Depending on where you live there will be many or few bats. I live in an urban area where there aren't that many (unfortunately). To prevent having to watch an almost always empty sky, I made this bat-detector to warn me when the bats are around, now I can watch the sky and be sure that they are there. This kit uses quality components to make a detector which is very good value for money. It functions well and is ideal for beginners. The Magenta 5 digital bat detector has a large frequency range of 10 kHz to130 kHz. The extended low frequency coverage makes it suitable for some insects and birds, as well as bats. Bats navigate with sonar, a kind of radar but with sound. Those sounds are short pulses of a high frequency, the wave length therefore is very small enabling them to "see" small things, such a their food: insects. Those frequencies can range from 20 kHz up to 100 kHz. Humans cannot hear higher than 16 kHz, so we have to lower the frequency. So just how accurate are the identifications given by this bat detector kit? The short answer is you get an accurate ID about 80% of the time. But the more complete answer is that it depends on two factors: the species and the Auto ID Sensitivity setting you use during recording.

The circuit board was designed to fit into easily available 40mm push-fit plumbing fittings as shown here: Bat detectors are mostly sold online. A web search of "bat detector" will bring up links to the major retailers. There are also a few generous retailers who donate a proportion of their sales of some products (including bat detectors) to BCT which you can find here. When choosing a bat detector the two key factors will be your budget and what you want to use the bat detector for.The BatBox Baton is perhaps even more simple to use than the Magentas, with just 1 button operation – the on/off button. You do not need to tune this detector – it will automatically detect all frequencies simultaneously as it works through ‘frequency division’, where all ultrasonic calls are divided by a factor of 10, pushing them into the human hearing range. Audio is played through the front facing speaker and when the Baton is plugged into a computer, you can see sonograms (visual representation of bat call) on the software included with the Baton. I managed to get some photos of them with both my phone and a DSLR camera by carefully pointing them up through the bottom opening of the bat house. We had at least three and possibly four in there! But I had little confidence in my bat identification skills so I had no idea who our new friends were. That’s when we started searching for a bat detector. A first look at the bats in our bat house. But who are they? Won’t any frequency corresponding to a multiple the 1:8 sampling rate disappear? Wouldn’t the frequency response profile have valleys centered on these frequencies? If you use the “ Accurate” setting on the app, you’ll end up with fewer recordings getting an ID, but they’re more likely to be accurate when you do. Now you’ll have an average 82% success ratio of correct ID’s, with several species reaching 100% accuracy. The bat classifiers performance spreadsheet is handy for deciding how accurate your id might be

There is another method of making bat-signals audible, called heterodyne. Here you mix the bat sounds with a tunable frequency, the result of that is the sum and the difference of those two frequencies. So when you have a bat making sounds at 40 kHz and you tune the detector to 45 kHz, you will have a signal at 85 kHz that you filter away (it isn't audibe anyway) and an audio signal at 5 kHz.Another issue with this kit which uses an ultrasonic receiver is the sensitivity range of the receiver, which has a peak around 40kHz, but again it works well over a very wide range of input signals as the analog signal is converted into a digital pulse train. The Batscanner is one of the easiest detectors to use, automatically scanning the whole frequency range and adjusting accordingly when it detects a bat, displaying the peak frequency on the digital display. This means you don’t have to tune anything and you won’t miss a bat because you’re tuned to the wrong frequency. The call output is clear and the Batscanner intelligently filters out non-bat low frequency calls giving you a clean, noise-free output. Baton& Duet– Frequency Division If you are looking to identify bat species more precisely from their calls then you will need a broadband bat detector ( frequency division, time expansion or full spectrum/direct sampling) and some sound analysis software.

I saw that there is an "Audio Challenge Contest" going on. How about sound you cannot hear, and then make that audible? So I made a simple bat detector, with just a handful of transistors a binary divider and an audio amplifier, no microcontrollers, Arduino or even Raspberri Pi, so no coding required. The spring peepers were calling loudly from our pond, but hearing their high pitched calls through the app came out only as very low thuds. Then, 15 minutes after the official time of sunset, I heard it. Not with my ears but through the phone. This practical guide is perfect for learning more about bat species identification, the equipment used and bat call analysis.There are more than 1,400 species of bats in the world with more than 40 here in the United States. So how can a bat detector tell what type of bat is flying overhead? Through a combination of solid scientific research, lots of ultrasonic recordings of bat echolocations, and some high tech digital analysis. Using complex, proprietary algorithms, Wildlife Acoustics researchers create “classifiers” to match the most likely species to a recording of a bat’s echolocation pulses. Hundreds of thousands of Mexican free-tailed bats swarm out of Carlsbad Caverns, NM on a summer night. Wildlife Acoustics is a big name in the world of wildlife audio research and they’ve built some of the most advanced wildlife sound identification software available. One of Wildlife Acoustics software products is called Kaleidoscope Pro Bat Auto ID. They’ve developed classifiers for 38 bat species in North America, which covers almost every species you’re likely to hear. But they’re also constantly adding to their list of classifiers for other regions of the world. At the time of writing they created classifiers for 37 species in the UK & Europe, 37 Neotropical species, and 21 in South Africa. You can see a complete list of species here. I hit stop on the recording and a second later a box popped up on the screen. It was the moment I had been waiting for, the most likely match for the species I had just recorded. “ Big brown bat” it said. Eptesicus fuscus. The app identified my bat as a Big Brown Bat! The Echo Meter Touch app lets you record your calls onto your phone or tablet, giving you an exciting record of the places you have been and the bats you have heard. If your device has GPS functionality then it will also tageach call and display them on Google Maps. Let’s use North America as an example. Based on the most recent Classifier Performance Table we can see that using the “ Sensitive” setting you’ll receive an accurate ID about 70% of the time on average. However, some species tend to get confused more easily, while others have more distinct echolocation calls. You’ll get an accurate ID about 97% of the time if it’s a Spotted Bat ( Euderma maculatum) and only 31% of the time if it’s a Cave Myotis ( Myotis velifer).