## Korean VLBI Network (KVN)

## Digital Filter Mode

The digital filter bank (DFB) is configurable to various modes according to the required number of streams and bandwidths.
The DFB enables us to select in frequency domain 16 data streams of 16MHz bandwidth from 4 streams of 512MHz bandwidth.
The corresponding data rate of 16x16MHz stream is 1024Mbps, which corresponds to maximum input data rate of Mark5b recorder.
Combining more than one stream, the DFB can produce streams with wider bandwidth such as 8x32MHz, 4x64MHz, 2x128MHz and 1x256MHz.

Band Width (MHz) |
Number of Streams |

16 |
16 |

32 |
8 |

64 |
4 |

128 |
2 |

256 |
1 |

A center frequency of a data stream is given by
BW * ( 0.5 + N ),
where BW and N represent a bandwidth of data stream and integer number, respectively.
If N is an even number, the data stream is upper side band. Otherwise, the data stream is lower side band.
Therefore, adjacent data streams have opposite side band each other.
The center frequency cannot exceed 512MHz.

Korean VLBI Network (KVN)