Hatfield & Dawson Consulting Engineers

Transcription

1 HATFIELD & DAWSON BENJAMIN F. DAWSON III, PE CONSULTING ELECTRICAL ENGINEERS TELEPHONE (206) THOMAS M. ECKELS, PE 9500 GREENWOOD AVE. N. FACSIMILE (206) STEPHEN S. LOCKWOOD, PE SEATTLE, WASHINGTON DAVID J. PINION, PE ERIK C. SWANSON, PE THOMAS S. GORTON, PE MICHAEL H. MEHIGAN, PE Suzanne Bosman Whatcom County Planning & Development Services 5280 Northwest Drive Bellingham, WA November 2013 JAMES B. HATFIELD, PE CONSULTANT MAURY L. HATFIELD, PE ( ) PAUL W. LEONARD, PE ( ) Dear Ms. Bosman; This purpose of this letter is to provide a basic framework for understanding the electromagnetic spectrum and how radio signals work, and to illustrate some key characteristics of the differences between AM radio and other uses of the spectrum. Electromagnetic Spectrum Bands The federal government, through the Federal Communications Commission ( FCC ), coordinates and regulates all uses of electromagnetic spectrum in the United States. Every portion of the spectrum is organized into types of uses. See attached United States Frequency Allocation chart and Radio Frequency Spectrum table. AM radio operates in the Medium Wave (MW) 1 band, and is different from FM which operates in the Very High Frequency band (VHF), 2 TV which operates in both the VHF band and the 1 MW is Medium Wave which is 300 khz to 3,000 khz (3 MHz). 2 VHF is Very High Frequencies from 30 to 300 MHz.

2 KRPI Site Selection and Radio Engineering Basics Page 2 Ultra-High Frequency band (UHF), 3 and cellular which also operates in the Ultra-High Frequency band. Other communications uses of the electromagnetic spectrum include Ham Radio, military communications, and emergency responder communications. There are also industrial spectrum uses that include heat sealing machines (for retail plastic packaging), fluorescent lighting, infrared temperature sensors, television remote controls, laser bar code scanners, etc. All of these common, everyday devices utilize different portions of the electromagnetic spectrum. Each portion of the spectrum has different uses and each portion of the spectrum behaves in a different manner. Different portions of the spectrum need different types of equipment in order to be harnessed for a useful purpose, and each portion of the spectrum has unique properties. As an example of the quality of these differences, consider a comparison between steel and ice. Both are solid structures that can be shaped into a bar, but the physical properties are quite different. Their melting points are different; their ability to resist fracture is different; and they can t be used for the same applications. Likewise, cellular spectrum has little in common with AM; and FM spectrum has little in common with AM. They are different frequencies and different spectrum uses, and for analytic purposes they should not be lumped together. 3 UHF is Ultra High Frequencies from 300 MHz to 3,000 MHz.

3 KRPI Site Selection and Radio Engineering Basics Page 3 Radio Propagation (how signals travel) FM and TV signals travel using line-of sight paths, so VHF antennas must be placed at elevated locations to transmit FM and TV signals. In the central Puget Sound region, these signals are primarily transmitted from towers at West Tiger Mountain, Cougar Mountain, Queen Anne Hill and Capitol Hill. In the northern Puget Sound region, FM and TV broadcasters tend to locate on Mt. Constitution on Orcas Island. The overwhelming majority of FM and TV stations in Western Washington transmit their signals from areas higher than 950 feet above mean sea level, to provide line-of sight service to radio receivers. VHF signals essentially travel the same way whether it is daytime or nighttime. The FM signal you listen to in your car traveled to your car receiving antenna on a direct, line-of-sight path from the transmission antenna. Similarly, cellular signals also travel by line-of-sight paths; cellular antennas must be elevated above obstructions such as trees or buildings in order to function at an optimal level. 4 In contrast, AM radio signals have unique propagation pathways. By analogy, if you placed an orange, sliced in half, wide (cut) face down on your desk, you d have a little dome. Imagine the orange core is an AM antenna holding the dome together like a tent. This is similar to what an AM signal looks like if you could see it. AM radio signals have two components, a groundwave signal (the part touching your desk in all directions) and a skywave signal (all the surfaces of the orange not touching your desk). The skywave signal bounces back to earth at night when one portion of the atmosphere's properties change by being shadowed from the sun. The groundwave signal travels along the surface of the Earth, and is the primary pathway to enable in-car or in-home reception of an AM radio station. Groundwave signals depend on specific properties of soil and topography; AM radio transmitters cannot typically be located on, or next to, hills, because such features impede groundwave signal propagation. 4 For AM radio, the entire length of each AM structure acts as an antenna. This contrasts with cellular signals, which are transmitted from panels or rods attached to another, non-transmitting structure, such as a monopole, light standard or building roof.

4 KRPI Site Selection and Radio Engineering Basics Page 4 After sundown, AM signals also travel using skywave propagation. Skywaves are radio waves that are reflected back to Earth by the ionosphere, and thus can travel much farther than do groundwaves. The ionosphere is the upper region of the earth s atmosphere located approximately 30 to 250 miles above the surface of the earth. Sunlight changes the physical properties of the ionosphere. During daytime AM signals are absorbed by the ionosphere, but at nighttime AM signals are reflected back to Earth. Tuning through the AM band at nighttime it is possible to experience skywave propagation. There are a number of radio stations from locations far away that can be received in this area. In particular, there are several San Francisco Bay area stations that have good coverage up and down the coast during nighttime hours. A good example of this phenomenon is radio station KFBK, which operates on 1530 khz in Sacramento, CA. KFBK cannot be received in the Puget Sound area during the daytime but at nighttime it is received quite well. The propagation change between daytime and nighttime often requires that a station use different antenna configurations and/or power levels during daytime and nighttime, in order to minimize interference to other stations. 5 Most stations use multiple antenna structures in order to reduce skywave interference, which affects the size of property needed for an antenna system. KRPI uses five structures in different combinations to change its signal. At least one AM station has 12 structures to shape its signal. Radio Physics (basic properties) 5 Interference is defined as unwanted signals degrading the performance of reception of a desired signal. Interference can be from several sources. These include: co-channel interference which is a signal broadcast on the same channel as the desired signal; adjacent channel interference which is a signal broadcast on a nearby channel; and electrical noise which is static that can come from electrical sources (hair dryer, flourescent lights, other electrical motors, power lines, etc.).

5 KRPI Site Selection and Radio Engineering Basics Page 5 Imagine a wave. In the common range for cellular frequencies of MHz, if you could see a cellular signal, the wavelength would be in the range between approximately four inches and approximately three feet long. If you could physically see an FM signal, the wavelength would be approximately six feet long. To transmit a signal, the wave needs an appropriately sized antenna to send the wave on its way to your radio. This is why cellular signals commonly use three to six foot long white rectangular panel antennas attached to towers or buildings. FM signals are transmitted from a bigger antenna element attached to a tower, as well. Cellular and FM only use the tower as a structure to elevate the antenna. In contrast, for AM radio, if you could physically see an AM signal, the wavelength would be 635 feet long at KRPI s of 1550 khz AM, and over 1,200 feet long at KGMI s of 790 khz AM. AM radio signals require structures that range in size from 150 feet tall to 750 feet tall. The entire piece of steel is the AM antenna. The KOMO 1000 antenna structures are each 500 feet tall to make the KOMO signal that you hear in your car. In addition, about half of an AM antenna system is buried in the ground. FM, TV, and cellular antennas don t operate that way. AM radio antennas require 120 copper wires around the base of each radiating element to develop the signal. These wires are the diameter of #2 pencil lead. The length of the wires is tied to the wavelength of the signal for example, for KRPI 160 feet and extend in a multidirectional pattern out from the above ground antenna structure. This takes up additional land. FM, TV, and cellular don t need large tracts of land for signal propagation in the way AM radio does.

6 KRPI Site Selection and Radio Engineering Basics Page 6 AM radio is also different from FM, TV, and cellular in another significant way. Many AM stations (including KRPI) must use a directional antenna at night to reduce potential interference to other stations on or near the same channel because of skywave propagation. KRPI also uses a directional antenna to protect a U.S. government monitoring station in Ferndale. A directional antenna system is one that produces more power in some directions and reduces the power in other directions. An understandable analogy for directional antennas is a floodlight. A floodlight puts a lot of light in one direction but behind it there is very little light. Directional antenna systems at AM frequencies require the use of multiple towers. FM, TV, and cellular don t need multiple towers to create a signal in the way AM does. The majority of AM radio stations in this area use directional antennas. KOMO, 1000 khz (3 towers); KIRO, 710 khz (2 towers); KJR, 950 khz (5 towers); and KNWX, 770 khz (3 towers), all use directional antenna systems to satisfy their interference and coverage requirements. And, adding towers increases the land-area requirement when attempting to site an AM transmission antenna. Because the physical properties of cellular, AM, and FM are all different(with different spectrum wavelengths, frequencies, transmission systems, and power levels) it should come as no surprise that the analysis of the properties of one area of the band may not readily apply to another area of the band. To use a rough analogy, extrapolating information in that manner would be like attempting to use an analysis of a Toyota Prius to explain why a Kenworth truck has a problem. Overview of AM Radio History and Regulation AM radio was developed approximately 50 years after Morse Code, and was advanced for commercial use just after the dawn of the 20 th Century. By 1920, AM radio was fully developed. The fundamental technology infrastructure required for AM radio has remained the same for nearly 100 years. The FCC regulates all non-federal use of radio spectrum, including AM radio. An AM radio station s location, and power are dictated and controlled by

7 KRPI Site Selection and Radio Engineering Basics Page 7 federal rules. The FCC Rules (along with international treaties relating to use of the spectrum) have been developed over the last 83 years and are designed to provide public service while minimizing interference to and from other broadcast facilities. The rules are codified in Title 47 of the Code of Federal Regulations. Radio Coverage AM radio signal strengths are measured in Volts per meter (V/m) 6. The FCC requires that AM radio stations provide a predicted 5 mv/m daytime signal and a 5 mv/m nighttime signal or a Nighttime Interference Free (NIF) signal, whichever is greater, over the city of license. KRPI s NIF signal is 38.5 mv/m. In this case, the FCC requires that KRPI cover all of Point Roberts with a minimum of 38.5 mv/m. The transmitter site needs to be located in Point Roberts to achieve this objective. AM radio receivers vary greatly in sensitivity and much has been written lately about the poor performance of AM receivers built today. The general practice for broadcaster use for coverage is 2 mv/m for coverage in vehicles, 5 mv/m to 25 mv/m for in home and 25 mv/m in downtown office buildings. On a Walkman-type portable radio, you may need as much as 5 millivolts (5 mv/m) of AM signal to have static-free reception. 7 The reason for these recommended AM signal levels is to overcome the effects of interference. Sources of interference include electrical noise from fluorescent lights, computers, TVs, office equipment, overhead power lines, and other appliances operating near a radio that can overload the AM receiver. In a city core, stations generally need more AM signal than this because of heavy attenuation inside large steel structures like office buildings. In your home, depending on the location, type of radio, and the utilization of any external antennas, you can have good reception with signals between 1 mv/m and 25 mv/m. KPRI is attempting to increase its daytime power to overcome these sources of interference. 6 1 mv/m (millivolts per meter) = V/m and 1 µv/m (microvolts per meter) = 0.000,001 V/m 7 International Telecommunication Union Recommendation 415-2, Type A Receivers, ITU-R, Volume 1997 BS Series

8 KRPI Site Selection and Radio Engineering Basics Page 8 Power is measured in Watts (W). One kilowatt (kw) is equal to 1,000W. The transmitter output power for an AM radio station in the United States ranges from 1 to 50 kw. Elsewhere in the world, AM radio stations operate at power levels ranging as high as 500 kw. 8 In the Puget Sound area KOMO 1000 khz, KIRO 710 khz, KYCW 1090 khz, KJR 950 khz, KRKO 1380 khz, and KKXA 1520 khz are all authorized and licensed to operate full time at this power. The proposed power for KRPI is 50 kw daytime and 50 kw nighttime. Antenna Theory AM antenna heights are referenced to a wavelength 9 (this only includes the radiating portion of the antenna structure). In AM broadcasting, 5/8 wavelength (or 225 ) antennas are more efficient than ¼ wave antennas. A ¼ wavelength (or 90 ) antenna is near the lower end of acceptable antenna heights. Antenna heights below 1/5 wavelength are undesirable as efficiencies decrease dramatically around this height resulting in reduced coverage. A 225 antenna provides the maximum coverage and is the theoretical maximum. The efficiency also decreases for antennas taller than 225, which results in reduced coverage. In summary, taller towers are more efficient for AM (to a point) and shorter towers decrease coverage and are more difficult to work with. The following table summarizes the heights and efficiencies of the proposed KRPI facility: 8 As a side note, the United States Navy operates a Very Low Frequency (VLF) transmitter site near Arlington, Washington with an output power of 3 million Watts. VLF frequencies are lower than those used by AM and travel around the globe along the surface of the Earth. 9 Wavelength or is determined by the following formula: = c/f where f is in Hz (1/S - where S is time in Seconds) and c is the speed of light in meters per second (299,792,458 m/s). A full wavelength for KRPI operating at 1550 khz is = m or ft. Antenna heights (and other antenna dimensions) are also expressed in electrical degrees where = 360 and ¼ = 90.

9 KRPI Site Selection and Radio Engineering Basics Page 9 Station Overall Height Active Element Active Element KRPI 1550 khz Element Height (electrical degrees) Efficiency (mv/m at 1 km for 1 kw) 150 feet 141 feet 43 meters mv/m The theoretical ideal antenna element height for KRPI is 356 feet tall and the theoretical minimum is 158 feet tall. KRPI has gone below the typically acceptable minimum threshold of 1/4 in order to develop an antenna system that is minimally intrusive. Please feel free to contact me should you have any questions. Sincerely, Stephen S. Lockwood, P.E.

10 Radio Frequency Spectrum Band name Abbreviation ITU band Tremendously low Extremely low Super low Ultra low Very low Low Medium High Very high Ultra high Super high Extremely high Terahertz or Tremendously high TLF ELF SLF ULF Frequency and wavelength in air < 3 Hz > 100,000 km 3 30 Hz 100,000 km 10,000 km Hz 10,000 km 1000 km Hz 1000 km 100 km VLF khz 100 km 10 km LF khz 10 km 1 km MF khz 1 km 100 m HF MHz 100 m 10 m VHF MHz 10 m 1 m UHF MHz 1 m 100 mm SHF GHz 100 mm 10 mm EHF GHz 10 mm 1 mm THz or THF ,000 GHz 1 mm 100 μm Example uses Natural and artificial electromagnetic noise Communication with submarines Communication with submarines Submarine communication, Communication within mines Navigation, time signals, submarine communication, wireless heart rate monitors, geophysics Navigation, time signals, AM longwave broadcasting (Europe and parts of Asia), RFID, amateur radio AM (medium-wave) broadcasts, amateur radio, avalanche beacons Shortwave broadcasts, citizens' band radio, amateur radio and over-the-horizon aviation communications, RFID, Over-the-horizon radar, Automatic link establishment (ALE) / Near Vertical Incidence Skywave (NVIS) radio communications, Marine and mobile radio telephony FM, television broadcasts and line-of-sight ground-to-aircraft and aircraft-to-aircraft communications. Land and Maritime communications, amateur radio, weather radio Television broadcasts, microwave ovens, microwave devices/communications, radio astronomy, mobile phones, wireless LAN, Bluetooth, ZigBee, GPS and two-way radios such as Land, FRS and GMRS radios, amateur radio Radio astronomy, microwave devices/communications, wireless LAN, most modern radars, communications satellites, satellite television broadcasting, DBS, amateur radio Radio astronomy, high- microwave radio relay, microwave remote sensing, amateur radio, directed-energy weapon, millimeter wave scanner Terahertz imaging a potential replacement for X-rays in some medical applications, ultrafast molecular dynamics, condensedmatter physics, terahertz time-domain spectroscopy, terahertz computing/communications, sub-mm remote sensing, amateur radio

11 UNITED NOT ALLOCATED Maritime Radionavigation (Radio Beacons) STATES STANDARD FREQ. AND TIME SIGNAL (20 khz) STANDARD FREQ. AND TIME SIGNAL (60 khz) Radionavigation (Radio Beacons) 3 khz 300 khz FREQUENCY 300 Radionavigation (Radio Beacons) Maritime Radionavigation (Radio Beacons) Radionavigation (DISTRESS AND CALLING) (SHIPS ONLY) (AM ) TRAVELERS INFORMATION STATIONS (G) AT 1610 khz 300 khz 3 MHz (TELEPHONY) (TELEPHONY) (DISTRESS AND CALLING) (TELEPHONY) STANDARD FREQ. AND TIME SIGNAL (2500kHz) Space Research STANDARD FREQ STANDARD FREQ. AND TIME SIGNAL 2850 (R) 3000 THE SPECTRUM (R) (OR) 3 MHz * ** (R) * (R) (OR) * STANDARD FREQ. AND TIME SIGNAL (5000 KHZ) STANDARD FREQ. Space Research ALS ** 54.0 (R) (OR) * * (R) (OR) (R) (OR) 88.0 STANDARD FREQ. AND TIME SIGNAL (10,000 khz) STANDARD FREQ. Space Research (R) * (OR) (R) (OR) (R) * * * STANDARD FREQ. AND TIME SIGNAL (15,000 khz) STANDARD FREQ. Space Research (OR) (R) (OR) STAND. FREQ. & TIME SIG. Space Research STANDARD FREQUENCY & TIME SIGNAL (20,000 KHZ) STANDARD FREQ. Space Research ISM 6.78 ±.015 MHz ISM ±.007 MHz ISM ±.163 MHz (R) * (OR) ** STANDARD FREQ. AND TIME SIGNAL (25,000 khz) STANDARD FREQ. Space Research ** ** ** ** 30 MHz 300 SERVICES COLOR LEGEND DETERMINATION Radio Astronomy (TV CHANNELS 2-4) (TV CHANNELS 5-6) (FM ) (R) (R) (R) (R) (R) MET. SAT. MET. SAT. MET. SAT. MET. SAT. MOB. SAT. OPN. Mob. Sat. OPN. MOB. SAT. OPN. Mob. Sat. OPN. NAV- Land (TV CHANNELS 7-13) 30 MHz ISM ±.02 MHz 300 MHz STD. FREQ. & TIME SIGNAL SAT. (400.1 MHz) MET. SAT. Space Opn.. SAT. MET. AIDS (Radiosonde) Met-Satellite Earth Expl. Earth Expl Sat Satellite EXPL SAT. MET-SAT. OPN. Earth Expl Sat Met-Satellite EXPL SAT. MET-SAT. MET. AIDS (Radiosonde) AIDS (SONDE) (S-S) Meteorological Satellite (TV CHANNELS 14-20) (TV CHANNELS 21-36) TV BROADCAST BROADCAST BROADCAST SPA CE ( Passive) ** -SAT ** EXPL SAT (TLM) (TLM) (TLM) -SAT (TLM) (TLM) ** ( TELEMETERING) SAT. (Space to Earth) ** (Aero. TLM) SAT. (Space to Earth) SAT. (Space to Earth) (space to Earth) Satellite (S- E) (R) (space to Earth) (Space to Earth) (R) (space to Earth) (R) (space to Earth) NAV. (Space to Earth) DET. SAT. SAT SAT. SAT. Sat. AERO. AERO. NAV. DET. SAT. AERO. NAV. DET. SAT. SAT. AIDS (SONDE) ** AIDS (Radiosonde) (s-e) MET. SAT. (s-e) EXPL. OP. (s-s) SAT. (s-s) (s-s) MOB. FX. S) SAT. (s-e)(s-s) OPERATION (s-e)(s-s) (s-e)(s-s) (LOS) (LOS) ** R- LOC. B-SAT. ** MOB FX BCST- MET. AIDS (Radiosonde) MOB FX R- LOC. B-SAT DETERMINATION SAT. BCST - SAT. ** FX-SAT (S - E) E-Expl Sat Radio Ast Space res. MOB** B- SAT. FX FX-SAT ASTRON. EXPL SAT AIDS AIDS OPERATION MHz ISM ± 13 MHz ISM ± 50 MHz GHz STANDARD FREQUENCY AND TIME SIGNAL STANDARD FREQUENCY AND TIME SIGNAL (Ground) SAT. AERO. NAV.(Ground) SAT. ** ** Space Research AERO. NAV. SAT NAV. AIDS - sat (s-e) SAT SAT Satellite Satellite Satellite MET. Satellite EXPL. Satellite (no airborne) Satellite (no airborne) MET. EXPL. SAT. EXPL. (deep space only) Meteorological Aids Satellite EXPL. EXPL. ** (Deep Space) NAV. Space Research SAT. Standard Freq. and Time Signal Satellite Space Research Land Satellite SAT. Space Research Land Satellite ** SAT. Land Satellite FX SAT. L M Sat Space Research Space Research Space Research EXPL. SAT. AERO NAV SAT Space Res.(act.) Radioloc. LOC. Earth Expl Sat Space Res. BCST SAT. FX SAT FX SAT EXPL. SAT. SAT. FX SAT STD FREQ. & TIME FX SAT SAT EXPL. SAT. ** RAD.AST ** EXPL. SAT. RES. EXPL. Earth Expl. Satellite (Active) Earth Expl. Satellite (Active) Standard Frequency and Time Signal Satellite Earth Exploration Satellite (S-S) std freq e-e-sat SAT. & time e-e-sat (s-s) SAT. Earth Exploration Satellite (S-S) Earth Exploration Satellite (S-S) SAT 3 GHz ISM 5.8 ±.075 GHz ISM ± GHz 30 GHz ACTIVITY CODE GOVERNMENT EXCLUSIVE NON-GOVERNMENT EXCLUSIVE AL USAGE DESIGNATION SERVICE EXAMPLE DESCRIPTION Primary Capital Letters Secondary 1st Capital with lower case letters GOVERNMENT/ NON-GOVERNMENT SHARED Standard Frequency and Time Signal Satellite Stand. Frequency and Time Signal Satellite 30 GHz (deep space) SAT EXPL. RE.. (space-to-earth) RES. SAT. - SAT. EXPL SAT Earth Expl. Sat (s - e) RES. SAT. SAT FX-SAT BROAD- CASTING BCST SAT. BCST SAT. BROAD- CASTING ** SAT. NAV. MOB. SAT NAV.SAT. FX SAT FX SAT FI XED SAT EXPL-SAT SAT -ES SAT -ES INTER - SAT RES. SAT LOC. RES.. ** ISM ±.250 GHz GHz IS DESIGNATED FOR UNLICENSED DEVICES ** LOC. LOC. Sat. LOC. SAT Satellite BROAD- CASTING BROAD- CASTING EXPL. EXPL SAT. Amatuer E A R T H EXPL. SAT RES. SAT. MO- BILE EXPL SAT. ISM ±.500 GHz Satellite EXPL. SAT. SAT. EXPL. Satellite ISM ± 1GHz 300 GHz * EXCEPT AERO (R) This chart is a graphic single-point-in-time portrayal of the Table of Frequency Allocations used by the FCC and NTIA. As such, it does not completely reflect all aspects, i.e., footnotes and recent changes made to the Table of Frequency Allocations. Therefore, for complete information, users should consult the Table to determine the current status of U.S. allocations. U.S. DEPARTMENT OF COMMERCE DMINISTRATION ANATIONAL TELECOMMUNICATIONS & INFORMATION U.S. DEPARTMENT OF COMMERCE National Telecommunications and Information Administration Office of Spectrum Management October 2003 ** EXCEPT AERO WAVELENGTH BAND DESIGNATIONS ACTIVITIES 3 x 10 7 m 3 x 10 6 m 3 x 10 5 m 30,000 m 3,000 m 300 m 30 m 3 m 30 cm 3 cm 0.3 cm 0.03 cm 3 x 10 5 Å 3 x 10 4 Å 3 x 10 3 Å 3 x 10 2 Å 3 x 10Å 3Å 3 x 10-1 Å 3 x 10-2 Å 3 x 10-3 Å 3 x 10-4 Å 3 x 10-5 Å 3 x 10-6 Å 3 x 10-7 Å VERY LOW FREQUENCY (VLF) LF MF HF VHF UHF SHF EHF INFRARED VISIBLE ULTRAVIOLET X-RAY GAMMA-RAY COSMIC-RAY Audible Range AM Broadcast FM Broadcast P L S C X Radar Bands Radar Sub-Millimeter Visible Ultraviolet Gamma-ray Cosmic-ray Infra-sonics Sonics Ultra-sonics Microwaves Infrared X-ray FREQUENCY 0 10 Hz 100 Hz 1 khz 10 khz 100 khz 1 MHz 10 MHz 100 MHz 1 GHz 10 GHz 100 GHz 1 THz Hz Hz Hz Hz Hz Hz Hz Hz Hz Hz Hz Hz Hz THE SPECTRUM 3 khz MAGNIFIED ABOVE 300 GHz PLEASE NOTE: THE SPACING ALLOTTED THE SERVICES IN THE SPEC- TRUM SEGMENTS SHOWN IS NOT PROPORTIONAL TO THE ACTUAL AMOUNT OF SPECTRUM OCCUPIED.