Ron HatchNavCom Technology, Inc.

10 March 2004

New L2C Signal BenefitsNew L2C Signal Benefits

Technical Benefits

Very significant signal-to-noise improvement over the semi-codeless current civilian access to L2 signal. (>17dB improvement)

The data-free segment allows the use of a phase-locked-loop for carrier-phase tracking. This greatly improves the cycle-slip threshold. (Our simulations show that with oscillator tracking logic, phase tracking with C/N0 less than 20 dB can be maintained)

Technical Benefits (2)

Longer codes on both L2CM and L2CL provide a significant improvement in the cross-correlation (and auto-correlation) properties. This gives a very significant improvement in acquisition reliability especially in the presence of weak or partially blocked signals

Assuming L2CM will be changed to a new ephemeris message with a convolution code, a significant improvement in the data message will be attained.

Practical Benefits

Both in agriculture and in marine applications—better performance in marginal situations. The StarFire Global DGPS uses the equivalent of floating ambiguity

carrier-phase navigation, thereby achieving ten cm. navigation—but it can often take as long as ½ hour to converge to this accuracy. Therefore, dropping below four satellites can cause this process to start all over.

Measurements from more satellites will remain available This can mean the difference between usable GPS and unusable GPS.

Reacquisition of obscured satellites will occur more quickly.

Shading Area A Shading Area B

Positioning Next to a Drill Rig

Conclusion

NavCom is designing the next-generation GPS to take advantage of the new L2C signals. We believe that the new signal will be of significant benefit to our existing customers—particularly in situations where the current system is only marginally available.