batcorder calibration

Why calibrate?

What happens if I use a calibrated system in contrast to an uncalibrated one? There are of course many different opinions, we will explain why we think a calibration is necessary.

How long does it take?

You will need to send the microphone for recalibration to us. Since you can't use the batcorder for that time, the return time is quite important for you. We will give tips on this page how to proceed best.

Adjust the batcorder

The batcorder needs to have the microphones calibration factor set - we will explain how to do that.

Why calibrate?

The microphone and its functionality is vital for recording bats. Without a working microphone no bat calls will be registered. The microphones sensitivity has strong influence on the detection distance. Reduced sensitivity means reduced detection distance. A difference of -6 dB  already halfs the detection distance (simplified). Since a difference of 6 dB between two microphones isn't that uncommon, you can expect that two detectors won't be able to record the same bats.

Even microphones of the same manufacture and the same type may have different sensitivity. While these difference often is small, it still can easily be 3 dB. If at usage the conditions are different for two microphones and for example one is often setup at rainy conditions, while the other isn't, soon these two differ again by 6 or more dB. So one can say there is an unpredictable aging effect due to environmental conditions.

If the detector is not regularly adopted to the new microphone sensitivity, the detection distance will gradually get lower. Since that happens rather slowly, one may not easily detect it for a long time, until the microphone is hardly recording any bats any more.

Yearly recalibration

With the start of the batcorder in 2007 we also started a recalibration service. We were the first offering such a vital service, without one exception we are still proud to be the sole vendor with this.We do recommend based on our experiences a yearly recalibration, best just after the last or before the next season - so in winter. We do only need the microphone (for batcorder 1.x also the batcorder) and do a sensitivity test. This will take 10 to 20 minutes and show deviance of the normal sensitivity. If necessary we then calculate a new correction factor which will be sent back to you with the microphone. This you will then set in the batcorder according to your device manual.

When to send?

We can do calibrations 365 days a year, but probably quite often you want to record bats. Thus best time is after the season. If you wait to long and do send just before season start (so mid of January for us), we probably are quite busy packing up orders and sending them out. That will delay calibrations. Yet if you send in autumn by end of November, it should be back with you after only a short delay.

What do I have to set at the batcorder?

Valid for batcorder 3 - for other models or if you are not sure please refer to the manual of your device.

  1. Start the batcorder
  2. Got to settings menu
  3. Move the cursors to the first field of Filecode
  4. Press REC and right arrow key
  5. The menu for setting the MCF opens up
  6. At second there is there CF (correction factor) which can be changed with up/down arrow keys
  7. The new CF is the MCF and for older batcorder 2 and 3 still needs to be adjusted by the BCF (batcorder correction factor) from the manual
  8. Rechnung saves the values and SET exits without saving

So in short

  • Send microphone to ecoObs in late autumn Rücksendeschein
  • Wait for 5 to 15 days to get the microphone back
  • Set the new MCF/CF in the batcorder
  • Done, detect bats