DodoPi Bat Recorder: "hey, we have a live one!"

Bats flying around in mid-winter! ...whatever next?

It may be relatively rare compared to the number of recordings made each night during the summer...

...but just one recording shows that there are bats out there.

the Dodotronic UltraMic: first impressions

I just splashed out £225 on this USB microphone.

Initially I just plan to experiment & compare it with my home-made analogue bat recorder.

If all goes well this may turn into yet another bat detector/logger project.

Common Pipistrelle Feeding Buzz

Bat echolocation is all about catching a meal.

After all, if bats could safely feed during the day, they wouldn't bother to stumble around in the dark of night. 

So its good to catch the occasional ultrasonic recording of bats catching their prey.

Bat Call Logger: more on call analysis

Following my last post I have had some time to analyse a few more bat recordings and consider how to streamline my work flow.

Until recently, I've been carrying out all file operations using Audacity.

But there are a few things I can do via the command line, which I've pulled together in a Gambas GUI program.

Bat Call Logger: full-spectrum analysis

With the recent step change in the weather, I was able to run the system last night and capture bat calls for the first time this year.

It looks like my modifications to the system are paying off.

I'm now getting full-spectrum (ultrasonic) recordings which are much easier to analyse than the previously used Frequency Division recordings.

Bat Camera: just a wild idea!

What if I triggered a camera from my bat detector?

I'm not looking for prize winning bat photos, just a possible aid to identification.

Would the system capture anything recognisable?

Bat Call Logger: implementing pre-capture

My bat call logger uses a very simple/crude means to trigger recording.

This seems to work, but a few recordings are blank, as if the triggering signal has stopped before the recorder kicked in.

By having a pre-capture function, I should be able to capture a sequence before the trigger takes affect.

Bat Call Logger: Wolfson audio card frequency response

Having got my Wolfson Audio card working happily with a Raspberry Pi 2, I decided to try and check the frequency response.

As this card is described as a 'audio card' and the only figures I've seen relate to the audible range, I didn't have high expectations regarding its use in my Bat Call Logger.

Anyway, to find the answer, it was just a question of setting up some test gear and running a few checks.

Bat Call Logger: recording ultrasound

My bat project has been on the back-burner for the last few months, as I understand that bats don't venture out much during the winter.

However, the Weather Man on BBC's Winterwatch did say he had seen them flying around on a few mild evenings during January!

So maybe its time to do a bit more work on my Bat Call Logger and check if there are any out there.

Bat Detector: automatic recording

Following on from my last post, this one gives revised details of my Pi based automatic recording system.

My original software just didn't work with real bat calls, and the microphone didn't have a very good response at high frequencies. 

But now this has been sorted out I'm getting 10-20 recordings per hour!

Bat Detector: electret microphones

Building your own Bat Detector is a relatively easy electronics construction project.

The tricky bit can be locating a suitable transducer or microphone that has a useful frequency response into the ultrasonic range used by common bats.

During the last few weeks I have been testing a number of devices, and here are my notes.