Mr. Rodrigo Amestica Profile

Rodrigo Amestica

Software Engineer at National Radio Astronomy Observatory

SPIE Involvement:

Author

Publications (8)

Proceedings Article | 6 July 2018 Presentation + Paper

Introducing hardware in the loop and model based simulation concepts in the ALMA observatory for software testing

Tzu-Chiang Shen, Ruben Soto, Alejandro Saez, Jorge Avarias, Norman Saez, Tomas Staig, Jorge Sepulveda, Jorge Castillo, Rodrigo Amestica, Jorge Ibsen, Stuartt Corder

Proceedings Volume 10707, 107070C (2018) https://doi.org/10.1117/12.2313688

KEYWORDS: Antennas, Optical correlators, Observatories, Computing systems, Signal processing, Hardware testing, Current controlled current source, Adaptive optics, Electronics, Control systems

Read Abstract +

Proceedings Article | 26 July 2016 Paper

Implementing the concurrent operation of sub-arrays in the ALMA correlator

Rodrigo Amestica, Jesus Perez, Richard Lacasse, Alejandro Saez

Proceedings Volume 9913, 99133K (2016) https://doi.org/10.1117/12.2231245

KEYWORDS: Information technology, Optical correlators, Signal processing, Antennas, Visibility, Interfaces, Current controlled current source, Calibration, Data processing, Observatories

Read Abstract +

The ALMA correlator processes the digitized signals from 64 individual antennas to produce a grand total of 2016 correlated base-lines, with runtime selectable lags resolution and integration time. The on-line software system can process a maximum of 125M visibilities per second, producing an archiving data rate close to one sixteenth of the former (7.8M visibilities per second with a network transfer limit of 60 MB/sec). Mechanisms in the correlator hardware design make it possible to split the total number of antennas in the array into smaller subsets, or sub-arrays, such that they can share correlator resources while executing independent observations. The software part of the sub-system is responsible for configuring and scheduling correlator resources in such a way that observations among independent subarrays occur simultaneously while internally sharing correlator resources under a cooperative arrangement. Configuration of correlator modes through its CAN-bus interface and periodic geometric delay updates are the most relevant activities to schedule concurrently while observations happen at the same time among a number of sub-arrays. For that to work correctly, the software interface to sub-arrays schedules shared correlator resources sequentially before observations actually start on each sub-array. Start times for specific observations are optimized and reported back to the higher level observing software. After that initial sequential phase has taken place then simultaneous executions and recording of correlated data across different sub-arrays move forward concurrently, sharing the local network to broadcast results to other software sub-systems. The present paper presents an overview of the different hardware and software actors within the correlator sub-system that implement some degree of concurrency and synchronization needed for seamless and simultaneous operation of multiple sub-arrays, limitations stemming from the resource-sharing nature of the correlator, limitations intrinsic to the digital technology available in the correlator hardware, and milestones so far reached by this new ALMA feature.

Proceedings Article | 26 July 2016 Paper

Porting the ALMA Correlator Data Processor from hard real-time to plain Linux

Rodrigo Amestica, Jesus Perez, Alejandro Saez

Proceedings Volume 9913, 99133J (2016) https://doi.org/10.1117/12.2230960

KEYWORDS: Optical correlators, Signal processing, Digital signal processing, Data processing, Visibility, Antennas, Computing systems, Operating systems, Current controlled current source, Observatories

Read Abstract +

The ALMA correlator back-end consists of a cluster of 16 computing nodes and a master collector/packager node. The mission of the cluster is to process time domain lags into auto-correlations and complex visibilities, integrate them for some configurable amount of time and package them into a workable data product. Computers in the cluster are organized such that individual workloads per node are kept within achievable levels for different observing modes and antennas in the array. Over the course of an observation the master node transmits enough state information to each involved computing node to specify exactly how to process each set of lags received from the correlator. For that distributed mechanism to work, it is necessary to unequivocally identify each individual lag set arriving at each computing node. The original approach was based on a custom hardware interface to each node in the cluster plus a realtime version of the Linux Operating System. A modification recently introduced in the ALMA correlator consists of tagging each lag set with a time stamp before delivering them to the cluster. The time stamp identifies a precise 16- millisecond window during which that specific data set was streamed to the computing cluster. From the time stamp value a node is able to identify a centroid (in absolute time units), base-lines, and correlator mode during that hardware integration. That is, enough information to let the digital signal processing pipeline in each node to process time domain lags into frequency domain auto-correlations per antenna and visibilities per base-line. The scheme also means that a good degree of concurrency can be achieved in each node by having individual CPU cores process individual lag sets at the same time, thus rendering enough processing power to cope with a maximum 1 GiB/sec output from the correlator. The present paper describes how we time stamp lag sets within the correlator hardware, the implications to their on-line processing in software and the benefits that this extension has brought in terms of software maintainability and overall system simplifications.

Proceedings Article | 27 June 2006 Paper

Time synchronization within the ALMA software infrastructure

Rodrigo Amestica, Birger Gustafsson, Ralph Marson

Proceedings Volume 6274, 627416 (2006) https://doi.org/10.1117/12.670298

KEYWORDS: Clocks, Computing systems, Global Positioning System, Intelligence systems, Receivers, Antennas, Data acquisition, Observatories, Control systems, Operating systems

Read Abstract +

Proceedings Article | 15 September 2004 Paper

ALMA correlator computer systems

Jim Pisano, Rodrigo Amestica, Jesus Perez

Proceedings Volume 5496, (2004) https://doi.org/10.1117/12.550066

KEYWORDS: Optical correlators, Computing systems, Control systems, Antennas, Data processing, Data archive systems, Current controlled current source, Human-machine interfaces, Binary data, Adaptive optics

Read Abstract +

Proceedings Article | 21 February 2003 Paper

The VLTI: a status report

Andreas Glindemann, J. Algomedo, Rodrigo Amestica, Pascal Ballester, Bertrand Bauvir, E. Bugueno, Serge Correia, Francisco Delgado, Francoise Delplancke, Frederic Derie, Philippe Duhoux, Emmanuel di Folco, Alberto Gennai, Bruno Gilli, Paul Giordano, Philippe Gitton, Stephane Guisard, Nico Housen, Alexis Huxley, Pierre Kervella, Mario Kiekebusch, Bertrand Koehler, Samuel Leveque, Antonio Longinotti, Sebastien Morel, Francesco Paresce, Than Duc, Andrea Richichi, Markus Schoeller, Massimo Tarenghi, Anders Wallander, Markus Wittkowski, Rainer Wilhelm, S. Menardi

Proceedings Volume 4838, (2003) https://doi.org/10.1117/12.458117

KEYWORDS: Stars, Telescopes, Interferometry, Sensors, Astatine, Adaptive optics, Observatories, Interferometers, K band, Mirrors

Read Abstract +

Proceedings Article | 5 July 2000 Paper

VLTI test siderostats: design, development, and performance results

Frederic Derie, Enzo Brunetto, Michel Duchateau, Rodrigo Amestica, Franco Carbognani, Marc Ferrari

Proceedings Volume 4006, (2000) https://doi.org/10.1117/12.390164

KEYWORDS: Telescopes, Toxic industrial chemicals, Standards development, Stars, Lithium, Mirrors, Interferometers, Optical testing, Interfaces, Control systems design

Read Abstract +

Proceedings Article | 16 June 2000 Paper

VLT astronomical site monitor: control, automation, and data flow

Stefan Sandrock, Rodrigo Amestica, Philippe Duhoux, Julio Navarrete, Marc Sarazin

Proceedings Volume 4009, (2000) https://doi.org/10.1117/12.388404

KEYWORDS: Telescopes, Stars, Lanthanum, Observatories, Charge-coupled devices, Sensors, CCD image sensors, Humidity, Astronomy, Control systems

Read Abstract +

Showing 5 of 8 publications

View contact details

UPDATE YOUR PROFILE

Is this your profile? Update it now.

Sign into your SPIE.org account

Don’t have a profile and want one?

Create an account on SPIE.org

Keywords/Phrases

Search In:

Publication Years