Five un-blogged things I did in July

  1. Got interested enough in transistors again that I started writing a book shaped object. Said object now has three chapters and is how I’d have wanted to learn about transistors. Work has paused for now, due to items 2 and 3 in this list.
  2. Went to the delayed winter meeting of the anatomical society, held in Dublin. My first flight since January 2020. At the conference I presented some work I’ve been doing using x-ray micro-ct to image microscope slides containing valuable histological material from now extinct or engendered species.
  3. SARS?CoV?2 (COVID) finally caught me. I may have got it at the conference, at the very very busy Dublin airport on the way home, or given incubation times, I was probably infected the day before I flew to Dublin. I was feeling slightly rough on the 7th of July, but tested negative; a precautionary test before an in-person meeting on the 8th gave the long dreaded positive result.
    Fatigue, loss of smell and taste, fever, sore throat and general aches and pains. It really kicked my arse. I don’t ever want it again.
  4. Used my newly acquired, temporary, immunity to covid to go out and do some things I’ve avoided for two years.
    Saw and really enjoyed the new Rise of Gru / Minions film at a real cinema.
    Returned to the cinema a few days later to see the National Theatre broadcast of Prima Facie with Jodie Comer. I’m crap at writing reviews, so I won’t. Just go see it.
    Final bit of culture this month was a trip to see (hear?) Jay Rayner’s band at Crazy Coqs, Zédel, Soho. Again, excellent. Go to a show.
  5. Made a friend.
    This dragonfly landed on my hand as I was walking home. I carried it towards a patch of grass and it flew away.

Birds of Dagenham

I’m a scientist, I like data. If I can collect and analyse data from the environment around me, I’m a happy scientist. I’ve been using BirdNet on my phone to identify birds by their sounds; it works pretty well, but sometimes gets confused by lots of birds together, I’ve taught myself a lot of bird sounds comparing what the app says and what I hear.

I’ve wanted to get an idea for what bird species visit my garden, leaving a phone running 24/7 isn’t really ideal, and anyway the BirdNet doesn’t work with streaming audio, you need to select and submit a period of sound containing the bird you’re interested in identifying. While ponding ways to make it work, I discovered BirdNET-Pi which runs a bird identifier on a Raspberry Pi computer.

I’ve had this running in my garden for two days, it hasn’t really tuned up any major surprises (anything surprising is 99.999% likely to be a misidentification). What it has done is show up the active times of the local birds, the sparrows are a bit over represented as they sit close to the microphone and swamp out fainter birds.

Top 10 detected bird species so far today

The software claims to have detected 71 species in two days, I’m sure many of these are incorrect, I did have the detection threshold set a bit too low at the start. There are also many identifications of Owls and Bittens that I’ve identified as distant dog barks and wind noise.

At present, the system is a lash up of a bare Pi circuit board and a cheap USB microphone. If I was to leave this running longer I would need to get a proper outdoor, weather proof microphone and a proper case for the Pi. Something I might consider in a few months. It would be very interesting see how the detected species changes though the year.

Stepping on bits of Dagenham I’ve not stepped on before.


Since the first lockdown, when we were all taking our allotted ‘one exercise session per day’ seriously, I’ve been walking around my home town a lot more then I have in years. Initially it was interesting to walk down side streets I’ve not been along before, or to let the dog choose a direction at each intersection and end up somewhere unvisited before. Over time, this became a bit of a game with myself, can I walk places I’ve never walked before, then it because even more specific, can I set foot on a piece of ground I had never stood on before.

While choosing new roads, this was easy; every step was a new one, but as my walking patterns got more settled; to the shop and back, to the park and back, the game became harder.

The rules I set myself:

  • 1) Private property is off limits
  • 2) At least one new step every trip out the house


It’s an easier game to play and explain away when I’m walking the dog. If I’m sure I haven’t ever set foot on the manhole cover in the middle of the road, it’s a lot easier to explain away should anyone ask, if I can say the dog pulled me that way.


Drains, bits of curbstone and the like are all good for a first step. I’m 99% sure I’ve never stepped on most of the ones I choose. A new pothole in the road is a good find, while I may well have stepped on the original surface, the newly revealed subsurface is ripe for another step.


I’ve had some first steps that I’m sure are the very very first step anyone has ever had, a tree being cut down while on my outward journey left me a nice low stump to step on on my return. A fence removed at the park got me several steps on a bit of land inaccessible for decades, a fallen tree at another park opened up a space between it and a fence – another tiny scrap of land that cannot have had any human footfall for at least 80 years.


There’s absolutely no reason for me to carry on wit this game with myself, but I shall. Many of the easy steps on my usual routes are now stepped on, so there’s still a challenge to find something new.

February count

I borrowed an idea from Diamond Geezer who is on his 20th year of counting things during the month of February.

I decided to count in five categories:
1) Cups of Tea drunk
2) 500ml bottles of coke zero drunk
3) Cycle trips
4) Meetings attended (in person and virtually)
5) Number of Radios I repaired

You may think that number 5 is just grasping for a fifth option to pad the list out, I couldn’t possibly comment.

As I write this, there are still 14.5 hours left in the day, so my numbers will change.

1) Cups of Tea drunk – 121 127
2) 500ml bottles of coke zero drunk – 22
3) Cycle trips – 8 9
4) Meetings attended (in person and virtually) – 21 25
5) Number of Radios I repaired – 1

My Tea consumption is greatly reduced from normal, I’m not quite sure why so this month, I’m usually a 6 to 7 cups of Tea per day person, with the occasional rise to 12 or more when I’m working on a particularly hard problem. This month I’ve averaged just over 4 (4.3 to be more precise). End of day update, now at 127 with an average of 4.5

Coke consumption is about where I’d expect it to be. About one bottle per day when at work – it pairs very well with Co-Op rough oat cakes.

Cycling is down this month due to terrible weather for cycling, and not being at work for some of the month, so no cycling required.

Meetings happen. I try hard to avoid those I really don’t need to be in. This number could be far higher if I didn’t decline calendar invitations more frequently. End of day update, 4 – yes 4! meetings sprung on me today. Bah!

Radios repaired, I do like fixing things. I was at a loose end one evening this month and decided to look over my old Eddystone EC10 receiver and fix it. There’s a twitter thread here, because have you really done anything if you’ve not told the world about it?

The Tonga Volcano

At around 04:15 UTC on 2022/1/15 the Hunga Tonga–Hunga Ha’apai Volcano exploded in the Pacific Ocean. A devastating event for anyone close by, and the tsunami generated affected seal levels anywhere with a pacific coast line.

The satellite videos of the eruption show a pressure wave spreading out ahead of the dust cloud. The Met Office tweeted this morning that they had detected the pressure wave with their network of manometers.

Image from the met office tweet showing the pressure wave from the eruption

I run a small personal weather station, I built around a raspberry pi 4 and a collection of sensors including a BME680 device which can monitor air pressure. I looked at the data collected yesterday and can see a positive spike in the local pressure at around 19:20 UTC, with an negative spike at 01:52 UTC on 2022/1/16.

Air pressure as monitored at my home weather station, showing spikes in the air pressure at the same time as the Met Office

My house is 16,546 km from the eruption centre (the shortest path, is over the north pole – Earth is a sphere), knowing this and the time the pressure wave arrived, we can calculate the speed of the pressure wave.

The difference between the pressure wave being created and it being detected is 15h 5 min or 54,300 seconds.

Basic GCSE Physics

Substituting values gives us a speed of 0.305 km/s or 305 m/s, close to, but not quite the speed of sound (~340 m/s).

The second, negative going spike is the pressure wave that took the longer path to me, it travelled roughly 7000 km more, so arrived somewhat later. The various “noise” in the measured pressure between the two spikes is due to pressure waves arriving via other paths.

Taking the difference in time between the first and the second pressure wave arriving, and knowing the circumference of the Earth (40,075 km), I can get a pretty accurate measurement of the distance to the eruption.
The first pulse took 54,300 seconds to arrive, the second took 77,940 seconds. The average speed can be calculated for the pulse to travel one complete one circumference of the Earth, substituting into the equation before with
D = 44,075 km
T = 54,300 + 77,940 sec
Gives speed = 0.303 km/sec or 303 m/s

Solving for distance, using this speed and the time taken for each pulse to arrive, gives a shortest distance to the eruption of 16,542 km and a longest distance of 23,615 km. In pretty good agreement with the distances measured from the map.