Major Contributions

Science Drivers

Instrument Parameters

Instrument Location

Major Players

Project Funding

The GBSRBS makes use of two dual-polarization, broadband, trapezoidal log-periodic antennas for the majority of its frequency coverage, which extends from 10 MHz to 3 GHz (0.1 meter to 30 meters). One or more crossed dipoles will cover the lowest band, from 10 MHz to 30MHz. The intermediate-frequency log periodic antenna is designed for the 30 MHz to 350 MHz band and will sit atop the prime focus of the 13.7-meter dish, pointing skyward. A scaled-down version of this antenna will act as a feed for the 13.7 m, covering 300 MHz to 3 GHz. The 13.7 m (45 ft) telescope was refurbished in 1992 in preparation for a return to operation as a NASA ground station for Orbiting VLBI.
Phase I of the project involves an Erickson dipole, donated by the Naval Research Laboratory, collecting single polarization data which is buffered by an NRL active balun preamplifier and then transported via coaxial cable to an HP 8553B spectrum analyzer. The spectrum analyzer sweeps the 18 - 70 MHz band once per second, linearly sampling 1670 frequency channels, each with a bandwidth of 30 kHz. The time resolution of the instrument is 1 second. A Measurement Computing PCI-DAS1200 Analog-to-Digital converter interfaces with the spectrum analyzer via an open source Linux driver (Comedi). In phase II, the spectrum analyzers will be replaced by several frequency converters, each translating different 20-MHz sections of the band to an IF to be sampled by a 14-bit Adlink PCI-9820 data acquisition card.
Click to enlarge
GBSRBS-H log periodic antenna
The 350-2500 MHz log periodic trapezoidal antenna, just before deployment to Green Bank. May be seen mounted on the 45-ft inside its green weatherproof shell on the GBSRBS main page
Modified on Thursday, 27-Apr-2006 16:46:15 EDT by Erin Mastrantonio