David Franc. Department of Commerce Office of Radio Frequency Management

Transcription

1 David Franc Department of Commerce Office of Radio Frequency Management

2 Oceanographic Radar Outline What It Does Some Examples What It Looks Like How It Works How Much It Costs Spectrum Considerations Requirements Sharing Allocations 2

3 What It Does Provides Maps of Ocean Surface Currents Speed and Direction Covering Thousands of Square Kilometers Near-real-time Hourly 0.2 km to 6 km Spatial Resolution 3

4 Existing Applications Federal, State, Local Agencies USCG Search & Rescue Water quality monitoring Rip current prediction Marine navigation Fisheries and ecosystem management Oil Spill response, both NOAA and state 4

5 Maritime Safety Search& Rescue MARCOOS HF Radar Network Coast Guard SAROPS Before HF Radar 5 After HF Radar

6 The Technology 6

7 Receive and Transmit Antennas 7

8 HF Radar Electronics Enclosure 8

9 9

10 Radar Specs Velocity Resolution: 2 to 4 cm/s * Range Resolution: 0.2 to 6 km ** Temporal Resolution: 10 to 60 min Range Extent: 1 to 200+ km * Velocity Accuracy: 5 to 10 cm/s *Depends on Transmit Frequency, Signal Processing ** Depends on RF bandwidth 10

11 Other Oceanographic Radar Measurements Surface Wind Direction Surface Current Speed Significant Wave Height Dominant Wave Period Dominant Wave Direction Surface Wind Speed Non-Directional Wave Spectrum Directional Wave Spectrum 11

12 12

13 US Operations Prior to 2004 No central data repository or standards Funding from grants, Congressionally-directed funds ~50-60 HFRs in use by research institutions Using experimental frequency licenses Self-Organized User base not well-defined NOT OPERATIONAL 13

14 National Network Research toward Operations: HF Radar Current Measurement Capability: Create national HFR data servers to provide Near-real-time and retrospective data Create real-time quality control algorithms Adopt, adapt or create data/metadata standards Obtain standard radar frequency licenses Acquire, deploy, and operate a national HFR surface current monitoring system 14

15 National Network of Regional Associations 11 RAs serve the entire US Coastline, including Great Lakes, the Caribbean and the Pacific Territories RAs are the legal entities that seek out user needs; design and implement the Regional Coastal Ocean Observing Systems (RCOOS) 15

16 Network Data Infrastructure >100 Sites Ingested 16

17 # Radars Network Growth: Jul 04-Jun 08 17

18 Radio Spectrum Considerations 18

19 Radio Spectrum Requirements Require spectrum in multiple bands ranging from near 4 MHz to near 42 MHz ~ 4.5 MHz - long range, low data resolution ~ 13 MHz - medium range, medium data resolution ~ 25 MHz and ~42 MHz - short range, high data resolution Operational experience has shown that the wider bandwidths required for high resolution data are not available at lower frequencies High resolution does not drive the requirement for higher frequencies, insufficient available bandwidth at lower frequencies is the driver 19

20 Radio Spectrum Requirements Nominal Frequency Assignment Bandwidth # of Assignable Frequencies* 4.5 MHz 25 khz 2 13 MHz 55 khz 2 25 MHz 100 khz 2 42 MHz 200 khz 2 * Assignable Frequency is defined as available for use by Oceanographic Radars operating in coastal areas in the U.S. 20

21 WRC-12 Agenda Item to consider possible allocations in the range 3-50 MHz to the radiolocation service for oceanographic radar applications, taking into account the results of ITU-R studies, in accordance with Resolution 612 (WRC-07) 21

22 Spectrum Sharing Studies ITU-R Studies Modeled 1660 Fixed/Mobile receive sites globally 4 wanted links per site (ranging short to long distance) Calculated the percentage of viable wanted links that were made unusable by radar interference Considered Low/High Sunspot numbers, and the 4 seasons Results: Ground wave predictable (separation distances of 50 To 130 km) Sky wave unpredictable most frequencies: <10% of viable links degraded- typically on the order of 0.1 to 5 % Worst Case - 9 MHz: <20% of viable links degraded 22

23 Study Limitations Conducted using Quiet Rural noise for wanted links- not typical conditions for many U.S. locations Rural noise level will result in more cases of radar interference levels falling below the noise floor Radar transmit power was set to the maximum 50 Wattstypical operations use less transmit power Study results appear to be much more pessimistic than 30 years of experimental operations have shown Only few interference cases reported Other cases either don t exist or were ignored and left unreported 23

24 Spectrum Efficiency GPS-timed signals - use of a single frequency by many oceanographic radar systems The instantaneous bandwidth of the radar transmit signal is less than 50 Hz The receiver IF bandwidth is 50 Hz The position of each radar in its frequency sweep is staggered so that the sweeping IF bandwidth of a radar does not align with any other swept transmit frequency 24

25 Bottom Line Operations such as those by the Coast Guard drive a need for assignments that allow for continued, protected operation Techniques to minimize spectrum use are available Sharing not any different than the sharing that occurs between radio services currently allocated on primary basis With minimal restrictions imposed, two frequencies in each frequency range of interest will meet U.S requirements Does add a limited number of additional users to the HF bands The physical properties of higher or lower frequency ranges do not provide the required measurement capability 25

26 Primary vs. Secondary Allocations Primary Allocations Allows application of restrictions through footnotes and WRC Resolution(s) Provides potential for better coordination operations Information available to resolve frequency issues Provides ensured data continuity for critical U.S. programs reliant on radar data Secondary Allocations Unrestricted NIB use of allocations by radiolocation service NIB operation by definition provides no mechanism for coordination When interference cases occur, no information available to identify and resolve issue Radar operators will continue to need avoid other HF users who obtain conflicting new assignments 26

27 U.S. Proposal to WRC-12 Creates Primary allocations that are reduced to Secondary status by a footnote Allocations in multiple bands near 4.5 MHz, 13 MHz, 26 MHz and 41 MHz Associated WRC Resolution that restricts radar transmit power, requires frequency re-use techniques U.S. proposal allows future fixed and mobile communications users to bump radars from operational frequencies No status or operational stability relative to current allocated services 27

28 Summary Mature Technology (30+ years) for Measuring Ocean Current Velocities over Large Coastal Areas Numerous Mission-Critical Applications Hourly, Near-real-time Spatial Resolution ~1 to 5 km Relatively Low Maintenance NOAA IOOS is Developing a Data Management and Distribution System for the Nation Primary allocations are needed to provide long-term operational stability - current U.S proposal does not meet this requirement 28