Accession Number : ADA309965

Title :   Analysis of Spectrum Characteristics of GPS Time Comparison Under Two Conditions,

Corporate Author : NATIONAL AIR INTELLIGENCE CENTER WRIGHT-PATTERSON AFB OH

Personal Author(s) : Hu, Jinlun ; Jian, Shuguang

PDF Url : ADA309965

Report Date : 01 APR 1996

Pagination or Media Count : 11

Abstract : In order to understand GPS time comparison characteristics associated with influences from SA (Selective Availability) effects, a number of experiments were carried out in early 1992. The data sampling time associated with the experiments was 10 seconds. Satellite tracking time was 1 hour. The results of frequency spectrum analysis clearly show that: (1) Under normal conditions, GPS time comparison spectrum characteristics are basically level. There are no clear periodic phenomena. Noise processes are phase modulated white noise. (2) When GPS time comparisons are influenced by SA effects, low frequency spectra are relatively clearer. There are obvious periodic phenomena. Among these, 5-15 minute period signals account for approximately 77%. This is nothing else than the cause which leads to obvious drops in GPS time comparison precision.

Descriptors :   *GLOBAL POSITIONING SYSTEM, *SPECTRUM ANALYSIS, FREQUENCY, DATA PROCESSING, WHITE NOISE, TIME, AVAILABILITY, SPECTRA, SAMPLING, NOISE, LOW FREQUENCY, PHASE MODULATION, SATELLITE TRACKING SYSTEMS.

Subject Categories : Navigation and Guidance
      Radiofrequency Wave Propagation

Distribution Statement : APPROVED FOR PUBLIC RELEASE