The WAPP, (so-named for ``Wideband Arecibo Pulsar Processor'', it having first
become available to astronomers as a pulsar processor, with standard spectral-line
modes appearing later), was nominally the replacement for the ``interim''
correlator. The WAPP provides eight sub-correlators,
each of these sub-correlators having sixteen 1024-lag chips.
Each of 4 pairs of sub-correlators
can be set up with their own independent bandwidths
and configurations. Table 5 specifies the available
configurations. The maximum bandwidth per sub-correlator is 100 MHz,
with 9 other alternative bandwidths being available in decreasing
octave steps. The WAPP offers 3- and 9-level operations, both for
standard autocorrelation (total-power) and auto+cross correlation (all
four Stokes parameters) modes. The WAPP also offers a direct-sampling
option. Details of the many WAPP capabilities are to be found at,
`http://www.naic.edu/alfa/gen_info/wapp_fact_sheet.shtml`

, with
the WAPP 8-board mode
being described at `http://www.naic.edu/~cima/cima_dual_board.html`

.

Config | Max Bw | Pol/Sbc | Lags/Sbc & Resn - |

per Sbc (MHz) | (kms `@` 1420 MHz) |
||

Single-Pixel 100-MHz Bandwidth | |||

9-level | 100 | 1 | 2048 (2.6) |

9-level | 100 | 2 | 1024 (5.2) |

3-level | 100 | 1 | 8192 (2.6) |

3-level | 100 | 2 | 4096 (2.6) |

3-level Stokes | 100 | Full Stokes | 2048 (2.6) |

Single-Pixel 195-kHz - 50-MHz Bandwidth | |||

9-level | 50 | 1 | 4096 (2.6) |

9-level | 50 | 2 | 2048 (5.2) |

3-level | 50 | 1 | 16384 (2.6) |

3-level | 50 | 2 | 8192 (2.6) |

9-level Stokes | 50 | Full Stokes | 2048 (2.6) |

3-level Stokes | 50 | Full Stokes | 8192 (2.6) |

ALFA 100-MHz Bandwidth | |||

3-level | 100 | 2 | 4096 (2.6) |

3-level Stokes | 100 | Full Stokes | 2048 (2.6) |

ALFA 50-MHz Bandwidth | |||

9-level | 50 | 2 | 2048 (5.2) |

3-level | 50 | 2 | 8192 (2.6) |

9-level Stokes | 50 | Full Stokes | 1024 (2.6) |

3-level Stokes | 50 | Full Stokes | 4096 (2.6) |

Notes:

1) The WAPP has its available bandwidths defined by the following filters: 100, 50, 25, 12.5, 6.25, 3.125, 1.563, 0.781, 0.391, 0.195 MHz

2) 9-level operation achieves 96% of the signal-to-noise of analog correlation, whereas 3-level achieves 81%.

Robert Minchin 2017-10-30