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NASA Tracking and Data Relay Satellite System (TDRSS)
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According to NASA:
The Tracking and Data Relay Satellites (TDRS) comprise the communication satellite component of the Tracking and Data Relay Satellite System (TDRSS). TDRSS is a communication signal relay system which provides tracking and data aquisition services between low-earth orbiting spacecraft and control and/or data processing facilities. The system is capable of transmitting to and receiving data from spacecraft over at least 85% of the spacecraft's orbit.
The TDRSS space segment consists of six on-orbit Tracking and Data Relay Satellites located in geosynchronous orbit. Three TDRSs are available for operational support at any given time. The operational spacecraft are located at 41°, 174° and 275° West longitude. The other TDRSs in the constellation provide ready backup in the event of a failure to an operational spacecraft and, in some specialized cases, resources for target of opportunity activities.
The TDRSS ground segment is located near Las Cruces, New Mexico, known as the White Sands Complex. Forward data is uplinked from the ground segment to the TDRS and from the TDRS to the spacecraft. Return data is downlinked from the spacecraft via the TDRS to the ground segment and then on to the designated data collection location.
The Tracking and Data Relay Satellite (TDRS) Project is providing follow-on and replacement spacecraft necessary to maintain and expand the Space Network. The contract to build three additional TDRS spacecraft, known as TDRS K, L, and M, was awarded to Boeing Space Systems in December 2007. TDRS K launched January 30, 2013, and TDRS L launched January 23, 2014. TDRS M's launch readiness date is scheduled for 2015. The contract also has options for one additional spacecraft, TDRS N. In addition to building the TDRS K, L, and M spacecraft, the contract also includes the modifications to the White Sands Complex (WSC) ground system required to support these new spacecraft.
The TDRS Project, established in 1973, is responsible for the development, launch, and on-orbit test and calibration of TDRS spacecraft. There have been four procurements of TDRS spacecraft, which include the Basic Program (TDRS F1-F6), the Replacement Program (TDRS F7), the TDRS H,I,J Program, and the TDRS K,L,M Program. TDRS Flight 7 was a replacement for Flight 2, which was lost aboard Challenger in 1986. The first seven spacecraft (TDRS F1-F7) are referred to as the First Generation, the H,I,J series are called the Second Generation, and the K,L,M series are known as the Third Generation. TDRS F1-7 spacecraft were built by TRW (now Northrop Grumman) in Redondo Beach, CA. The TDRS F8-10 (H,I,J) spacecraft were built by Hughes (now Boeing) in El Segundo, CA.
The NASA Space Network consists of the on-orbit telecommunications TDRS satellites, placed in geosynchronous orbit, and the associated TDRS ground stations, located in White Sands, New Mexico and Guam. The TDRS constellation is capable of providing nearly continuous high bandwidth (S, Ku, and Ka band) telecommunications services for expandable launch vehicles and user spacecraft in low Earth orbit. Examples include: the Hubble Space Telescope, the Earth Observig Fleet and the International Space Station. The TDRS System is a basic agency capability and a critical national resource.
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Paired Frequency Bands |
| Paired Bands | Use | Service | Table |
| 2025.8 - 2117.9 MHz | S-band Single Access (TDRS transmit) | Space Operation | F |
| 2200 - 2300 MHz | S-band Single Access (TDRS receive) | Space Research (space-to-Earth) | F |
| 2103.4 - 2109.4 MHz | S-band Multiple Access (TDRS transmit) | Space Operation | F |
| 2285 - 2290 MHz | S-band Multiple Access (TDRS receive) | Space Operation (space-to-Earth) | F |
| 13.4 - 14.05 GHz | TDRS downlink | Space Research | F |
| 14.6 - 15.25 GHz | TDRS uplink | Space Research (Earth-to-space) | F |
| 13.75 - 13.8 GHz | Ku-band Single Access (TDRS transmit) | Space Operation | F |
| 14.891 - 15.116 GHz | Ku-band Single Access (TDRS receive) | Space Research (space-to-Earth) | F |
Frequencies |
| Frequency | Bandwidth | Use | Service | Table |
| 2036 MHz | - | TDRS command uplink | Space Operation | F |
| 2211 MHz | - | TDRS telemetry downlink | Space Operation | F |
| 13.731 GHz | - | TDRS telemetry downlink | Space Operation | F |
| 14.785 GHz | - | TDRS command uplink | Space Operation | F |
| 15.15 GHz | - | TDRS reference frequency signal uplink | Space Operation | F |
Frequency Bands |
| Band | Use | Service | Table |
| 25.25 - 27.5 GHz | Ka-band Single Access (TDRS receive) | Space Research | F |
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Proposed Air-Ground Broadband for Passengers Aboard Aircraft
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The FCC has proposed the establishment of a new air-ground mobile broadband service in the 14.0-14.5 GHz band. The current primary allocation is to the Fixed Satellite Service. The FCC proposes to achieve compatibility through “spatial diversity” rules, which would limit the directions in which antennas can point. Since the 14.0-14.5 GHz band is used for sending transmissions from the Earth towards satellites orbiting over the equator, U.S. earth stations all point south, more or less. Antennas in the proposed system would point north (in the case of ground stations) or downwards (in the case of the antennas on the aircraft), which should reduce their interference with satellite users.
The following information is edited from the FCC's Notice of Proposed Rulemaking,FCC 13-66:
We propose to establish a new, terrestrial-based air-ground mobile broadband service with aircraft in the 14.0-14.5 GHz band. The service would provide multi-gigabit broadband connectivity to aircraft flying within the contiguous United States. The service is intended for the business and personal use of passengers aboard aircraft, and will have no role in aeronautical operations or as a safety of life and property service.
The 14.0-14.5 GHz band is allocated on a primary basis to the FSS as an uplink (Earth-to-space) band for geostationary orbit (GSO) FSS operations. The air-ground mobile broadband service would operate on a secondary basis to GSO satellite systems and future non-geostationary orbit (NGSO) satellite systems, and on a co-secondary basis with the National Aeronautics and Space Administration (NASA) Tracking and Data Relay Satellite System (TDRSS) that operates under a Federal Fixed Service (FS) and Mobile Service (MS) allocation. In addition to coordinating with NASA TDRSS in the 14.0-14.2 GHz band, we propose that air-ground mobile broadband would also be required to coordinate with Radio Astronomy Service (RAS) users in the 14.47-14.5 GHz band, in accordance with the procedures set forth for other services in this band. To implement this service, we propose to amend Part 2 of the rules to add a secondary allocation in the non-Federal Aeronautical Mobile Service (AMS) for air-ground mobile broadband in the 14.0-14.5 GHz band.
We propose that under the rules we implement for the 14.0-14.5 GHz band to support the new allocation, we would require a licensee to use this spectrum for air-ground mobile broadband only. We also seek comment regarding the appropriate regulatory framework for the proposed provision of service. We seek comment on our proposal to classify the services as Commercial Mobile Radio Service (CMRS) given the proposed air-ground use of the spectrum. With respect to whether and how to apportion the spectrum, we seek comment on Qualcomm’s proposal to create two 250 megahertz licenses as well as on alternate approaches such as licensing the entire 500 megahertz of spectrum to a single licensee or dividing the spectrum into more than two blocks. Given the proposed air-ground use of the band, we propose to license the spectrum on a nationwide basis. We also seek comment on whether to adopt an open eligibility standard and whether to adopt any specific aggregation limits applicable to the initial licensing of the band.
To the extent that we adopt a geographic licensing scheme for the 14.0-14.5 GHz band, and permit the filing of mutually exclusive applications, we seek comment on a number of proposals relating to competitive bidding. We propose that the Commission conduct an auction in conformity with the general competitive bidding rules set forth in Part 1, Subpart Q, of the Commission’s rules, and seek comment regarding bidding credits for small businesses.
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Frequency Bands |
| Band | Use | Service | Table |
| 14 - 14.5 GHz | - | ARMR | N |
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Radio Astronomy Formaldehyde (H2CO) Observations
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Radio astronomers observe molecular lines of formaldehyde at both 14.49 GHz and 4830 MHz. According to the European Science Foundation's Committee on Radio Astronomy Frequencies (CRAF):
At 14.4885 GHz an important formaldehyde (H2CO) line exists, which has been observed in the direction of many galactic sources. Since these lines originate from the upper levels of ortho-formaldehyde their study gives valuable information on the physical conditions of the interstellar medium, because the excitation energies required to produce such lines are different from the energies required to produce the H2CO lines observed at 4829.66 MHz.
There is no formal allocation to the radio astronomy service in these bands, but the international footnote 5.149 and the U.S. footnote US203 note that consideration should be taken to the use of 14.47-14.5 GHz and 4825-4835 MHz band segments for radio astronomy.
In the U.S., there is an increasing use of the entire 14-14.5 GHz band by vehicle-, ship-, and airplane-based Internet terminals that communicate through geostationary satellites (14-14.5 GHz is used as the uplink band). Such activities are required by the FCC to be coordinated with the radio astronomy service.
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Frequency Bands |
| Band | Use | Service | Table |
| 4825 - 4835 MHz | Radio astronomy observations of formaldehyde (4829.66 MHz) | Radio Astronomy | - |
| 14.47 - 14.5 GHz | Radio astronomy observations of formaldehyde (14.4885 GHz) | Radio Astronomy | - |
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