A one-page document describes a Ka-band transponder being developed for use in deep-space radio science. The transponder receives in the Deep Space Network (DSN) uplink frequency band of 34.2 to 34.7 GHz, transmits in the 31.8 to 32.3 GHz DSN downlink band, and performs regenerative ranging on a DSN standard 4-MHz ranging tone subcarrier phase-modulated onto the uplink carrier signal. A primary consideration in this development is reduction in size, relative to other such transponders.
The transponder design is all-analog, chosen to minimize not only the size but also the number of parts and the design time and, thus, the cost. The receiver features two stages of frequency down-conversion. The receiver locks onto the uplink carrier signal. The exciter signal for the transmitter is derived from the same source as that used to generate the first-stage local-oscillator signal. The ranging-tone subcarrier is down-converted along with the carrier to the second intermediate frequency, where the 4-MHz tone is demodulated from the composite signal and fed into a ranging-tone-tracking loop, which regenerates the tone. The regenerated tone is linearly phase-modulated onto the downlink carrier.
This work was done by Matthew S. Dennis, Narayan R. Mysoor, William M. Folkner, Ricardo Mendoza, and Jaikrishna Venkatesan of Caltech for NASA’s Jet Propulsion Laboratory. NPO-45598
This Brief includes a Technical Support Package (TSP).
Ka-Band Transponder for Deep-Space Radio Science
(reference NPO-45598) is currently available for download from the TSP library.
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Overview
The document is a Technical Support Package for NASA's Ka-Band Transponder for Deep-Space Radio Science, identified as NPO-45598. It outlines the technical specifications and operational principles of the transponder, which is designed for communication in deep-space missions.
The Ka-band transponder operates within the Deep Space Network (DSN) uplink frequency range of 34.2 GHz to 34.7 GHz and transmits in the downlink frequency range of 31.8 GHz to 32.3 GHz. It employs a super-heterodyne receiver that locks onto the uplink carrier frequency, ensuring reliable communication with spacecraft. The transponder's architecture includes a voltage-controlled crystal oscillator (VCXO) that serves as a reference frequency for local oscillators (LOs), which are critical for signal processing.
The document details the generation of local oscillator signals, including an 8.0 GHz phase-locked oscillator (PLO) that is multiplied to 32 GHz for the first LO and a 2.2 GHz PLO for the second LO. The ranging mode receiver tracks a standard 4 MHz ranging tone subcarrier, which is phase-modulated onto the carrier. This subcarrier is downconverted along with the carrier to a second intermediate frequency (IF) of 67 MHz, where the composite signal is processed. The original 4 MHz tone is demodulated and used in a tracking loop to enhance the signal-to-noise ratio (SNR) of the transmitted tone.
The transponder's design includes a two-stage downconverter, with the first LO frequency set to the nominal transmit frequency of 32 GHz and the second LO frequency at 2.215 GHz. The VCXO in the carrier tracking loop locks onto the carrier at the second IF, facilitating accurate signal tracking and transmission.
The document emphasizes the proprietary nature of the information and its compliance with U.S. export regulations. It also provides contact information for further inquiries, including an email address for the Innovative Technology Assets Management at JPL.
Overall, this Technical Support Package serves as a comprehensive resource for understanding the capabilities and functionalities of the Ka-band transponder, highlighting its significance in advancing deep-space communication technologies.
