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Phase lock loop acquisition and tracking of carrier frequency modulated by single sinusoid, obtaining parameter values through mathematical model and digital simulation
A computer model is reported of a PLL (phase-lock loop), preceded by a bandpass filter, which is valid when the bandwidth of the bandpass filter is of the same order of magnitude as the natural frequency of the PLL. New results for the PLL natural frequency equal to the bandpass filter bandwidth are presented for a second order PLL operating with carrier plus noise as the input. However, it is shown that extensions to higher order loops, and to the case of a modulated carrier are straightforward. The new results presented give the cycle skipping rate of the PLL as a function of the input carrier to noise ratio when the PLL natural frequency is equal to the bandpass filter bandwidth. Preliminary results showing the variation of the output noise power and cycle skipping rates of the PLL as a function of the loop damping ratio for the PLL natural frequency equal to the bandpass filter bandwidth are also included.
Arrays of phase-locked semiconductor injection lasers integrated monolithically on the same substrate are one potential method for obtaining higher power levels (in controlled mode operation) than those available from a single laser. This paper describes basic methods for analyzing the electrical and optical characteristics of these devices, and discusses problems associated with maintaining a stable operation in a single array mode ('supermode'). Various experimental results are presented and compared with theory.
Programmable oscillator and zero-beat detector acquires phase-lock of carrier by frequency scanning. Generation of high-level dc pulse at instant of zero crossing provides positive trigger for decision gate to stop search and close loop for phase-coherent tracking.
A first-order digital phase locked loop is analyzed by application of a Markov chain model. Steady state loop error probabilities, phase standard deviation, and mean loop transient times are determined for various input signal to noise ratios. Results for direct loop simulation are presented for comparison.
The performance of a carrier phase locked loop (PLL) driven by a periodic Doppler input is studied. By expanding the Doppler input into a Fourier series and applying the linearized PLL approximations, it is easy to show that, for periodic frequency disturbances, the resulting steady state phase error is also periodic. Compared to the method of expanding frequency excursion into a power series, the Fourier expansion method can be used to predict the maximum phase error excursion for a periodic Doppler input. For systems with a large Doppler rate fluctuation, such as an optical transponder aboard an Earth orbiting spacecraft, the method can be applied to test whether a lower order tracking loop can provide satisfactory tracking and thereby save the effect of a higher order loop design.
Signal/noise performance of frequency locked loop FM threshold extension demodulator compared to phase locked loop demodulator and conventional FM discriminator
Five, 8.36 μm-emitting quantum-cascade lasers (QCLs) have been monolithically phase-locked in the in-phase array mode via resonant leaky-wave coupling. The structure is fabricated by etch and regrowth which provides large index steps (Δn = 0.10) between antiguided-array elements and interelement regions. Such high index contrast photonic-crystal (PC) lasers have more than an order of magnitude higher index contrast than PC-distributed feedback lasers previously used for coherent beam combining in QCLs. Absorption loss to metal layers inserted in the interelement regions provides a wide (∼1.0 μm) range in interelement width over which the resonant in-phase mode is strongly favored to lase. Room-temperature, in-phase-mode operation with ∼2.2 kA/cm{sup 2} threshold-current density is obtained from 105 μm-wide aperture devices. The far-field beam pattern has lobewidths 1.65× diffraction limit (D.L.) and 82% of the light in the main lobe, up to 1.8× threshold. Peak pulsed near-D.L. power of 5.5 W is obtained, with 4.5 W emitted in the main lobe. Means of how to increase the device internal efficiency are discussed.
A discriminator aided technique for acquisition of phase lock to a suppressed carrier signal utilizes a Costas loop which is initially operated open loop and control voltage for its VCXO is derived from a phase detector that compares the VCXO to a reference frequency thus establishing coarse frequency resolution with the received signal. Then the Costas loop is closed with the low-pass filter of the channel having a bandwidth much greater (by a factor of about 10) than in the I channel so that a frequency discriminator effect results to aid carrier resolution. Finally, after carrier acquisition, the Q-channel filter of the Costas loop is switched to a bandwidth substantially equal to that of the I-channel for carrier tracking.
Multi-filter phase locked loop demodulation
Optical communication synchronization with phase lock tracking loop and analysis of shot noise processes
Transient behavior of first order phase locked loop in presence of noise, solving Fokker-Planck equation for loop dynamics by numerical integration
Numerical evaluation of transient response for third-order phase-locked system for possible use in tracking high Doppler rates
Simulation equations are developed for first and second order digital phase locked loops. Examples of loop simulation are given to determine loop performance with respect to several loop parameters.
Spectra taken for a pulsed variable spacing phase-locked laser diode array (VSA) were recorded and processed to determine the magnitude of wavelength fluctuations present in the diode's output field. Analysis revealed that a pulsed VSA emits primarily into a single longitudinal mode.
A type II 1.06-micron optical phase-locked loop (OPLL) for use in a coherent homodyne receiver is discussed. Diode-laser-pumped solid-state lasers are used for both the local oscillator and transmitter, because their phase noise is significantly lower than that of diode lasers. Closed-loop RMS phase noise of less than 12 mrad (0.69 deg) is achieved, and modulation-demodulation in bulk modulators at rates from 20 kHz to 20 MHz with less than 19 deg of modulation depth is demonstrated.
Phase error behavior of phase-locked loop tracking system in presence of gaussian noise determined by fokker-planck equation
Phase locked-loop tracking with sine wave modulation in Apollo communication systems