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An interesting fact re: satellite count on app.

Discussion in 'Inspire 1 Discussion' started by PetePerrim, Feb 25, 2015.

  1. PetePerrim

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    i just wanted to point out this interesting little anomaly. On the app screen it only gives you satellite signal strength but if you plug a second monitor or goggles into your controller and turn on the osd function for the second screen you will see the number of satellites you're hooked up to, but only on the second screen. Weird Huh?
     
  2. blade strike

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    They have removed this from the new firmware. The OSD via monitor will only show signal as well. I don't understand the logic behind this and would like sat count. Or at least an option to toggle it on or off.
     
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  3. jrs

    jrs

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    Can you view from the iPad and a pair of ziess from 1 controller?
     
  4. PB30X

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    Second this as well!! Sat lock is more important than signal, because the signal has been known to fade in and out versus a true lock.. Been using GPS afield for years (HUNTING & HIKING) and accuracy always depends on weather, foliage, and location.. With that being said, first Initialization and lock on the most satellites will give you clear perception as to what is going on.. This indeed is where we see this "drift" come from, trust me.. You can be standing dead still in any given location, and suddenly your location will drift pending how many sats you have locked and communicating... I'm quite sure many have used GPS navigators hiking, camping, etc.. When you lock into a weigh point or location, even the very next day you come to the same exact spot and presto, you will see how accurate weigh points and locks matter the most... So Yes, I believe it is crucial for those who use GPS frequently.. Be ready, when drift occurs!!
     
  5. blade strike

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    The neo8 once locked wont drift like you're saying unless you don't have sight of the sky. These gps units update 10x fast than your standard hiking handhelds.

    The Inspire has no GPS issues, it's all compass related. Compass starts to give errors and that's when the craft drops down to atii. It's really that simple.
     
  6. blade strike

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    Yes you can.
     
  7. Kilrah

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    Very likely because they don't want people to rely on the sat count, and they'd be right about it because it's a basic but very poor indication of positioning quality. It's HDOP/VDOP that matter, and that's likely what the bars show.
    You can get as good a position with 6 sats as with 15, and have poor position with 9.

    I remember in the days where I helped develop an OSD, we were initially based on sat count for home point setting but had to switch to HDOP simply because it's not because you have 10 sats that your position estimation is good... it might take another 30 seconds or so from the time you lock to the sats until HDOP really drops. But it can also drop in a second, so you never know and is why the info is there.
     
    #7 Kilrah, Feb 25, 2015
    Last edited: Feb 26, 2015
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  8. Rig

    Rig

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    I don't see the downside to having both. More data can't be bad for the pilot. If the pilot sees there are 10 sats, but HDOP/VDOP bars indicate poor strength, then it's still a red flag. I really liked having sat count on HDMI out, bummed they dropped it and even more curious as to why.
     
  9. blade strike

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    Great points, thanks for th post.
     
  10. catware

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    Does the Inspire 1 have a threshold number of satellites for GPS mode vs ATTI mode? On the Phantom 2, when it drops from 6 to 5 it will always drop to ATTI mode. Yet my handheld Garmin GPS can have a highly accurate solution fix with just 3 satellites locked. So if the Inspire 1 has a similar minimum number, it would be important to know this, otherwise as @Kilrah wrote the HDOP would be good enough. (I never care how many satellites my Garmin has locked -- I simply look at its accuracy estimate.)
     
  11. Quadpilot

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    A poster on another forum (RCGroups) made an interesting point: The Inspire uses not only the US Satellite system but has access to the Russian GLONASS sat system. The two systems are not compatible however, so the FC cannot combine the two sat signals to come up with a position, or increase the position accuracy by combining the signals. Depending on its location, it will use one or the other system, whichever gives the greater accuracy. Typically, 5 sat signals from either system can fix a pretty accurate position, but if the Inspire receives a total of 9 sats, 5 US and 4 GLONASS, or vice versa, then a dropout of one sat signals to 4 sats will result in weak accuracy for both systems. That's why having number of satellites indicated in the app doesn't necessarily indicate good position accuracy, since it wouldn't indicate which system is supplying the signal. The bars are a better indication, as mentioned by @Kilrah, of GPS accuracy. The P2 and Vision only use the US system, so sat count is an accurate indication of GPS lock on those birds.
     
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