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 output datastreams corresponding to the 16 BBCs (USB and LSB) are enabled. If running the DDC mode with less than 16 BBCs per board the unused datastreams should be disabled.

This is done by placing the vsi_bitmask directive in the fila10 configuration file of the board (e.g. ddc_U_core3H_1.fila10g).

Note: The directive must be placed prior to the vdif_frame command

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

Bitmask logic:

Note: DWORD 1 and 3 must be indentical; DWORD 2 and 4 must identical.

The above example would disable the output streams from BBCs 13-16 and 5-8

Each half-byte contains the bit-mask for the signa and magnitude bits of the uper and lower side band produced by the corresponding BBC.

F = 1111   (sign and magnitude enabled for upper and lower sideband)

C = 1100  (Check: sign and mag enabled for ??? sideband)

3 = 0011 (Check: sign and mag enabled for ??? sideband)

A= 1010

5 = 0101