Talk:Selective availability

I believe everything said here is on the GPS page, and have thus changed this to a redirect. Original content of this page follows. AdamW 22:51, 27 Mar 2005 (UTC)

This is an artificial error introduced into the satellite data by the US DoD to reduce the possible accuracy of a position to 100 meters for commercial users. Without SA typical C/A code (commercial) GPS position accuracy would be about 20 metres. However to deny this accuracy to potential hostile users, the US Defense Department has the ability to corrupt the satellite's signals to degrade the accuracy to as much as 100 metres. In addition to this, other sources of error include :

1)Satellite clock and ephemeris errors

2)Environmental errors caused by atmospheric sources

3)Signal multipath reception errors

4)Receiver induced errors

The first two of these sources of error are removed by the use of DGPS which improves the accuracy of the GPS positions that are obtained to about 10 metres depending on the GPS receiver used and the configuration of the satellite constellation.