[Lowfer] 454 Khz info

[BOB RIESE]

A Nationwide DGPS (NDGPS) Service is being established under the
authority of Section 346
of the Department of Transportation and Related Agencies Appropriation
Act, 1998 P.L. 105-66
U.S.C. 301 note (Ref. 9). This service is an expansion of the MDGPS to
cover areas of the
country where service from MDGPS is not available. When complete, this
service will provide
uniform differential GPS coverage of the continental U.S. and selected
portions of Hawaii and
Alaska regardless of terrain, man made, and other surface obstructions.
This is achieved by
using a terrain-penetrating medium frequency signal optimized for surface
application. This
service, along with MDGPS, provides a highly reliable GPS integrity
function to terrestrial and
maritime users.
NDGPS accuracy is specified to be 10 meters or better. Typical system
performance is better
than 1 meter in the vicinity of the broadcast site. Achievable accuracy
degrades at an
approximate rate of 1 meter for each 150 km distance from the broadcast
site.
When each site is brought online, it meets all FOC requirements as set
forth by the USCG for
their MDGPS service. This includes integrity, availability, and accuracy.
Sites are being
activated as funds are becoming available.
The NDGPS Service will achieve FOC when it is provides dual coverage of
the continental
U.S. and selected portions of Hawaii and Alaska with single coverage
elsewhere. Given the
current funding environment, FOC is expected by the end of calendar year
2007.
The service is operated to the RTCM SC-104 broadcast standard. This
standard has also been
adopted by the international community as ITU-R 823 and has been
implemented in over 40
countries, maritime and non-maritime, worldwide.



Bob  K3DJC