Re: Bluetooth GPS & Sirf III chipset


How can the receiver, placed in a wheelhouse with a steel ceiling,
still show a low HDOP when it is receiving many satellites that are
very high in the sky?

The HDOP or "Horizontal Dilution of Precision" is based on satellite
positions. It is one factor needed to get good GPS calculations. The
HDOP doesn't take into account the quality of the environment (tree
cover, buildings, roofs), the quality of the receiver, or the quality
of the signals (sunspots, atmospheric effects). You don't even need a
GPS receiver to calculate the HDOP. All you need is your approximate
location and the locations of the satellites.

If you are tracking more than 4 satellites, some GPS receivers use the
extra satellites to estimate accuracy. This approach is probably
better than just using the HDOP, but it still isn't very good. Use
the estimates and HDOP as negative indicators - if either of them are
bad, then your calculated position is definitely bad.

.

Relevant Pages

  • Re: Bluetooth GPS & Sirf III chipset
    ... still show a low HDOP when it is receiving many satellites that are ... GPS receiver to calculate the HDOP. ... Reflected signals, if the only source for that satellite, will be wrong but the receiver will not be able to detect this fact. ...
    (sci.geo.satellite-nav)
  • Re: =?iso-8859-1?q?Re:_Question_on_AirMap=AE_600C?=
    ... the Garmins and Magellans store for you; HDOP, satellites, and heading ...
    (rec.aviation.piloting)
  • Re: Precision of GPS-receiver
    ... thats exactly what I didn't want to hear:(This sounds like HDOP ... What it says is that the worst case error in the range measurements ... satellites used for the position computation. ... Especially good if all tracking satellites are used for the computation. ...
    (sci.geo.satellite-nav)
  • Re: Lidl Satellite reciever etc. from 28th August
    ... The SL 65 receiver, as well as being supplied with a twin LNB ... handset - you'll get all that channels information, ... Are you sure it's the type of LNB that gives access to two satellites? ...
    (uk.tech.digital-tv)
  • Re: Deternining when GPS data is good
    ... PocketPC to get the location using I-Blue737 Bluetooth GPS. ... DOP, does not ... of the satellites used in the solution. ... If your receiver doesn't do RAIM, ...
    (sci.geo.satellite-nav)