DOPINCR sets the frequency increments to use in setting frequencies using DOPPLER. The frequencies will be rounded to the nearest N * DOPINCR(1) + DOPINCR(2). The default for DOPINCR(1) when the RDBE is not in use is 10 kHz, the setting interval for the BBCs for the DBBC, LBA, and the legacy VLBA and Mark III/IV systems. For the RDBE_DDC option for DBE, the default is 15.625 kHz. For mixed legacy/DBBC/MARKIV and RDBE observations systems, the default is 250 kHz, the smallest value that is a multiple of both 10 kHz and 15.625 kHz. It is best not to use DOPPLER with the RDBE_PFB personality because of the tight tuning restrictions and the fact that the offset DOPINCR(2) depends on the LO setup. The ATCA LO is set in intervals of 1 MHz + 0.5 MHz.
The values are in kHz. A new value may be given for each scan, although usually a single value would be used for the whole experiment.