COMSEARCH®
Taming
the Spectrum
In this issue:
CASE
CORNER: MARKET
TRENDS:
Satellite Video Transmission and the Analog to Digital Conversion Process
Modern Wireless Conveniences - New Interference Issues
Archived Issues
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Satellite Video Transmission and the
Analog to Digital Conversion Process
by Ken Ryan and Gary Edwards
The changing frontier for television broadcasters and cable television providers includes the
Broadcasters attempting to determine potential interference sources into C-band downlinks,
What’s New in the Real World?
A recent interference issue into domestic Ku-band VSATs and Hubs has been interference from automobile radar detectors. Several times over the past year Ku-band satellite users have stated that earth stations located near a highway or a parking lot have experienced in-band noise on the lower transponders in the 11.7–12.2 GHz range. It has been determined that the source of interference is a local oscillator built into many common radar detectors. Earth station owners have discovered that if the
interference originates from parked vehicles
Figures 1 and 2 show the relative position of a domestic Kuband rooftop earth station and a parking area on an adjacent rooftop. Figure 3 shows the spectrum analyzer plot of the
New York, NY
Azimuth 180 to 360°
Date: December 13, 2000
Time of Day: 11:47
Ant. Polarization: V
Ant. Centerline: 6 ft.
Sweeping RFI from radar detector operating in automobiles located on rooftop of the middle parking garage to the west of the earth station.
Frequency Range of RFI: 11,700 to 12,100 MHz
Maximum Signal Level Measured: -138 dBW
In this instance, it was determined that the mini-van shown in Figure 4 was the source and
What’s New in the Regulatory World?
Recent actions by the Federal Communications Commission (FCC) have shown that currently authorized spectrums can be subject to reallocation at any time. The reclassification of the 3650– 3700 MHz spectrum for a proposed wireless service (1) left many earth station operators scrambling to get their antennas licensed prior to the December 1, 2000, deadline. Those that did not make the filing deadline were subject to
having their earth stations granted under a secondary status, not eligible for protection unless they were within ten miles of a “grandfathered” or previously licensed antenna authorized for reception of the same band.
A FCC NPRM initiated by the Fixed Wireless Communication Coalition (FWCC) calls for
restrictions on the amount of spectrum satellite earth stations may license and protect, leaving
In addition to the FCC activities discussed above, it is important to note that there is another
Comparison of Interference Criteria for FM-TV and Digital TV
The traditional method for analyzing the effects of interference into FM-TV has involved determining the maximum permissible level of interference power at co-channel operation and
|
Maximum Permissible Levels of Interference Analog FM-TV at C-band |
||
| Satellite Downlink EIRP | 34 | dBW |
| Gain of 4.5m Receive Antenna | 44 | dBW |
| Free Space Loss | -196.4 | dBW |
| Received Satellite Signal Power | -118 | dBW |
| Required Carrier-to-Interference Ratio | 25 | dB |
| Max. Permissible Level of Interference | -143.4 | dBW/MHz |
For digital video, or digital systems in general, the long term interference objective is set to provide a C/I ratio necessary to degrade the carrier-to-noise (C/N) ratio by not more than 0.5 dB, or 10 dB below the thermal noise floor. A sample calculation is shown below:
|
Maximum Permissible Levels of Interference Digital Video TVRO at C-band |
||
| Satellite Downlink EIRP | 25 | dBW |
| Gain of 4.5m Receive Antenna | 44 | dBW |
| Free Space Loss | -196.4 | dBW |
| Digital TVRO System Noise Temperature | 150 | K |
| Digital Signal Noise Bandwidth | 8 | MHz |
| Received Satellite Signal Power | -127.4 | dBW |
| Received Noise Level (kTB) | -137.5 | dBW |
| Downlink Carrier-to-Noise Ratio | -10.1 | dBW |
| Max. Permissible Level of Interference | -156 | dBW/MHz |
| Resulting Carrier-to-Noise Plus Interference Ratio | 9.6 | dB |
Typically an interference objective will be derived using link analyses. In those instances where
The Proactive Approach to Interference Free Operation
Earth station owners need to realize that with the introduction of more stringent interference
A proactive approach in evaluating the environment prior to the switch from analog to digital is
A paper study against terrestrial microwave in shared C and Ku-band services would be the first
In order to detect the other forms of potential interference, such as cellular, PCS, engine noise,
After establishing a clear picture of the interference environment, the next logical step is to update
Although the domestic Ku-band downlink frequency range of 11700–12200 MHz is not currently
A Case Study:
A Broadcasting Network’s
C-band Satellite Earth Stations
Analog to Digital Transmission Conversion
A majority of the television broadcasters with C-band satellite earth stations have begun the
Office Interference Analysis
Comsearch’s first step in assisting an earth station operator with this project was to complete an
On-Site RFI Measurements
One such particular receive site was for a broadcaster located in Philadelphia, Pennsylvania (see
Federal Communications Commission Regulations
Earth station owners need to realize that with the introduction of more stringent interference
Summary
The case study on the Philadelphia site project reinforced the obvious need to evaluate and protect your earth station site from potential interference sources, especially when dealing with a
station. It is invaluable when you upgrade, expand, or negotiate issues with other shared users of
Reference List
(1) Federal Communications Commission, ET Docket No. 98-237, FCC 00-363.
(2) Federal Communications Commission, IB Docket No. 00-203.
(3) Federal Communications Commission, ET Docket 01-75.
(4) Federal Communications Commission, ET Docket No. 98-237, FCC 00-363.
(5) Federal Communications Commission, IB Docket No. 00-203.
by Les Polisky and Timothy Fitzgerald
Most of us may take it for granted, but literally thousands of devices we use every day are subject to FCCs Part 15 rules. Examples of such devices include cordless phones, computers, baby monitors, garage door openers, keyless entry, electronic toll
collection, and microwave ovens to name only a few. Part 15 of the FCC rules establishes the operational criteria that allow us to use and enjoy these devices which provide the conveniences of our everyday lives. By allowing these technologies to utilize spectrum without licenses, consumers, industry, and the regulatory bodies themselves have all benefited from the handiness offered by Part 15.
However, in recent years, the concerns of licensed spectrum users have intensified as the use of Part 15 devices have increased markedly, thus threatening the operation of their licensed systems with harmful interference.
The FCC established Part 15 Rules to set guidelines for low-powered devices to utilize spectrum without requiring a license. These non-licensed devices are required to operate under the constraint that they must not cause harmful interference to, and must accept interference from licensed users. Among the goals of
Part 15 (at the time of its inception) was to allow the flexibility of emerging technologies to utilize spectrum while at the same time maintaining the integrity of the licensed user’s systems. It is doubtful, however, that even in the FCC’s broadest projections, one could have predicted that Part 15 devices would evolve and proliferate to where they are today.
RADAR DETECTORS
Unfortunately, as the popularity of low-powered unlicensed devices has increased, so too has the potential for harmful interference to licensed operators. Numerous unlicensed devices have emerged in recent years and have become objects of great concern to licensed users. For example, radar detectors have been exempt
from the rules and regulations set forth in Part 15 because they are receiving devices and operate above 1GHz. However, there has been a successful push in recent years by the satellite industry that will soon end this exemption as they have shown, through measurements, that the RADAR detectors are a source of disruptive interference to earth station
operations at Ku-Band. As a result, radar detectors are going to be subject to modified and more stringent Part 15 rules. In addition to radar detectors, newer technologies such as Ultra-Wideband (UWB), Wireless-Fidelity (Wi-Fi), and RF lighting have drawn the attention of the telecommunication licensees who fear that interference from these devices will destroy the integrity of their operations. The satellite industry has lobbied heavily to protect its licensed users by advocating, at a minimum, stricter limits for the power outputs of unlicensed users.
As Part 15 devices continue to emerge and evolve, it is clear that there will be many complex obstacles and issues to be confronted as the conflicting goals of both the integrity of licensed use and the flexibility and accessibility of unlicensed use are at stake.
Interference from radar detectors and Part 15 devices have been measured and verified as degrading sources to both Ku-Band VSATs and conventional earth stations. Because radar detectors are designed to function as receive only, they have not been held to the limits set forth under Part 15. However, as these detectors
have evolved and their design has been altered to not only detect police radar but also elude detection and even jam, it has been found that these devices emit power levels that cause harmful interference. Because the degrading effects of interference from radar detectors can be so great, it has been concluded that these devices should be subject to Part 15 rules.
Although Part 15 rules were intended to allow the use of low-powered devices to operate without a license, when in close proximity to sensitive equipment the use of these devices can be crippling. VSATs have been one of the most widely publicized victims of damaging radar detector emissions, and conventional Ku-Band earth stations have also been disturbed.
The effects of these radar detectors is especially damaging to digital data and video causing errors, video drop out, or loss of video synchronization. VSATs are relied upon to perform numerous functions in our economy, and any disruption to their operation can be inconvenient, costly, and even dangerous.
The interruption of the services delivered by VSATs is indeed disturbing, and its effects costly. Throughout our economy, VSATs are relied upon to make life easier for all of us. From the pay-at-the-pump conveniences that we enjoy at the gas station, to the secure ATM transactions that we rely on, VSATs add
convenience that few would be willing to forfeit. In addition to these functions VSATs are used to track inventories, validate credit cards, and deliver e-mail. Perhaps most importantly VSATs are used for telemedicine, law enforcement, disaster recovery and satellite tracking where any disruption can threaten the very safety that these devices are often designed to ensure. The
satellite industry has lobbied successfully to ensure that RADAR detectors are made subject to Part 15 rules, and that their permitted emissions are below the levels that have caused interference to VSATs and conventional earth stations.
ULTRA-WIDE BAND (UWB)
Although radar detectors have been targeted for their interference by the satellite industry, new and emerging technologies have also become threats to telecommunication license holders looking to protect their rightful claim to their interference-free use of the spectrum. Technologies such as Ultra-Wideband, Wi-Fi networks, and Field Disturbance Sensors all
have the potential to interfere with authorized users. Although these technologies have not been fully developed and deployed, it is certain that the license holders would prefer to raise their issues of concern before any potential problems are realized.
UWB is an emerging Part 15 technology that offers high bandwidth at low cost and low power requirements. UWB technology is designed to utilize very short pulse modulation to transmit a high volume of pulsed signals at low power bursts¾covering the spectrum from 1-10 GHz. By design, it is claimed that this technology will not cause interference because it will constantly be dispersed across a wide range of frequencies at very low powers. Because the power outputs are so low, other systems sharing the same spectrum will simply interpret the UWB signals as low-level noise. UWB is being
looked upon very favorably to perform operational functions such as radar imaging, vehicle collision avoidance and broad bandwidth communications.
UWB is utilized by law enforcement, the military, and the telecom industry for its unique radar capabilities. Among these capabilities is the ability to penetrate the ground and walls as well as provide detailed views through walls with an accuracy of within 1 inch. Law enforcement departments are enthusiastic about
the potential of UWB technology to assist in search and seizure exercises. Rescue units see UWB’s potential value in assisting with rescue and recovery efforts such as collapsed buildings and other disasters. Industrial uses of this technology can include construction¾where the ability to see through walls will assist in locating structural beams. The ability to quickly and easily determine oil tank levels is another important use that industries are eager to take advantage of. These radar capabilities will offer a wide range of users great value and capabilities that will clearly be beneficial.
Because of concerns expressed by the airline, cellular, and television broadcasting industries, the deployment of UWB will initially be very conservative. GPS devices are utilized by the airline industry for various navigational functions during flights, including landings, and operate between 1.2-1.6 GHz. Since UWB
is designed to operate in this frequency band, the airline industry is obviously concerned that interference impact the safe operation of aircraft. The cell phone industry has also expressed concerns that the use of UWB technology in the spectrum below 3.1 GHz could affect the service of millions of mobile phone users. Additionally, the National Association of Broadcasters (NAB) has voiced concerns that UWB technology
could degrade C-band earth stations, which are relied upon to distribute broadcast programming.
To allay some of these fears and concerns, the FCC has permitted a limit to deployment of the UWB technology. Initially, UWB deployment will be limited to spectrum above 3.1 GHz and can not exceed a published spectral power density level. Also, any emissions below 1.6 GHz must be suppressed by 34 dB.
The use of UWB has been restricted to wireless LANs and vehicular radar systems for collision avoidance. The use of UWB’s radar imaging capabilities will be initially limited to law enforcement and public safety units.
WIRELESS LOCAL AREA NETWORKS (WLANs)
Another Part 15 technology that is rapidly advancing into the mainstream is wireless fidelity, or Wi-Fi, networks. These devices operate in the unlicensed 2.4 GHz spectrum and will be increasingly relied upon in future years for wireless connectivity to the Internet and LANs. Based on the IEEE standard 802.11, Wi-Fi
networks are relatively inexpensive. By most projections, these devices are predicted to explode in popularity as many hotels, restaurants, airports, workplaces, and convention centers include access points throughout their facilities. The expected growth of the Wi-Fi industry has the radio satellite operators worried, as they fear the proliferation of the devices in neighboring bands could have an adverse impact on operations that utilize the 2320-2345 MHz band. The buffer of frequencies that exists from the high end of the Digital Audio Radio Service (DARS) band and the beginning of the unlicensed 2400 MHz band is not enough to alleviate the fear of interference from the Wi-Fi
operations.
Sirius and XM Radio are the two radio satellite broadcasters that occupy the band between 2320-2345 MHz. Although the two operators acknowledge that there have not yet been any problems from Wi-Fi operations, it is felt that preventive measures should be imposed to circumvent problems in the future. The DARS
operators have even gone as far as to develop filters that can be used by Wi-Fi manufacturers and incorporated these filters into their systems in an effort to better control interference with the DARS band. Wi-Fi industry officials maintain that their systems will never interfere with the satellite radio operations. Furthermore, the Wi-Fi industry maintains that if any future problems were to arise, the satellite operators could just as easily fix them themselves through the employment of better filters on the DARS receivers.
FIELD DISTURBANCE SENSORS
Field disturbance sensors are devices that establish a radio frequency field and detect any changes to that field resulting from the movement of objects within that field. These devices are effectively utilized as intrusion alarm sensors. Under Part 15, these devices have been permitted to operate for many years in the 24.05-24.25 GHz band. This technology, however, has come under the scrutiny of amateur radio operators who feel that the higher power level these devices are permitted to operate in presents a needless threat of interference.
As new technologies continue to emerge, new interference concerns will undoubtedly arise. Because Part 15 has established an environment where emerging technologies have enjoyed the freedom to develop and grow without the restraints of heavy regulations, the devices we now rely on for convenience, productivity, and safety have proliferated our society.
At the same time, these very devices have created an atmosphere where telecommunications licensees must constantly fight to protect their operations and the lawful use of their spectrum in an interference-free environment.
The FCC has taken steps to exercise more control and ensure the interference-free operation of licensed users by expanding the rules of Part 15 to apply to more systems and by making the emissions criteria for these systems more stringent. Although they have a clear obligation to protect telecommunications licensees, one key goal of Part 15 remains to allow the
freedom of technology to advance without the presence of overwhelming and unnecessary regulations. It remains the job of the FCC to carry out this balancing act for the sake of both the licensed and unlicensed users of spectrum.
MICROWAVE
FCC Expands Eligibility for Cable Television Relay Service
The FCC adopted a Report and Order (R&O) that expanded eligibility for licenses in the CARS service to all Multi-channel Video Programming Distributors. In addition, all applicants in the CARS band are now required to complete prior coordination as outlined in Part 101. Dkt No 99-250, Details: DOC-222569A1.pdf
FCC Amends Part 15 of Its Rules
The FCC has amended its rules to promote the introduction of new digital transmission technologies for high-speed wireless communications. Dkt No 99-231, DOC-222567A1.pdf DOC-222567A2.pdf FCC-02-151A1.pdf
FCC Sets Rulemaking to Establish Remedial Measures for Failure to Construct Digital TV Facilities
All commercial broadcasters were required to construct their digital facilities by May 1, 2002. DOC-222561A4.pdf FCC-02-150A1.pdf
FCC Adopts Service and Licensing Rules for Reallocated Spectrum
The FCC adopted a R&O implementing new service rules governing a total of 27 MHz of spectrum. DOC-222572A1.pdf DOC-223251A1.pdf
FCC Releases Study on Telephone Trends
The report provides answers to some of the most frequently asked questions about the telephone industry asked by consumers, members of Congress, other government agencies, telecommunications carriers, and members of the business and academic community. DOC-222737A1.pdf
FCC and Industry Canada Sign Arrangement on Principles Governing Use Of 37.5- 42.5 GHz
DOC-222876A1.pdf
FCC Announces Formation of Spectrum Policy Task Force
The Spectrum Policy Task Force will seek public comment on issues related to the Commission's Spectrum Policies - DOC223142A1.pdf
FCC Initiates Proceeding to Promote Commercial Development of Spectrum in the 71-76 GHz, 81-86 GHz and 92-95 GHz Bands
Proceeding to examine methods to promote the commercial development and growth of spectrum in the 71-76 GHz, 81-86 GHz, and 92-95 GHz bands. DOC-223386A1.pdf DOC-223386A2.pdf DOC-223386A3.pdf
DOC-223386A4.pdf FCC-02-180A1.pdf
Wireless Telecommunications Bureau (WTB) Announces Plans for Electronic Filing of FCC Form 602
Beginning September 10, 2002, the WTB will make available electronic filing of FCC Form 602, FCC Ownership Disclosure Information for the Wireless Telecommunications Services via its Universal Licensing System (ULS) (DA No. 02-1644). DA-02-1644A1.pdf
OET Establishes Waiver Process to Permit Existing Ultra Wideband Devices to Continue Operation
(Dkt No 98-153) The FCC’s Office of Engineering and Technology (OET) adopted an Order today establishing a waiver procedure that will permit the continued operation of Ground Penetrating Radar (GPR) devices and wall-imaging devices. Under the new procedure, eligible users may operate under a blanket waiver to Part 15 regulations provided that they register their devices with the Commission. The waiver will be
contingent on finding no evidence of harmful interference to authorized services. DOC-224279A1.pdf
FCC to Amend Application Processing Fees
Effective September 10, 2002, the Federal Communications Commission will amend the application processing fees it charges applicants, licensees, and permittees. The Commission will make adjustment to reflect changes in the cost-of-living increases in the Consumer Price Index-Urban as of October 1, 2001. DOC-224312A1.pdf
The FCC adopted rules focused on the nature of the customer approval required before a telecommunications carrier can use, disclose, or permit access to customer information. (Dkt No 96-115, 96-149, 00-257). DOC-224366A1.pdf DOC-224366A2.pdf DOC-224366A3.pdf DOC-224366A4.pdf DOC-224366A5.pdf
SATELLITE
FCC Requires Radar Detectors to Comply With Emission Limits to Prevent Interference to Satellite Services
The FCC has imposed new emission limit and certification requirements for radar detectors. (Dkt No 01-278) DOC-224518A1.pdf
Globalstar Moving Forward
In two separate actions this past week, Globalstar is showing signs that it is adapting its MSS system and is in for the long haul. On July 24, 2002, Globalstar announced that it has demonstrated a wireless phone that can use the same radio spectrum to connect to both satellite and terrestrial communications networks. This type of technology referred to as Ancillary Terrestrial Component (ATC), allows existing satellite phone spectrum to also be used over
dedicated terrestrial networks, with call capacity managed and reallocated, in real time, between satellite and terrestrial networks via a common control center. Calls can be made over either network using the same phone handset, offering users truly universal service over a single phone system. The FCC is currently examining the regulatory implications of allowing such networks.
On July 17, Globalstar awarded a contract to Space Systems/Loral (SS/L) for the design and future construction of its 2 GHz satellite system, which will provide greater capacity and enhanced Globalstar services when the new constellation is fully deployed toward the end of this decade. This system will operate in the 1990-2025 MHz for the user terminal uplink and 2165-2200 MHz band for the user
downlink service. The constellation will consist of 56 low-earth-orbit satellites and four geostationary satellites to supplement coverage and capacity. The award calls for delivery of the 60 satellites starting in 2006.
DARS Continues to Roll on
On July 22, 2002, XM Satellite Radio ended the second quarter with more than 136,500 total subscribers exceeding most Wall Street projections. With XM's retail distribution rolling, General Motors is expanding factory installation of XM from the Cadillac DeVille and Seville to 23 additional GM models in the 2003 model year. Also, on July 1, Sirius Satellite Radio announced its 100-channel service of 60 commercial-free music channels and 40 news,
sports, and entertainment channels are now available across the continental United States.
Americom Sets Stage for Business Growth and Fleet Expansion in 2003 & 2004
On June 18,
SES Americom announced that it signed contracts to launch four new satellites. The satellites AMC-10, AMC-11, AMC-13, and AMC-15 will provide a variety of services. These new satellites are in addition to two other satellites, AMC-9 and AMC-12, already announced for launch. Additionally, AMC-16 has been contracted to be built. The purpose of the satellites are shown in the table below:
| Satellite Name |
Orbital Slot (degrees longitude) |
Frequency Band |
Purpose |
Operational Date |
| AMC-10 |
135 W |
C |
Cable TV, replaces C3 |
2004 |
| AMC-11 |
131 W |
C |
Cable TV, replaces C4 |
2004 |
| AMC-13 |
172 E |
C |
Transpacific Services |
2004 |
| AMC-15 |
105 W |
Ku and Ka |
Americom2Home |
2004 |
| AMC-9 |
79 W |
C and Ku |
US, Mexico, and Caribbean |
2003 |
| AMC-12 |
47 W |
C |
Transatlantic Services |
2003 |
| AMC-16 |
Ground spare |
Ku and Ka |
Americom2Home |
N/A |
Federal Communications Commission Revised Rules for DBS Satellites
In a Report and Order released June 13, 2002, IB Docket No. 98-21, the FCC revised the rules and policies governing the Direct Broadcast Satellite (DBS) service. The changes will streamline the regulation of this service, acknowledging changes in the industry and helping promote fair and increased competition in the multi-channel video programming distribution (MVPD) market.
The current rules in Part 100, for the most part, were adopted almost 20 years ago when DBS was envisioned to be essentially a broadcast-type service. Since that time, the service has instead grown into a robust and successful segment of the satellite industry with programming services provided on a subscription basis. The FCC believes that the service rules should now be revised to reflect the way that DBS actually operates. The Report and Order modifies DBS
regulation to more closely reflect the regulation of other satellite services, moves the rules for DBS to Part 25, and eliminates Part 100.
|
DBS Channel Assignments by Orbital Location |
|||||||||
| PERMITTEES/LICENSEES |
TOTAL |
175 |
166 |
157 |
148 |
119 |
110 |
101 |
61.5 |
| DIRECTV |
46 |
|
|
|
|
11* |
3* |
32* |
|
| EchoStar |
85 |
|
|
|
24* |
21* |
29* |
|
11* |
| R/L DBS |
11 |
|
|
|
|
|
|
|
11 [1] |
| Dominion |
8 |
|
|
|
|
|
|
|
8* [2] |
| Unassigned |
150 |
32 |
32 |
32 |
8 |
0 |
0 |
0 |
2 [3] |
FCC Cancels Echostar Ka-band Satellite Application and Echostar Vows to Challenge
On July 1, 2002,
the FCC’s International Bureau cancelled Echostar Satellite Corp’s authorization to construct, launch, and operate a Ka-band satellite system in the fixed-satellite service. The FCC claims that EchoStar has failed to satisfy the initial mandatory implementation milestone explicitly set forth in its authorization. This milestone requires EchoStar to commence construction of its Ka-band satellite system by January
2002. Consequently, EchoStar’s authorization is null and void. The orbit locations that had been assigned to EchoStar are available for reassignment.
In response, EchoStar says the decision is wrong and should be reversed. They claim the decision is based on the clearly inaccurate premise that EchoStar has not commenced construction of its first Ka-band satellite. The FCC apparently based that decision on an incorrect reading of EchoStar's satellite contract documents. EchoStar's commitment and progress are demonstrated by the imminent launch this year of a satellite equipped with the first ever commercial Ka-band satellite payload over North America. Echostar IX is a hybrid Ku and Ka band satellite. EchoStar says it is the first ever commercial Ka-band payload in North America. The completed satellite was allocated to EchoStar at 121 degrees West Longitude. Echostar intends to petition the FCC and believes that once the FCC examines all of the documentation it will reinstate its license.
____________________________________________________________
[1] Used by EchoStar pursuant to a grant of Special Temporary Authority.
[2] Dominion leases eight transponders on EchoStar III. EchoStar holds a license for 11 of the 32 DBS frequencies at 61.5° W.L. EchoStar is subleasing six of the transponders back from Dominion, subject to the control of Dominion as the licensee.
[3] Used by EchoStar pursuant to a grant of Special Temporary Authority