Linearized Phase Detector Zero Crossing DPLL Performance Evaluation in Faded Mobile Channels

Qassim Nasir,Saleh Al-Araji

doi:10.4236/cs.2011.23021

Qassim Nasir, Saleh Al-Araji

Open Access

https://doi.org/10.4236/cs.2011.23021

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Abstract

Zero Crossing Digital Phase Locked Loop with Arc Sine block (AS-ZCDPLL) is used to linearize the phase difference detection, and enhance the loop performance. The loop has faster acquisition, less steady state phase error, and wider locking range compared to the conventional ZCDPLL. This work presents a Zero Crossing Digital Phase Locked Loop with Arc Sine block (ZCDPLL-AS). The performance of the loop is analyzed under mobile faded channel conditions. The mobile channel is assumed to be two path fading channel corrupted by additive white Gaussian noise (AWGM). It is shown that for a constant filter gain, the frequency spread has no effect on the steady state phase error variance when the loop is subjected to a phase step. For a frequency step and under the same conditions, the effect on phase error is minimal.

Highlights

Phase Lock Loops (PLLs) are used in a wider range of communication applications such as carrier recovery synchronization, and demodulation [1]
The loop has faster acquisition, less steady state phase error, and wider locking range compared to the conventional Zero Crossing DPLL (ZCDPLL)
It has been shown that the AS-ZCDPLL loop offers improved performance in the lock range and acquisition with reduced steady state phase error [5]

Summary

Introduction

Phase Lock Loops (PLLs) are used in a wider range of communication applications such as carrier recovery synchronization, and demodulation [1]. A PLL is a closed loop system in which the phase output tracks the phase of the input signal It consists of a phase detector, filter, and voltage controlled oscillator. In this paper an Arc-Sine ZCDPLL is analyzed under mobile faded channel. The mobile radio channel is characterized by fast Rayleigh fading and random phase distribution. This considerably degrades the tracking performance and increase the jitter of the loop. The performance of ZCDPLL-AS with phase and frequency step inputs in the mobile radio environment is studied. The fading in each path of the channel follows Rayleigh distribution and has power spectral density as given by Jakes [6].

ZCDPLL-AS System Operation in Mobile Faded Channels

Phase Step plus Noise

Simulation Results

Conclusions