ATNF VLBI Wiki

When using both DAS in parallel with the 64 MHz filters (1 Gbps total recording rate), the output for each DAS is written to separate files. For correlation it is most convenient to merge the two DAS to a single datastream.

The start times of files to be merged must match exactly. If they do not, one or other can be shifted with lbasync. E.g.

 
cd DAS2
lbasync -o ../DAS2_fix -t 60 *.lba

Once the file times agree, they can be merged pairwise and converted to Mark5b format with lbamerge:

cd ../merge
lbamerge -mark5b ../DAS1/v558a_das1_Mp_073_000000.lba ../DAS2_fix/v558a_das1_Mp_073_000000.lba ./v558a_merge_Mp_073_000000.mk5b

There is a wrapper script for lbamerge that will combine all files in two directories assuming they have matching names (differing only by s/das1/das2/):

lbamerge_all.py ../DAS1/ ../DAS2_fix/ 

Files for one DAS which do not have a match in the other DAS's directory will be joined with a duplicate of themselves.