Archive for the 'Beginner’s Guide' Category

Satellite Navigation current status

Tuesday, January 15th, 2008

what GNSS signals do we have …

Wednesday, June 13th, 2007

  • C1 ; Ranging to the satellite based on the Civil message.
  • P1 ; Ranging to the satellite based on the Encrypted (high-security) message.
  • L1 ; Number of cycles since satellite acquisition.

  • P2 ; Ranging to the satellite based on the Encrypted (high-security) message.
  • L2 ; Number of cycles since satellite acquisition.

GLONASS and GPS differences

Saturday, April 14th, 2007

  1. GLONASS is not complete. Whereas GPS has 32 satellites transmitting signals GLONASS only has 14 which does not guarantee world-wide coverage.
  2. GLONASS uses FDMA for its transmissions whereas GPS uses CDMA. in FDMA each satellite uses a different frequecy to transmit the same ranging code. in CDMA each satellite uses the same frequency with different ranging codes per satellite.
  3. GLONASS is providing a second Civilian signal on L2 which helps civilian users to properly eliminate the ionospheric error.
  4. GLONASS satellites are upgraded more often. This is due to a russian satellite design constraint or due to cost-saving measures but the GLONASS satellites have to be replaced much more often than GPS ones (every 5 to 7 yrs). This appears as a problem but it allows GLONASS to introduce new capabilities much faster than GPS.

What is GNSS about …

Wednesday, September 27th, 2006