The next-generation Very Large Array (ngVLA) is an astronomical observatory planned to operate at centimeter wavelengths (25 to 0.26 centimeters, corresponding to a frequency range extending from 1.2 GHz to 116 GHz). The observatory will be a synthesis radio telescope constituted of approximately 214 reflector antennas each of 18 meters diameter, operating in a phased or interferometric mode.
We provide an overview of the current system design of the ngVLA. The concepts for major system elements such as the antenna, receiving electronics, and central signal processing are presented. We also describe the major development activities that are presently underway to advance the design.
The Atacama Large Millimeter/submillimeter Array (ALMA) will be composed of 66 high precision antennae located at
5000 meters altitude in northern Chile. This paper will present the methodology, tools and processes adopted to system
engineer a project of high technical complexity, by system engineering teams that are remotely located and from
different cultures, and in accordance with a demanding schedule and within tight financial constraints. The technical and
organizational complexity of ALMA requires a disciplined approach to the definition, implementation and verification of
the ALMA requirements. During the development phase, System Engineering chairs all technical reviews and facilitates
the resolution of technical conflicts. We have developed analysis tools to analyze the system performance, incorporating
key parameters that contribute to the ultimate performance, and are modeled using best estimates and/or measured values
obtained during test campaigns. Strict tracking and control of the technical budgets ensures that the different parts of the
system can operate together as a whole within ALMA boundary conditions. System Engineering is responsible for
acceptances of the thousands of hardware items delivered to Chile, and also supports the software acceptance process. In
addition, System Engineering leads the troubleshooting efforts during testing phases of the construction project. Finally,
the team is conducting System level verification and diagnostics activities to assess the overall performance of the
observatory. This paper will also share lessons learned from these system engineering and verification approaches.
The Atacama Large Millimeter Array (ALMA) Photonic Local Oscillator (PLO) is an advanced photonics system that
generates and distributes all of the Local Oscillator (LO) and timing references for the ALMA radio telescope array.
These LO and timing references are used by the receivers and electronics at the antennas, and by the Correlator in the
central building. Due to the unprecedented combination of high sky frequencies (up to 950 GHz) and long baseline
lengths of up to 15 kilometers, the ALMA 1st LO requirement is particularly stringent, with extremely precise timing and
synchronization needed down to the ~10 femtosecond level.
Two new uniplanar mixer designs are described. These mixers are being tested at ifA-band, but will be scaled to higher millimeter wave frequencies. The goal is to develop broad-band monolithically integrated mixers which utilize surface-oriented hot electron devices as nonlinear elements.