Thursday, 19 October 2017

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?

Tuesday, 17 October 2017

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...

Thursday, 12 October 2017

Bat Call Logger: the hardware

My bat call logger combines a frequency division bat detector with a Pi based audio recorder.


Recordings are simply triggered by a short stream of pulses from the detector (i.e. "activity").


Having spent a bit of time trying to optimise the hardware, I now need to document what I've done, before I forget why I've done it!

Wednesday, 27 September 2017

Nokia 3310: the Good, the Bad and the Ugly

Now that I've been using my new Nokia 3310 for a few weeks, I have a better idea of its strengths and weaknesses.


Its a good basic phone, but it has a few bad & ugly aspects to its design.


So here is a more detailed review than the one posted at the beginning of September.

Saturday, 23 September 2017

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!

Monday, 18 September 2017

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.

Friday, 15 September 2017

Gambas: working with JSON

The JSON file format is widely used by internet sites when returning data requested by an a.p.i. call.


It is relatively easy to handle JSON data in Gambas, once you have an understanding of its basic structure.


Here we use the Gambas method Json.Decode() in a couple of examples.

Friday, 8 September 2017

BlissFlixx: Pi HDMI config.txt settings

I recently set up another Raspberry Pi as a BlissFlixx set-top box using an earlier post.


Although the system worked, I quickly realised that I'd missed a couple of config settings from my original post.


So this update includes those important settings.

Wednesday, 6 September 2017

The new Nokia 3310: just another stupid phone

I've read a lot of inaccurate customer reviews of the new Nokia 3310 recently, which probably goes to show that most people don't read manuals anymore.


Well I do, and I've just received my new Nokia 3310 from Carphone Warehouse.


So here is a more accurate than average review.