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blue string and compass app

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Philip Sargent
2026-02-03 15:32:53 +00:00
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handbook/survey/gps.htm
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@@ -45,10 +45,13 @@ of the entrance. </p>
<p>Yes, you will have to manually do a surface survey leg using your survey instruments between the GPS point and the cave entrance tag station, and record that in your cave survex file.
<p>If you are doing surface prospecting and do not have daylight-capable survey kit with you (actual physical tape measure, compass/clino) then <em>estimate</em> the distance and direction from your GPS recorded location and the cave entrance, e.g. "10m towards entrance in direction 025 degrees". You do have a notebook with you of course. This will be transcribed onto your "New Cave" form. Your phone does have a compass capability: download the app and use it. Take a photo of the GPS point with the entrance in view behind. If you have set up your phone correctly (ahem), your phone camera will record the compass direction of the photo.
<p>If you are doing surface prospecting and do not have daylight-capable survey kit with you (actual physical tape measure, compass/clino) then <em>estimate</em> the distance and direction from your GPS recorded location and the cave entrance, e.g. "10m towards entrance in direction 025 degrees". You do have a notebook with you of course. This will be transcribed onto your "New Cave" form. <a href="/handbook/computing/phonecompass.html">Your phone does have a compass capability</a>: download the app and use it. Take a photo of the GPS point with the entrance in view behind. If you have set up your phone correctly (ahem), your phone camera will also record the compass direction of the photo.
<p>Use a bit of string (blue baling twine from basecamp) 15m long, with a knot in it at the 10m length, to get the distance correctly.
<p> A notebook and pencil are essential when looking at lots of entrances: no, your memory is not good enough. Takes a screen-shot of the GPStest screen whenever you want a proper GPS location and upload the screenshot to the digital wallet for a new cave. Use the timestamp on the screenshots to correlate everything. A screenshot is proper evidence, your memory is not.
<p>Also <em>sketch</em> the entrance in comparison to other holes close by - in the notebook, which you have with you, and always bring 2 pencils.
<h4>SBAS</h4>
Check whether your phone is using SBAS "Satellite-based Augmentation Services", which is another name for EGNOS, the differential GPS system.