Effects of the Rooftop Environment on GPS Time Transfer

Abstract

We examine the effects of the rooftop environment on GPS time transfer, in particular the effects of multipath reflections from nearby metallic objects. Three different antenna sites on the roof of the NIST laboratories at Boulder, Colorado, were selected, each with different multipath characteristics that we discuss. Simultaneous tests were conducted at each site with the same model of L1 band GPS receiver, but with different types of antennas. Four different types of active antennas with low-noise amplifiers were used at each site: a patch antenna, a patch antenna with a simple choke ring attached, a quadrifilar helix, and a "pinwheel" antenna with an aperture coupled slot array design. Results are presented that demonstrate how each antenna performs in each multipath environment, with the time deviation (sigma sub x(tau)) used as a metric. We also discuss the potentially harmful effects on time transfer caused by RF interference from other active GPS antennas located on the same roof.

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Document Details

Document Type
Technical Report
Publication Date
Jan 01, 2007
Accession Number
ADA474207

Entities

People

  • Andrew N. Novick
  • Michael A. Lombardi

Organizations

  • National Institute of Standards and Technology

Tags

Communities of Interest

  • Space

DTIC Thesaurus Topics

  • Air Conditioning Equipment
  • Antennas
  • Artificial Satellites
  • Carrier Frequencies
  • Environment
  • Frequency
  • Graphs
  • Intervals
  • Jet Propulsion
  • Measurement
  • Power Supplies
  • Radio Frequency Interference
  • Reflection
  • Spectrum Analyzers
  • Standards
  • Time Intervals
  • Warning Systems

Fields of Study

  • Engineering

Readers

  • Electromagnetic Wave Scattering and Antenna Radiation Engineering
  • Positioning, Navigation, and Timing (PNT) Technology.
  • Radio communications and signal processing.

Technology Areas

  • Space