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Geiger Counters



iPhone Ratemeter Software to Display Geiger Counter Readings


  • Position the geiger counter (or other source of clicks) next to the device's microphone.
  • Set the period in seconds, typical 60 is used for a one minute sliding average.
  • Optionally turn Normalize on if a different period is used, and it is desired to normalize readings to one minute.
  • Starting at the maximum value, adjust the threshold slider until clicks are detected.
  • The delay slider can be used if single clicks are being interpreted as multiple clicks by sliding it to the right. The maximum delay is about a quarter of a second. This is used to produce a "dead time" during which clicks will not be registered.
The displayed CPM reading will be in gray until the first measurement period has elapsed, it will then turn black to indicate the reading is valid.

Touching the info button in the lower right corner will bring up the graph of readings. The graphed values are displayed with a blue line through them, and a red best fit line is also displayed. This fit is a moving average of five samples, so it will be a straight line until you have more than five samples. Touching the info button on the graphing view will bring you back to the main view.

If the recording switch is turned on, readings will be saved to a file, the name of the file is a timestamp of when the recording file was started.

If the Location switch is turned on, your location will also be written with each reading. If your device does not provide location information, the switch will automatically turn back off.

You can access saved recording files on your computer via iTunes:

  • Go to iTunes, and select your iPad from the DEVICES list at the left
  • Tap the Apps tab
  • Under File Sharing, select iGeiger from the list of Apps
  • All of the recording files will be under iGeiger Documents. You can transfer these files to your computer.

The format of a recording line is:


A typical recording line is:

2011-10-15 17:50:14,43,-77.3745,38.3013,252.054

Here are some details on directly connecting an audio line source to your iPad/iPhone/iPod Touch

Email your comments and questions to

Last modified October 24, 2011