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  • Ka-band High-rate Telemetry System Upgrade for the NASA Deep Space Network

    Paper number

    IAC-09.B2.4.6

    Author

    Mr. Remi LaBelle, Jet Propulsion Laboratory, United States

    Coauthor

    Mr. Abner Bernardo, Jet Propulsion Laboratory - California Institute of Technology, United States

    Coauthor

    Mr. James Bowen, Jet Propulsion Laboratory - California Institute of Technology, United States

    Coauthor

    Mr. Michael Britcliffe, Jet Propulsion Laboratory - California Institute of Technology, United States

    Coauthor

    Mr. Neil Bucknam, Jet Propulsion Laboratory - California Institute of Technology, United States

    Coauthor

    Mr. Christopher Link, Jet Propulsion Laboratory - California Institute of Technology, United States

    Coauthor

    Ms. Ezra Long, Jet Propulsion Laboratory - California Institute of Technology, United States

    Coauthor

    Ms. Leslie Manalo, Jet Propulsion Laboratory - California Institute of Technology, United States

    Coauthor

    Mr. James A. O'Dea, Jet Propulsion Laboratory - California Institute of Technology, United States

    Coauthor

    Mr. David Rochblatt, Jet Propulsion Laboratory - California Institute of Technology, United States

    Coauthor

    Mr. John Sosnowski, Jet Propulsion Laboratory - California Institute of Technology, United States

    Coauthor

    Mr. Watt Veruttipong, Jet Propulsion Laboratory - California Institute of Technology, United States

    Year

    2009

    Abstract
    The NASA Deep Space Network (DSN) has a new requirement to support Category A (Cat A) missions (within 2 million kilometers of Earth) with simultaneous S-band uplink, S-band downlink and Ka-band downlink.   The S-band links are required for traditional TT&C support to the spacecraft, while the Ka-band link is intended for high-data-rate science returns.  Several 34-meter DSN antennas have previously been upgraded to support the Category B (Cat B or deep space) Ka-band, at 31.8 - 32.3 GHz, referred to as Ka1.  However, this upgrade task, referred to as Ka-band Phase 2 or Ka2, is the first time the DSN will be used to support the Cat A downlink band at 25.5 - 27.0 GHz.  The initial Cat A support is required for the James Webb Space Telescope (JWST) in 2013 and possibly other missions. The upgrade is currently being implemented into 3 different 34-meter BWG antennas in the DSN, one at each of the complexes in Canberra (Australia), Goldstone (California) and Madrid (Spain). 
    The current mission requirements for the Ka2 upgrade dictate a low-noise, cryogenic system for the front end and a high-data-rate system for the back end.  The key requirements for the Ka2 system are as follows:  
    G/T $>$= 60.7 dB/K (vacuum) at 45 deg elevation
    System noise temperature (vacuum) $<$= 36 K
    Pointing accuracy $<$ 5.5 mdeg (mean radial error)
    Antenna gain measurement accuracy $<$ 0.4 dB
    Compression point dynamic range $>$ 135 dB-Hz (in a 1 Hz bandwidth)
    Data rate: 1 to 150 Mbps, QPSK
    Symbol rate: up to 350 Msym/sec, QPSK
    Doppler measurement accuracy $<$ 0.05 mm/sec, 1 sigma
    The task adds a new dichroic reflector (M6A) and feed/LNA subsystem to enable simultaneous Cat A S-band transmit, S-band receive and Ka-band receive at 3 different 34-meter beam waveguide (BWG) antennas.  The M6A mirror is a new design that is optimized for performance ($<$ 7K noise contribution across the band) and manufacturability for low-cost.  The new mirror is required to be selectable using a shuttle mechanism, so that the antenna can operate in any of 3 modes (up/down/down):  S/S/X, X/X/Ka1 or S/S/Ka2.   
    The RF design is driven by both the dynamic range and bandwidth requirements. The system temperature requirement is met by using cryogenic low-noise amplifiers, cooled to 10K.   The dynamic range requirement is achieved with a low-noise fiber optic link, to transport the X-band IF signals from the antennas to the Signal Processing Centers (SPC), which are up to 20 km away.  In order to minimize equipment in the antennas, a block Ka-to-X band downconverter is used in the antennas.  Further downconversion and channel selection, with an X-to-IF downconverter, is then done in the SPC.  Telemetry processing is done using a “2-box” commercial telemetry subsystem, consisting of a demodulator and telemetry processor. The demodulator assembly also generates an IF test signal, that is upconverted to Ka-band and routed to the antennas via fiber optic link for injection at the LNA inputs. Software development was limited to modifications to the existing DSN monitor and control programs, to reduce development time and cost.  The operator interfaces remain basically the same to allow a quick transition from development to transferred operations.   This reduces the required “soak” period and the required operator personnel training.
    System test data will be presented to show that the requirements were met and the DSN is ready for Cat A Ka-band operational support.
    
    Abstract document

    IAC-09.B2.4.6.pdf

    Manuscript document

    IAC-09.B2.4.6.pdf (🔒 authorized access only).

    To get the manuscript, please contact IAF Secretariat.