Abstract: An apparatus and method for improving the capture performance of frequency and phase locked loops. The invention permits improved capture performance while, at the same time, maintaining the signal-to-noise ratio performance of the loop while the loop is tracking. The invention estimates the transient response of an automatic control loop. This estimate is used to control elements added to a PLL to accelerate acquisition, and eliminate the noise contribution of those added elements while the loop is tracking. The system uses the variation in the gradient of the loop transient response to derive an estimate of the loop's distance from lock. The system then uses this estimate to control loop parameters which affect the loop's acquisition.

Abstract: A system and technique is disclosed which enables the measurement and display of aircraft groundspeed using a modified FMCW radar altimeter. The system is constructed to have a conventional FMCW altimeter transmitter and receiver for transmitting and receiving vertical return signals, and a narrowbeam forward-looking antenna and associated receiver for detecting return signals from the forward angle. The transmitted signal is triangularly modulated to produce returns on both the upsweep and downsweep of the modulation and the difference between the frequencies of those returns, as detected by the forward looking antenna, is proportional to aircraft slant velocity. The system also detects slant range and altitude and combines them with slant velocity to produce an output representing the aircraft groundspeed.

Abstract: Interferometer gyro includes a source of light which is divided into two portions. Each of the two portions is modulated with a respective frequency, one being a fixed frequency and the other being a variable frequency. The modulated light portions are then introduced into a fiber optic coil, the rotation of which about an axis of sensitivity is desired to be measured. After the light portions have traversed the optical fiber, they are each again modulated by the respective other frequency, then compared to produce a signal indicating the phase difference therebetween. The phase difference signal is integrated to produce a signal for varying the variable frequency such that the phase difference produced is null. The rate of rotation of the optic fiber about its axis of sensitivity is then determined by the comparison of the fixed and variable frequencies.