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- The Spectrum Monitor e-Zine Milcom Column Index - Update 8 Oct 2020
- The Milcom MT Files (1998-2013) Articles Index
UFO Milsat Program
Ultra High Frequency Follow-On (UFO) Program
By Larry Van Horn, N5FPW
Copyright © 2007-2013 by Monitoring Times magazine and the author.
Reproduction is not permitted with permission of the copyright holders. This article orgonally appeared in the April 2007 Milcom column in Monitoring Times magazine.
The United States Navy began replacing and upgrading its ultra-high frequency (UHF) communications network in 1993 with the first launch of a new generation of military satellites
This new constellation of customized satellites was built by Hughes Space and Communications Company, which is now Boeing Satellite Systems, Inc.
Known as the UHF Follow-On (UFO) series, these 601 model satellites support the Navy's global communications network, serving ships at sea and a variety of other U.S. military fixed and mobile terminals. They are compatible with ground- and sea-based terminals already in service. The UHF Follow-On satellites are intended to replace the Fleet Satellite Communications (FLTSATCOM) and the Hughes-built Leasat spacecraft.
In March 1996, under a contract modification for $150 million, the Navy ordered a high-power, high-speed Global Broadcast Service (GBS) payload to be incorporated onto payloads F8 through F10. This GBS package is revolutionizing communications for the full range of the Defense Department's high-capacity requirements, from intelligence dissemination to quality-of-life programming. The first GBS payload was put into service in 1998, and the final one was launched in November 1999.
In November 1999, the Space and Naval Warfare Systems Command's Communications Satellite Program Office added an 11th satellite to the contract. This satellite was launched on December 18, 2003 and will help sustain the constellation into the latter part of the decade.
Model 601 Platform
The UFO spacecraft has proven to be a very flexible platform for the evolution of critical advanced DOD communications services. These satellites consist of four different versions of the body-stabilized, three-axis Boeing 601 model platform.
The Boeing 601 satellite consist of two main modules. The bus module houses the bus electronics, propulsion subsystem, and battery packs. The payload module contains the communications equipment and antennas. The satellite dimensions when stowed were 11 feet high and 10.5 by 11.1 feet wide. Table one is a summary of various parameters for each of the four UFO satellite blocks.
Table One: UFO Satellite Block Summary
Spacecraft Block Weight Power L (ft) W (ft) Payload
F1 - F3 I 2600 lbs 2500 watts 60 23 UHF/SHF
F4 - F7 II 3000 lbs 2800 watts 60 23 UHF/SHF/EHF
F8 - F10 III 3400 lbs 3800 watts 75 22 UHF/EHF/GBS
F11 IV 3000 lbs 2800 watts 60 23 UHF/EHF
The first seven satellites and F11 measure more than 60 feet long from the tip of one three-panel solar array wing to the tip of the other. Spacecraft F8 through F10 each have four solar panels on a side, making the spacecraft 75 feet tip to tip. These arrays generate a combined 2,500 watts of electrical power on the first three satellites, 2,800 watts for F4 through F7 and F11, and 3,800 watts for F8 through F10 with the GBS communications payload.
The arrays are folded against the spacecraft bus for launch, forming a cube roughly 11 feet per side. The satellites weigh an average of 2,600 pounds with the UHF payload, 3,000 pounds with the additional EHF payload, and 3,400 pounds with the GBS payload.
The Atlas rocket series was chosen to provide the launches from Cape Canaveral, Florida. The Atlas I rocket was used for the F1 through F3 satellites. The Atlas II was chosen for F4 through F8, and an Atlas IIA for F9 and F10. The Atlas IIIB was used to launch UFO F11.
Increased Comm Capability with the UFO Birds
These UFO satellites were manufactured in El Segundo, California. Using a building-block approach, Boeing and the Navy enhanced the constellation's capabilities in stages. Satellites F1 through F3 carry UHF and SHF (super-high frequency) payloads to provide mobile communications and fleet broadcast services. Starting with F4, an additional EHF (extremely high frequency) payload was added to provide protected communications. F7 introduced an enhancement to the EHF package that essentially doubled traffic capacity in that band. The SHF payload was replaced by the high data rate GBS package on F8 through F10. F11 carries an enhanced EHF package and an upgraded UHF payload as well.
The UFO satellites offer DoD and the Navy increased communications channel capacity over the same frequency spectrum used by previous systems such as the FLTSATCOM and Leasat constellations. Each spacecraft has 11 solid-state UHF amplifiers and 39 UHF channels with a total 555 kHz bandwidth. The UHF payload comprises 21 narrowband channels at 5 kHz each and 17 relay channels at 25 kHz. By comparison, each FLTSATCOM platform offers 22 channels for two-way tactical communications. The 23rd channel on a FLTSATCOM carries the fleet broadcast service downlink. The F1 through F7 spacecraft include an SHF subsystem, which provides command and ranging capabilities when the satellite is on station as well as the secure uplink for Fleet Broadcast service, which is downlinked at UHF like its FLTSATCOM and Leasat cousins.
The Navy added an extremely high frequency communications package beginning with the fourth spacecraft. This addition comm capability includes 11 EHF channels distributed between an earth coverage beam and a steerable 5° spot beam and is compatible with Milstar ground terminals. The EHF subsystem provides enhanced antijam telemetry, command, broadcast, and fleet interconnectivity communications, using advanced signal processing techniques.
This new EHF Fleet Broadcast capability supersedes the need for the SHF fleet uplink and is replacing that communication function. With the launch of UFO F7 in 1996, the EHF package was enhanced to provide 20 channels through the use of advanced digital integrated circuit technology.
Some specifics communication information for some of the UFO satellites:
UFO F2 UHF payload, 39 UHF channels, transmit antenna/receive antenna
UFO F4, F5, F6 EHF payload, 8 EC services, 14 SBA services, spot beam antenna, EC horns
UFO F7 Enhanced EHF payload, 8 EC/SBA services or 32 SBA/EC service
UFO F8, F9, F10 Global Broadcast Service Payload, four x 24 Mbps transponders, three steerable transmit antennas, two receive antennas (1 steerable)
UFO F11 Digital payload, UHF services, EHF services
GBS Service Launched in 1998
The GBS payload replaced the SHF payload on spacecraft F8, 9, and 10. This new package includes four 130-watt, 24 megabits-per-second (Mbps) military Ka-band (30/20 GHz) transponders with three steerable downlink spot beam antennas (2 at 500 nmi and 1 at 2,000 nmi) as well as one steerable and one fixed uplink antenna. This modification resulted in a 96 Mbps capability per satellite. The three UFO GBS equipped spacecraft gives DOD a near-global coverage (except for the polar regions).
The latest payload UFO F11 is most similar to F7, providing UHF and enhanced EHF communications. The UHF payload incorporates a new UHF digital receiver, providing two additional UHF channels and greater flexibility in configuring communication services. We are currently working to identify the two new frequencies associated with this new comm package on UFO F11.
Table 2 is the launch summary for the UFO constellation. Table three is a complete listing of all the known bandplans/frequencies (less the new UHF channel capability on UFO F11) being used by these satellites.
Table Two: UFO Satellite Launch Summary
Sat/USA Launch Date Intl Desig/SSC# Miscellaneous NotesF1/None 3/25/1993 93-015A/22563 Launch failure, satellite left in useless orbit
F2/USA 95 9/3/1993 93-056A/22787 Initial slot 71.5 deg east, now 29 deg east
F3/USA104 6/24/1994 94-035A/23132 15.5 deg west
F4/USA 108 1/29/1995 95-003A/23467 177 deg west
F5/USA 111 5/31/1995 95-027A/23589 CONUS orbital slot (co located w/F6/7)
F6/USA 114 10/22/1995 95-057A/23696 105 deg west (Note: Tested at 171.5 deg west replaced Leasat 3, UFO Quebec?)
F7/USA 127 7/25/1996 96-042A/23967 CONUS orbital slot (co located w/F5/6)
F8/USA 138 3/16/1998 98-016A/25258 172 deg east
F9/USA 140 10/20/1998 98-058A/25501 22.5 deg west
F10/USA 146 11/23/1999 99-063A/25967 72.5 deg East
F11/USA 174 12/18/2003 03-057A/28117 Indian Ocean orbital slot (co located w/F10)
Note: Information in this table current as of November 2005. FSC-7 is operational over the Pacific and co located with UFO F4/F8. Leasat 5 is also parked in geo orbit just west of Australia and is reportedly being used by the Royal Aussie Navy. FSC-8 is co located with UFO F9. The UFO satellites listed above, FleetSatCom birds FSC-7/8, and Leasat 5 make up the current operational UHF constellation for the Department of Defense.
Table Three: UFO Bandplans-Frequencies
Fleet Broadcast Service
Row 1 Channel Number
Row 2 November Bandplan
Row 3 Oscar Bandplan
Row 4 Papa Bandplan
Row 5 Quebec Bandplan
Channel 1 250.350 250.450 250.550 250.650
Channel 1 Alternate 250.400 250.500 250.600 250.700
Navy Fleet Relay (25 kHz) channels (41 MHz offset)
Channel 2 251.850 251.950 252.050 252.150
Channel 3 253.550 253.650 253.750 253.850
Channel 4 255.250 255.350 255.450 255.550
Channel 5 256.850 256.950 257.050 257.150
Channel 6 258.350 258.450 258.550 258.650
Channel 7 265.250 265.350 265.450 265.550
Channel 8 266.750 266.850 266.950 267.050
Channel 9 268.150 268.250 268.350 268.450
Channel 10 269.650 269.750 269.850 269.950
Channel 11 260.375 260.575 260.425 260.625
Channel 12 260.475 260.675 260.525 260.725
Channel 13 261.575 262.075 261.625 262.125
Channel 14 261.675 262.175 261.725 262.225
Channel 15 261.775 262.275 261.825 262.325
Channel 16 261.875 262.375 261.925 262.425
Channel 17 263.575 263.775 263.625 263.825
Channel 18 263.675 263.875 263.725 263.925
UFO 5 kHz Non Processed Channels
Channel 19 243.915 243.995 244.075 244.155
Channel 20 243.925 244.005 244.085 244.165
Channel 21 243.935 244.015 244.095 244.175
Channel 22 243.945 244.025 244.105 244.185
Channel 23 243.955 244.035 244.115 244.195
Channel 24 243.965 244.045 244.125 244.205
Channel 25 243.975 244.055 244.135 244.215
Channel 26 243.985 244.065 244.145 244.225
Note: Non Processed Channel is a satellite transponder in which the received signal is amplified and frequency-translated, but the digital data is not reconstituted before retransmission.
UFO 5 kHz Channels
Channel 27 248.845 248.975 249.105 249.235
Channel 28 248.855 248.985 249.115 249.245
Channel 29 248.865 248.995 249.125 249.255
Channel 30 248.875 249.005 249.135 249.265
Channel 31 248.885 249.015 249.145 249.275
Channel 32 248.895 249.025 249.155 249.285
Channel 33 248.905 249.035 249.165 249.295
Channel 34 248.915 249.045 249.175 249.305
Channel 35 248.925 249.055 249.185 249.315
Channel 36 248.935 249.065 249.195 249.325
Channel 37 248.945 249.075 249.205 249.335
Channel 38 248.955 249.085 249.215 249.345
Channel 39 248.965 249.095 249.225 249.355
Copyright © 2007-2013 by Monitoring Times magazine and the author. Reproduction is not permitted without permission of the copyright holders. This article originally appeared in the April 2007 Milcom column in Monitoring Times magazine.