TOWARDS MODELS OF REALISTIC COMPUTING MACHINES IN COMPUTER SCIENCE

The paper presents an approach to system modelling in design of both hardware and software systems. It is based on the definition of models of machines that can be directly implemented. The paper shows how to render less abstract and more realistic the abstract machines defined by theoreticians, so that they can capture implementation and technological-oriented aspects, such as testability, and allow an easy transition to final implementations. A realistic abstract machine for lambda-calculus is then presented and the design of system for lambda-expressions evaluation is illustrated. The architecture chosen for the system is based on a collection of finite state automata, evolving concurrently and communicating via a broadcast system. Some conclusive remarks about the use of realistic models arc finally drawn

R&D experiences on FPGAs and astronomical applications at IASF Milano

The paper describes R&D activities that were or are currently developed at the INAF - IASF Milano and that involve the usage of FPGAs for astrophysical applications. They span from the emulation of radiation induced faults in SRAM-based FPGAs to the development of a backend unit for the SKA low frequency antennas and astronomical detectors

Cabinet clock distribution network for low-frequency aperture array

Square Kilometer Array (SKA)-Low is the radio telescope operating in the lowest frequency band of the SKA, from 50 up to 350 MHz. It consists of 512 stations, each composed of 256 dual-polarization log-periodic antennas for a total of 262,144 independent signal paths. The low-frequency aperture array (LFAA) is the portion of the SKA-Low telescope including the antennas and the related electronics. Signal processing is hosted in a temperature controlled and shielded facility: the central processing facility (CPF), for all the core stations, or remote processing facilities (RPF), for stations in the array arms, to limit the maximum fiber length. Such a geographically distributed and interconnected radio telescope, spanning ∼65  km in diameter, requires that frequency and timing reference signals are distributed to the processing facilities with high stability and precision to ensure the required system performances. We present the realization of the clock and pulse per second distribution network inside the LFAA signal processing cabinet where subracks containing signal acquisition boards are housed. We describe the different parts of the chain, and we report on the total jitter introduced by this structure

Open Day presso l’INAF IASF di Milano Report delle prime tre edizioni (2019, 2020, 2022)

Nel 2019, l’Istituto di Astrofisica Spaziale e Fisica cosmica di Milano (IASF), una delle due sedi di Milano dell’INAF (Istituto Nazionale di Astrofisica), ha inaugurato il proprio Open Day, una giornata dedicata agli studenti universitari. Il personale dello IASF ha aperto le porte agli studenti interessati a svolgere un progetto di ricerca presso la propria sede o, in generale, a scoprire una realtà professionale dedicata allo studio dell’Universo. Gli incontri si sono divisi in due parti: nella prima sono stati presentati l’Istituto, la sua storia, le attività di ricerca in corso e le Tesi a disposizione (triennali e magistrali), mentre nella seconda si è aperta una discussione libera tra i presenti durante una merenda offerta dallo IASF-Milano. Le tre edizioni svolte finora (2019, 2020 e 2022) hanno visto una buona partecipazione (circa 25-40 presenze all’anno) e hanno permesso di avvicinare ulteriormente lo IASF-Milano alle Università del territorio, dando ai partecipanti una percezione di disponibilità e accessibilità della ricerca e del personale dello IASF. Dopo una pausa dovuta alla pandemia (anno 2021), lo IASF-Milano ha riaperto le porte nel 2022 in quella che ci auguriamo possa diventare una lunga tradizione

The Digital Signal Processing Platform for the Low Frequency Aperture Array: Preliminary Results on the Data Acquisition Unit

A signal processing hardware platform has been developed for the Low Frequency Aperture Array component of the Square Kilometre Array (SKA). The processing board, called an Analog Digital Unit (ADU), is able to acquire and digitize broadband (up to 500MHz bandwidth) radio-frequency streams from 16 dual polarized antennas, channel the data streams and then combine them flexibly as part of a larger beamforming system. It is envisaged that there will be more than 8000 of these signal processing platforms in the first phase of the SKA, so particular attention has been devoted to ensure the design is low-cost and low-power. This paper describes the main features of the data acquisition unit of such a platform and presents preliminary results characterizing its performance

The Signal Processing Firmware for the Low Frequency Aperture Array

The signal processing firmware that has been developed for the Low Frequency Aperture Array component of the Square Kilometre Array is described. The firmware is implemented on a dual FPGA board, that is capable of processing the streams from 16 dual polarization antennas. Data processing includes channelization of the sampled data for each antenna, correction for instrumental response and for geometric delays and formation of one or more beams by combining the aligned streams. The channelizer uses an oversampling polyphase filterbank architecture, allowing a frequency continuous processing of the input signal without discontinuities between spectral channels. Each board processes the streams from 16 antennas, as part of larger beamforming system, linked by standard Ethernet interconnections. There are envisaged to be 8192 of these signal processing platforms in the first phase of the Square Kilometre array so particular attention has been devoted to ensure the design is low cost and low power

Development of a New Digital Signal Processing Platform for the Square Kilometre Array

A novel digital hardware platform has been designed for the Low Frequency Aperture Array (LFAA) component of the Square Kilometre Array (SKA). This board, called Analog Digital Unit (ADU), is a 6U board containing sixteen dual-inputs Analog to Digital Converters (ADC) and two Field Programmable Gate Array (FPGA) devices, capable of digitizing and processing 32 RF input signals. We present the main features of the board and the signal processing firmware that has been developed for LFAA. Although the ADU has been conceived mainly for the low frequency band (50-350 MHz), its use has been proved effective also for higher frequencies (375-650 MHz). In this paper we describe also the application of ADU as the digital acquisition and processing system for PHAROS2, a cryogenically cooled 4-8 GHz Phased Array Feed (PAF) demonstrator. The final part is focused on the future developments of the board

The low frequency receivers for SKA 1-low: Design and verification

The initial phase of the Square Kilometre Array (SKA) [1] is represented by a ~10% instrument and construction should start in 2018. SKA 1-Low, a sparse Aperture Array (AA) covering the frequency range 50 to 350 MHz, will be part of this. This instrument will consist of 512 stations, each hosting 256 antennas creating a total of 131,072 antennas. A first verification system towards SKA 1-Low, Aperture Array Verification System 1 (AAVSl), is being deployed and validated in 2017

REPLICA2Pro: Task Relocation by Bitstream Manipulation in VIRTEX-II/Pro FPGAs

Kalte H, Porrmann M. REPLICA2Pro: Task Relocation by Bitstream Manipulation in VIRTEX-II/Pro FPGAs. In: Alderighi M, ed. Proceedings of the 3rd Conference on Computing Frontiers. New York: ACM; 2006: 403-412.One vision of dynamic hardware reconfiguration is to deliver virtually unlimited hardware resources to a set of hardware tasks implementing arbitrary functions. By using partial reconfiguration, these tasks can be allocated and de-allocated on the reconfigurable architecture while others continue to operate. However, the exact placement of each task can only be determined during runtime according to the current resource allocation. This requires relocating each task from its original position after place and route to an area of available resources. The process of relocating tasks can result in a major time overhead. In order to solve this problem we have developed the REPLICA2Pro (Relocation per online Configuration Alteration in Virtex-2/-Pro) filter, which is capable of performing task relocations by manipulating the task’s bitstream during the regular allocation process without any extra time overhead. The filter architecture, our reconfigurable system approach as well as our design flow and an experimental system setup are presented in this paper