The Green Bank Telescope

National Radio Quiet Zone

Description

The National Radio Quiet Zone (NRQZ) was established by the Federal Communications Commission (FCC) in Docket No. 11745 (November 19, 1958) and by the Interdepartment Radio Advisory Committee (IRAC) in Document 3867/2 (March 26, 1958) to minimize possible harmful interference to the National Radio Astronomy Observatory (NRAO) in Green Bank, WV and the radio receiving facilities for the United States Navy in Sugar Grove, WV. The NRQZ is bounded by NAD-83 meridians of longitude at 78d 29m 59.0s W and 80d 29m 59.2s W and latitudes of 37d 30m 0.4s N and 39d 15m 0.4s N, and encloses a land area of approximately 13,000 square miles near the state border between Virginia and West Virginia.

Map of National Radio Quiet Zone

Coordination Requirement

NRQZ coordination is required for all new or modifed, permanent, fixed, licensed transmitters inside the NRQZ, as specified for federal transmitters by NTIA manual section 8.3.9 and for non-federal transmitters by the FCC in 47 CFR section 1.924. 

The applicable radio services include but are not limited to: Public Mobile, Wireless Communications, Maritime, Aviation, Private Land Mobile, Personal Radio, Fixed Microwave, International Fixed Public, Satellite Communications, Radio Broadcast, Experimental Radio, Auxiliary and Special Broadcast, Cable Television Relay, Amateur Radio, Personal Communications Service, General Wireless Communications Service. Geographic Area Licensed Services are NOT exempt from NRQZ coordination.  Applicants for some radio services are required to file their applications through independent frequency coordinators (e.g. APCO, AASHTO, PCIA, and IMSA). The coordinators assume the responsibility of notifying the Interference Office that an FCC application has been filed and hold the application until the Interference Office responds with its evaluation.

Preliminary Evaluations

As a service to applicants who are planning to install transmitters within the NRQZ, our NRQZ Office can evaluate proposed transmitter installations long before an applicant decides upon a final transmitter location or equipment configuration. These preliminary evaluations can help the applicant determine the best location for a transmitter while keeping NRQZ interests in mind and can ultimately expedite the application process. The result produced by the preliminary evaluation is the maximum power that can be radiated by the proposed transmitter towards Green Bank. Requests for preliminary evaluations should be submitted to the NRQZ Office and should contain the following information:

  • Name and address.
  • Radio service.
  • For each proposed transmitter:
    • Frequency or frequencies
    • Signal Bandwidth (if unknown, this information can be gathered from the technology type or the emission designator)
    • Antenna location in latitude and longitude to nearest second.
    • Antenna site ground elevation above mean sea level (AMSL).
    • Antenna height above ground level (AGL).

Coordination Process

In order to minimize harmful interference to the operations of the NRAO in Green Bank and the Navy Informations Operation Command (NIOC) at Sugar Grove, all requests for new or modified, permanent, fixed, assigned or licensed transmitters within the NRQZ shall be coordinated by the applicant, prior to submission to the FCC or NTIA, with:

NRQZ Administration Office
National Radio Astronomy Observatory
P. O. Box 2
Green Bank
WV 24944

Email: nrqz@nrao.edu

As a convenience to NRQZ applicants, and to expedite the coordination process, you may download the following nrqzApplicationMaker software, courtesy of AKP Consulting Engineers:

NRQZ Application Download.zip
3 MB

The software has detailed instructions to guide you through the application process, resulting in a complete application file. Send the complete, zipped file to nrqz@nrao.edu for evaluation.

Alternatively, the applicant should forward the following information to the Interference Office:

  • Name and address of applicant.
  • Radio service and Call Sign.
  • FCC File or NTIA Assignment Number.
  • For each proposed transmitter:
    • Frequency or frequencies
    • Signal Bandwidth (if unknown, this information can be gathered from the technology type or the emission designator)
    • Antenna location in latitude and longitude to nearest tenth of a second.
    • Antenna site ground elevation above mean sea level (AMSL).
    • Antenna height above ground level (AGL).
    • Antenna make, model number, and maximum antenna gain in dBd or dBi.
    • Maximum transmit power (dBW or W)
Should the Effective Radiated Power (ERP) of your transmitter exceed what is allowable under the limit, the following information may be additionally requested:
  • A detailed system configuration that includes all system gains and losses.
  • Antenna gain with horizontal and vertical patterns in one degree increments (in Planet or TIA-804-B Antenna File Format).
  • Antenna azimuth (degrees true) and elevation.

Transmitter Evaluation

The NRQZ Office reviews all applications to ensure that the computed power flux density at the reference point does not exceed frequency-dependent thresholds.

In some instances, the transmitter power requested by an applicant exceeds the level that is harmful to observations in Green Bank or Sugar Grove. When this occurs, applicants should discuss possible modifications to their transmitters (e.g. using a directional antenna, relocating the antenna to an area that provides additional terrain shielding, or selecting a different frequency where the power density limits are different) with the Interference Office. In our experience, a technical solution can almost always be found to provide the area coverage desired by the applicant while simultaneously minimizing the impact of the interference upon Green Bank or Sugar Grove. In the extremely rare case when differences between the applicant's desires and the Interference Office's evaluation cannot be resolved, both the applicant and the Interference Office should forward comments on the transmitter installation to the FCC or IRAC for a final resolution.

We emphasize that the Interference Office has no authority in the granting of an FCC license or a Federal Government frequency assignment. The Interference Office only has the privilege of submitting its comments on a particular transmitter installation to the FCC or IRAC.

Applicants who feel that their applications have been evaluated unfairly or inadequately can contact the office of the Green Bank Site Director for a review of their circumstances.

Reference Point

The reference point for calculations of transmitter power density is the prime focus of the Green Bank Telescope (GBT). The location of the GBT prime focus is:

Latitude: 38d 25m 59.2s N (NAD83)
Longitude: 79d 50m 23.4s W (NAD83)
Ground Elevation: 806 Meters or 2644 Feet AMSL (NAVD88)
Height: 139.6 Meters or 458 Feet AGL

GBT

Power Density Thresholds

Based on a 20 kHz measurement bandwidth, the calculated power density of the transmitter at the reference point should be less than:

  • 1 x 10-8 W/m2 for frequencies below 54 MHz
  • 1 x 10-12 W/m2 for frequencies from 54 MHz to 108 MHz
  • 1 x 10-14 W/m2 for frequencies from 108 MHz to 470 MHz
  • 1 x 10-17 W/m2 for frequencies from 470 MHz to 1000 MHz
  • The greater of (freq2 (in GHz) x 10-17 W/m2 ) or (the power density limit of Table 1, Recommendation ITU-R RA.769) for frequencies above 1000 MHz

except for frequencies that reside in the radio astronomy observing bands listed in the US Table of Frequency Allocations, in which case the power densities listed in Table 1 of Recommendation ITU-R RA.769 shall apply. For a comprehensive list, click here.

For more information about the NRQZ please contact:

Paulette Woody

Phone: 304-456-2107, Fax: 304-456-2276, Email: nrqz@nrao.edu

NRAONSFAUI

The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

Last updated 1 November 2010 by Carla Beaudet