The Atacama Large Millimeter/submillimeter Array (ALMA) Band 1 receiver covers the frequency range of 35-50 GHz. An extension of up to 52 GHz is on a best-effort basis. A total of 73 units have to be built in two phases: 8 preproduction and then 65 production units. This paper reports on the assembly, testing, and performance of the preproduction Band 1 receiver. The infrastructure, integration, and evaluation of the fully-assembled Band 1 receiver system will be covered. Finally, a discussion of the technical and managerial challenges encountered for this large number of receivers will be presented.
The Atacama Large Millimeter/submillimeter Array(ALMA) Band 1 receiver covers the 35-50 GHz frequency band. Development of prototype receivers, including the key components and subsystems has been completed and two sets of prototype receivers were fully tested. We will provide an overview of the ALMA Band 1 science goals, and its requirements and design for use on the ALMA. The receiver development status will also be discussed and the infrastructure, integration, evaluation of fully-assembled band 1 receiver system will be covered. Finally, a discussion of the technical and management challenges encountered will be presented.
Under the "Memorandum of Understanding between the National Radio Astronomy Observatory/Associated Universities Incorporated, Herzberg Institute of Astrophysics (HIA) and the University of Calgary related to Canadian ALMA Construction Phase Work Packages", HIA is committed to deliver a suite of seventy-three Band 3 100 GHz receiver cartridges to the ALMA Project. After the acceptance of each cartridge at the Front End Integration Centers, HIA is responsible to perform any post-delivery maintenance, repair and rework of the cartridges for a warranty period of up to one year. This paper defines a framework for the maintenance and repair services for the Band 3 cartridges after the post-delivery warranty period has expired. This framework consists of a detailed work breakdown structure, timelines and labour effort estimates of the major tasks related maintenance and repair services of ALMA Band 3 cartridges.
This paper describes the key design features and performance of HARP, an innovative heterodyne focal-plane array
receiver designed and built to operate in the submillimetre on the James Clerk Maxwell Telescope (JCMT) in Hawaii.
The 4x4 element array uses SIS detectors, and is the first sub-millimetre spectral imaging system on the JCMT. HARP
provides 3-dimensional imaging capability with high sensitivity at 325-375 GHz and affords significantly improved
productivity in terms of speed of mapping. HARP was designed and built as a collaborative project between the
Cavendish Astrophysics Group in Cambridge UK, the UK-Astronomy Technology Centre in Edinburgh UK, the
Herzberg Institute of Astrophysics in Canada and the Joint Astronomy Centre in Hawaii. SIS devices for the mixers were
fabricated to a Cavendish Astrophysics Group design at the Delft University of Technology in the Netherlands. Working
in conjunction with the new Auto Correlation Spectral Imaging System (ACSIS), first light with HARP was achieved in
December 2005. HARP synthesizes a number of interesting features across all elements of the design; we present key
performance characteristics and images of astronomical observations obtained during commissioning.
The Band 3 receiver, covering the 84-116 GHz frequency band is one of the 10 channels that will be installed on the
Atacama Large Millimeter Array (ALMA). A total of 73 units have to be built in two phases: 8 preproduction and then
65 production units. This paper reports on the assembly, testing and performance of the preproduction series of these
state-of-the-art millimeter receivers.
The NRC Herzberg Institute of Astrophysics (NRC-HIA) is currently responsible to contribute Band 3 (84-116 GHz)
receivers to the international ALMA project - a partnership involving North America, Europe and, now, Asia. Not only
are the technical requirements for these receivers far more stringent than those for any existing radio astronomy receivers
operating at these frequencies, but the delivery schedule for these receivers is equally challenging. Since the Asian
partnership joined the ALMA project in 2006, NRC-HIA has been asked to deliver an additional 11 cartridges, for a total
of 73 units. Some of these new cartridges will be used for the ALMA Compact Array (ACA) and others as spares.
Moreover, the project has also requested that these additional cartridges be delivered in the same time period as the
original 62 units. To meet this requirement, production must increase from the existing rate of one unit every four weeks
to one every two, taxing the existing production infrastructure at NRC-HIA. Additional test facilities and human
resources must be planned to sustain the required production rate over the next several years. Industrial involvement is
one of the important elements in our production plan. In order to supplement the existing human resources at NRC-HIA,
we are planning to outsource a number of low-risk and labor-intensive tasks to industry. However, NRC-HIA will retain
overall project management responsibility and will conduct all the cartridge integration and acceptance test activities in-house.
This paper focuses on the resource estimation, planning and project management required to deliver the Band 3
receivers to the ALMA project on time and on budget.
This paper describes the development of a 3-stage cryogenic low noise InP HEMT amplifier for ALMA Band 3 receivers. A detailed design is given using Hughes 0.1 μm low noise InP HEMTs for producing a low power dissipation amplifier, < 9 mW. The amplifier design uses a hybrid circuit in order to provide the flexibility for optimizing the active devices and passive components. The optimal impedance matching for low noise and low input return loss were obtained by computer aided simulation to achieve 5 K noise temperature, 36 dB gain, flatness ±1 dB and -10 dB input return loss at 12 degrees Kelvin in the 4-9 GHz band. The amplifier will be used as a cold IF preamplifier with a SIS mixer in the Band 3 receivers now being constructed for the Atacama Large Millimetre Array (ALMA).
A 350GHz 4 × 4 element heterodyne focal plane array using SIS detectors is presently being constructed for the JCMT. The construction is being carried out by a collaborative group led by the MRAO, part of the Astrophysics Group, Cavendish Laboratory, in conjunction with the UK-Astronomy Technology Centre (UK-ATC), The Herzberg Institute of Astrophysics (HIA) and the Joint Astronomy Center (JAC). The Delft Institute of Microelectronics & Sub-micron Technology (DIMES) is fabricating junctions for the SIS mixers that have been designed at MRAO.
Working in conjunction with the 'ACSIS' correlator & imaging system, HARP-B will provide 3-dimensional imaging capability with high sensitivity at 325 to 375GHz. This will be the first sub-mm spectral imaging system on JCMT - complementing the continuum imaging capability of SCUBA - and affording significantly improved productivity in terms of speed of mapping. The core specification for the array is that the combination of the receiver noise temperature and beam efficiency, weighted optimally across the array will be <330K SSB for the central 20GHz of the tuning range.
In technological terms, HARP-B synthesizes a number of interesting and innovative features across all elements of the design. This paper presents both a technical and organizational overview of the HARP-B project and gives a description of all of the key design features of the instrument. 'First light' on the instrument is currently anticipated in spring 2004.
A new Auto-Correlation Spectral Imaging System (ACSIS) for the James Clerk Maxwell Telescope (JCMT) is being developed at the National Research Council of Canada, in collaboration with the Joint Astronomy Centre and the United Kingdom Astronomy Technology Centre. The system is capable of computing the integrated power-spectra over 1-GHz bandwidths for up to 32 receiver beams every 50 ms. An innovative, multiprocessor computer will produce calibrated, gridded, 3-D data cubes so that they can be viewed in real-time and are in hand when an observation is over. When connected to arrays of receivers at the Nasmyth focus of the telescope, the system will be able to rapidly make large-scale images with high spectral resolution and map multiple transitions. The ACSIS system will be mated initially with the multibeam 350-GHz receiver system. Heterodyne ARray Program (HARP), under development at the Mullard Radio Astronomy Observatory in Cambridge, England. In this paper we describe ACSIS, how it is designed and the results of key performance tests made.
Receiver B3 is a common-user facility instrument for the JCMT and was commissioned in December 1996. It includes the following features: (1) Frequency coverage of 315 to 372 GHz with optimum performance at 345 GHz. (2) Two spatially- coincident channels with orthogonal linear polarizations. (3) An IF of 4 GHz with an instantaneous bandwidth of 1.7 GHz in each channel. (4) Single side-band capability with the rejected side-band terminated on a cold load. (5) High- efficiency, frequency-independent optics. (6) Independent adjustment of the local oscillator power to the two mixers. (7) Internal ambient and cold loads for accurate receiver calibration. (8) Fully automated operation.
A neural network approach to determine the heading orientation of a known object in a noisy image is presented. The gray-scaled image is first preprocessed by the following four procedures: 1) An edge map of the object is extracted using the Sobel edge operator; 2) The discrete 2-D Fourier transform is applied to the edge map to eliminate the translational variance; 3) The Fourier power coefficients are mapped into a polar coordinate system; 4) The amplitudes of the Fourier coefficients in each five-degree angular sector are summed to form a 1-D input vector to the neural network. A backpropagation neural network with one hidden layer was trained with a sequence of seven noise-free object outlines with heading ranging from 0 to 90 deg in 15 deg increments. After the training was complete, the network was tested with three noisy images taken from randomly selected object orientations. The network successfully classified the appropriate headings in each case. These results illustrate the robustness of this neural network design in performing heading classification from noisy images