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Here you can find a collection of documents which should support our WP on phasing ALMA.
- This presentation by Bremer describes the present system and how the VLBI phasing is done. It also gives an overview over the next (NOEMA) system.
- Online description of the present system at Plateau de Bure http://www.iram.fr/IRAMFR/TA/backend/cor6A/index.html
- More details on phasing at PdB given in an email by Bremer.
- Presentation by Torres about the next BdB correlator and how the VLBI mode will be implemented
- An FPGA based Phased Array Processor for the Sub-Millimeter Array is the master thesis of Vinayak Nagpal supervised by Weintroub.
- Adam Deller's memo on VLA phasing and a summary.
- ALMA has chosen to use a set of 128 orthogonal Walsh functions, both for the sideband separation using 90-degree phase switching at the first local oscillator, and for spurious rejection using 180- degree phase switching at the first local oscillator with demodulation by means of a digital sign change shortly after the digitizer. A set of orthogonal Walsh functions can be defined and ordered in many different ways (PAL, Natural or Paley ordering, WAL, CAL & SAL sequency ordering) and with different phasing definitions (e.g. Harmuth phasing, or "positive phasing".) It is proposed here that ALMA standardize on a set of Walsh functions in WAL order with positive phasing. A numerical table is included, and is available in machine readable form.
- Document forwarded by Dave Graham on array phasing ideas from NASA for the DSN at 162B.pdf
- Document forwarded by Dave Graham on phasing of the MWA at Mitchell_IEEE_RTScalibration.pdf
- White paper on phasing by Geoff Crew is in the dropbox
