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A heterodyne function is often also built into the other types of detector. A heterodyne bat detector simply shifts all the ultrasound frequencies downward by a fixed amount so we can hear them. A "heterodyne" is a beat frequency such as can be heard when two close musical notes are played together.
At the UK National Bat Conference, Wildlife Acoustics announced the Echo Meter handheld bat detector. [8] The device will be available in December 2011. The detector is capable of monitoring for bats using heterodyne, frequency division or Real Time Expansion (RTE). RTE is Wildlife Acoustics proprietary technique for shifting bat sounds to the ...
A heterodyne bat detector will only handle a small range of bat frequencies, so it is necessary to keep retuning the heterodyne frequency to find the point of maximum loudness or, in the case of bats with a hockey stick call, the frequency which gives the lowest sound. This gives the lowest plop sound from the CF end of the calls.
P. pygmaeus (55 Pip) call on heterodyne bat detector, recorded in stereo 187 kHz The frequencies used by this bat species for echolocation lie between 53 and 86 kHz, have most energy at 55 kHz and have an average duration of 5.8 ms.
Instead, a single-element optical detector can also act like diversity receiver via synthetic array heterodyne detection or Fourier transform heterodyne detection. With a virtual array one can then either adaptively select just one of the LO frequencies, track a slowly moving bright speckle, or add them all in post-processing by the electronics.
Most articles on devices that would be considered "detectors" are in category:measuring instruments and category:sensors. See also the article on sensors . Subcategories
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Figure 1 shows a particular implementation format of the synthetic array method. This implementation is called "rainbow heterodyne detection" because the local oscillator has its frequencies spread out like a rainbow across the surface of the detector. The output from the detector is a multi-frequency signal.