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December 2009
Vol 9 Issue 2
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Changes to the 4.9 GHz Public Safety Band
—Fixed Links and How Should they be Coordinated?
The 4.9 GHz (4940–4990 MHz) band is allocated for public safety use under Part 90 of the FCC rules. In this 50 MHz band, channels of 1 to 20 MHz bandwidth may be used for video or broadband data via hotspots or temporary nodes. For example, a system could be used to send large files such as maps or pictures to vehicles or mobile units or to send video back to a monitoring center. 
On one hand, these broadband services are not easily accommodated by traditional public safety land mobile radio systems in the VHF/UHF or 800 MHz bands. On the other hand, the transmitter power and antenna gain limitations of the band as well as propagation conditions mean that base stations can cover smaller cells rather than wide areas like high power land mobile base stations.
In WP Docket No. 07-100, the FCC recently modified the rules to give primary status to permanent fixed point-to-point links used to interconnect 4.9 GHz base stations or for other broadband communication purposes. Previously, fixed links were accorded secondary status for operation to base, mobile, and temporary fixed uses based on the concern that devoting bandwidth to fixed links might not be the best use of the limited spectrum. With the modified rules, the Commission agreed with industry comments that allowing fixed links such as base station interconnections is proper and necessary to foster development of the band. Fixed links for non-broadband purposes such as interconnection of land mobile base stations will continue to receive secondary status.
A public safety organization is eligible to license the 4.9 GHz band over its area of operation and generally may implement base, mobile, or temporary fixed stations wherever necessary to give the desired coverage. In contrast, stations that form fixed links must be individually licensed on a site-by-site basis.
Presently, regional planning committees (RPCs) have responsibility for developing usage plans for the band in their region, and licensees are expected to cooperate in the selection and usage of channels to manage interference. The existing usage plans would be aimed at managing shared frequency usage of multiple licensees in overlapping operation areas. With primary fixed links in the band, there are new scenarios of potential interference (among the fixed links and between the fixed links and omnidirectional or sector coverage areas) that must be managed. With the change to primary status for fixed links, the FCC is also considering in a Further Notice of Proposed Rulemaking (FNPRM) how those links should be coordinated. The FCC proposed in the FNPRM that the notification and response prior coordination process of §101.103(d) (Part 101 coordination) should be used.
Of the 4.9 GHz interference scenarios, potential interference among fixed links that use directional antennas is the one most appropriately managed by Part 101 Coordination. Part 101 Coordination is most effective when direct interference calculations can be used to show that nearby systems would not interact with harmful interference and thus licensees can easily agree they can operate together. For highly directional point-to-point links the Part 101 Coordination process generally allows a high degree of frequency reuse while avoiding harmful interference. In the 4.9 GHz band, antenna gain is limited by rule to a maximum of 26 dBi to improve compatibility with mobile systems. This gain limitation means the antennas will have broader beamwidths and less sidelobe suppression than antennas used in the Part 101 fixed microwave bands. Thus, while Part 101 Coordination could be effective among fixed links in the 4.9 GHz band, the degree of frequency re-use that is possible may be lower than other fixed microwave bands.
The other scenarios of potential interference, fixed to mobile and mobile to mobile, would still be managed by the regional plan and by cooperation among the licensees. Mesh interconnections to relay traffic using the sector or omnidirectional antennas of a network would be treated as part of the mobile network rather than as fixed links for coordination purposes. Systems that are designed to use such mesh interconnections may be expected to manage interference among the mesh links and mobile links. Designating certain channels for fixed usage in an area could be an effective method of avoiding fixed-to-mobile interference if the licensees agree.
Some commenters to the FNPRM proposed that the RPCs should be responsible for registering and coordinating fixed links. While this idea has some appeal it is not clear that resources would be available for RPCs to take on this responsibility or that an effective RPC and plan is in place in all areas where licensees would desire to use fixed links. Part 101 Coordination has the advantage that it takes place among the licensees directly and thus does not depend on the operation of a third entity like an RPC. The comment and reply comment periods to the FNPRM have passed and it is now up to the FCC to decide what method should be used to coordinate fixed links in the 4.9 GHz band. Return to top.
- Post Digital Television Transition -
The Evaluation and Mitigation Methods for Off-Air Digital Television
Reception in-and-around Wind Energy Facilities
Introduction
The year 2009 will be a memorable year for terrestrial television broadcasting. It will mark the event when the total changeover in the terrestrial television signal modulation from analog to digital takes place. This changeover was due to take place on February 17th, 2009 by Congressional mandate but was delayed until June 12th, 2009 because the government could not fi ll the large demand for purchase coupons for the set top boxes that were necessary for the television sets owned and in use that did not have digital receivers. On February 17th about 500 of the 1800 U.S. terrestrial television high-power stations had already switched their broadcast modulation to exclusively digital modulation. The other 1300 stations were still broadcasting their programming in both analog and digital formats.
But on June 12th all high-power stations ceased their analog operations and all broadcasts are now in digital format. Exempt from the digital requirement are low-power TV broadcasters. This applies to low-powers stations, Class A broadcasters and translators. There are 7100 of these stations in the Unites States with the majority being translators. Since translator stations just rebroadcast high-power stations to a limited local audience, although not required to be in digital, it is expected they will be because they just rebroadcast what they receive from the high-power stations.
For certain wind energy facility developments in the U.S., the off-air television reception in the presence of wind turbines has been a very difficult issue. The reason for this has been that most wind energy facility developments are in locations that are at a considerable distance from the metropolitan areas where the television broadcasters are normally located. This means that the television signals are usually marginal or weak in the areas near wind energy facilities. When the wind turbines are installed and operating, they tend to have three dynamic affects on signals that make reception worse; they attenuate the signal making it weaker, they cause signal reflections, and they create multipaths. All of these conditions have a very noticeable affect on an analog modulated television signal.
Digital versus Analog Television Technology
There have been no big technology changes in terrestrial television broadcast services since 1953 when color was introduced to the broadcast television services. Since that time the National Television System Committee (NTSC) rules governed the formats and technology for analog terrestrial television broadcast. In 2009 the Advanced Television System Committee (ATSC) rules will supersede the NTSC and it will govern the digital modulation, formats and technology for terrestrial television broadcast. Figure 1 shows the broadcast spectrum of a single television channel per the NTSC. Figure 2 shows the broadcast spectrum of multiple (as many as six, but usually four) Standard Defi nition Television (SDTV) channels or up to two High Defi nition Television (HDTV) channels.
As can be seen from Figures 1 and 2, the digital modulation utilizes the spectrum allocated for terrestrial television broadcast much more efficiently. The improvement in efficiency has allowed the FCC to re-claim the frequencies that were used by television broadcasters for Channels 52–69 (698–806 MHz) for 4G communication services and Public Safety. The frequencies to be used for 4G communication services were auctioned off to telecommunication companies and the U.S. Treasury netted billions of dollars from the auction.
Digital versus Analog Television Reception in the Vicinity of Wind Energy Facilities
The analog waveform of the television broadcast signal was subject to variations in signal level by the presence of the wind turbine blade motion, which produced distortions in the video output in contrast, brightness and clarity. Changing reflections produced by the wind turbine blades caused ghosting. For digital modulation the signal level is also subject to level variations and reflections but as long as the signal remains above the operational threshold of the receiver, the video produced will be unaffected.
The one affect caused by the wind turbines that is common to both analog and digital modulation is that the television signal will be attenuated by the presence of the wind turbines. Although the attenuation affect is common, the digital modulation can withstand the attenuation affect to a greater extent because it requires a much lower signal level to produce excellent video. This characteristic of digitally modulated television signals as compared to analog modulation is illustrated in Table 1, which shows the signal strength required for producing excellent video for both digital and analog modulation across all of the television frequency bands. However, it should be also noted that in areas where the present analog TV signalis of marginal quality but viewable, the comparable level digital signal may not be viewable.
The level required by the digitally modulated signal is much lower than that for a comparable high quality analog modulated signal. In Table 2 another difference between digital and analog television is described. For analog television, as the signal is degraded by external effects, the video quality is reduced in a sliding scale of performance. For digital television, as the signal is degraded, the video will remain excellent until the signal level falls below the operational threshold of the receiver and then, video blocking, pixilation and/or frame freezes occur. If the degradation does not clear, the video will totally go to a blank screen. If it does clear, the video goes back to excellent conditions. This quick slide from excellent video, to noticeable degradation, to no video is known as the “Cliff Effect.”
Evaluating Digital Television Broadcast Reception
The signal level of the digital television signal is measured using a spectrum analyzer and the video is observed and recorded using a laptop computer with a capability of recording to a DVD. The two indicators of video performance are the measured signal level in dBµV/meter and the subjective observation of the video quality. The video quality must be observed for all multiple broadcasts of standard video on a channel or the one or two broadcasts of high defi nition television programming on a channel.
The purpose of the measurements is to determine whether the reception of digital broadcast stations in the area is possible. If the determination is made that digital television broadcast stations produce signal levels that produce quality television, then the wind energy developer may have an obligation to make sure that the residents in the area retain that capability after the wind turbines are installed.
As stated earlier, the attenuation introduced by the wind turbines is the one factor that must be overcome if reception is degraded. The attenuation will occur if one or more wind turbines are in the path of the broadcast television signal. In most cases the attenuation can be overcome with an improved digital television receiving system.
Description of an Improved Digital Television Receiving System
Once the wind turbines are installed and it is known where the television broadcasters in the area are located, an external antenna site at a home or a business can be selected and installed that will have an unobstructed view toward the television broadcast station(s). It is recommended that the antenna be mounted high enough to clear any local obstacles such as trees and terrain. The antenna should have high gain with an amplifier installed at its terminals. A rotatable mast will support the antenna so that it can easily be directed in azimuth to peak up on a desired television station broadcast location. From the amplifier, the television signal will be connected to points in the residence or business receivers by low-loss double shield coaxial cable. At points where the television signal is to be split to reach various TV sets in the home or business, active splitters will be used. An active splitter has an amplifier that will boost the signal back to its original level before it is split. It is recommended that these systems be installed by a reputable television technician.
Conclusions and Recommendations for the Television Reception Issue in the Digital Age
The television digital transition gives the Wind Energy developers a new strategy to use in dealing with this difficult issue. Television reception of off-air digital signals will be possible in more places than before. Good reception will require a good receiving system and one can be provided at a reasonable cost. This cost establishes a fair and reasonable response to loss of television coverage. Return to top.
MICROWAVE
Declaratory Ruling issued Establishing Timeframes for State and Locality Processing of Applications for Wireless Towers—This Declaratory Ruling promotes the deployment of broadband and other wireless services by reducing delays in the construction and improvement of wireless networks. (Dkt No 08-165, FCC No 09-99)
DOC-294711A1.pdf DOC-294711A2.pdf DOC-294711A3.pdf DOC-294711A4.pdf
DOC-294711A5.pdf DOC-294711A6.pdf FCC-09-99A1.pdf FCC-09-99A2.pdf
FCC-09-99A3.pdf FCC-09-99A4.pdf FCC-09-99A5.pdf FCC-09-99A6.pdf
Moving Toward a Digital Democracy—Comments sought by the FCC (DA No 09-2431, Dkt No 09-137, 09-47, 09-51) DA-09-2431A1.pdf
FCC Expands Use of Web 2.0 Tools for Open Internet Inquiry—DOC-294257A1.pdf
Open Internet/Broadband Industry Practices—The FCC Seeks Public Input on Draft Rules To Preserve the Free and Open Internet. (Dkt No. 09-191 07-52, FCC No. 09-93) FCC-09-93A1.pdf FCC-09-93A2.pdf FCC-09-93A3.pdf FCC-09-93A4.pdf FCC-09-93A5.pdf FCC-09-93A6.pdf
Protecting Children in an Evolving Media Landscape—Notice of Inquiry seeking comment on how to empower parents to help their children take advantage of the opportunities offered by electronic media technologies while protecting children from the potential risks. (Dkt No 09-194, FCC No 09-94) FCC-09-94A1.pdf FCC-09-94A2.pdf FCC-09-94A3.pdf FCC-09-94A4.pdf FCC-09-94A5.pdf FCC-09-94A6.pdf
Electronic Comment Filing System (ECFS) Version 2.0 Launched—
DOC-293952A1.pdf
Broadband Task Force Status Report—Status of U.S. Broadband National Plan
DOC-293719A1.pdf
Radio/Television Program Distribution on School Buses—The FCC Media Bureau issues a report to Congress regarding commercial proposals for broadcasting radio or television programs for reception on board specially-equipped school buses. (Dkt No 09-68, DA No 09-1999) DA-09-1999A1.pdf
Annual Telecommunications Industry Revenue—DOC-293261A1.pdf
SATELLITE
FCC Allocates spectrum and service rules for Vehicle-Mounted Earth Stations
The FCC Amends Parts 2 and 25 of the Rules to Allocate Spectrum and Adopt Service Rules and Procedures to Govern the Use of Vehicle-Mounted Earth Stations in Certain Frequency Bands Allocated to the Fixed-Satellite Service.
In this Report and Order the FCC adopts allocation, technical and licensing rules to permit the domestic, U.S. licensing of Vehicle-Mounted Earth Stations (“VMES”) as a primary application of the Fixed Satellite Service (“FSS”) in the relevant Ku-band frequencies 11.7–12.2 GHz (space-to-Earth) and 14.0–14.5 GHz (Earth-to-space). In Part 25 of the Commission’s rules, the FCC defines VMES as an earth station operating from a motorized vehicle that travels primarily on land, receives from and transmits to geo-stationary satellite orbit (“GSO”) FSS space stations, and operates within the United States pursuant to the requirements set out in Part 25 of the rules. They amend Part 25 of the rules and add a new section 25.226 setting forth technical and licensing rules for VMES as a mobile application of the Ku-band FSS. They also adopt two footnotes to the U.S. Table of Frequency Allocations (“U.S. Table”) contained in Part 2 of the Commission’s rules.
http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-09-64A1.doc
FCC Clarifies Procedures Governing the Use of Satellite Earth Stations on Board Vessels in the 5925–6425 MHz/3700–4200 MHz Bands and 14.0–14.5 GHz/11.7–12.2 GHZ Bands
In this Order on Reconsideration, the FCC considered four petitions seeking reconsideration and/or clarification of the Commission’s 2005 Report and Order (ESV Order) in which it adopted licensing and service rules for earth stations on vessels (ESVs) operating in the 5925–6425 MHz/3700–4200 MHz band (C-band) and the 14.0–14.5 GHz/11.7–12.2 GHz band (Ku-band). In acting upon these petitions—filed by ARINC Incorporated (ARINC), the Boeing Company (Boeing), the Fixed Wireless Communications Coalition (FWCC) and Maritime Telecommunications Network (MTN)—the FCC resolves various concerns raised regarding the operational restrictions placed on ESVs that are designed to protect the fixed-satellite service (FSS), operating in the C-band and Ku-band, and the terrestrially-based fixed service (FS), operating in the C-band, from harmful interference. The revisions or clarifications focused in part on the antenna pointing error requirements, coordination reporting requirements, off-axis e.i.r.p. spectral-density limits, certification of antenna tracking system and point of contact information requirements.
http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-09-63A1.doc
FCC International Bureau Establishes Website for List of Previously Approved Non-Routine Earth Station Antennas
In the Part 25 Earth Station Fifth Report and Order, the FCC adopted streamlined procedures for reviewing non-routine earth station license applications. As part of that Report and Order, the Commission directed the International Bureau to create a list of approved non-routine earth station antennas to be posted on the FCC-IB website. The Commission concluded that a website listing approved non-routine antennas, including antenna gain patterns and the conditions placed on the use of each antenna, would help applicants in preparing applications for non-routine earth station licenses and expedite review of these applications.
In this Public Notice, the FCC International Bureau announces the creation of the website listing approved non-routine earth station antennas. This website can be found at www.fcc.gov/ib/sd/NRESA/. The website lists all non-routine earth station antennas approved since the Commission released the Part 25 Earth Station Fifth Report and Order. The list also contains the file number of the application requesting that antenna, and the call sign of the license authorizing use of that antenna. The Bureau will add new non-routine antennas to the list as it authorizes them. Earth station applicants proposing to use an antenna that is on this list will no longer need to attach antenna radiation plots as an exhibit to their applications, as required by Section 25.132(b)(3) of the Commission's rules. Rather, they need only provide an attachment to their applications citing the particular non-routine earth station antenna they plan to use, and an application file number and call sign of a license in which that type of non-routine antenna has been approved. Barring any countervailing considerations, the Bureau will grant the application for the non-routine antenna, provided that the applicant seeks to offer the same kinds of services as the previously authorized antenna and with the same or substantially similar operating conditions. http://hraunfoss.fcc.gov/edocs_public/attachmatch/DA-09-425A1.doc
FCC Grants DIRECTV Enterprises, LLC application for authorization to launch and operate DIRECTV RB-2, a satellite in the 17/24 GHz broadcasting satellite service at the 102.825 degrees W.L. orbital location
The FCC granted DIRECTV Enterprises, LLC (DIRECTV) authority to construct, launch and operate a 17/24 GHz Broadcasting-Satellite Service (BSS) space station at the 102.825° W.L. orbital location, which is offset 0.175 degrees from the 103° W.L. orbital location specified in Appendix F to the 17/24 GHz BSS Report and Order, at a reduced power and without full interference protection. DIRECTV is authorized to operate in the 17.3–17.7 GHz (space-to-Earth) and the 24.75–25.15 GHz (Earth-to-space) frequency bands as specified in this Order.
http://hraunfoss.fcc.gov/edocs_public/attachmatch/DA-09-1624A1.doc
FCC Grants L-3 Communications Titan Corporation authority to operate one mobile earth station terminal to be mounted on a vehicle and used in the continental United States
The FCC granted L-3 Communications Titan Corporation (L-3 Communications) authority to operate one mobile earth station terminal to be mounted on a vehicle and used in the continental United States. L-3 Communications will provide Land Mobile Satellite Service (LMSS) using the standard Ku-band frequencies of 14.0–14.5 GHz (Earth-to-space) and 11.7–12.2 GHz (space-to-Earth), and will communicate with leased transponders on currently operating U.S.-licensed satellites to provide communications support for the United States Military.
http://hraunfoss.fcc.gov/edocs_public/attachmatch/DA-09-587A1
Comsearch has a NEW website design!
Please contact us with any comments or suggestions
Comsearch offers a free online tool for performing 3650 MHz searches at www.3650search.com
www.3650search.com is designed to help licensees efficiently manage their spectrum usage while protecting incumbent users in the band. The tool leverages the FCC’s 3650 MHz ULS data and is augmented by our own databases to provide critical information about:
- nearby licensed 3650 MHz systems‚
- co-channel and adjacent channel earth stations‚
- federal radio location stations and‚
- Government radar systems.
We invite you to try it today!
Comsearch launches the next generation of iQ·link®
iQ·link is Comsearch’s flagship fixed network design and management software tool for microwave point-to-point and point-to-multipoint backhaul. As networks continue to expand and add capacity‚ and wireless microwave continues to be a popular‚ cost-effective choice for operators‚ we decided that it was time to breathe new life into our 18 year old spectrum manager. Building on a proven foundation‚ Comsearch has energized iQ·link for the future with iQ·link®XG 9.0, which represents a complete re-architecture of the product.
iQ·linkXG key improvements include:
The industry’s leading operators are using iQ·link’s robust capabilities to plan‚ create‚ deploy‚ optimize‚ and manage some of the world’s largest networks. iQ·link supports the full microwave radio spectrum and has been used to design Point-to-Point (PTP) and Point-to-Multipoint (PMP) backhaul and fixed access networks in bands ranging from 2–60 GHz for a broad range of wireless systems including Cellular‚ PCS‚ GSM‚ UMTS‚ TETRA‚ 3G‚ WiMax‚ LTE and more.
For more information on what iQ·linkXG can do for you‚ visit our website or contact us at 1-800-318-1234.
SpectrumViewSM
Comsearch‚ a CommScope Company‚ brings you SpectrumViewSM—a simple, yet comprehensive look at spectrum holdings for any wireless carrier in any wireless market nationwide. In the last two auctions alone‚ over 200 licensees acquired close to 2000 licenses for AWS and 700 MHz spectrum. Combine that with spectrum holdings for other services such as Cellular‚ PCS‚ and WCS‚ and the spectrumscape is extraordinarily complicated. SpectrumView cuts through the clutter to give you a clearer picture of who has what spectrum where.
SpectrumView identifies potential partnerships and competitors for wireless telecom licensees. County boundaries are the basis for all FCC license areas, so we identify each carrier at the county level or partial county level‚ then aggregate that back up to the appropriate market area. We also sum up the amount of spectrum per carrier as well as population covered by each license. For partial counties‚ we calculate the percentage of geographic area and percentage of population covered by the license. We take into account leases recorded with the FCC‚ ownership changes‚ frequency disaggregation‚ and market partitioning. Detailed research is performed on each licensee name to determine the true operating company.
For more information on Comsearch’s SpectrumView‚ please click here or call 1-800-318-1234.
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