Thursday 25 January 2024

Drone: DJI Mini 2 SE

PXL_20240126_132139601 So, I finally bought a drone. DJI Mini 2 SE: £269, plus £50 for a spare battery, direct from DJI. These are some notes.

The CAA's Registration requirements for drones and model aircraft tells me I don't need to get a flyer ID, but I do need an Operator ID: I am in the "below 250g - not a toy - with camera" class I think. Having done that, my operator GBR-OP-MD2CPWDBCK93.

A sample of the State of the Art: Lents 2024, Saturday, M1.

First steps

Open the packaging. Rm tabs from device (propellor confinement, gimbal guard, battery etc). The battery tab says rm the battery to charge, but I don't have a separate charger, so just plug in a USB C cable. Read quick start guide. Guide semi-implies connecting control unit to drone to charge. But don't; I think it just means charge both. White lights count up on drone, 1 and 2 (of four). Green count up on control, 1 and 2 (of four) now after ~15 mins up to 3. It all gives the impression of being nicely solidly built. Control unit has two joystick controls to screw in, do that.

After about an hour: controller fully charged, lights have gone off. Press "power" briefly and all four light up.

After about two hours: drone counting up to 3 lights now. Note that I may have the drone on a low-power USB source.

DJI Fly App

For unclear reasons the Android (but not iPhone?) App isn't in the Play Store, it's a separate download. Do that, giving it permission to install.

Connect controller to phone

You need to connect the controller to the phone, via an USB-to-USB cable. But! Not just any cable; you need to use theirs, and watch out, because the one inserted in the well is I think for iPhone. The one I wanted - USBC-to-USBC - is supplied, but you need to swap it in. If you were to be so stupid as to for example take the thing home and forget that one cable and then use a "straight" USBC-to-USBC then it doesn't work; the phone thinks the controller is trying to charge it.

Anyway, having done that your phone connects to the controller, you turn the drone on. This is non-intuitive: since a brief press on the power button shows you the battery status, to turn on you do a brief press, then a long press. Same for the controller. It then beeps gently to itself and stretches its motors or something. The controller then connects to the drone, with which it is pre-paired.

Mine then wanted to do a firmware update, which took about a minute. Then the drone needs turning on again, and then I can see myself from the drone's camera. Woo.

Watch this space... looks like a nice tutorial.

OK, so it turns out that actually flying it is fairly easy, compared to setting it up :-).

I started out in our (small, enclosed) back garden. If you press the "take off" button it, err, takes off. Then you can press the landing button. Or, you can just press "down"; it will "stop" at about 1' off the ground then descend bleeping, and land. And so on to creeping about the garden. You get eight degrees of freedom: with the left joystick, up / down / rotate left or right; with the right, forward / back / translate left or right. Instead of the takeoff button you can just startup the motors and move up.

Then I went out by the river. Vid #1 is basics: take-off to head height, forward-backward, up-down, and so on. Vid #2 is Wesus, and shows the zoom, as well as some incompetent panning and adjusting. Vid #3 is almost interesting, our Chesterton 4x. I had the max-height set to 15m for all this.

Taking off and landing on grass seems fine - some of the tutorial vidz show people with flat helipad type things.

Note for idiots like me: when recording video, "not recording but ready to start" is a large red dot. Whereas "currently recording" is a smaller red square. I'm glad I finally worked that out.

Another note for idiots: don't forget the SD card. It will still record, but lower quality, to your phone.

A bit more

I went out early-for-me on Thursday and got some more vidz. Sadly some of the best footage wasn't captured because I got out of phase with record on / off, duh. Here is Queens' women. I discover that it is possible to get flight info - height, location - as a subtitle, but it is difficult to burn those subtitles onto the video; unless I find an easier way I won't bother. The VLC media app displays the subtitles; here's an example.


Battery life

DJI claim 31 minutes and that seems broadly accurate. One battery did me a division. I think that might be "hover time"; I think I noticed that if I went off and chased people down, it would eat into the life.


Sometimes, before takeoff, I hear an odd noise and the drone decides the gimbal is stuck. Just picking it up and poking it gently seems to fix this. Ah, and this is because it is checking the gimbal is free to move; if you make it take off from the box, often there isn't enough space. Solution: just hold it while it is powering on.

Sport mode

It has three speed modes: cinematic, normal and sport. I quickly tired of cinematic, which is slow. Today I discovered that "normal" is rather slow for recording rowing, so switched to "sport". If you do this, it warns you that it may tilt a bit more, and something-something-gimbal.

Files not closing

I notice that if I turn the drone off without turning off "record", the file doesn't close properly, and won't play. The solution (per this forum) is just to put the card in the drone, and power it on and then off. Well it worked for me.

Sound / screen recording

I have yet to master this, but: one piece of the puzzle is that I have the Nova launcher installed, which changes some Android defaults. So to enable landscape mode recording, I need to go into the Nova launcher settings and say "auto rotate".

Right, I have made this work. Hurrah. Firstly, make sure screen rotate is setup unless you want veeery teensy video. Second, the screen capture files are big: about 3G for ~10 mins; and I think it would like some buffer space too; so I went back and cleared out 15G for it to move in. Even then it sometimes stops earlier than it should. Here for example is Lents W3 (silent) vs Lents W3 (sound).

The with-voiceover vidz are more popular than the without, by a factor of about 4 to 1 measured by Youtube watch-count, so from Thurs on to avoid duplicating the stream, the drone-stored video is unlisted, but linked from the screen capture version.

To be clear, if that isn't, the drone-stored stuff is saved to SD card in flight, and is at whatever resolution the camera provides. The screencapture-with-sound version is stored on my phone via the radiolink to the drone, and is at whatever resolution Android and the DJI app decides to interpolate it to. I think it may also be subject to occasional lag / catch-up.

TODO: get CamFM on there too.

Your questions answered

Q: Can't W(M)C follow the racing further down the course with his drone?
A: Tricky. RF contact tends to degrade past about 500 m and risks losing contact past that. Not only does that lose the video feed it risks losing overall contact with the drone; and flying it without its feed is much harder. The theoretical range is much larger but I think the trees (and, I suspect I'm going to discover today, rain) get in the way.

Q: Is drone or cycling-with-GoPro footage better?
A: I don't know. What do you think?


Saturday 20 January 2024

Book review: Peril at End House

PXL_20240120_131905926~2 Another Christie / Poirot. Like the others it is OK; I am after all still reading these things. But I always finish them thinking them somewhat formulaic.

I won't tell you the plot but now I'm finished, it isn't clear to me how the wasp / bullet in the first "attempt" was produced by... errm well I suppose I am going to tell you the plot so don't read on if you don't want to know... by Nick. And having said that much, I can say that mixing in the evil Australian gold-diggers into the plot does muddy the waters nicely, although possibly straining coincidence a bit. Continuing, it seems odd that if Maggie really was affinanced to M. Seton, she did not make rather more of his death.

Tuesday 9 January 2024

Book review: The Witches of Karres

The Witches of Karres is, in Wiki's words, "a space opera novel by James H. Schmitz. It deals with a young space ship captain who finds himself increasingly embroiled in wild adventures involving interdimensional alien invaders, space pirates, and magic power". The cover I show here is from Wiki; mine is the rather more boring Gollanz "masterworks" edition.

Overall, good lightweight fun with a slightly surreal feel.

I have no knowledge of JHS, and had when I read this no idea when it was written, which made for an interesting no-info reading experience. A review says, "the plot isn't really defensible", but no more so than many another such; the author happily sprays around made-up terms and names, but it all fits together more coherently than at first appears. And it is all very "light", in the sense that when bad-ish things happen, they aren't allowed to linger too long before good triumphs. Overall it is naive-ist, but so was a lot of 1960's stuff.

Apparently the book was expanded from a short story / novella, which may explain the slightly weird-in-retrospect intro: Our Hero picks up three child "witches", and yet these witches - and the planet they are from - subsequently turn out to be immensely powerful and quite able to take care of themselves.

Friday 5 January 2024

Book review: History of the Warfare of Science with Theology in Christendom

PXL_20240102_205627400~2A History of the Warfare of Science with Theology in Christendom is a known "bad book", a proponent of the "Conflict thesis" which is now generally rejected. See for example thonyc who is a splendid source for this kind of stuff.

But I was curious and, pre-innoculated, felt unlikely to succumb to its whiles, and so felt safe to read it second hand. It is well enough written, in a popular style, but does bang on a bit. The game, if you feel inclined to play it, is to guess when Our Author is misrepresenting what happened, and using the new-found power of the internet then look it up. 

An example is Michael Servetus, from the thonyc link above. White tells us he was burnt at the stake, and strongly implies or perhaps even states that this was due to his scientific ideas. But, he was a heretic burnt for his views on the Trinity. And so on.

So in the end I can't recommend the book even for entertainment or even historical value.

Monday 1 January 2024

Christmas 2023

After 2022's slight hiccup, 2023 saw a return to the now-traditional pattern: four nights and three days chez Mother, then time at home and with Mfd+J up to the New Year. Pix. We start with Christmas Eve, when we drove to M-u-W for the village Carols on the Green (musicians).

Christmas Day featured my half, accompanied this year by Toby (I won, by a margin of him exploding up the Churchill hill) but not Lara; she and Nina did 5k I think, as did E, separately. Then the meal, culminating in Christmas Pudding, and listening to The King. I got some tasteful Beard Baubles. We played Lara's "Taboo" (Rob; Mother; Miranda; Daniel), not as forbidding as it sounds.

Boxing Day to R+N's for coffee, lunch, walk and then an afternoon of Frobelsterne and books.


On the nameless day after Boxing Day we were quiet, mostly chez Mother. RLT came round for lunch, N working, and we finally remembered to take the picture of the children by the tree.


Back home, Weina has been looking after baby Marbles. I copy (and fb) a couple of Mother's 1952 pix of a trip to Paris and the 1953 Coronation.

The next day, Thurs 28th, home (with morning run through Bruern). One of the racks of coat hooks in the little cupboard have fallen off. Fixup by going through into the breezeblock, which had been half done anyway. Friday 29th, Mfd+J around for lunch, a joint M/D/E effort featuring Tuna. Saturday 30th, I row at 10 am, thence misc stuff including feeling inspired to put in some shoe shelves in the little cupboard to replace the not-very-useful orange wire rack. Get the lowest in; the space of course does not feature right angles.

New Year's Eve, D and E and I walk to Ely.


The weather is fine: sun in the morning, never too cold, the wind at our backs and the rain didn't last. We stopped at the Five Miles From Anywhere for a drink after 15k; and at the "choice", chose the east side, which gives a better approach to Ely. We hadn't gone quite as fast as last year, so all felt like going to the cathedral which really imprssed me; must go back. Thence a local cafe, and the train home. Selfie. Evening: to Mfd+J for the civilised New Year's Eve, featuring Dominion (D won both) and Tokaji.

And lastly, New Year's Day featured the Chesterton Club 10k (don't look) and E and I went down the backs in the new Pye-n-Mash double. Which was great fun, even though as always slightly nerve-wracking.


Oh, and I get the second shelf in, and dig out some Prudential+Ecology financials for E.