High dynamic global positioning system receiver

A Global Positioning System (GPS) receiver having a number of channels, receives an aggregate of pseudorange code time division modulated signals. The aggregate is converted to baseband and then to digital form for separate processing in the separate channels. A fast fourier transform processor computes the signal energy as a function of Doppler frequency for each correlation lag, and a range and frequency estimator computes estimates of pseudorange, and frequency. Raw estimates from all channels are used to estimate receiver position, velocity, clock offset and clock rate offset in a conventional navigation and control unit, and based on the unit that computes smoothed estimates for the next measurement interval

Code-regenerative clean-up loop for a ranging transponder

Digital processing system phase locks on received ranging signal and creates clean replica of received ranging code. System is broadly applicable to variety of terrestrial ranging problems, including oceanic navigation

Sine-Gordon Revisited

We study the sine-Gordon model in two dimensional space time in two different domains. For beta > 8 pi and weak coupling, we introduce an ultraviolet cutoff and study the infrared behavior. A renormalization group analysis shows that the model is asymptotically free in the infrared. For beta < 8 pi and weak coupling, we introduce an infrared cutoff and study the ultraviolet behavior. A renormalization group analysis shows that the model is asymptotically free in the ultraviolet.Comment: 43 pages, Latex 2.0

Digital carrier demodulator employing components working beyond normal limits

In a digital device, having an input comprised of a digital sample stream at a frequency F, a method is disclosed for employing a component designed to work at a frequency less than F. The method, in general, is comprised of the following steps: dividing the digital sample stream into odd and even digital samples streams each at a frequency of F/2; passing one of the digital sample streams through the component designed to work at a frequency less than F where the component responds only to the odd or even digital samples in one of the digital sample streams; delaying the other digital sample streams for the time it takes the digital sample stream to pass through the component; and adding the one digital sample stream after passing through the component with the other delayed digital sample streams. In the specific example, the component is a finite impulse response filter of the order ((N + 1)/2) and the delaying step comprised passing the other digital sample streams through a shift register for a time (in sampling periods) of ((N + 1)/2) + r, where r is a pipline delay through the finite impulse response filter

Digital filter for reducing sampling jitter in digital control systems Patent

Digital filter for reducing jitter in digital control system

Digital phase-lock loop having an estimator and predictor of error

A digital phase-lock loop (DPLL) which generates a signal with a phase that approximates the phase of a received signal with a linear estimator. The effect of a complication associated with non-zero transport delays related to DPLL mechanization is then compensated by a predictor. The estimator provides recursive estimates of phase, frequency, and higher order derivatives, while the predictor compensates for transport lag inherent in the loop

Quasars as very-accurate clock synchronizers

Quasars can be employed to synchronize global data communications, geophysical measurements, and atomic clocks. It is potentially two to three orders of magnitude better than presently-used Moon-bounce system. Comparisons between quasar and clock pulses are used to develop correction or synchronization factors for station clocks

Simple quasi-exponential slope generator

Circuitry for digitally generating an exponentially decaying wave function permits discrete values to be sampled from the exponential waveform for comparison with a binary number of specified accuracy. This exponential-decay generator employs a simple binary counter to count in the sequence of exponential decay

Technique minimizes the effects of dropouts on telemetry records

Recorder deficiencies are minimized by using two-channel system to prepare two tapes, each having noise, wow and flutter, and dropout characteristics of channel on which it was made. Processing tapes by computer and combining signals from two channels produce single tape free of dropouts caused by recording process

Fixed lag smoothers for carrier phase and frequency tracking

The application of fixed lag smoothing algorithms are presented for the problem of estimation of the phase and frequency of a sinusoidal carrier received in the presence of process noise and additive observation noise. A suboptimal structure consists of a phase-locked loop (PLL) followed by a post loop correction to the phase and frequency estimates. When the PLL is operating under a high signal-to-noise ratio, the phase detector is approximately linear, and the smoother equations then correspond to the optimal linear equations for an equivalent linear signal model. The performance of such a smoother can be predicted by the linear filtering theory. However, if the PLL is operating near the threshold region of the signal to noise ratio, the phase detector cannot be assumed to be linear. Then the actual performance of the smoother can significantly differ from that predicted by linear filtering theory. Both the theoretical and simulated performance of such smoothers derived on the basis of various models for the phase of frequency processes are presented