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     VSI4/VSIB Real-Time Multichannel Spectrometer
     Copyright (C) 2009 Jan Wagner
     License: GNU GPL v3
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About

  This spectrometer software uses a Metsähovi VSIB card to
  capture 4, 8 or 16-channel 2-bit data directly from a sampler
  or converter such as the Metsähovi VSIC Converter or the
  similar Haystack VSI-4 Sampler Adapter Board.

  Data of four or eight channels is integrated over 
  a specified time period. 

  At the end of every period, the time-integrated
  spectra of every channel are output into a file.

  The FFT size is almost arbitrary. The smallest
  size is 1024 points. Sizes up to 2 million (2^20)
  points per each channel have been tested real-time.

Limitations

  Currently the program uses only one CPU core.

  Old Pentium4 and AMD2212 seem to handle 512 Mbps
  rates fine (8 channels, 32 Ms/s/ch, 2-bit).

  If more processing such as overlap-add and windowing
  is desired, the 8-channel processing might have
  to be split into 2 x 4-channel processing which
  runs on two CPU cores.

  Current FFT uses Intel Performance Primitives. This 
  is stupid because the Intel FFT doesn't take advantage 
  of multi-core CPUs like FFTW does. At some point,
  for much faster FFTs, it is advisable to move to
  the FFTW library.

Future
 
  At the moment, vsi4spec accepts only VSIB data input.

  It is possible to extend this to take Mark5B+ VSI I/O 
  board input as well.

  Likewise the data could be received from the network
  in say a 2048 Mbps multicast data stream (512 MHz wide 
  single IF at 2-bit sampling).