From cwhite at nrao.edu Fri May 3 14:06:55 2002 From: cwhite at nrao.edu (Carolyn White) Date: Fri, 03 May 2002 14:06:55 -0400 Subject: [alma_na] ALMA NA DH Meeting - Monday Message-ID: <3CD2D1BF.30005@nrao.edu> There will be an ALMA NA DH Meeting Monday, May 6 at 1700 UT. Please dial 434-984-0244. Thanks Carolyn From cwhite at nrao.edu Fri May 3 14:08:11 2002 From: cwhite at nrao.edu (Carolyn White) Date: Fri, 03 May 2002 14:08:11 -0400 Subject: [alma_na] ALMA Bi-Lateral DH Meeting Message-ID: <3CD2D20B.5080300@nrao.edu> The next ALMA Bi-Lateral DH Meeting will be Tuesday, May 28 at 1430 UT. We will send out another reminder later in the month. Thanks Carolyn From soliver at NRAO.EDU Mon May 6 15:15:20 2002 From: soliver at NRAO.EDU (Stacy Oliver) Date: Mon, 6 May 2002 12:15:20 -0700 Subject: [alma_na] [almanews] ALMA Memos 421 Released Message-ID: ALMA MEMO #421 GaAs-BASED CRYOGENIC AMPLIFIER FOR ALMA 2SB MIXER Christophe Risacher and Victor Belitsky Onsala Space Observatory, Sweden 2002/04/18 Keywords: Cryogenic LNA, GaAs HEMT, InP HEMT, 2SB SIS mixer As part of Onsala Space Observatory instrumentation activities, a 4-8 GHz cryogenic low-noise amplifier was developed. This 2-stage LNA demonstrates 26 dB gain with noise temperature of 5.0 K using commercial GaAs transistors MGFC4419G from Mitsubishi. The total power consumption is of about 12 mW while with a total power consumption tuned down to 4 mW, the gain drops to 24 dB and the noise is of 6.0 K. This performance is in a very good agreement with simulations and believed to be among the best-reported using GaAs transistors. The amplifier design was carried using Agilent ADS, HFSS and Momentum CAD software. This amplifier will be used as a cold IF amplifier for mm and sub-mm wave receivers with SIS and HEB mixer, primarily for APEX Project as well in our development of ALMA band 7 sideband separation mixer providing two independent IF channels (USB and LSB) of 4-8 GHz, therefore fulfilling the 8 GHz bandwidth requirements for ALMA. In this paper we present details on the amplifier design, performances (modelled and measured) and gain-stability comparison between GaAs and InP transistor based amplifiers. View a pdf version of ALMA Memo #421. http://www.alma.nrao.edu/memos/html-memos/alma421/memo421.pdf Download a postscript version of ALMA Memo #421. http://www.alma.nrao.edu/memos/html-memos/alma421/memo421.ps _______________________________________________ Almanews mailing list Almanews at listmgr.cv.nrao.edu http://listmgr.cv.nrao.edu/mailman/listinfo/almanews From cwhite at nrao.edu Tue May 7 15:54:37 2002 From: cwhite at nrao.edu (Carolyn White) Date: Tue, 07 May 2002 15:54:37 -0400 Subject: [alma_na] December/January NSF Report Message-ID: <3CD830FD.80309@nrao.edu> The December 2001/January 2002 NSF Bi-Monthly Report is available at: http://www.cv.nrao.edu/~cwhite/almaus/mr/ Please contact cwhite at nrao.edu if you have trouble with the files. Thanks Carolyn From cwhite at nrao.edu Mon May 13 09:29:01 2002 From: cwhite at nrao.edu (Carolyn White) Date: Mon, 13 May 2002 09:29:01 -0400 Subject: [alma_na] ALMA NA DH Meeting Today Message-ID: <3CDFBF9D.2080801@nrao.edu> There will be an ALMA NA DH Meeting today, Monday, May 10 at 1700 UT. Please dial 434-984-0244. Thanks Carolyn From cwhite at nrao.edu Mon May 13 09:50:33 2002 From: cwhite at nrao.edu (Carolyn White) Date: Mon, 13 May 2002 09:50:33 -0400 Subject: [alma_na] Date Corrected Message-ID: <3CDFC4A9.8070001@nrao.edu> There will be an ALMA NA DH Meeting today, Monday, May 13 at 1700 UT. Please dial 434-984-0244. Thanks Carolyn From cwhite at NRAO.EDU Mon May 13 10:05:40 2002 From: cwhite at NRAO.EDU (Carolyn White) Date: Mon, 13 May 2002 10:05:40 -0400 (EDT) Subject: [alma_na] ALMA NA DH Meeting Minutes Message-ID: ALMA NA DH Meeting - 2002-May-06 Attendees - Glendenning, Gray, Kingsley, Mangum, Payne, Perfertto, Porter, Radford, Rafal, Simon, Sramek, Webber Issues From Venice and Granada Meetings --------------------------------------- Venice Meeting - The meeting started with status reports from Rafal and Kurz. Following these reports, much of the remaining discussions were in closed session. By the end, the ACC had made the following decisions: - AEC is to produce a Project Plan which includes fewer details - The ACC will cease to exist, and an ALMA Board will be created (ad-hoc for now, which includes four NA members, four European members, and one Chilean). - Create the Joint ALMA Office in two steps: 1) will begin to advertise for permanent office; 2) appoint interim positions for ALMA Director, ALMA Project Manager, and ALMA Scientist. There may or may not be an ALMA Engineer. The ACC expects to have interim operations in place by 2002-Jun-01. The AMAC Meeting will likely focus on the antenna procurement, front end design and production, computing (interest expressed), and system engineering. Under the above management plan, the AMAC will report to the ALMA Board. The charge to the AMAC has not yet been made. The ACC discussed the role of the ASAC. There is concern that the ASAC has not been givin sufficient guidance by the ACC. It was decided that the Project Scientist will generate a charge to the ASAC prior to each ASAC Meeting to focus questions that the Board needs more information on. Granada Meeting - Back End PDR - Sramek is still collecting comments and other documentation which will include clarification and firm up unresolved issues. One outcome of the PDR is that the engineering interface definitions are not complete. Some scheduling issues still remain. Computing - Glendenning states there were no controversial issues at the meeting; see his meeting summary. Front End - There is the issues between partners whether front end schedule strives to meet the antenna schedule or if the front end schedule should determine the antenna schedule. The Europeans do not see wisdom in delivering partial front ends with fewer than four front end bands. There is additional uncertainty caused by ongoing management changes in the front end area. We clearly need to get real LO prototype to the cartridge designers. It does appear that important work at RAL is going well. Rafal would like to see an early cryostat #2 delivered to Tucson. Tucson is working with RAL on chasis. System Engineering - Gray reports that site scope works proceeding rapidly; expect to have user accounts soon. The product tree is maturing. We have clarified the definition of ICD's. Site Development - Radford reports that we now have a task division and structure that is workable. Radford will be going to Chile next week to complete OSF site access road studies to deliver to Hofstadt. Hofstadt is encouraged at progress of recent negotiations. Antenna - Parts are in Texas; expect to have delivery 15 - 20th of May. The second panel manufacture has started; expect to have all panels in four months. Working on various issues at VLA site. Porter reported that import duty issues are resolved. Full time site activity starts on May 20. The next meeting will be Monday, May 13. From awootten at NRAO.EDU Mon May 13 10:59:45 2002 From: awootten at NRAO.EDU (Al Wootten) Date: Mon, 13 May 2002 10:59:45 -0400 (EDT) Subject: [alma_na] Date Corrected In-Reply-To: <3CDFC4A9.8070001@nrao.edu> References: <3CDFC4A9.8070001@nrao.edu> Message-ID: <200205131459.KAA12750@polaris.cv.nrao.edu> I had to miss last week's meeting owing to a conflict. I would be happy to discuss the Granada calibration meeting should the agenda allow. Al Carolyn White writes: > > There will be an ALMA NA DH Meeting today, Monday, May 13 at 1700 UT. > Please dial 434-984-0244. > > Thanks > > Carolyn > > > _______________________________________________ > alma_na mailing list > alma_na at listmgr.cv.nrao.edu > http://listmgr.cv.nrao.edu/mailman/listinfo/alma_na > From soliver at NRAO.EDU Tue May 14 13:20:18 2002 From: soliver at NRAO.EDU (Stacy Oliver) Date: Tue, 14 May 2002 10:20:18 -0700 Subject: [alma_na] [almanews] ALMA Memos 372 and 393 Released Message-ID: ALMA MEMO #372 An Amplitude Calibration Strategy for ALMA R.Moreno (IRAM), S.Guilloteau (IRAM/ESO) 2002/05/10 Keywords: Calibration, Receiver We propose an amplitude calibration strategy for ALMA which attempts to reach the 1 % precision for absolute calibration. Key points and major difficulties are identified. Polarization is ignored in this first step. We first review the properties of possible calibration sources. Planets and specially giant planets satellites are the preferred reference sources for flux calibration. Asteroids are too complex for such a purpose, but are useful as e.g. targets for relative pointing & focus determination. Stars are too weak. Quasars have to be used for various intermediate steps: bandpass, pointing, focus, and relative amplitude calibration. The amplitude calibration precision may be divided into 3 major items: absolute flux scale, relative amplitude calibration (as function of time and antenna), and bandpass (dependence on frequency). Absolute amplitude depends on receiver gain and atmospheric opacity correction, and on pointing & focus control. The semi transparent vane is found to be 3 to 10 times less sensitive to atmospheric parameters than the dual-load calibration system. Accurate pointing & focus control can be done within reasonably short time (1 minute or so). Relative amplitude calibration can be checked to 1 % accuracy at mm wavelengths by observation of a nearby quasar, but integration time considerations prevents reaching better than about 3 % at submm wavelengths. Bandpass calibration, and specially the sideband ratio determination, is the longest calibration procedure. Within 3 minutes, this can be calibrated to 1 % at mm wavelengths, but only to 3 % at submm frequencies. Based on these considerations, we recommend 1) to further develop the semi-transparent vane system, 2) to keep the 1 % accuracy goal at mm wavelengths, 3) to relax the specification to 3 % in the submm domain, and 4) implement the coherent signal from the subreflector for bandpass calibration purpose. View a pdf version of ALMA Memo #372. http://www.alma.nrao.edu/memos/html-memos/alma372/memo372.pdf Download a postscript version of ALMA Memo #372. http://www.alma.nrao.edu/memos/html-memos/alma372/memo372.ps ---------------------------------------------------------------------------- ----------------------------------- ALMA MEMO #393 DSB versus SSB and Bandwith/Sensitivity tradeoff S.Guilloteau (IRAM/ESO) 2002/05/14 Keywords: Receiver, Correlator The ALMA performances will depend on the receiver design and performances. Conflicting requirements on cost, reproducibility, maintainability, bandwidth and noise temperature affect the receiver design, and the capabilities of ALMA. This memo reviews the possible tradeoff between receiver complexity and ALMA performances, considering DSB vs SSB and Bandwidth vs Receiver noise tradeoffs. Realistic scientific applications are considered. This memo reproduces the numerical results obtained in memo 304 using a different approach. However, the conclusion differ because I also account for a scheduling strategy in which high frequency observations are made only when the weather allows. Combined with a reasonable assumption on the distribution of continuum (or dual-line) observations vs single spectral line cases, this assumption favors DSB mixers at high frequencies. DSB receivers may provide a 10 % advantage above 500 GHz, while SSB receivers would provide a 10 % advantage below that frequency. Analysis of the Bandwidth/Receiver noise trade-off indicate that reduction of a factor 2 in detection bandwidth can be compensated by improvement by 25 -- 30 % in Receiver noise. View a pdf version of ALMA Memo #393. http://www.alma.nrao.edu/memos/html-memos/alma393/memo393.pdf Download a postscript version of ALMA Memo #393. http://www.alma.nrao.edu/memos/html-memos/alma393/memo393.ps _______________________________________________ Almanews mailing list Almanews at listmgr.cv.nrao.edu http://listmgr.cv.nrao.edu/mailman/listinfo/almanews From cwhite at NRAO.EDU Tue May 21 13:11:03 2002 From: cwhite at NRAO.EDU (Carolyn White) Date: Tue, 21 May 2002 13:11:03 -0400 (EDT) Subject: [alma_na] May 13 ALMA NA DH Meeting Minutes Message-ID: ALMA NA DH Meeting - 2002-May-13 Attendees - Glendenning, Gray, Kingsley, Mangum, Payne, Perfetto, Rafal, Simon, Sramek, Webber, White, Wootten Wootten gave a report on the Calibration Meeting. A calibration group was formed. The group worked through the Project Book and plan to have an updated version in two weeks. The group appointed Brian Butler as head of the calibration effort and his first item will be to review the Project Book. Guilloteau noticed an error in the Vertex specification for dual load (memo will be revised). There are issues with both the subreflector calibration and dual load semitransparent vane system; testing needs to be done. There has been progress on two designs in the water vapor radiometer area; testing is being conducted at OVRO, VLA and BIMA. A WVR sub-group of the calibration group was created. Holdaway is working on the total power issues and preparing a memo. Webber questioned the WVR group if there are optical coupling issues and if the LO leakage from WVR goes into the front end? The front end WVR groups need to coordinate these issues as well as several other items. At the calibration meeting the group also discussed the photonic calibration system. Rafal suggested that we may want to have a document that explains how each specification will be verified. Kingsley reported that Vertex is on site. Shipments will start arriving this week and erection starts on the 20th-27th. The transporter meeting last week was very productive; we are working on the tilt specification issues. Fast switching may also be a problem; the compressor/front end group will work through this. The antenna group is working to finalize their product tree for system engineering. Guilloteau may be claiming problems with dual load at his facility. Sramek is continuing to document the back end PDR that took place in Granada. Sramek is compiling a list of issues to be sent to the back end staff. Most of the meeting viewgraphs are available on SiteScape. The back end plan is being re-vamped. Glendenning stated that preparations for the antenna involves several areas: (1) site infrastructure; (2) programming activities; (3) setting up computers for site (monitors, database, etc.); (4) working on documentation and plans for phase 2. The next version of TICS will be in August 2002. Perfetto gave the status of the holograph, which is being tested to make electronic sequences work well. The reference and transmitter seeds are being tested: 1) the latest data looks alight; Brooks is working on receiver data. The control software for the holography is progressing. The evaluation receiver is making progress as well. The first cooled down unit is expected next week. The assembly of the 2nd receiver is practically in the same phase as evaluation receiver #1. Compressor #2 is complete and being tested in the lab; compressor rotates only in aziumth. Payne described the activities in phontoics. Shillue is on-track with this. Simond has accepted the position and starts June 3. Ellison completed first test on photodiodes. Webber reported that the custom correlator is due in 10 days; we expect to have preliminary results in two to three weeks. Gray reported on the progress being made with SiteScape. Oliver will be sending out an announcement soon. The initial release is for users to be accustomed to the program and send in comments/suggestions. We ask that users do not link URL's yet. Rafal reports that at the ACC teleconference on May 21 we expect the current version of the Project Plan to be released. Rafal is working on attendance requirements for the AMAC meeting. Rafal is still working with fiscal on the financial reporting the DH require. The next meeting will be Monday, June 3. From soliver at NRAO.EDU Wed May 22 16:30:22 2002 From: soliver at NRAO.EDU (Stacy Oliver) Date: Wed, 22 May 2002 13:30:22 -0700 Subject: [alma_na] FW: [almanews] ALMA Memos 424 and 425 Released Message-ID: ALMA Memo # 424 Development of 4-Gsps 2-bit ADC with GaAs ICs for radio astronomy Mahoko Okiura(The University of Tokyo / NRO), Satoru Iguchi(NAO), Sachiko K. Okumura(NRO), Munetake Momose(Ibaraki University), Kin?fya Matsumoto(Kyushyu Toukai University), and Noriyuki Kawaguchi(NAO) 17/05/2002 Keywords: Analog to Digital converter We developed two sets of the prototype of 4-Gsps 2-bit Analog to Digital converter (ADC) with GaAs IC for the realization of 4 GHz sampling in an ADC system of Atacama Large Millimeter / submillimeter Array (ALMA). This consists of three sets of 12-Gbps Decision Circuits and 12-Gbps Demulitiplexers, and has a capability of sampling in a bandwidth of 6 GHz. Toward the implementation of GaAs IC in the ADC system, we measured the sampling jitter of the ADC using the Ultra-Wide Band Correlator (UWBC) developed for the Nobeyama Millimeter Array (NMA). The measured Allan standard deviation of phase, corresponding to the stability of sampling timing is 2.3x10^-15 at 10 seconds, and the Allan standard deviation due to the Flicker-frequency noise is 0.8x10^-15. It is shown that the coherence loss successfully becomes 0.95 at coherence time of 86400 seconds (24 hours). The Alan standard deviation of sampling timing and its long-time stability are acceptable for the application of radio astronomical ADC system. View a pdf version of ALMA Memo 424. http://www.alma.nrao.edu/memos/html-memos/alma424/memo424.pdf Download a postscript version of ALMA Memo 424. http://www.alma.nrao.edu/memos/html-memos/alma424/memo424.ps ____________________________________________________________________________ ____________ ALMA Memo # 425 The B?ifot Orthomode Junction Edward J. Wollack (NASA/GSFC),Wes Grammer (NRAO),Jeff Kingsley (NRAO) 22/05/2002 Keywords: Orthomode Transducer, Orthomode Junction, Polarization Diplexer, Waveguide Junction Wideband dual-polarization performance is desired for low-noise receivers and radiometers at centimeter and millimeter wavelengths. The use of a waveguide orthomode transducer (OMT) can increase spectral coverage and sensitivity while reducing exit aperture size, optical spill, and instrumental polarization offsets. For these reasons, an orthomode junction is favored over a traditional quasi-optical wire grid for focal plane imaging arrays from a systems perspective. The fabrication and performance of wideband symmetric B?ifot OMT junctions at K-, Ka-, Q-, and W-bands are described. Typical WR10.0 units have an insertion loss of <0.2 dB, return loss ~20dB, and >40dB isolation over a >75-to-110 GHz band. The OMT operates with reduced ohmic losses at cryogenic temperatures. View a pdf version of ALMA Memo 425. http://www.alma.nrao.edu/memos/html-memos/alma425/memo425.pdf Download a postscript version of ALMA Memo 425. http://www.alma.nrao.edu/memos/html-memos/alma425/memo425.ps _______________________________________________ Almanews mailing list Almanews at listmgr.cv.nrao.edu http://listmgr.cv.nrao.edu/mailman/listinfo/almanews From cwhite at nrao.edu Fri May 24 10:51:52 2002 From: cwhite at nrao.edu (Carolyn White) Date: Fri, 24 May 2002 10:51:52 -0400 Subject: [alma_na] ALMA Bi-lateral IPT Meeting Message-ID: <3CEE5388.3080709@nrao.edu> There will be an ALMA Bi Lateral IPT Meeting on Tuesday, May 28 at 1430 UT. Please dial 434-972-7268. Thanks Carolyn From mrafal at nrao.edu Mon May 27 22:01:02 2002 From: mrafal at nrao.edu (Marc Rafal) Date: Mon, 27 May 2002 22:01:02 -0400 Subject: [alma_na] Joint ALMA Office Message-ID: <000701c205eb$8715c700$6401a8c0@hppc> I am pleased to pass on the following information about the Joint ALMA office. The ACC has reached agreements with the following individuals for the interim positions that will make up the new Joint ALMA office: ALMA Director Paul Vanden Bout ALMA Project Manager MassimoTarenghi ALMA Project Scientist St?phane Guilloteau These appointments are effective 1 June 2002 and will continue until a search for permanent staff is completed in approximately six months. We are fortunate to have such a uniquely experienced team to launch the central management organization for ALMA construction. Please join me in welcoming them in their new challenging rolls. From rsimon at nrao.edu Wed May 29 14:08:37 2002 From: rsimon at nrao.edu (Richard Simon) Date: Wed, 29 May 2002 14:08:37 -0400 Subject: [alma_na] Hurricane ALMA References: <3CEE5388.3080709@nrao.edu> Message-ID: <3CF51925.9090202@nrao.edu> In the news today: ...At last report, Hurricane Alma was about 1,800 kilometers west of Acapulco and moving further out to sea at about 13 kilometers an hour... A couple of recent news reports with details: http://www.voanews.com/article.cfm?objectID=B31B0AB4-05F2-4761-A59267CBFF444190 or http://www.cnn.com/2002/WEATHER/05/28/mexico.hurricane.alma.ap/index.html From soliver at NRAO.EDU Thu May 30 19:01:19 2002 From: soliver at NRAO.EDU (Stacy Oliver) Date: Thu, 30 May 2002 16:01:19 -0700 Subject: [alma_na] [almanews] ALMA Memos 422, 426, and 427 Released Message-ID: ALMA MEMO #422 The Dual-Load Calibration device revisited S.Guilloteau (IRAM/ESO) 2002/05/23 Keywords: Receiver, Calibration, Atmosphere Following ALMA memo 371, I re-investigate the dual load calibration scheme which has been proposed for ALMA. This memo improves on the requirements derived in memo 371 by using a better prediction for the atmospheric fluctuations at short time scales. It is shown that because of atmospheric properties and of the antenna geometry, a dual-load system located in the ALMA antenna subreflectors needs to switch at a rate in excess of 20--30 Hz to be efficient in the submillimeter regime. Moreover, integrations in excess of 10 seconds are required to get sufficient calibration accuracy at these frequencies. Because of the exceedingly high rate, and since the system has not been demonstrated to allow an absolute calibration, it is proposed to abandon this development. View a pdf version of ALMA Memo #422. http://www.alma.nrao.edu/memos/html-memos/alma422/memo422.pdf Download a postscript version of ALMA Memo #422. http://www.alma.nrao.edu/memos/html-memos/alma422/memo422.ps ____________________________________________________________________________ _______________ ALMA MEMO #426 4-Gsample/s, 2-bit SiGe Digitizers for the ALMA Project. Paper II David Deschans 1,2, Jean-Baptiste Begueret 1, Yann Deval 1, Pascal Fouillat 1, Alain Baudry 2, Guy Montignac 2 1 Laboratoire IXL, Universite de Bordeaux, 351 Cours de la liberation, 33405 Talence, France 2 Observatoire de Bordeaux, BP 89, 33270 Floirac, France 2002/05/16 Keywords: Analog-to-digital converter (ADC), SiGe technology, high speed bandpass ADC We report on the design details and first dynamic tests of high speed analog-to-digital converters (ADC) with characteristics approaching those desired for the ALMA project. A conventional flash ADC architecture has been adopted with monolithic ADCs implemented in BiCMOS 0.35 um and 0.25 um SiGe (Silicon-Germanium) processes. We concentrate here on our 2-bit, 0.35 um designs and test results, while details on our 3-bit designs and 0.25 um SiGe technology will be given in another paper. The main features of these 2-bit ADCs are 4 GHz clock rate, 3 quantization levels, and an input bandwidth from 2 GHz up to 4 GHz. The two chips tested in this work dissipate 650 and 975 mW under 2.5 V supply; the die areas are 5.4 mm2 and 6.5 mm2, respectively. View a pdf version of ALMA Memo #426. http://www.alma.nrao.edu/memos/html-memos/alma426/memo426.pdf Download a postscript version of ALMA Memo #426. http://www.alma.nrao.edu/memos/html-memos/alma426/memo426.ps ____________________________________________________________________________ ___________________ ALMA MEMO #427 Antenna Position Calibration Melvyn Wright Radio, Astronomy laboratory, University of California, Berkeley 2002/05/16 Keywords: Antenna Position, Calibration This memo summarizes the antenna position calibration used at Hat Creek, and discusses its application to the CARMA and ALMA telescopes. Observations of quasars over wide range of HA and DEC provide data from which the antenna positions are determined. If the antenna positions are in error by many wavelengths, 2pi phase ambiguities may make this process difficult, especially when the atmospheric phase coherence is poor on long baselines. In this case the antenna positions can be first determined from the phase difference between the sidebands in a double sideband system, or across a wideband single sideband. In addition to the antenna positions, there may be axis offsets on the antennas which can be fitted from the quasar data or measured mechanically. These offsets should be stable and not change when the antennas are moved. View a pdf version of ALMA Memo #427. http://www.alma.nrao.edu/memos/html-memos/alma427/memo427.pdf Download a postscript version of ALMA Memo #427. http://www.alma.nrao.edu/memos/html-memos/alma427/memo427.ps _______________________________________________ Almanews mailing list Almanews at listmgr.cv.nrao.edu http://listmgr.cv.nrao.edu/mailman/listinfo/almanews