An upgrade to the very long baseline interferometry (VLBI) science receiver (VSR) — a radio receiver used in NASA’s Deep Space Network (DSN) — is currently being implemented. The current VSR samples standard DSN intermediate frequency (IF) signals at 256 MHz and after digital down-conversion records data from up to four 16-MHz baseband channels. Currently, IF signals are limited to the 265-to-375-MHz range, and recording rates are limited to less than 80 Mbps. The new digital front end, denoted the Wideband VSR, provides improvements to enable the receiver to process wider bandwidth signals and accommodate more data channels for recording. The Wideband VSR utilizes state-of-the-art commercial analog-to-digital converter and field-programmable gate array (FPGA) integrated circuits, and fiber-optic connections in a custom architecture. It accepts IF signals from 100 to 600 MHz, sampling the signal at 1.28 GHz. The sample data are sent to a digital processing module, using a fiber-optic link for isolation. The digital processing module includes boards designed around an Advanced Telecom Computing Architecture (ATCA) industry-standard backplane. Digital signal processing implemented in FPGAs down-convert the data signals in up to 16 baseband channels with programmable bandwidths from 1 kHz to 16 MHz. Baseband samples are transmitted to a computer via multiple Ethernet connections allowing recording to disk at rates of up to 1 Gbps.
This work was done by Andre Jongeling, Elliott Sigman, Robert Navarro, Charles Goodhart, Steve Rogstad, Kumar Chandra, Sue Finley, Joseph Trinh, Melissa Soriano, Les White, and Robert Proctor of Caltech and Benno Rayhrer (contractor) for NASA’s Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at www.techbriefs.com/tsp under the Electronics/Computers category. NPO-41191
This Brief includes a Technical Support Package (TSP).
Digital Front End for Wide-Band VLBI Science Receiver
(reference NPO-41191) is currently available for download from the TSP library.
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Overview
The document is a Technical Support Package for the Digital Front End for Wide-Band Very Long Baseline Interferometry (VLBI) Science Receiver, referenced as NPO-41191 by NASA. It serves as a comprehensive overview of the technological advancements and methodologies developed for high-performance digital signal processing in the context of aerospace applications.
Key components of the document include the specifications and capabilities of various hardware elements utilized in the system. Notably, the Virtex 2 Pro FPGA is highlighted, which offers a range of 2 to 100 million gates of digital logic, up to four IBM PowerPC processors operating at 400 MHz, and up to 24 RocketIO multi-gigabit transceivers capable of handling data rates of 3.125 Gbit/sec. This FPGA technology is crucial for managing the high data throughput required in wide-band VLBI applications.
The document also discusses the use of Infineon transceivers and cables, which enable twelve 2.7 Gbit/sec fiber links to be accommodated on a single fiber ribbon cable. This compact design is essential for efficient data transmission in space applications. The optical transceivers are noted for their small form factor, which is advantageous in minimizing space and weight in aerospace systems.
Additionally, the document outlines the signal processing architecture, which includes components such as an IF sampler, ADCs (Analog-to-Digital Converters), and advanced processing engines. The integration of these elements is designed to enhance the performance and reliability of the digital front end, facilitating high-resolution data collection and analysis.
The Technical Support Package emphasizes the collaborative nature of the research, indicating that the results are part of a broader initiative under NASA's Commercial Technology Program. It aims to disseminate aerospace-related developments that have potential applications beyond their original context.
Overall, the document serves as a resource for understanding the technological innovations in digital signal processing for VLBI, showcasing the capabilities of modern FPGAs, transceivers, and signal processing architectures. It also provides contact information for further inquiries and highlights the importance of these advancements in the field of aerospace technology.
