[BC] GPS recommendations

[Martin Acuff]

Many GPSes use WAAS (e.g. Garmin GPSMAP 60CSx); I haven't previously seen mention of WAAS in this thread.  See:

      <http://en.wikipedia.org/wiki/WAAS>

excerpt:

      "The Wide Area Augmentation System (WAAS) is an air navigation aid developed by the Federal Aviation Administration to augment the Global Positioning System (GPS), with the goal of improving its accuracy, integrity, and availability.
      Essentially, WAAS is intended to enable aircraft to rely on GPS for all phases of flight, including precision approaches to any airport within its coverage area."

While WAAS is intended for air navigation, it's used in many ground-based units.

      -- Marty

At 11:29 6/15/2012, RichardBJohnson at comcast.net wrote:
>It is common to presume that GPS position cannot be accurately known without an additional reference signal, perhaps from CORS or NDGPS (http://www.gps.gov/systems/augmentations/)

>The government ...

>http://www.gps.gov/systems/gps/performance/accuracy/

>...says that some receivers provide better than the "theoretical" 7.8 meter accuracy. How is this possible? No, it is not done with smoke and mirrors. If your receiver is not moving like an airplane moves, one can obtain the GPS position over-and-over again and average the result.