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  • 1
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    SATS: Small, Automated Tracking System - - Elements of a Better System for Satellite Tracking and Telemetry (1994)
    In:  Other Sources
    Details
    Publication Date: 2018-06-08
    Description: JPL has been exploring applications of precise Global Positioning System (GPS) techniques to navigation and data communication for Earth orbiting spacecraft. GPS tracking can be exploited in several different ways, depending on the orbital altitude of the spacecraft of interest, to support orbit and trajectory determination. At low-Earth orbits below 3000 km, 'upwards-looking' GPS tracking analogous to ground-based GPS tracking can be used to provide real-time orbit determination for navigation. At Earth orbiting altitudes between 3000 km and 8000 km, visibility of GPS rapidly decreases and it becomes advantageous to add a nadir pointing antenna in order to continuously see enough GPS signals to navigate an orbiter. For orbits above 8000 km, JPL has developed the GPS-like tracking (GLT) technique which dispenses with the on-board GPS receiver in favor of a transmitting beacon whose phase is tracked, simultaneously with normal GPS signals, by a ground network of 'enhanced' GPS receivers. The systems referred to above all have the potential to provide inexpensive and autonomous navigation/orbit production and, in some cases, integrated data communication for a wide class of Earth orbiters and should be of interest to designers of NASA, military, and commercial space systems.
    Keywords: Communications and Radar
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    NASA TECHNICAL REPORTS
  • 2
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    New Ground and Space-Based GPS Tracking Techniques For High-Earth and Deep Space Orbit Determination Appplications (1994)
    In:  Other Sources
    Details
    Publication Date: 2018-06-08
    Description: Satellites of the Global Positioning System (GPS) can be used to provide precise position and velocity information for receivers on the surface of the Earth, in aircraft, or in low-Earth orbit.
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    NASA TECHNICAL REPORTS
  • 3
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    Relative Sensor with 4Pi Coverage for Formation Flying Missions (2004)
    In:  CASI
    Details
    Publication Date: 2018-06-06
    Description: The Terrestrial Planet Finder (TPF) pre-project, an element of NASA s Origins program, is currently developing two architectures for a mission to search for earth-like planets around nearby stars. One of the architectures being developed is the Formation Flying Interferometer (FFI). The FFI is envisioned to consist of up to seven spacecraft (as many as six "collectors" with IR telescopes, and a "combiner") flying in precise formation within +/-1 cm of pre-determined trajectories for synchronized observations. The spacecraft-to-spacecraft separations are variable between 20 m and 100 m or more during observations to support various configurations of the interferometer in the planet-finding mode. The challenges involved with TPF autonomous operations, ranging from formation acquisition and formation maneuvering to high precision formation control during science observations, are unprecedented. In this paper we discuss the development of the formation acquisition sensor, which uses novel modulation and duplexing schemes to enable fast signal acquisition, multiple-spacecraft operation, and mitigation of inherent jamming conditions, while providing precise formation sensing and integrated radar capability. This approach performs delay synthesis and carrier cycle ambiguity resolution to improve range measurement, and uses differential carrier cycle ambiguity resolution to make precise bearing angle measurements without calibration maneuvers.
    Keywords: Spacecraft Design, Testing and Performance
    Type: Proceedings from the 2nd International Symposium on Formation Flying Missions and Technologies; NASA/CP-2005-212781
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Digital GPS-Signal Processor With P-Code/No-P-Code Option (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Size, power, and cost reduced by exploiting commonality. Digital signal processor for Global Positioning System (GPS) receiver set to operate in "code" mode when P code known, or in "codeless" mode when P code not known. In codeless mode, processor performs full-quadrature processing, resulting in signal-to-noise ratio (SNR) 6 dB greater than SNR's of processors not performing at full quadrature.
    Keywords: ELECTRONIC SYSTEMS
    Type: NPO-18831 , NASA Tech Briefs (ISSN 0145-319X); 18; 5; P. 85
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    NASA TECHNICAL REPORTS
  • 5
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    Relay Support for the Mars Science Laboratory Mission (2013)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Lunar and Planetary Science and Exploration; Space Communications, Spacecraft Communications, Command and Tracking
    Type: IEEE Aerospace Conference; Mar 02, 2013 - Mar 09, 2013; Big Sky, MT; United States
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    NASA TECHNICAL REPORTS
  • 6
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    Chip Advancer For GPS Receiver (1989)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: Instrument errors made negligible. For each integration interval, both delay and rate of change of delay initialized to small fraction of chip - for example, to order of 10 to the negative 7th power - thereby making feedback control and extraction of delay highly accurate and flexible. With appropriate selection of sampling rate relative to chip rate, commensurability errors reduced to extremely small levels. In Global Positioning System (GPS) receiver, pseudorandom code sequence generated by simple digital logic incorporating effects of time, delay, and rate of change of delay. Flexibility in starting time and sum interval very useful in aligning correlation interval with beginnings and endings of data bits.
    Keywords: ELECTRONIC SYSTEMS
    Type: NPO-16996 , NASA Tech Briefs (ISSN 0145-319X); 13; 6; P. 40
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    NASA TECHNICAL REPORTS
  • 7
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    Counterrotator And Correlator For GPS Receivers (1989)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Description: Accurate, all-digital, high-speed processor comprising correlator and down-converter developed for receivers in Global Positioning System (GPS). Processor reduces roundoff and commensurability errors to extremely small values. Use of digital chip and phase advancers provides outstanding control and accuracy in phase and feedback. Great flexibility imparted by provision for arbitrary starting time and integration length. Minimum-bit design requires minimum number of logical elements, thereby reducing size, power, and cost.
    Keywords: ELECTRONIC SYSTEMS
    Type: NPO-16998 , NASA Tech Briefs (ISSN 0145-319X); 13; 6; P. 34
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    NASA TECHNICAL REPORTS
  • 8
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    Challenges of Communications and Tracking for Solar System Small Body Exploration (2011)
    In:  Other Sources
    Details
    Publication Date: 2019-08-14
    Description: This presentation will address: (1) Communications capabilities that will be needed for space missions for Small Planetary Body exploration (2) Utilization of large ground-based radar capabilities for Small Body remote sensing and mission planning
    Keywords: Space Communications, Spacecraft Communications, Command and Tracking
    Type: 4th Meeting of the NASA Small Bodies Assessment Group; Mar 24, 2011 - Mar 26, 2011; Washington, DC; United States
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    NASA TECHNICAL REPORTS
  • 9
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    Relay Support for the Mars Science Laboratory Mission (2013)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The Mars Science Laboratory (MSL) mission landed the Curiosity Rover on the surface of Mars on August 6, 2012, beginning a one-Martian-year primary science mission. An international network of Mars relay orbiters, including NASA's 2001 Mars Odyssey Orbiter (ODY) and Mars Reconnaissance Orbiter (MRO), and ESA's Mars Express Orbiter (MEX), were positioned to provide critical event coverage of MSL's Entry, Descent, and Landing (EDL). The EDL communication plan took advantage of unique and complementary capabilities of each orbiter to provide robust information capture during this critical event while also providing low-latency information during the landing. Once on the surface, ODY and MRO have provided effectively all of Curiosity's data return from the Martian surface. The link from Curiosity to MRO incorporates a number of new features enabled by the Electra and Electra-Lite software-defined radios on MRO and Curiosity, respectively. Specifically, the Curiosity-MRO link has for the first time on Mars relay links utilized frequency-agile operations, data rates up to 2.048 Mb/s, suppressed carrier modulation, and a new Adaptive Data Rate algorithm in which the return link data rate is optimally varied throughout the relay pass based on the actual observed link channel characteristics. In addition to the baseline surface relay support by ODY and MRO, the MEX relay service has been verified in several successful surface relay passes, and MEX now stands ready to provide backup relay support should NASA's orbiters become unavailable for some period of time.
    Keywords: Lunar and Planetary Science and Exploration; Space Communications, Spacecraft Communications, Command and Tracking
    Type: IEEE Aerospace Conference; Mar 02, 2013 - Mar 09, 2013; Big Sky, MT; United States
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