Nov 3, 2009 RN - 1 Jet Propulsion Laboratory California Institute of Technology Current Developments for VLBI Data Acquisition Equipment at JPL Robert Navarro Doug Wang Melissa Soriano Les White Eric Clark © 2009 California Institute of Technology. Government sponsorship acknowledged. 7 th US VLBI Technical Meeting

Nov 3, 2009 RN - 2 Jet Propulsion Laboratory California Institute of Technology JPL VLBI Roadmap VLBI Systems for Radio Reference Frame and Time & Earth Motion Precision Observations: –Replace aging VLBI Data Acquisition Terminal hardware (based on MarkIV hardware) with modern Digital Backend based system. –At the same time, upgrade to Mark5C disk packs for data storage. –Make incremental improvements to JPL VLBI Software Correlator to support Mark5C hardware and data formats. –Maintain compatibility with other VLBI centers for DSN support of Host Country activities. VLBI Systems for Double Differential One Way Ranging –Incremental upgrades to Wideband VLBI Science Receiver (WVSR). –WVSR optimized for narrow band processing. (But, modified version of channelization firmware planned for JPL Roach Board firmware). –Developed initially for radio science experiments. Can follow spacecraft frequency predicts to millihertz accuracy. Long Term Goal is to have flexible JPL digital backend system that can handle both tasks. Moving to Digital Backend hardware based on Roach board gets us closer to goal, but not all the way there. –Different requirements, operating modes, file formats, system interfaces require two systems for now.

Nov 3, 2009 RN - 3 Jet Propulsion Laboratory California Institute of Technology Plans for Modernized JPL VLBI DAT System Plan is for two IF system to cover up to 500 GHz of bandwidth. An IF Switch will handle up to 10 IF inputs. Sampling Bandwidth of each IF is 640 MHz but 1dB bandwidth of each system after anti-aliasing filters is 500 MHz Accepts DSN IF input band of MHz. Good for S band (2.3 GHz), X band (8.4 GHz) and Ka band (31.2 GHz) Planning on using JPL IF sampler module, CASPER ROACH board for Digital Processing and Channelization. Upgrade to Mark5C disk packs for data storage Would like to use DSN based Wideband VLBI Science Receiver as underlying basis of system control software and develop VEX interface layer on top of that structure. –Need to interface to JPL Deep Space Network monitor & control infrastructure.

Nov 3, 2009 RN - 4 Jet Propulsion Laboratory California Institute of Technology Block Diagram of new JPL VLBI DAT System

Nov 3, 2009 RN - 5 Jet Propulsion Laboratory California Institute of Technology Usage of ROACH Board at JPL Roach Board boots to Borph version of Linux. Remote boot used with operating system hosted on remote computer over network. Linux Memory Mapped drivers for PPC440 processor series implemented for similar boards using PPC440GX processor. Allows EBC bus access at User Level, not kernel level of Linux. Runs in Borph environment. Implemented simple data capture design with 1 GHz sampling iADC card using CASPER framework. Successfully tested out 10GbE interface from between two Roach Cx4 Ports. Developed version of data capture design that sends data out 10GbE interface to anther computer with 10GbE NIC. Investigating best network parameters and performance of this link. Currently have two Roach Boards at JPL for VLBI backend development. Would like to order about 10 more ROACH boards in the next few months.

Nov 3, 2009 RN - 6 Jet Propulsion Laboratory California Institute of Technology JPL Digitizer to Roach Interface Developments Developed interface board to connect optically isolated 1280 MHz ADC to ROACH board. Board is currently being assembled and should be ready for test in Mid October. This ADC will be used for JPL’s VLBI digital backend and for radio science experiments that require a very low noise spurs in the spectrum over narrow (~1 KHz) bandwidths. Interface board developed and in initial testing. Initial firmware also developed. Raw samples 1280 MHz digitized samples captured over Digitizer to ROACH interface board.

Nov 3, 2009 RN - 7 Jet Propulsion Laboratory California Institute of Technology Firmware Developments for VLBI Backend Wideband 1280 MHz real to seven channel 160 MHz wide channel filterbank completed. Channels centered at 80, 160, 240, 320, 400, 480 and 560 MHz. Firmware for narrow band channels (variable 32 MHz to 1 KHz) developed and tested on Wideband VLBI Science Receiver Hardware (XC2VP50 chips) and currently being ported to ROACH FPGA (SX95T) Firmware currently only sends data over EBC and Gigabit Ethernet Interface to disk at rates up to 400 Mbit/sec. 10Gbit Interface to Mark5C (VDIF) not yet developed.

Nov 3, 2009 RN - 8 Jet Propulsion Laboratory California Institute of Technology Plans for Modernized Software Systems Input files: VEX-formatted.SKD files Output Data: Mark 5C disk modules in VDIF format Output Configuration: PCFS formatted log file compatibility Interface to JPL Deep Space Network monitor & control infrastructure Configuration flexibility for new/changing experiment goals

Nov 3, 2009 RN - 9 Jet Propulsion Laboratory California Institute of Technology Outstanding Software Issues Input files: VEX-formatted.SKD files –Will all experimenters follow this path? Output Data: Mark 5C disk modules in VDIF format –What are other station/correlator plans? Bonn Haystack USNO JIVE Output Configuration: PCFS formatted log file compatibility –What do external correlators require from log files?

Nov 3, 2009 RN - 10 Jet Propulsion Laboratory California Institute of Technology JPL VLBI DAT Modernization Summary NASA Deep Space Network navigation requirements are main driver for VLBI Data Acquisition modernization at JPL –Improve system sensitivity (higher bandwidths), maintainability, accuracy and flexibility. Support non-DSN customers at Deep Space Network sites. Maintain compatibility with Haystack Mk5 systems. Maintain expertise and flexibility to make modifications for internal customers and science experiments. Leverage off developments in VLBI community Look for opportunities to make technical contributions to developments of new VLBI data recording systems.