Reliable X-Band and Ka-Band Deep Space Transmission

The Small Deep Space Transponder (SDST), developed by General Dynamics and NASA’s Jet Propulsion Laboratory, is a spacecraft terminal for X-Band and Ka-Band telecommunications with NASA's Deep Space Network. It is currently flying on multiple deep space missions totaling over 1,000,000 in-flight operational hours.

  • NASA's Deep-Space Network (DSN) Compatible
  • Radiation and SEU Tolerant
  • MIL-STD-1553 Interfaces – Standard and Low Power
  • Option for Ka-Band downlink (independent of X-band Functionality)

Product Details

Current Missions

The Small Deep Space Transponder (SDST) is currently flying on multiple deep space missions totaling over 1,000,000 in-flight operational hours including:


Making extensive use of MMICs, multi-chip modules, and a new signal processing ASIC, the Small Deep Space Transponder's (SDST) flexible design provides the capability to meet the telecommunication needs of nearly every deep space mission. The SDST has two configurations. The X/X configuration consists of an X-band receiver and an X-band 880F1 exciter. The X/X/Ka configuration consists of an X-band receiver, an X-band 880F1 exciter and an X-band 840F1 exciter. The 840F1 exciter drives an external x4, X-to-Ka-band multiplier mounted to the user’s Ka-band power amplifier, allowing interconnection by coaxial cable rather than waveguide.

  • Deep-Space Network Compatible
  • Redundant I/O for Cross-Strapping
  • X-Band Receiver, X and Ka-Band Exciters
  • 2.1 dB Typical Noise Figure @25°C
  • -158 dBm Typical Sensitivity @ 25°C
  • Temp Compensated Receiver VCO
  • Low Exciter Spurious, Phase Noise, and Allan Deviation
  • Radio Science Mode (using USO Input)
  • 6 ns Typical Ranging Delay Variation
  • 30 Mbps Max TLM Symbol Rate
  • 0.5 ns Typical Carrier Delay Variation
  • MIL-STD-1553 Interface – Standard and Low Power
  • External Power Converter Synchronization Capability
  • Operates Under Launch Environments
  • Radiation and SEU Resistant
  • Internal Telemetry Modulation Encoder
  • Internal Command Detector with External Baseband Input
  • Mounting in Either of Two Axes
  • Firmware Options:
    • Carrier Tracking Loop Bandwidth
    • Command Detector Subcarrier Frequencies and Data Rates
    • Custom Command/Telemetry Interface Format




Small Deep Space Transponder Data Sheet



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Mass 7.0 lbs (3.2 kg) maximum
Input Supply Voltage 22 to 36 VDC, or ±11 to ±18 VDC
Input Supply Power Receiver Only: 12.5 W nominal
Receiver + X-Band Exciter: 15.8 W nominal
Receiver + X and Ka-Band Exciters: 19.5 W nominal
Envelope Size 7.13”L x 6.55”W x 4.50”H
External Synch Frequency 125 kHz nominal
Radiation Total Dose 50 krads (Si) (part level), 100 krad optional
Operating Temperature -40 to +60° C