SCHED is able to fill in many items in setup files based on knowledge of possible frequency setups at the stations as described in the frequency catalog. This allows the user to only specify basic information. A reasonable minimum set is: NCHAN, BBFILTER, BITS, POL (can be DUAL), and either FREQREF (and FREQOFF) or BAND. The frequency catalog also allows SCHED to check user specified values against standard sets to warn of any oddities.
Most users will not touch the frequency catalog. If they need a setup that does not conform to what is in the catalog, they should just make the necessary setup files and ignore the warnings after making sure that the special files are correct. Be very careful doing this. There are filters on many of the LO and IF cables, at least on the VLBA, that most users probably are not aware of. Any special setup files that do not match one of the standards should be shown to Craig Walker for approval. If it is a good one, it may be added to the standards. However, the standard set is essentially complete for the VLBA. If SCHED complains about your's, it is likely to be in error. If a user really wants his/her own frequency catalog, use the input parameter FREQFILE to specify the file name.
There is a lot of information about available frequencies, receivers, frequency ranges, filters etc, especially at the VLBA, in the standard frequency catalog. A table of information about possible setups for observations within a frequency range can be made by running SCHED with FREQLIST = lowfreq, highfreq (eg freqlist=4800,8900) as the only input. The frequencies are in MHz. If only one frequency is given, the second will be set equal to the first. SCHED will produce a table in file frequencies.list containing details of the information available on how to set up these frequencies at all known sites. SCHED will then quit. Note that it is not necessary to transfer this information to your setup files -- SCHED will do that automatically based on your frequency and polarization requests in the setup file. To examine the catalog itself, look at $SCHED/catalogs/freq.dat or, if reading the html version of the manual, click here..