A Costas loop with tangent error signal for use in Navstar GPS avionics

This paper describes an augmented Costas loop for use in low-cost avionics for the Navstar Global Positioning System. A standard loop has been augmented with supplementing feed-back to give a tracking error voltage proportional to the tangent of the phase error, rather than to the sine. The augmented loop yields increased performance in the presence of input phase acceleration and jerk, as caused by maneuvers of the GPS user vehicle. Many Monte Carlo simulation results are given.