SBIR-STTR Award

Various DOD C3I communications systems can be seriously affected by the disturbances in the earth's ionosphere. One way to alleviate this problem is to use alternate C3I assets during the times of predicted signal outages due to ionospheric scintillation fading. However, current prediction technique based on monthly climatology of ionospheric fading does not provide real-time solutions. Past experiments using signals broadcast from the navstar global positioning system (GPS) satellites to measure amplitude and phase scintillation in real time have been successful. But the cost of these gps receivers is very high rendering them impractical to be deployed in large number in a theatre battlefield environment. A very inexpensive ionospheric scintillation monitor (ISM) based on state-of-the-art high-performance commercial GPS receiver is proposed. Phase I effort will produce a prototype ISM capable of measuring, in real time, the amplitude scintillation index and the phase jitter. Detrending algorithms to remove the effects of receiver oscillator phase noise and GPS selective availability will be developed and experimented during Phase I.

Various DoD C3I communications and radar systems can be seriously affected by the disturbances of the earth's ionosphere, especially for those located at near-equatorial regions such as Kwajalein, Diego Garcia, Ascension Island and the Gulf region. One way to alleviate this problem is to use alternate C3I assets during times of predicted signal outages due to ionospheric scintillation fading. However, current prediction techniques based on monthly climatology of ionospheric fading does not provide real-time solutions. The proposed Ionospheric Scintillation Monitor (ISM), based on state-of-the-art commercial high-performance C/A-code GPS receiver technology, is so inexpensive that it may be deployed in large numbers in a theatre battlefield environment. The Phase I effort has successfully produced a prototype ISM capable of providing the basic real-time measurements for estimating the amplitude scintillation index and the equivalent phase scintillation index. Off-line detrending algorithms to remove the effects of oscillator phase noise and selective availability have been successfully developed and tested. The Phase II effort will produce the complete ISM in which the detrending algorithms will be done in real-time so that parameters of the ionospheric scintillation environment will be derived in real-time. This ISM will also produce real-time measurements of satellite code/carrier divergence. The Phase II ISM will be capable of parallel tracking of all GPS satellites in view, thus providing simultaneous measurement of the scintillation parameters in many directions.