search

tobinfisher / Firmware

PX4 Firmware for PX4FMU autopilot and PX4IO servo / failsafe board
https://pixhawk.ethz.ch/px4/
0 stars 0 forks source link

GPS intermittently does not lock on satellites #7

Closed tobinfisher closed 10 years ago

tobinfisher commented 10 years ago

HK GPS unit sometimes is unable to lock on any satellites when sitting on kitchen table, close to window, with a good view of a decent amount of sky. At other times, it can lock on 6 or more satellites from this location.

meglington commented 10 years ago 
Tobin,
This may be due to the location of the GPS SVs in the sky. You could
use a GPS sky plot program to visualize where the GPS SVs are in the
sky. It could be that at that time of the day, there are no high
elevation SVs visible outside your window. Trimble has an online
line tool here:http://www.trimble.com/GNSSPlanningOnline/
(I haven't tried it though, because it Microsoft SilverLight and my
Windows computer's hard drive just failed.)
MikeOn 11/15/2013 07:54 PM, Tobin wrote:

  HK GPS unit sometimes is unable to lock on any satellites when
    sitting on kitchen table, close to window, with a good view of a
    decent amount of sky. At other times, it can lock on 6 or more
    satellites from this location.
  —
    Reply to this email directly or view
      it on GitHub.
tobinfisher commented 10 years ago

Very interesting. I couldn't get that site to work, but I tried a different one (http://satpredictor.navcomtech.com/) and with a 20 degree elevation mask, it showed that only 6 satellites should be visible and GPS coverage would be marginal at the time I was having problems. The site predicts the same level of coverage for right now, and again I am again unable to connect with any satellites. I'll be curious to try again a bit later in the day when coverage is predicted to be better.

Thanks for the explanation!

On Nov 15, 2013, at 8:15 PM, Mike Eglington notifications@github.com wrote:

Tobin, This may be due to the location of the GPS SVs in the sky. You could use a GPS sky plot program to visualize where the GPS SVs are in the sky. It could be that at that time of the day, there are no high elevation SVs visible outside your window. Trimble has an online line tool here:http://www.trimble.com/GNSSPlanningOnline/ (I haven't tried it though, because it Microsoft SilverLight and my Windows computer's hard drive just failed.) MikeOn 11/15/2013 07:54 PM, Tobin wrote:

HK GPS unit sometimes is unable to lock on any satellites when sitting on kitchen table, close to window, with a good view of a decent amount of sky. At other times, it can lock on 6 or more satellites from this location. — Reply to this email directly or view it on GitHub. — Reply to this email directly or view it on GitHub.