Crow Systems - Bat Call Converter Instructions

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Using Your Bat Call Converter - Batteries, Recording, Analyzing, Specifications
Back to the Bat Detector page | Bat detector FAQ's

Installing the Battery: Open the battery compartment cover located on the bottom of the detector by sliding it in the direction of the arrow on the cover. Install one 9 volt alkaline battery by snapping it onto the battery clip. Fit the battery into its compartment and reinstall the cover. Your Bat Detector has integrated reversed battery protection. If the battery is installed improperly, the circuit will not be harmed. Simply reinstall the battery properly for normal operation. The detector is now still OFF and no power will be used until the earphone is plugged in.

Turning Bat Detector ON: After installing a battery, insert the earphone plug into the larger of the two jacks located on the side of the detector - see picture. Make sure the earphone plug is inserted fully! No part of the plug shaft should be visible when the plug is fully inserted. The detector is now ON and ready to detect ultrasonic sounds.

Turning the Bat Detector OFF: Simply remove the earphone plug from the detector and it will turn OFF. Note: If the detector will not be used for three weeks or longer, remove the battery to prevent possible damage to the detector from leaking battery acids - damage due to leaking batteries is NOT covered under the warranty! Contact the battery manufacturer if a leaking battery damages your detector.

Testing and Using your Bat Detector: To test operation of the detector, first install a fresh battery and plug in the earphone as described above. Place the earphone clip over an ear in a comfortable position. Rub your fingers together about 1/2 foot in front of the detector's sensor opening or lightly shake a piece of aluminum foil or set of keys in front of detector. You should hear a buzzing noise at the earphone. The bat detector can pick up any ultrasonic noise within its detection frequency range of ~25kHz to 75kHz {25,000 to 75,000 cycles per second} - bats, computers, TVs, crickets, car engines, leaking gas pipes, chimney swifts, etc. Detection range (distance) will vary depending upon the air quality, source intensity and distance, frequency, and direction of the ultrasonic sound. Fortunately, bats emit very loud, distinctive calls that are easy to differentiate from other ultrasonic noises.


If detector volume becomes weak, or if the detector fails to sense ultrasonic sounds - first check to see if the earphone plug is fully inserted in its jack. Next, ensure that the battery is properly attached and battery clips are clean. If neither of the above fixes the problem, test or replace the battery.
Note: Never allow the detector to get wet! If it is exposed to water - immediately turn the unit off {see above}, remove the battery, and allow detector to dry thoroughly before using.
If exposed to salt water or acidic rain water, return detector for non-warrentee service.

Range: The maximum range of the detector {when detecting an 'ideal' bat call} is about 75-90ft linear - see below. The range varies with call intensity, direction, and species of bat. Maximum range is achieved when the detector opening is oriented towards the bat, the bat is facing the sensor while calling, and there are no large obstructions between the bat and the sensor. When using the detector, slowly scan the area in all directions (up too!) to try to locate any bats. If you are near a large, solid object when using the detector (such as a house, wall, or car), you might hear distorted calls due to the ultrasonic calls reflecting off of the solid object. When finished using your detector, be sure to unplug the earphone, as this is what turns the detector power off - see above. For best results, first try the detector on bats that you can actually see flying over. This way you'll get to know the typical pattern of bat hunting calls before venturing out into the night.

A note on range: The linear range is the measure of the absolute distance between the sensor and a calling bat. In real-world applications, the detector will be used to cover a three-dimensional hemisperical area, so the effective horizontal range is double the linear range. Imagine that you're facing North - the range is about 90 feet to the North. Now, standing in the same spot, you turn to face South - so the range South is 90 feet too. So your  effective horizontal coverage area has a diameter of 180 feet.

Recording a Bat Call: Using the detectors built-in recording output jack {the smaller of the two jacks located on the side of the detector - see picture}, you can save the converted bat calls to any recording device with a "mic in" or "microphone input" jack. Recording directly from your Detector to a desktop computer does not work very well as the computer emits ultrasonic noise as well as electromagnetic interference. Using a laptop computer might work, but we recommend a small hand-held recorder. Locate the recorder as far as possible from the detector. After recording a call to the hand-held recorder, you can then record it into your computer by playing the recorded call into either the built-in or external microphone of your computer. You could also hook up your recorders output to the "mic in" or "line in" jack on your computer - see owners manuals for your recorder and computer sound card. Once recorded into your computer as a .WAV file, you can use Waveflow®© to clean up and edit the recordings. Spectrogram®© generates spectrograms to visually display the bat call freqency and modulation information.
See program instructions for Operating System compatibility and registration information.

Cable for Recording: To record calls, you'll need a cable from your detector to your recorder. Use a shielded audio type cable of no more that about 4 feet. See specifications for the size and type of jack that the detector uses. Your local Radio Shack® or home audio shop should be able to supply you with any cables / adapters needed to connect your detector to your recorder.

Principles of Operation: The detector senses a bat's call with an ultrasonic transducer. The detected call is amplified using low power circuits for long battery life. The amplified signal is filtered to remove unwanted noise. This signal is then converted into a digital frequency which is divided by 128 - resulting in a low frequency sound audible to humans. An output is provided for recording these audible calls using your tape recorder or other recording device. This frequency-division type detector will detect a broad range of bat calls - from about 25kHz to 75kHz without the need of constant tuning. The resulting audible signal is of a fixed volume - it shows the frequency and modulation of the original bat call, but does not contain any of the original calls volume or amplitude information. When analyzing the frequency and modulation characteristics of a converted bat call, be sure to multiply the displayed frequency by 128 in order to determine the original bat call frequency!
This basic detector is intended as a cost-effective alternative to the very expensive, research grade bat identification and bio- acoutstic research equipment. It is not designed for detailed acoustical analysis of bat calls nor is it intended to be used for species identification (though ID is possible in some cases). It is a great tool for bat presence determination, population density or dynamics studies, roost locating, and general educational purposes.

Specifications: Back to Top
Size: 3.75" x 2.37" x 1.5" / 93 x 25 x 38mm  Detection Frequency: {approx min / max}: 25kHz-75kHz
Weight: 5oz / 146gr with battery & earphone Detection Range {approx. max}: 75-90 ft linear,
effective range 150 - 180 feet - see instructions.
Battery Types: One 9 volt alkaline or similar. Rechargeable types OK - but will reduce run time. Operating Voltage Range: 6V min to 12V max
Battery life {approx}: Alkaline - 600 hours / 24 days with detector ON.
Rechargeable - approximately 130 hours / 5 days with detector ON.
Headphone Jack: 1/8" mono audio jack. Also serves as the On / Off switch. Other earphone / headphone types may be used, but they must have a 1/8" mono audio plug!!
Operating temperature range min/max:
­5 to +145ºF / ­20 to+70ºC
Recorder Output: 3/32" mono audio jack - 0 to 0.85V peak square wave - sleeve negative (circuit ground).

"If men had wings and bore black feathers, few of them would be clever enough to be crows" - Henry Ward Beecher

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