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The Small Deep Space Transponder is a transponder designed by JPL specifically for deep space probes.〔Sam Zingales, "Small Deep-Space Transponder Development," http://deepspace.jpl.nasa.gov/technology/TMOT_News/DEC95/zingales.htm (Dead site: see (archived version ), retrieved 11 March 2015)〕 It unifies a number of communication functions - receiver, command detector, telemetry modulator, exciters, beacon tone generator, and control functions - into one 3-kg package. The SDST is designed to handle X band uplink and both X band and Ka band downlink. JPL estimates that performing the same functions with separate units (as was done previously) requires over twice the mass and 4 or 5 individual subassemblies.〔(【引用サイトリンク】title=Technology: SMALL DEEP SPACE TRANSPONDER )〕 ==Functions== The capabilities of the SDST include:〔(【引用サイトリンク】title=Small Deep Space Transponder (SDST) DS1 Technology Validation Report )〕 *X-band receiver/downconverter capable of carrier tracking at or below −156 dBm. *Command detector unit function. *Telemetry modulation function. *X- and Ka-band exciters. *Beacon mode operation. *Coherent and noncoherent operation choice. *X- and Ka-band ranging. *Differential one-way ranging (DOR) for both X-band and Ka-band. *Command and Data Handling (C&DH) communication via MIL-STD-1553. *Data interface via EIA-422 (also known as RS-422). *External ports for temperature sensors. *External port for an analog signal. ==Missions== SDST has been used in the following missions: *Deep Space 1. This was a developmental mission that used the transponder for the first time, as part of an effort to qualify new technologies for flight. *''Deep Impact'' *''Dawn'' used a pair of SDSTs *Mars Exploration Rovers *Mars Reconnaissance Orbiter *MESSENGER *STEREO *Spitzer Space Telescope *A pair of SDSTs were used in the cruise stage of Phoenix (spacecraft). The lander used only UHF communication. *The Mars Science Laboratory includes two SDSTs, one on the descent stage and one on the lander itself. The SDST on the descent stage was the main transponder for the cruise and landing portions of the flight, with the SDST on the rover as a backup. The descent stage crashed after lowering the rover, and the SDST on the lander became the active transponder. As many tightly constrained, high-performance systems, the SDST has a number of idiosyncrasies in operation.〔 However, as the ''Dawn'' telecom 'lessons learned' section points out, the use of common hardware such as the SDST allows knowledge of these characteristics from previous projects.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Small Deep Space Transponder」の詳細全文を読む スポンサード リンク
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