ALMA Wideband Sensitivity Upgrade (WSU)

 

   

New: The latest program news can now be found on the WSU ALMA Observatory website: https://www.almaobservatory.org/en/scientists/alma-2030-wsu/wsu-program/

 

 

The ALMA Wideband Sensitivity Upgrade (WSU) is a major initiative to enhance ALMA science potential, instrumentation, and software systems for sustained, high-capability operations through the 2030s. The WSU will dramatically increase the observational capabilities of ALMA and translate to new opportunities across a range of scientific topics. The initiative is well underway, with planned completion of core elements by the end of this decade.

The ALMA 2030 Development Roadmap, a Board-approved vision for ALMA sustainability and enhancement, identified the WSU initiatives as top priority. The goals of the WSU include an increase in bandwidth by a factor of 2 (ultimately x4), as well as increased digital sensitivity and improved sensitivity of key receivers.

The initial and most critical stage of the WSU is the upgrade of the signal chain for increased bandwidth and improved digital efficiency. Nearly every hardware component in the existing signal chain is being replaced in this first stage and includes the IF Switch, Digitizer, Data Transmission System, a new Fiber Optic Cable, and a major new digital correlator - the Advanced Technology ALMA Correlator (ATAC) and a new Total Power GPU Spectrometer (TPGS). ATAC will be located at the Operations Support Facility (OSF) at 3000 m elevation rather than the Array Operations Site at 5000 m where the current Baseline Correlator resides and will provide improved power efficiency and ease of support. The relocation requires creation of a new correlator room in the OSF. 

Future stages will implement receivers with broader bandwidth and higher sensitivity.  The signal chain upgrade will include at least one new, high bandwidth receiver, Band 2. Additional high bandwidth receivers with improved sensitivity are expected to follow. The WSU also includes a major upgrade of both online and offline software systems, including a new calibration and imaging pipeline and data processing system.

The entire ALMA partnership is contributing to the success of the WSU; North American contributions to the new signal chain include:

- ATAC

- the new OSF Correlator Room, 

- the Digital Transmission System (DTS) in  collaboration with East Asia.

- a project to develop a prototype of the Band 6v2 receiver

 

WSU news

- November 2025: The WSU Fiber Optics System passed its Critical Design and Manufacturing Readiness Review

- August 2025: successful System Preliminary Design Review of the technical and programmatic baseline for the overall WSU project

- June 2025: The OSF (Observing Support Facility) Correlator Room (OCRO) passed the Critical Design and Manufacturing Review

- June 2025: halfway point in the production of the new Band 2 receivers. 

- April 2025: the ALMA Board approves two WSU elements: the ALMA Total Power GPU Spectrometer (TPGS) and the WSU Fiber Optic (FOS) project

- January 2025: New correlator room construction project kicked off

- December 2024: Wideband IF Processor (WIFP) conditionally passes its Preliminary Design Review (PDR) ; ALMA Board approves construction of the new correlator room

- November 2024: The new WSU spectrometer for the Total Power Array passed its Conceptual Design Review

- October 2024: The new Data Transmission System (DTS) underwent and passed its Preliminary Design Review

- September 2024: Band 2 receivers complete pre-production

- July 2024: WSU passes the delta Systems Requirement and Initial Program Plan reviews

- June 2024: WSU Correlator and Correlator Room Preliminary Design Reviews Passed

- November 2023: NRAO and NAOJ partner to produce Band 2 and develop upgrade Band 6

- February 2023 Approval of the development of a second-generation correlator and digital transmission system (DTS)

 

Resources

- ALMA project WSU website: https://www.almaobservatory.org/en/scientists/alma-2030-wsu/

- WSU at a glance slide (June 2025)

- WSU brochure (December 2024)

- Development study report: Evaluate Suitability of Next Generation FPGA Technology and 400 Gigabit Ethernet Switches for Use in a 2nd Generation ALMA Correlator, 2024

- Development study report: A Detailed Characterization of Spectral Regridding for the WSU Era, 2024

- ALMA Memo 626, "Estimates of ALMA WSU Data Properties", January 2024

- ALMA Memo 625, "Proof of Concept of the ALMA WSU Data Transmission System", August 2023

- ALMA Memo 621 "The ALMA2030 Wideband Sensitivity Upgrade", October 2022

 

Presentations

- WSU Presentation at Far-IR Lines Workshop (June 2025)

- AAS special session, Tuesday January 14, 2025: New perspectives on protoplanetary disks in the era of JWST and the ALMA Wideband Sensitivity Upgrade

- AAS special session, January 2024: ALMA as a high-z powerhouse: the impact of the Wideband Sensitivity Upgrade

- WSU presentation at NRAO Imaging workshop, June 2023

- AAS special session, January 2023

- Development project presentation: Band 6v2 receiver upgrade A Navarrini, 2021

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