2016_ITS_Spectrum_Surveys_in_Miami_and_Suitland_FINAL_(4).pdf

SPECTRUM SURVEY RESULTS FROM

THREE NOAA SATELLITE EARTH

STATION FACILITIES

John Carroll Geoffrey Sanders

(Rev -)

May 2016

1. INTRODUCTION

The Middle Class Tax Relief and Job Creation Act of 2012,Section 6401 (a), (3) directed the Secretary of Commerce to identify 15 MHz of U.S. Government use spectrum between 1675 to 1710 MHz suitable for repurposing, i.e., sharing with commercial wireless carriers. The

REPORT TO THE PRESIDENT, IDENTIFICATION OF 15 MEGAHERTZ OF SPECTRUM

BETWEEN 1675 AND 1710 MHZ FOR REALLOCATION FROM FEDERAL USE TO NON-

FEDERAL USE PURSUANT TO SECTION 6401(a) OF THE MIDDLE CLASS TAX RELIEF AND JOB CREATION ACT OF 2012, February 2013 was the response from the Secretary of Commerce which identified 1695 to 1710 MHz as the band to be designated for sharing with the wireless carriers.

After the Report to the President that identified the band(s) that would be part of the Advanced Wireless Service-3 (AWS-3) auction, the Department of Commerce (DOC) established the Commerce Spectrum Management Advisory Committee (CSMAC) to examine the potential impacts to National Oceanic and Atmospheric Administration (NOAA)’s ground stations as a result of repurposing the 1695 to 1710 MHz band. Working Group 1 (WG-1) was specifically formed to address this issue. WG-1 was made up of members from both the Government and industry. The resulting report recommended the use of a backstop monitor system to detect potential RFI from the wireless carriers, as well as being able to identify the responsible carrier.

Before spectrum sharing is implemented, it is important to examine the current RF environment at NOAA satellite ground stations. This provides a baseline understanding of the existing RF environment including seasonal and diurnal variations, illustrates what unwanted emissions (if any) are present in this band now and provides a record of how the noise in this band evolves as sharing is implemented.

This report describes the methodology and results of short-term spectrum surveys performed in Suitland, MD and Miami, FL by the Institute of Telecommunication Sciences (ITS), part of the DOC’s National Telecommunication and Information Administration (NTIA). These measurements were taken on behalf of NOAA’s National Environmental Satellite, Data, and Information Service (NESDIS) Office of Satellite Ground Services (NOAA/NESDIS/OSGS).

The spectrum measurements took place at three locations: NOAA’s Satellite Operations Facility (NSOF) on November 17, 2015, NOAA’s Atlantic Oceanographic and Meteorological Laboratory (AOML) on December 8th, 2015 and NOAA’s National Hurricane Center (NHC) on December 9th 2015.

Subsequent to the field measurements, data analysis was performed to create a composite graphic of spectrum usage at both locations. Results of the measurements and analyses are presented in this report.

2. MEASUREMENT SYSTEM DESIGN AND CONFIGURATIONS

The measurement system itself consisted of a receive antenna, a low-noise radiofrequency (RF) front-end preselector (with internal noise diode calibration source) and associated control hardware and a spectrum analyzer (SA). The antenna was mounted on a non-conductive tripod and placed in close proximity to the satellite receive antennas.

2.1. Receive Antenna

The measurement antenna was an omnidirectional Cobham antenna, model number OA2-0.3- 10.0V/1505. The antenna was passive (that is, it did not incorporate a low-noise amplifier) and vertically polarized. Its gain between 1695 to 1710 MHz was +2dBi relative to isotropic. The antenna was mounted on a non-conductive tripod between 3 ft (1 m) and 6 ft (2 m) above the rooftop level, depending on measurement location.

2.2. Front-End Preselector

The front-end preselector design is described in [1] and [2]. Although [1] and [2] reference measurements of high-power radar systems, this front end design is applicable to general spectrum measurements where the measurements take place in an unknown spectrum environment where nearby high-power signals like television, cellular and radar signals could cause non-linear operation of the downstream spectrum analyzer.

The front end consists of a noise diode calibration source, a stepped RF attenuator, a set of tunable microwave bandpass filters, and a broadband low-noise amplifier (LNA) with a frequency response range that match those of the filters. The measurements antenna is connected to the input of the front end. The output of the front-end box feeds into the input of a measurement device, in this case a spectrum analyzer. Figure 1 shows the measurement system configuration.

Figure 1. Spectrum Survey Measurement System

2.3. Spectrum Analyzer and Analyzer Parameters

The spectrum analyzer used during this measurement effort was a Keysight E4440A. It was operated with its internal preamplifier turned off and zero RF attenuation at the input. The spectrum analyzer’s resolution bandwidth was set to 100 kHz. Across the measured 1695 to 1710 MHz range, each sweep contained 151 frequency bins so the full power across this frequency range was recorded during each sweep.

In a single measurement “event”, both peak and average data were acquired in a 100 kHz resolution bandwidth. Peak-power measurements were performed with the analyzer over 20 consecutive sweeps using the spectrum analyzer’s peak-detector. In this mode, the analyzer’s peak detector latches to the highest level that occurs within each sampling interval for each spectrum analyzer frequency bin. Thus the peak measurements show, for each trace, the highest power level that occurs in the measurement bandwidth at each frequency in the measured spectrum. Average power was measured by using the spectrum analyzer’s RMS detector and recording 20 consecutive sweeps. In this mode, the analyzer’s RMS detector calculates the mathematical average over the sampling interval for each spectrum analyzer frequency bin.

2.4. NSOF-Specific Setup

The measurement antenna was located on the roof of the NSOF building at an approximate height of 53 ft (16.2 m) AGL (with a building height of 50 feet (15.2 m) and a tripod height of 3 feet (1 m)). The NSOF facility is located approximately 6.3 miles (10.1 km) Southeast of downtown Washington, D.C., as shown in Figure 2. 40 feet (12.2 m) of low-loss RF cable connected the receive antenna to the input port of the front-end preselector. The measurements at NSOF took place for 23 hours and 46 minutes.

Figure 2. Location of NOAA's NSOF relative to downtown Washington, D.C.

2.5. AOML-Specific Setup

The measurement antenna was located on the roof of the AOML building at an approximate height of 43 ft (13.1 m) AGL (with a building height of 40 feet (12.2 m) and a tripod height of 3 feet (1 m)). The AOML facility is located approximately 3 miles (4.8 km) East-Southeast of downtown Miami, as shown in Figure 3. Figure 4 shows the measurement receive antenna on the roof of the AOML facility with the Miami skyline in the distance. 40 feet (12.2 m) of low-loss RF cable connected the receive antenna to the input port of the front-end preselector. The measurements at AOML took place for 5 hours and 12 minutes.

Figure 3. Location of NOAA's AOML relative to downtown Miami

Figure 4. Measurement system receive antenna with Miami skyline in distance

2.6. NHC-Specific Setup

The measurement antenna was located on the roof of the NHC building at an approximate height of 36 ft (11 m) AGL (with a building height of 30 feet (9.1 m) and a tripod height of 6 feet (2 m)). The NHC facility is located approximately 12 miles (19.3 km) west of downtown Miami on the campus of Florida International University, as shown in Figure 5. Figure 6 shows the measurement receive antenna with the NOAA Geostationary Operational Environmental Satellite (GOES) receive antennas in the background. 30 feet (9.1 m) of low-loss RF cable connected the receive antenna to the input port of the front-end preselector. The measurements at NHC took place for 6 hours and 5 minutes.

Figure 5. Location of NOAA's AOML relative to downtown Miami

Figure 6. Measurement system receive antenna with GOES antennas in background

3. RESULTS

The data was post-processed into plots of power versus frequency between 1695 MHz and 1710 MHz. Minimum, mean, median, and maximum (also known as M4) statistics were computed for each 100 kHz peak and RMS-detected frequency bin at each location. At, NSOF, the measurement event described in Section 2.3 was repeated 276 times throughout the measurement duration for a total of 5520 frequency sweeps over which the M4 statistics were computed. At AOML, the measurement event was repeated 50 times throughout the measurement duration for a total of 1000 frequency sweeps. Finally, at the NHC, the event was repeated 60 times for a total of 1200 frequency sweeps.

3.1. NSOF

The peak-detected and RMS-detected M4 statistics for the NSOF are shown in Figures 7 and 8, respectively.

Figure 7. Peak-detected M4 power values per 100 kHz between 1695 and 1710 MHz.

Figure 8. RMS-detected M4 power values per 100 kHz between 1695 and 1710 MHz.

3.2. AOML

The peak-detected and RMS-detected M4 statistics for the AOML are shown in Figures 9 and 10, respectively.

Figure 9. Peak-detected M4 power values per 100 kHz between 1695 and 1710 MHz.

Figure 10. RMS-detected M4 power values per 100 kHz between 1695 and 1710 MHz.

3.3. NHC

The peak-detected and RMS-detected M4 statistics for the NHC are shown in Figures 11 and12, respectively.

Figure 11. Peak-detected M4 power values per 100 kHz between 1695 and 1710 MHz.

Figure 12. RMS-detected M4 power values per 100 kHz between 1695 and 1710 MHz.

4. REFERENCES

[1] Sanders, F. H., R. L. Hinkle, and B. J. Ramsey, “Measurement Procedures for the Radar Spectrum Engineering Criteria (RSEC)”, NTIA Report TR-05-420, NTIA, U.S. Department of Commerce, March 2005.

http://www.its.bldrdoc.gov/pub/ntia-rpt/05-420/index.php

[2] ITU-R Recommendation M.1177-4, “Techniques for measurement of unwanted emissions of radar systems”, April 2011. http://www.itu.int/rec/R-REC-M.1177/en http://www.its.bldrdoc.gov/pub/ntia-rpt/05-420/index.php http://www.itu.int/rec/R-REC-M.1177/en