These are the units that are very useful for bat detecting. Many of them have good pick-up range; and produce favorable recording results. These results are often clear enough, to enable you to make decent sonograms. Especially if the system retains amplitude.
Amplitude retaining FD bat detectors do exist. An excellent overview, and simple explanation of amplitude retention may be seen Here.
Two models of FD detectors that immediately come to mind are:
The Ciel CDB205 and The BatBox Baton.
The Ciel CDB205 is a Frequency Division bat detector that allows you to observe the whole spectrum of bat sounds from 18 to 120 KHz simultaneously. The whole spectrum is divided by 10 and can then be heard on the integrated speaker. It can also be connected to a recording device over the high level line out, for analysis or listening at a later date. The unit comes with an integrated LED torch for detecting in the dark. Requires a 9v battery which is not included with the device.
The BatBox Baton is a simple but versatile bat detector having a monitor speaker allowing reduction of frequencies between 20kHz to 120kHz. The division factor is 10, reducing the sounds of a 50kHz bat to 5kHz. The unit comes with a version of BatScan sound analysis software, developed especially for the Baton.
Having owned, and extensively used both of these kits; I can recommend the BatBox Baton as the better detector of the two.
The Ciel 205 had neat little features that I liked: The translucent green buttons are illuminated, when powered on, the volume is adjustable, and it has the built in LED "torch" (AKA flashlight) to find your way out of the woods with. Each of these features prove to be cool; especially if the majority of use will be during Bat Walks. The CDB205 has recently been replaced with a new version, now known as Revision 2. The 9v - PP3 battery is installed by plugging it into a (heavy-duty plastic) 9v battery snap, inside the compartment in the back.
The BatBox Baton is slim and compact, making it even more portable than your average bat detector. It's single Power On/Off button is inconspicuous - Illuminating with 4 rather muted points of LED light 'round the button itself. Indicating the On/Off status of the unit. Depending on what was available on the date of manufacture - You may get Blue or Red lights. Battery compartment is robust and simple. I use re-chargeable 9v - PP3 NiMH batteries. And, I've replaced batteries in my unit countless times - Without anything ever breaking down or wearing out.
As I've posted on this blog before: One of my main concerns, in regards to the performance (and value) of a bat detector, is it's ability to pick up bats well, and at good distances. Well, the Ciel is a nice detector, and I had used mine quite a bit. However, the BatBox Baton's sensitivity was simply amazing. Thanks in part, to it's use of a MEMs microphone element - It picked up bats very well (and clear), from unprecedented distances away.
Until now, the Baton had been the "Undisputed Champ" of long-distance bat detecting. But, it has finally met it's match - With the release of Dodotronic's Ultramic200K microphone. This new, USB microphone is able to pick-up/record bats at distances of 50 meters away! : )
So, the record stands...until the next bat detector comes out, that can beat it!
Tune-in tomorrow - Same Bat-time, same Bat-channel!