Forum: General Topics
Forums / General Topics / Magnetic Bearings
| Subject: | Magnetic Bearings | |
jyates 20:30 | Hi, Just wondering if it would be possible to add a feature to allow for magnetic bearings (by inputting magnetic variation)? I took my phone flying over the weekend (my scanned aeronautical maps worked a treat)... But I had some issues with the Route function, as it displays bearings in True... and I fly based on Magnetic bearings (Compass and/or DI aligned to compass). Not a huge deal, coz you just add/subtract the applicable magnetic variation, but would be a nice feature to have... The only other issue I had was the battery on the phone dying... but it was about 3hours into a 3.4 hour flight... and I had used TMJ for about 1/2 hour before that... so I got 3.5 hours of usage... not too bad for a little Nokia 6275i!! I guess I'll have to start flying the aircraft with cigarette lighter sockets so I can use my car charger ;) cheers, Jared | |
Stephen 10:14 Location: Phone Model: | Hi Jared, It should be fairly straightforward to add a manual Magnetic Variation input. I had originally concluded that magnetic readings would be too complex to calculate as I was hoping that the phone would be able to work out the local variation itself, but if manual control is sufficient then that certainly makes things easier! I've found this site, which allows precise calculation of magnetic variation for a particular location, which should be useful: http://www.ngdc.noaa.gov/geomagmodels/Declination.jsp I'll try to include it in the next version... Incidentally, regarding your battery running out, something like this might come in handy - I haven't tried it myself but it looks pretty useful. Cheers, Stephen | |
jyates 10:40 | I am a little surprised there is nothing in the GPS system itself which adjusts for magnetic bearings to be honest... An automated magnetic variation would be lovely ;) But I can fully understand that it is likely to be some wildly complex algorithm that would be required given the non-uniform nature of the earths magnetic field... So a 'simple'[1] manual mag variation input would be nice... the only caveat would be that it was relatively easy to change on the fly... here in NZ, we're a very North/South country... so the variation can change several times on one flight! :) cheers, Jared [1] I'm starting to sound like one of the users at work who says things like "It's just adding a checkbox to the screen, how hard can it be?" ;) | |
Stephen 12:20 Location: Phone Model: | Here in the UK around London the variation is pretty small (<2degs), which admitedly is another reason why I hadn't bothered to add this in the past! Looking at the 20ish-degree variations in New Zealand I can now see why it could be more useful! I just had a quick look at the GPS NMEA spec - it does actually include magnetic bearings and variation (eg GPVTG), however in looking at the logs from 3 different GPS Bluetooth devices, none of them include the magnetic values, eg: $GPVTG,56.18,T,,M,2.39,N,4.43,K,A*0C The 56.18,T field gives the True course, but the magnetic course field (,,M) is empty. I guess its a bit beyond the scope of a cheap bluetooth unit - I suppose it would have to have some kind of database storing the entire globes magnetic variations for the next few years...! Cheers, Stephen | |
yano 11:17 Location: Phone Model: | Hi Stephen! your amazon tip fits perfectly what I was also looking for! I've ordered right now the PowerMonkey eXplorer with solar-slave! ... ;) Cheers, yano | |
Stephen 17:43 Location: Phone Model: | Hi Yano, Cool, I'd be interested to hear how successful it is, might get one myself...! Cheers, Stephen | |
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