Cracker by Damian Christie

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Cracker: Stoned in Charge

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  • BenWilson,

    Droid, soz. Could be on iPhone, it's called "Ulysse Speedometer". There's lots of these types of apps.

    Auckland • Since Nov 2006 • 10631 posts Report Reply

  • Stephen R,

    Thanks, I'll have a look.

    Wellington • Since Jul 2009 • 259 posts Report Reply

  • Rich of Observationz,

    Is there another dangerous machine that you would you put people in charge of without ever reviewing their ability to use it?

    Well, on a fly-by-wire airliner, the pilot, maintenance engineers and cabin crew have all been through some kind of formal licensing procedure. The people who coded the flight control software, less so.

    Back in Wellington • Since Nov 2006 • 5550 posts Report Reply

  • Allan MacLachlan,

    It’s one of the cool things about GPS. You can test your speedo quite easily. I have an app that hassles me if I’m going over 100km/h on my phone.

    GPS doesn't always give an accurate speed reading - ever had a look at your GPS track if using a fitness app like MapMyRun? It can be out by a few metres here and there, which must have an impact on your speed calculations, so GPS is not as infallible as many people believe.

    Part of being a good driver is being aware of distance and speed - if you are having to use an app to keep under the speed limit, then you are probably not sufficiently aware of your speed, and you should be paying more attention to the task at hand.

    Auckland • Since May 2007 • 17 posts Report Reply

  • Stephen R, in reply to Allan MacLachlan,

    Part of being a good driver is being aware of distance and speed - if you are having to use an app to keep under the speed limit, then you are probably not sufficiently aware of your speed, and you should be paying more attention to the task at hand.

    I think some of the point here is that your speedo is only likely to be within 10%, so you could potentially be managing your speed carefully to 99kph according to your speedo, and still be pinged under the new 4kph allowance. Having an external indication of how close your speedo is to what the police are measuring is a useful tool, even if imperfect, if that imperfection is less than the speedometers.

    That and although GPS has an uncertainty in it's measurement, that uncertainty will be in the same direction over short to medium periods of time, since it's based somewhat on the position of the satellites. Looking at a GPS track driving around, I can tell which direction I was going since I can tell the lane I was in, even though the theoretical uncertainty is more than the distance between lanes.

    That was true last I looked even with multiple days between GPS tracks.

    Wellington • Since Jul 2009 • 259 posts Report Reply

  • BenWilson, in reply to Allan MacLachlan,

    GPS doesn’t always give an accurate speed reading – ever had a look at your GPS track if using a fitness app like MapMyRun? It can be out by a few metres here and there, which must have an impact on your speed calculations, so GPS is not as infallible as many people believe

    It's certainly not very accurate for an instantaneous reading. But for a reading over time, since it is based on absolute location, and is smoothed out by the accelerometer (which gets very confused by being waved around as you run), it's far more accurate than something counting the number of times your wheels turn. In a vehicle going 27 meters per second, with a polling interval of a few seconds at a time, and the "meter here meter there" averaging out to the exact location, you've got an excellent doublecheck on your speedometer (and also, for that matter, the odometer). You'll definitely be able to detect it being out by 10%. The app I'm talking about gives you continuous feedback on how many satellites it is using, so you know when it's getting a really good reading.

    Part of being a good driver is being aware of distance and speed – if you are having to use an app to keep under the speed limit, then you are probably not sufficiently aware of your speed, and you should be paying more attention to the task at hand.

    My point was that our speed can rove up or down 5km/h at 100km/h within perfectly normal driving (in Auckland, which has hills). The only way NOT to do that is to micromanage your speed, braking and accelerating at every little deviation, or sit well below the limit.

    In terms of the actual need to use the app, I only every use it on long motorway trips. It's very easily to lose concentration on the speedo, since you're focusing on the road. I can't see it being a negative to have an app that helps. It would be nice to say that I never ever, ever forget to glance at my speedo every 5 seconds, but that's not realistic.

    Auckland • Since Nov 2006 • 10631 posts Report Reply

  • Rich of Observationz,

    The GPS system supports Doppler measurement of velocity rather than dead reckoning from position - certainly high-end receivers would integrate this - I'm not sure about the average phone or car GPS.

    Back in Wellington • Since Nov 2006 • 5550 posts Report Reply

  • BenWilson, in reply to Rich of Observationz,

    Intriguing, didn't know that was available. Software can use any algorithm, taking into account multiple sources - cell tower, satellites, and accelerometer, and possibly the map knowledge of your probable altitude (in case you've only got 3 satellites locked in), all together and smoothed. Doppler shift is probably quite accurate for working out velocity, although as with the accelerometer, I'd think that waving around isn't going to help matters, if the polling interval is slow.

    Auckland • Since Nov 2006 • 10631 posts Report Reply

  • Rich of Observationz,

    Software can use any algorithm

    En principe, oui.

    But in practice not many chipsets / interface layers pass through the raw data to do that, so you're stuck with whatever the manufacturer deigns to implement.

    In the early days of GPS, when only limited satellites were visible, it was quite common to interface an atomic clock (rubidium time standard) which effectively gave you an extra satellite. Modern GPS can use < 4 satellites and integrate with cellular to get a position with obscured visibility of the sky (there are always plenty of satellites, but they tend to be behind buildings).

    Back in Wellington • Since Nov 2006 • 5550 posts Report Reply

  • BenWilson, in reply to Rich of Observationz,

    But in practice not many chipsets / interface layers pass through the raw data to do that, so you’re stuck with whatever the manufacturer deigns to implement.

    Yup, on Android all of the above mentioned interfaces are available, although a particular phone might not present them (although why it would bother to have the hardware at all in that case, I don't know). There are a few more as well. Magnetic compass readings, humidity and pressure sensors, the list goes on. All adds up to the chance of a better reading, with the right software. I just trolled through some of the developer doco, and most people seem to do it off absolute location smoothed over previous readings, which is what I recall the developers of the software I use saying they did for the most part. It's hard to argue with "you've gone this distance in this time, hence this is your speed".

    Software specifically designed for boy racers used the accelerometer more, because boy racers want to know their true horsepower, their 0-100km/h and their standing quarter mile (fuck that anywhere but a race track in my last muscle car which got to 100km/h in 5.5s - I shudder to think what it would have got to by the end of a quarter mile), and they really need to know the g forces for some of that. Also cornering g-forces really only come from the accelerometer. One app I have makes a little movie of it all overlaid on the view out the window. Strikes me as the absolutely perfect thing to use if you really want to get busted to the maximum limit the police can manage, as they watch your collection of geocoded clips shortly before crushing your car.

    Auckland • Since Nov 2006 • 10631 posts Report Reply

  • Rich of Observationz, in reply to BenWilson,

    I've never seen any (portable) API to get GPS pseudoranges or doppler speeds on an Android (nor have the contributors on SO.

    Various GPS devices can acquire this, but I think the information may get lost in the Android's layers.

    I'd be quite interested to know of one to get pseudoranges though - I'd like to make a navigation app that works on an airliner in flight using the limited satellite visibility through the window, plus the fact that they tend to fly along a predictable path.

    Back in Wellington • Since Nov 2006 • 5550 posts Report Reply

  • Sacha, in reply to Rich of Observationz,

    The people who coded the flight control software, less so.

    The acceptance testing on software like that would be brutal, however.

    Ak • Since May 2008 • 19680 posts Report Reply

  • BenWilson,

    I think I'd have to read the Android source to find out if the Location.GetSpeed() method uses the Doppler info.

    Heh, yes, a naughty app for using on airlines when you're supposed to turn all that stuff off. I haven't tried any mid air tracking. There's apps for it already, so it's clearly possible.

    Auckland • Since Nov 2006 • 10631 posts Report Reply

  • BenWilson,

    How did this conversation end up sounding like a couple of stoned geeks?

    Auckland • Since Nov 2006 • 10631 posts Report Reply

  • Rich Lock, in reply to Sacha,

    The people who coded the flight control software, less so.

    The acceptance testing on software like that would be brutal, however.

    This crash was a result of the fly-by-wire not reacting in the manner the piot’s expected (warning: link is vid of plane crashing).

    From Wikipedia:

    The crew applied full power and the pilot attempted to climb. However, the elevators did not respond to the pilot’s commands, because the A320 computer system engaged its ‘alpha protection’ mode (meant to prevent the aircraft entering a stall.)……normally, a pilot would not attempt to fly an aircraft so close to stalling with the engines at Flight Idle (minimum thrust). But in this instance, the pilots involved did not hesitate to fly the aircraft below its normal minimum flying speed because the whole purpose of the flyover was to demonstrate that the aircraft’s computer systems would ensure lift would always be available regardless of how the pilots handle the controls.

    back in the mother countr… • Since Feb 2007 • 2728 posts Report Reply

  • Damian Christie,

    Jeez, talk about thread-jacked Trev.

    I've heard people talk about those signs that tell you your speed, I've only seen the ones that say "Slow Down". :/

    Wellington • Since Nov 2006 • 1164 posts Report Reply

  • Sacha, in reply to BenWilson,

    I'm sure you have nothing to do with that, Ben :)

    Ak • Since May 2008 • 19680 posts Report Reply

  • JonathanM,

    Interesting read Damian - thanks!

    Any chance you have a link or citation for the Canadian study on fatal crashes? An odds ratio of 40 sounds quite close to 5*8 (odds for cannabis * odds for alcohol), suggesting that either no interaction was included in the model, or that the interaction was small or non-significant, which would be an interesting result.

    As an example of why it's interesting, let's suppose that being under the age of 30 increases your chance of a fatality by 4. Then, though we'd say "Smoking cannabis increases your chance of being in a fatality by 5 times, but if you're under 30 it's 20 times", that betrays what is really going on - the effect of cannabis is 5 times regardless of age.

    Thus, in this case, it may well be 5 times regardless of whether or not you've also been drinking. The combined activities simply increase your risk because they're combined: there's no additional risk on top of the risk you get from both activities separately - no interaction of effects. That's surprising.

    Since Jul 2012 • 64 posts Report Reply

  • Damian Christie, in reply to JonathanM,

    Hey Jonathan - thanks - it was interesting to research/write. I don't have a link I'm sorry but there might be something on the ICADTS site that can help find that study if you're really keen.

    Honestly, and perhaps embarrassingly, I didn't realise that's how odds worked. If you'd asked I would've probably said you add them together, but of course I can see why that makes no sense now.

    I would say a couple of things - first that the risk of crashing with both pot and alcohol is higher, but even with lower levels of alcohol than would be considered impairing if consumed on its own. But I don't know if the 40x risk is reflective of that or not.

    Second, these figures vary from study to study, although they tend to stay in the same order (pot, alcohol, pot+alcohol). The 'true' numbers might not multiply quite so tidily.

    Related to that, it was really interesting to see the risk in Norway studies, compared to most other studies. They found risk of 200x or thereabouts, but an American research explained it to me thus: In Norway drink/driving and drug/driving are very socially unacceptable, and so those who do it tend to be 'outlaws on the edge of society', so they're crashing for other reasons, not just booze/pot.

    Wellington • Since Nov 2006 • 1164 posts Report Reply

  • bluebook,

    I cut my toenails this morning. That's how important i think cannabis and driving is. I do appreciate you all want to leave your mark on the world though, it's just a shame that this will be it.

    auckland • Since Dec 2013 • 4 posts Report Reply

  • Damian Christie, in reply to bluebook,

    ...if your mark on the world is leaving snide comments on subjects you apparently have no interest in, then I think you win.

    Wellington • Since Nov 2006 • 1164 posts Report Reply

  • JonathanM,

    Thanks Damian - will take a look around the ICADTS site and see what I stumble across. Much appreciated.

    Since Jul 2012 • 64 posts Report Reply

  • bluebook,

    I dunno I may be out of my league here because I learned my trade on nzd and trademe lol, but to me another 20yrs of health initiatives and we just may create the perfect human being! The man at the symposium from Australia said a couple of things though - we need to give kids reasons to live, something spiritual even, and I think that's a good account of the problem - inspire the kids hearts?

    auckland • Since Dec 2013 • 4 posts Report Reply

  • Kyle Matthews,

    Any chance you have a link or citation for the Canadian study on fatal crashes? An odds ratio of 40 sounds quite close to 5*8 (odds for cannabis * odds for alcohol), suggesting that either no interaction was included in the model, or that the interaction was small or non-significant, which would be an interesting result.

    Possibly. Or possibly there is an amplification factor from mixing the two, like some drugs and alcohol shouldn't be taken together because they react badly.

    In this instance, your risk might be amplified because alcohol increases your risky driving and lack of awareness, and cannabis reduces your reaction time (I'm just guessing about impacts). Therefore you're more likely to end up in a bad situation because of alcohol and more likely to not be able to get yourself out of it because of the cannabis.

    Since Nov 2006 • 6243 posts Report Reply

  • Sacha, in reply to Kyle Matthews,

    some drugs and alcohol

    alcohol and some other drugs
    #fify

    Ak • Since May 2008 • 19680 posts Report Reply

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