Changes between Version 8 and Version 9 of Help/AudioMapping/Calibration

Timestamp:

2025-01-13T18:20:38+01:00 (2 weeks ago)

Author:

stoecker

Comment:

Use wikitr:

Help/AudioMapping/Calibration

@@ -6 +6 @@
 An error of 5 seconds per hour could mean you are 100m or more out after four hours surveying on a bike, and more in a car, if you are relying on the clock in the audio device to indicate position on a GPS track.
 
-To calibrate, you need to enter a number close to but not exactly 1.0 in the calibration setting of JOSM's [wiki:Help/Preferences/Audio Audio Preferences]. This number is the ratio of the sound recorder's notion of how long a recording is to the accurate length. For example, if the audio recording of a 3 hour interval turns out to be 3 hours and 15 seconds long, your calibration number is (3 x 60 x 60 + 15)/(3 x 60 x 60), which works out at 1.00139 (five decimal places is ample). If your recorder's clock runs fast, the number will be slightly less than 1.0. If it is very much different from 1.0, throw away your voice recorder!
+To calibrate, you need to enter a number close to but not exactly 1.0 in the calibration setting of JOSM's [wikitr:/Help/Preferences/Audio Audio Preferences]. This number is the ratio of the sound recorder's notion of how long a recording is to the accurate length. For example, if the audio recording of a 3 hour interval turns out to be 3 hours and 15 seconds long, your calibration number is (3 x 60 x 60 + 15)/(3 x 60 x 60), which works out at 1.00139 (five decimal places is ample). If your recorder's clock runs fast, the number will be slightly less than 1.0. If it is very much different from 1.0, throw away your voice recorder!
 
 == procedure ==
@@ -14 +14 @@
  2. Measure how long your recorder thinks this is. You '''can't''' do this by playing back the recording on the recorder and timing it, because that will be using the same clock for playback as it used to record. You need to take the digital file and determine this according by comparing the purported sampling rate to the actual sampling rate. You can do this in JOSM or more accurately using a sound editor:
 
-   * Using a sound editor such as [http://audacity.sourceforge.net/ Audacity], open the clip and delete the portions before and after your two marks. The pips are easy to edit visually. Read the length from the duration display (in Audacity this runs along the top of the soundtrack waveform).
+   * Using a sound editor such as [https://audacity.sourceforge.net/ Audacity], open the clip and delete the portions before and after your two marks. The pips are easy to edit visually. Read the length from the duration display (in Audacity this runs along the top of the soundtrack waveform).
 
    * In JOSM, 
      a. open a GPX file (any will do providing it is long enough), 
-     b. [wiki:Help/Action/ImportAudio Import Audio] on the GPX layer's context menu to make an audio marker layer,
+     b. [wikitr:/Help/Action/ImportAudio Import Audio] on the GPX layer's context menu to make an audio marker layer,
      c. play the audio until you hear your starting cue, 
-     d. [wiki:Help/Action/MakeAudioMarkerAtPlayHead Make an Audio Marker at the play head]
+     d. [wikitr:/Help/Action/MakeAudioMarkerAtPlayHead Make an Audio Marker at the play head]
      e. repeat for the end point.
      f. look at the labels for the two points, which are in GPS time offset from the start of the track; the difference is the measured sound track duration.
 
- 3. Divide the measured time by the real time and enter the result in [wiki:Help/Preferences/Audio Audio Preferences].
+ 3. Divide the measured time by the real time and enter the result in [wikitr:/Help/Preferences/Audio Audio Preferences].
 
  4. Repeat for each mapping session until and unless you are sure the discrepancy is constant enough. Also, consider that the discrepancy may vary according to the sound quality settings on your recorder.
 
-Back to [wiki:Help Main Help]
+Back to [wikitr:/Help Main Help]