# aae 450 – senior design

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AAE 450 – Senior Design. J. Darcey Kuhn ERV Team – Communications January 23, 2001. Parameters. High Gain Antenna Sizes – Beamwidth and antenna gain Capacity (i.e. number of channels of each type) – or bandwidths and frequencies - PowerPoint PPT Presentation

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• AAE 450 Senior Design

J. Darcey KuhnERV Team CommunicationsJanuary 23, 2001

• ParametersHigh Gain Antenna Sizes Beamwidth and antenna gainCapacity (i.e. number of channels of each type) or bandwidths and frequenciesUplink & Downlink signal strength and quality to Deep Space Network (DSN) support communications, science data, voice, video, engineering telemetry, and navigationhttp://deepspace.jpl.nasa.gov/dsn/

• High Gain AntennaBeamwidth: from an antenna pattern, the angle between the half-power (3 dB) points of the main lobe, when referenced to the peak effective radiated power of the main lobehttp://132.163.64.205/fs-1037/dir-004/_0572.htm

• High Gain Antenna

A useful rule of thumb for calculating beamwidth is 3 dB beamwidth = 70 / D (degrees)where is wavelength and D the antenna diameter

• High Gain AntennaAntenna Gain (Isotropic) for a uniformly illuminated antenna with physical area A, the directive gain at the center of the main beam is given by:

http://web.bham.ac.uk/eee1roj8/wbe/wbe031.htm

• High Gain Antenna

G = 4**A/2A= d2/4

Gain is normally expressed in dBs by taking 10*log(G)Surveyor: 42.41 dBSpace Shuttle: Uplinking: 42.39 dBDownlinking: 43.14 dB

• Bandwidths & FrequenciesBandwidth: Amount of data that can be transferred in a fixed amount of timeSpace Shuttle uses S-band (1,700 to 2,300 MHz) & Ku-band (15,250 to 17,250 MHz) to transfer informationKu-band located in the payload bayKu-band (12-18 GHz / = 2.5 to 1.67 cm) can handle higher quantities of data than the S-band systems (3 channels of data)All transmissions broadcasted by Surveyor utilized X-band radio signals near 8.4 GHz

• Deep Space NetworkDSN is an international network of antennas that supports interplanetary spacecraft missionsCurrently consists of three deep-space communications facilities placed approximately 120 degrees apart around the world CA, Spain, and Australia

• Antenna MountingHigh-gain antenna sits at the end of a long boomTwo rotating joints, called gimbals, hold antenna to boomGimbals will allow the antenna to automatically track and point at the Earth

• Future Enhancementshttp://deepspace.jpl.nasa.gov/dsn/array/index.html

• Future EnhancementsCost AnalysisPowerConsumptionSignalSignal-to-Noise RatioWeightHistorically lowFailure Probability Low Gain Antenna as back-up

• Related Skills

Matlab, Fortran 77, UNIX, AutoCAD, CCurrently enrolled in 490E (Satellite Systems)Two co-op tours with United Space Alliance at Johnson Space Center uplinking data from the MCC to ISS

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