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antonts

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About antonts

  • Rank
    Well-known member
  • Birthday 26/12/1971

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  • Aircraft
    Alpha 160
  • Location
    Sydney
  • Country
    Australia
  1. In general case - not. There are two variables - speed and height, both affect vertical speed and interdependable between each other. So the same zero vertical speed can be achieved with given mass, power setting and trim with full range of height and speed, it depends on miriads of conditions (design, temperature, current air pressure, weight balance etc). It can happen that only height increased and exactly compensated reduced weight with decreased drag, but it will be the same event like to win a lotto. May be it is possible to build a plane which has stable speed in some m
  2. land surveyors, mine marksheiders, construction engineers etc always use TRUE direction - all maps are in TRUE, as in TRUE there is no need for any correction with position and time, and it works even if you do not have any earth magnet field at all like in deep underground mine surrounded with iron ore. For more than 100 years everybody uses gyrocompass, not as we all know on planes, but ground-linked, with weight pointing down by gravity and self-alighning with Earth rotation vector (axle). Very simple device, but it allows precision up to centimeters in several kilometers of underground tun
  3. usual problem is not he enemy, just not to be on the opposite sides with guys who build and own gps, it is simple, but from local governments. In centre of Moscow all car GPSes show noncence (total mess or Vnukovo airport) due to intentional local signal override around the Kremlin.
  4. yes, right. Without SA GPS gives 5m accuracy after all filters, so the point constantly drifts 3m. And if we use these points to count differences - we receive nonsense, as drift (random error) is comparable to measurement (the same 3m of track per second). But - experimental fact! - 2m/s, walking pace, is perfectly determinable and measurable on usual modern userlevel gps (mobile, bracelet etc). And this is not a result of filters, because it immediately changes value when you turn or accelerate. It simply measures Doppler shift and knows where are the satellites - and it allows to derive
  5. [quote="Garfly, post: 570843, member: 2534" Doesn't that give us Track as opposed to Heading? How can the GPS know which way our nose is pointing? yes, track of course. I always think about land applications where they are the same. if you do it in uni lab in year 2000. If you recount speed this way every 1 sec with velocity 2 m/s (so shift is 2m) and average precision 10m (ie every point will be jumping +-couple of meters at every measurement) what you get? Yes, total nonsense. Thats the reason why no one real gps uses this ever. Take your mobile and try it walking with an
  6. GPS directly calculates position (point) and speed (vector), so to get heading you need just to move somewhere. It means speed vector is not "point B minus point A divide by time spent", it would be terribly unprecise, but directly derived from received signals thru measuring Doppler effect. In case of compass velocity is not relevant, but vector direction gives the heading. 2 antennas required only if you want to get direction data without any movement, in this case it determines positions of 2 points (antennas) and can derive vector direction between them.
  7. QNH is pressure on sea level, or, in opposite words, "sea level is on this pressure level". If we set QNH less then actual (bigger pressure height) it means we said to barometer that it got sea somewhere HIGHER than in reality, so it shows LESS difference between current position (measured pressure height) and sea. Its confusing, for right logic and no errors you have to spend time and mind efforts, so just memorise "subscale goes the same direction". If we turn the knob and rise QNH - main needle goes also UP.
  8. industrial hall sensor is usually a solid ring, not like clampmeter - this significantly increases precision and reliability, but you have to pull the cable thru the hole, not just hang the sensor on existing cable as is It does not matter, you can measure current at any point of circuit. Sensor measures just magnet field, not potential of the cable, so it can be used on 1000s V cables or on earth connection without any need for level convertor. Its outputs are completely isolated from the circuit, that is very convenient for data inputs and signal processing.
  9. NO. Thirty years ago it was not a hall sensor but inductive loop sensor, hall meter could be there only as zero magnet flux indicator. This type of sensor does require zeroing, as it is able to measure only CHANGE of current (DC current produces zero magnet flux change so zero inducted current in coil). It is acceptable for tester/hand meter/etc, but not for permanent instrument. These hall ammeters measure not inducted current but flux itself, even if it is constant.
  10. extremely unreliable and unprecise way. Cable resistance vary with temperature (due to load and enviroment change, 100C is real change range for space under car bonnet, for aircooled engines even more) too much to be counted stable, also this layout creates significant magnetic loops to catch all external EMI. For DC circuits it is not so significant, but anyeay strong EMI will affect your instrument. as I said above - use hall sensors! hall dc ammeter 100A 1%
  11. ammeter is a good testing/adjustment instrument, it can give information "who sucks all the power from system" and "how much power I really have in my generator", but generally useless as indicator "something is wrong" - voltmeter is much more sensitive when things come to "not enough power". For ammeter it is difference between 40 and 45 Amp (if generator provides 42), for voltmeter - between 13.5 and 12.0, and even more useful rate of change, if you rev engine/generator from idle overloaded generator will rise voltage veeeeeeeery slow (as it has to charge the battery with tiny excessive curr
  12. yeeees! electricians, and especially we, communication/security techs, are BLOODSUCKERS! Personally me is a great humanist, my rate starts from silly $100. Its just because no one can do even basic things. Plug in equipment in socket, restart (switch off-on) everything, search for records on the stupidiest recorder, make a swipe key in simple software etc. It looks like system western education flaw - no one learns anything in technology, gets simple exprerience etc. It does not require years of learning, just to play with kids electrical toy kit in kindy - lights, batteries, switches, wire
  13. no personal data share anymore, now it is possible only with business plans! If you switch to business your phone continues to work, no number change and plans are generally the same as personal, but you need ABN.
  14. telstra data share sim. This is not a standalone contract/plan but just a trailer for existing main phone (unfortunately now it is available only with business plans, not personal). You pay $5 pm and share your existing data allowance with this secondary card, without voice calls. If you have 20G allowance on phone you never use them all, so effectively your data on secondary sim does not cost anything, and if it is sleeping it costs $5 pm. I use it with spare 4g/eth router, which I can connect to any equipment anywhere, on any construction site or unfinished installation and get full inter
  15. if GPS system (satellites etc) fails - loss of your current position will be the smallest problem in the world. At least any smart mobile/tablet can position you with precision of 2-3 miles just on mobile network, without gps reception at all, this is enough to find the way home. Erebus and other DR losses happened due to independent systems, where you have to rely on youself only.
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