CRDDOP requests Doppler frequency setting for the VLBA legacy system BBCs. It is much like DOPPLER except that it should only affect the BBCs, not the RDBE. This is needed because the legacy system still controls the antenna pointing and does not have access to power levels from the RDBEs, which are controlled by the separate new control system. The total power data from the legacy BBCs are used to make the pointing measurements. See the discussion of CRDFREQ for more details about using the CRDxx parameters.
When using CRDDOP, you must also set CRDBW and one (and only one) of CRDCH1 or CRDSETCH.
As an alternative to requesting SCHED do Doppler calculations, you can force a specific frequency with CRDFREQ.
Specify CRDNODOP to turn off the BBC Doppler setting.
It is not recommended to attempt to use DOPPLER and CRDDOP at the same time, although it might work.