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.

Thursday, 24 August 2017

Editing GPS coordinate data with the Prune GPS Tool

This is a great tool when working on GPS track files (.gpx) that are downloadable from the internet.


You can view tracks (e.g. recommended walks) overlaid on a map, and edit the route by adding, deleting or simply dragging the data points to a different location.


And once you have made your changes, you can copy the .gpx files to your Garmin GPS ready for your next outing.

Monday, 14 August 2017

Caroline on Pirate BBC Essex?

On the 14th August 1967 the UK government introduced the Marine Offences Act in a desperate attempt to stop offshore "Pirate" radio stations.


It was pretty successful as, one-by-one, the stations turned off their transmitters and their staff headed for home.


But Caroline didn't stop, and now on the 50th anniversary of this legislation, Caroline is not only transmitting via the web, but also on the Medium Wave radio band!

Friday, 11 August 2017

Increasing the VOLUME in Linux

One annoying characteristic of Lubuntu in particular (and I suspect Linux in general) is that the playback volume is often too quiet, especially on laptops.


This problem is due to differences in audio recording levels, and is most noticeable when listening to audio via a web browser (e.g. watching a video).


Having put up with this for years, today is the day I feel I need to take some action.

Wednesday, 9 August 2017

Robots are coming! (...and the future is looking grim)

We live in a very exciting age, with scientific discoveries, inventions and technological development moving at an incredible pace.


The next few decades are likely to produce products which will really help humanity, especially in the field of medicine.


But what will happen to us and the world we live in, in the longer term, say in one or two hundred years from now?

Thursday, 20 July 2017

Why don't my domestic LED lights last forever?

Domestic LED lighting is a far better alternative than incandescent or flourescent lights.


LEDs produce light while generating practically no heat, and they seem to last forever when used in electronic equipment.


So why have 2 of my expensive bathroom LED lights gone kaput?

Wednesday, 12 July 2017

Is it damp under my house (part 3): I wasn't expecting that!

We have had some fantastic summer days during the last couple of weeks, here in Sunny Southern England.


Daytime temperatures have regularly been in the high 20s/low 30s (...and I'm talking Centigrade here not Fahrenheit).


So surely the under-floor area of my house is now bone dry?

Tuesday, 11 July 2017

Garmin eTrex 10: simple configuration for beginners

Configuring and using a Garmin eTrex for the first time can prove difficult for beginners.


You really need to configure the basics before you leave home, and then reset certain data before you set off on your walk.


So this post attempts to provide a basic procedure to ease some of the frustration for new users.

Friday, 23 June 2017

Mycroft: the open source Alexa

Mycroft AI is a voice assistant similar to Amazon's Echo/Alexa, with a speaker module that the user can shout instructions to.


In both cases the user can "wake up" the unit, and then ask a question or issue a command (e.g. "What's the weather like in Nairobi?").


But what makes Mycroft especially interesting to an old hacker like me, is that it is open source!

Thursday, 15 June 2017

Chicks at play: RaspiCam 90fps

Our blue tit chicks came out of hiding a few days after leaving the nest, and now they are regular visitors at our feeders.


They need to learn the snatch-and-run technique, rather than spending too much time out in the open where they are vulnerable to predators.


Using a RaspiCam to capture video at 90fps results in slow-motion video and gives a better idea of their behaviour.

Thursday, 8 June 2017

BirdBox2017: end of another season

It's been a very successful year for our blue tits, great tits and our two Raspberry Pi powered bird boxes.


The last of our bird box chicks left the safety of their nest yesterday, and so ends another season for us.


Out of 15 eggs in two boxes, 14 chicks got the chance to explore the world outside and potentially become food for sparrowhawk chicks or maybe the short-term plaything for one of the local cats.

Tuesday, 6 June 2017

Diaspora: just Facebook for teckies?

There has been quite a bit of discussion in the press this year about the vast amount of personal data being mined by social media companies like Facebook.


Diaspora is an open source, distributed, social media site with the aim of addressing the balance.


So what does Diaspora have to offer, and how can a competitor to Facebook expect to win over its user-base?

Wednesday, 31 May 2017

Ether: a tale of two blockchains

The price of Ether (ETH) has rocketed this year and is currently 23 27 times greater than 6 months ago.


For anyone that bought ether last year, this is very good news indeed.


But there are two reasons to be cheerful for anyone that has held onto their ether for at least the last 11 months.

Thursday, 25 May 2017

The Brave Browser

It was only a week or so ago that I was grumbling to someone about the internet, and the time it can take to load a web page.


Using Firefox with NoScript, I have to take a decision on whether to allow scripts to run, but these are not always limited to the page of interest.


When viewing newspaper and magazine websites like Radio Times, I find it quite alarming that it wants to load dozens, possibly hundreds of script libraries belonging to Google, Facebook, Twitter & so on.

Tuesday, 23 May 2017

The Entroware Triton: my new box

My old ASUS x401A  laptop has served me well for the last 4+ years but all good things must come to an end.


The screen flicker/blanking just got too annoying, so I had to dust off my wallet and part with some cash.


So how does my shiny new Triton compare with the old ASUS?

Friday, 19 May 2017

BirdBox2017: something is eating my SD card

2017 is turning out to be a great bird box season for us.


Both of our Raspberry Pi camera boxes are occupied, with the first set of chicks almost ready to leave the nest.


For the last few days my only concern has been whether I'll run out of SD card space before the chicks depart.

Wednesday, 17 May 2017

Gambas Video Reverser

I recently needed to reverse a video clip, to make the action run backwards.


I couldn't find a Linux video editor with this feature built in, so I ran a series of command line instructions...


...then I decided it would be useful to wrap these instructions into a GUI application.

Friday, 12 May 2017

Looking for a Linux Video Editor?

I'm a bit of a sucker when it comes to video editors.


Although I don't do a great deal of video work (except during the bird box season) if I stumble across a video editor, I have to install it.


And so it was a couple of days ago when I discovered Shotcut.

Friday, 5 May 2017

Gambas MP4Box: a batch .h264 to .mp4 video packager

Using RaspiVid software with a RaspiCam results in a .h264 encoded video file.


Most media players require .h264 to be "packaged" into a suitable video container format like .mp4.


This very simple Gambas project uses the program MP4Box to convert or package a bunch of .h264 files into .mp4 files ready to be edited or played using popular applications.

Thursday, 4 May 2017

Replacing the DHT22 with a Bosch BME280

I compared the humidity readings from two DHT22 and was alarmed by the difference between them.


Although they are cheap, the Bosch BME280 doesn't have to cost that much more, and provides pressure measurement in addition to humidity and temperature.


Although many of the BME280s available cost around £20, I splashed out £7.61 and bagged a bargain on Amazon.

Saturday, 29 April 2017

BirdBox2017: what's happening?

Here we are, already at the end of April, but there has been plenty of action.


We have suffered technical issues, system crashes and technical incompetence.


But we have also had a lot of nest building and a fair number of eggs.

Monday, 27 March 2017

Gambas cli programming: ncurses text based user interface

Many command-line programs are more than just one liners.


They often need to display data and allow users to interface by both viewing data and making selections.


In this post I look at the Gambas component gb.ncurses and attempt to make an interactive display.

Friday, 24 March 2017

Using a Wacom tablet on Linux

The CAD boys used graphics tablets back in the days when I still worked in industry.


Using a pen with a tablet provides a very precise input method for controlling a computer application.


But are these low cost Wacom tablets any good, and do they work on a Linux computer?

Wednesday, 22 March 2017

Internet Radio example using Gambas cli

Now that I'm taking Gambas command-line programming more seriously, I thought I might rewrite the software on my internet radios.


As mentioned in a recent post, Gambas can be used to write cli programs (command-line interface) as well as the more usual gui (graphical) applications.


So this post just describes the software aspects of this project, while the other design details can be found in earlier posts.

Saturday, 18 March 2017

Ethereum: what's happened to Ether?

Since I purchased a small number of ETH last July, the quoted price has bounced along, not doing a lot.


But in the last 3 weeks, both trading volume and ETH value have increased dramatically.


So what is going on?

Wednesday, 15 March 2017

Gambas: command-line programming

I must have been using Gambas for small projects since I fully switched to Linux for my home computing needs almost 10 years ago.


Gambas was a natural choice for me as I'd spent several years in industry using Visual Basic, Delphi and Turbo Pascal.


But up until quite recently, it had not occurred to me that there might be some benefit in using Gambas for command-line programming.

Thursday, 9 March 2017

Is it damp under my house? ...part 2

It is now 5 months since we nailed down oak flooring in our ground floor living rooms after extensive maintenance and re-decoration.


I've been monitoring the under floor temperature and relative humidity ever since to determine whether we had fixed our damp and ventilation problems.


So now that I have data, what does it all mean?

Tuesday, 7 March 2017

BirdBox2017: a few problems

This system was deployed just over a month ago and has been visited by blue tits almost every day.


It is basically doing its job by recording lots of video clips of both the inside and outside views of the bird box, which is mounted on the side of our pergola.


However, it does have a couple of problems that are rather annoying.

Thursday, 2 March 2017

Raspberry Pi 3: integral wifi problems

A couple of days ago I was given a nice new Pi 3.


I already have one other Pi 3 (and 14 other non-Pi 3 models) but it developed a fault, so this new one was a welcome birthday present.


Unfortunately it took most of yesterday afternoon to get the integral wifi for work!

Wednesday, 1 March 2017

Launching & Closing Apps via Gambas

It is really easy to launch and close applications on Linux using Gambas.


This may be useful if you need to run an application when certain conditions are met, and shut it down when conditions change.


An example is my BirdBoxMonitor program that needs to load a browser and display video streams.

Saturday, 25 February 2017

The Gimp: basic photo editing

There are probably a few steps you need to go through when returning home from a day of picture taking.


The real no-hopers can be deleted straight away, but the rest should be downloaded and at least given a second chance.


So this post suggests a few basic techniques that may be applied to any potential "keepers".

Thursday, 23 February 2017

The Gimp: replace that boring sky

Getting the exposure right for landscape photography can be challenging.


You may end up with your subject just right but the sky burnt out, or an interesting sky but a foreground that is too dark.


Or you could just cheat by combining 2 images using a photo editor.

Sunday, 19 February 2017

Millers Wood: a great place for bird photography

Although bird photography can be a very rewarding activity, it can also be frustrating.


Your attempts to get a perfect shot can often be spoilt by visual obstructions like branches, or distracting backgrounds like buildings or litter, or just the long distance between you and your target bird.


Then there may be noisy dogs or unruly children to contend with (...or vice versa).

Monday, 13 February 2017

Finding the IP on a Pi using hostname

I was looking for a really easy method of finding the IP address on a Raspberry Pi.


I wanted a method I could use in a program to tell which bird box was returning data asynchronously.


And I was hoping to avoid having to hunt for the IP address string, buried somewhere in a block of text created by a command like ifconfig.

Saturday, 4 February 2017

BirdBox2017: double Zero deployed!

I attached the new bird box & external camera to our pergola late yesterday afternoon, and by 8:30 this morning we had our first visitors.


Blue tits are very inquisitive, and certainly do not require a couple of months to get used to a new box (as some tv experts would have you believe).


So the 2017 season appears to have got off to a good start!

Saturday, 21 January 2017

File system repair: forcing fsck on Linux/Raspberry Pi

I lost remote (VNC) contact to my Pi at a critical time and could not even get a response to ping!


So I had no option but to break the connection to its supply, a 12Volt battery.


Result; corrupted files and a damaged file system.

Wednesday, 18 January 2017

BirdBox2017: using motionEye & streamEye

After a couple of weeks of investigation, procrastination and frustration, I think I have reached a decision.


I am going to use motionEye to stream and display video to a remote laptop.


But this has meant a lot of upgrading to the heart of (what was) my 2015 bird box.

Monday, 9 January 2017

Garmin eTrex 10: what's your position buddy?

It's struck me once or twice, when out walking, that I don't know exactly where I am.


Imagine that there is some kind of medical emergency, and I need to call for an ambulance.


"Where are you sir?"

Thursday, 5 January 2017

BirdBox2017: a new year, a new birdbox?

Well, not exactly. No plans to build a new box, but I would like to add a second camera.


As well as the main event inside the bird box, there is often quite a bit of action on the outside, especially during the early weeks, and at the end, when the chicks fledge.


So with only a few weeks left until I need to deploy my two Raspberry Pi powered bird boxes, I need to get on with development.

Tuesday, 3 January 2017

Pi Zero: adapting the USB socket

Although the Raspberry Pi Zero is about half the size of a credit card, the connectors stick out sideways, which affectively increases the boards footprint once connected.


To make matters worse, the USB socket is the micro version, so you need an adaptor if you only have a standard USB wifi dongle.


So in order to make a really small, headless Zero system, you need to do something radical.