Both use fixed land-based radio beacons to compensate GPS-position errors due to issues, such as tropospheric and ionospheric propagation
effects and satellite-position uncertainty.
After graduate school, Bill spent three years at The Aerospace Corporation working on various projects associated with radar systems and ionospheric propagation
, leaving that position to join Ball Aerospace.
And L should include the following factors: 1 the ionospheric propagation loss [L.sub.p], which includes the absorption loss, polarization loss generated by the Faraday effect, multipath effects, and so on; 2 the radar system loss [L.sub.s], which contains the loss produced by the weighting processing, the beam forming, the antenna efficiency, and so on; 3 sea wave additional loss [L.sub.w].
For the latter, the sea wave additional loss and ionospheric propagation loss are mainly considered and how to calculate them is discussed in Sections 2.3 and 2.4.
[30.] CCIR, "Ionospheric propagation
and noise characteristics pertinent to terrestrial radio communication systems design and service planning (Fading)," Reports of the CCIR, Vol.
* Transmitted frequencies must belong to the HF band ranging from 3 MHz to 30 MHz in order to exploit the ionospheric propagation channel;
As explained in the previous section, ground range distance, elevation angle and frequency are variables involved in the ionospheric propagation issue and they are strongly interconnected.
VHF low band is also susceptible to noise and ionospheric propagation. Ionospheric propagation occurs when the upper layers of the Earth's atmosphere is excited by solar activity, creating a mirror effect reflecting radio signals back to earth many miles further than would be possible by line of site.
Although still susceptible to ionospheric propagation, it is not as pronounced as on VHF low band.