later in the plot text file. Here is a user link to 'Scratch-Plot' : http://www.kbhscape.com/plot.htm Also, the difference between a geodetic direction and a UTM grid direction can be determined with 'Geodetic/UTM-Grid Utility' by entering the latitude and longitudes and comparing geodetic directions to grid directions. And here is a user link to 'Geodetic/UTM-Grid Utility' : http://www.kbhscape.com/gps.htm |
#10
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I have posted a law-of-cosines calculation example several times where
coordinates of an intersection point are determined from two GPS locations with a bearing from each location...to the intersection point. I can find one of those in my files and post it later if that is needed. Oh, intersection of two directions is fundamentally a law-of-sines calculation and that is a much easier calculation than a law-of-cosines calculation. A law-of-cosines calculation is use for the intersection of two distances... But it could been done graphically with 'Scratch-Plot' because one of the newer features of 'Scratch-Plot' is a plot by azimuth and distance. Just set-up a scale of UTM coordinates, plot each GPS location in UTM coordinates, plot a line from each location with an azimuth direction and a dummy-distance so that the lines intersect, mouse-click a point at the intersection of the lines, and check the coordinates of the mouse-click point immediately in the help file or later in the plot text file. Compass directions with declination should also be adjusted with UTM convergence before they are used with UTM coordinates... |
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