BirdNet Systems Testing #3: single call repeatability test

One final test method

 Is BirdNet really so bad?

or is there an 'age related' issue, i.e. 'me'

BirdNet-Pi: USB audio module testing

I've bought a couple more modules

so thought I'd do some tests to compare performance.

This post concerns the use of USB audio modules in connection with miniature electret microphone capsules.

BirdNet-Pi: more thoughts on microphones & audio

There's a lot of talk on the Github Discussions page about microphone quality.

So naturally I have been giving the matter some consideration and have conducted a few simple checks.

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.

BatGuru: a British bat ID helper

My BatGuru is a program written in Gambas which helps me identify British bat species based upon echolocation call data.

It simply saves me having to juggle the key parameters in my head as I scan the charts in my reference book.

But identifying bats from their calls is tricky due to the wide variability of their calls.

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: 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 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 Call Analysis: second thoughts

I'm still trying to reconcile my bat call recordings with the data provided in the Jon Russ book "British Bat Calls".

This caused me to question whether my home-brew bat detector was a reliable witness.

Just how much faith can I have that my FD detector is producing sensible recordings?

Bat Call Analysis: more difficult than it looks!

So I've now got a few hundred recordings from my Bat Logger, collected over a number of nights.

Time to settle down with Audacity and a pint of IPA, and analyse a bunch of waveforms.

Identifying the bat in question is easy, right? Its just a matter of determining frequency, repetition rate...

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.

Raspberry Pi audio vs. Adafruit USB audio

Many people on the internet comment about the poor sound quality of the Raspberry Pi audio output when taken direct from the 3.5mm jack socket.

One alternative is the Adafruit USB audio adaptor, which provides a mic input and headphone output.

Both the Pi jack and Adafruit audio outputs sounded a little harsh to me, so I decided to do a few checks using sine waves and a scope.

The Pi-Mote 433MHz control unit for the RaspberryPi

This controller allows a user to remotely control power sockets via a simple program.

Having just received my kit from Energenie, this post is basically an introduction to using the system, driven by a Gambas program.

I've also included information on the serial data format, which was captured using the method described in an earlier post.

Hacking 433MHz Remote Controllers

With the introduction this week of the Energenie Pi-Mote control board, my first reaction was to reach for my credit card and place an order.

I don't know just yet what I'm going to do with it, but it seemed like a relatively cheap toy to play with.

While waiting for this starter kit to arrive, I remembered that I was given a 433MHz control kit earlier this year, but had not got around to doing anything with it.

Simple Video Editing with Avidemux

Avidemux is a relatively simple to use video editor. It is cross-platform, free open source software (FOSS), so you can use it on Linux, Windows or a MAC box.

Illustrations in this post are from Avidemux running on Lubuntu Linux.

Before we start, there are a few points which need clarification.