IVS-4th General Meeting, Concepción- Chile, Jan 2006 DBBC - A Flexible Platform for VLBI Data Process G. Tuccari, S. Buttaccio, G. Nicotra - Istituto di Radioastronomia CNR - Italy Y. Xiang - Shanghai Astronomical Observatory, CAS – China M. Wunderlich - Max Planck Institute fuer Radioastronomie, Bonn - Germany 4thGeneral Meeting International VLBI Service 4th General Meeting International VLBI Service January 9-13, 2006 Universidad de Conception NEXT GENERATION VLBI2010

IVS-4th General Meeting, Concepción- Chile, Jan 2006 DBBC Project ‘DBBC’ is a project supported by the European VLBI Network for the development of a Digital Base Band Converter The main goal was to replace the existing terminal with a complete compact system to be used with any VSI compliant recorder or data transport Hardware programmability is the main feature in order to optimize the architecture to the needed performance having the possibility to arrange different architecture in the same hardware support The new development is compatible with the existing terminals and correlators

IVS-4th General Meeting, Concepción- Chile, Jan 2006 DBBC Project (cont.) The new backend is fully up-gradable and ready to process larger bandwidth with new generation correlators Upgrade or improvements is mostly only software Upgrade is also possible in hardware replacing compatible ‘pin- to-pin’ processing modules Data out as VSI interfaces

IVS-4th General Meeting, Concepción- Chile, Jan 2006 DBBC General Features 4 RF/IF Input from 16 in the range GHz Four polarizations or bands available for a single group of 64 output data channel selection (support 2 VSI) 2 30,29 Hz frequency sampling clock Channel bandwidth ranging between 250KHz and 16 MHz (MK4) Channel bandwidth between 32 and 512 MHz (wide modes) Tuning step 1 Hz Multiple architecture using fully re-configurable FPGA Core Modules (Down-Converter, Equally Spaced Multichannel, etc.) Modular realization for cascaded stack processing

IVS-4th General Meeting, Concepción- Chile, Jan 2006 DBBC General Schematic ADB 1 PC FS PC 2 30,29 MHz Synthesizer H-Maser 2xVSI 64 ch CORE HSI HSO PCI Interfaces AGC/ Filter IFD 1,2,3,4 IFC 1,2,3,4 IFB 1,2,3,4 IFA 1,2,3,4 ADB2 ADB 3 ADB 4 HSIR HSOR CORE HSI HSO HSIR HSOR AGC/ Filter AGC/ Filter AGC/ Filter CORE HSI HSO HSIR HSOR FILAFILA FILAFILA CCM CCMR CCM CCMR CCM CCM R HSO CCM Analog Monitor

IVS-4th General Meeting, Concepción- Chile, Jan 2006 System Components ConditioningModule FiLa board – First/Last (VSI int., DA monit, Clock and Timing ,29 Hz Synthesizer, Communication, JTAG channel) ADBoard – Analog to digital conversion CoreModule boards – processing unit FPGAs Core Firmware Configurations PowerDistributor PC Board + PCI interfaces (commercial) System Management Software, Field System oriented

IVS-4th General Meeting, Concepción- Chile, Jan 2006 Schematic System Top View 8U x 84 TE x 500 mm ADBCoreModule VSI IF2 IF3IF4 10 MHz 1 PPS IF1 PC and Interfaces FiLa FiLaVSI Ethernet DISKDISK JTAG Adapter Monitor IF1 IF2 IF4 FiLa ConditioningModule min 1 – max 4 ConditioningModule FiLaVSI PowerDistributor IF3

IVS-4th General Meeting, Concepción- Chile, Jan 2006 ConditioningModule Pre-AD Conversion Signal Conditioning Pre-AD Conversion Nyquist Band Definition 4 IFs input selection Output Power Level Control Total Power Measurement

IVS-4th General Meeting, Concepción- Chile, Jan 2006 FiLa Board First and Last board in the stack First: Communication Interface JTAG programming channel 1PPS synchronizer Hz synthesizer Last: 2 VSI Interfaces DA Converter

IVS-4th General Meeting, Concepción- Chile, Jan 2006 ADBoard Analog to Digital Converter Analog input: GHz Sampling clock: Hz Output Data: 2 x Hz DDR

IVS-4th General Meeting, Concepción- Chile, Jan 2006 CoreModule Basic processing unit Max Input Rate: 4 x Gb/s Max Output Rate: Gb/s ( MHz) Digital Down Converter: 1 CoreModule = 1 BBC Programmable architecture Equally Spaced Multichannel: 1 CoreModule = 64 channels

IVS-4th General Meeting, Concepción- Chile, Jan 2006 Core Module Board HIS/HSIR Cascade-able Input Bus 2 29 MHz DDR HSO Shared Output bus 64, 128MHz CCM Control / Configuration bus 32bit CCM Monitor bus to DA converter 12 MHz 1 FPGA VirII-1152pin, 3000 ( – 8000 compatible) Stack cascade method to join up to 16 boards

IVS-4th General Meeting, Concepción- Chile, Jan 2006 DBBC 4 ADBoard + 8 CoreModule Stack

IVS-4th General Meeting, Concepción- Chile, Jan 2006 Digital Base Band Converter

Digital Base Band Converter

IVS-4th General Meeting, Concepción- Chile, Jan 2006 PC Board: System Management Software Standard commercial PC board including HD Configuration files for each FPGA stored on HD Software interface for FPGA configuration Software interface for servicing FPGAs (I/O registers access) Software interface for AD level control Field System – like commands in standalone and remote (ethernet)

IVS-4th General Meeting, Concepción- Chile, Jan 2006 Minimal Architecture With fixed configuration and external RF control and clock generation: 1 ADBoard 1 CoreModule (multichannel configuration, or any other) 1 FiLa board (VSI interface, DA converter, etc) Components cost < 3.5 K€

IVS-4th General Meeting, Concepción- Chile, Jan 2006 Maximum Architecture With fixed configuration and external RF control and clock generation: 4 Conditioning Modules 1 FiLa board 4 ADBoard 16 CoreModule 1 FiLa board PC and PCI interfaces

IVS-4th General Meeting, Concepción- Chile, Jan 2006 DBBC System in January 1 st 2006 Ready for testing in radiotelescopes Next TOG in Westerbork in March demonstration on field Program with observations/optimization Update program for improving performance: - FPGA Virtex4 device for double processing clock and price reduction - Faster AD sampler for input bandwidth increasing - AD sampler placed inside the receiver and sampled data sent through an optical fiber - RFI Mitigation Board: the first CoreModule (same hardware) acts as RFI processor in transfer the pure sampled data with proper configuration.

IVS-4th General Meeting, Concepción- Chile, Jan 2006 First Results with the mDBBC prototype (collaboration Italy-China) First digital x analog fringes detected on Nov 23, 2004 in the Seshan-Urumuqi baseline First digital x digital fringes detected on Feb 2, 2005 in the Noto-Seshan baseline

IVS-4th General Meeting, Concepción- Chile, Jan 2006 Conclusions The DBBC system is an high flexible instrument because is able to produce independent tunable channels for a full compatibility with the existing acquisition system and correlators. One CoreModule board is replacing a BBC module. Combination of up to 4/16 IFs in a single module is possible. The DBBC system is able to handle also equi-spaced multichannel configuration for producing contiguous not tunable channels. One CoreModule board is able to produce multiple channels. More solutions are possible within the same system with software selection

IVS-4th General Meeting, Concepción- Chile, Jan 2006 The DBBC is here: Please ask if you need to have a look inside!