DBBC3 FAQ

Configuring the BBCs (DDC_U mode)

open c:/DBBC_CONF/config_ddc_u.txt

1 3024.0 64
2 3152.0 64
3 3280.0 64
4 3408.0 64
5 0.0 64
6 0.0 64
7 0.0 64
8 0.0 64
9 ....

column 1: BBC number

column 2: Frequency in MHz. Setting a frequency to 0.0 will disable the BBC

column 3: Bandwidth in MHz

Notes:

• If defining less than 8 BBCs per block the vsi-bitmask must be set in order to not output any data streams for the disabled BBC. The vsi_bitmask command must be set prior to the vdif_frame command:

vsi_bitmask 0x0000FFFF 0x0000FFFF 0x0000FFFF 0x0000FFFF
vdif_frame ...

        The above example sets the mask for 4 BBCs per block

• If defining bandwidths < 128 MHz the clock devisor must be set with the vsi_samplerate directive before setting the vdif_frame command:

vsi_samplerate 128000000 2

The above line will set the sampling clock for 64 MHz bands.

Setting the vsi-bitmask

By default all 32 datastreams are enbabled. If running the DDC mode with less than 16 BBCs per board the unused datastreams should be disabled.

ToDO: write up information on the bit-mask logic