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VLBI Wiki | Main / DFB3DAS
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DFB3DAS

DFB3 for VLBI

Technical Notes

Current State

The Parkes Pulsar backend DFB3 has a baseband mode, used with APSR. This instrument fulfills the basic requirements of a broadband VLBI backend.

  • 1 GHz or 256 MHz front end bandwidth
  • Divide by 16 filterbank (ie 64 MHz channels with 1 GHz front end).
    • 16 MHz channels with 256 MHz front end
  • Bits selectable from 1-8
  • UDP data transport with simple 24 byte timing header

Requirements

To convert to system suitable for VLBI the following changes are needed

  • More filterbank options (divide by 32 and divide by 64 have filters already designed)
    • Giving 32/16 MHz channels with 1 GHz front end or 8/4 MHz with 256 MHz front end)
  • VDIF packet headers
  • Packet sizes to conform to VDIF requirements, specifically an integral number of packets/sec
  • Tsys monitoring

Potential extra work

  • Linear->circular conversion (optionally)
    • including calibration of x-y phase correction
  • Single stage filter design (not the current "high resolution" filter followed by a reverse filter.
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Page last modified on December 22, 2010, at 11:50 AM