The RtFC depends on 4 distributed programs to transfer data from
LBADR recordering systems to a central location, and then invoke the
DiFX software correlator. The software is written in Perl, with a
support programs used to extract a short time interval of data from the
recorded data, and optionally only a subsection of the recorded data
channels. Currently the system works interactively, support could be
added to schedule automatic fringe checks.
For normal LBA sessions, the fringe tester is run from a VNC session on
pam0:1 (pkpam if at Parkes).
The four programs are:
obs.pl runs an external programs (vsipack) to
extract the requested time fragment from the (large) data files and
optionally "compress" the data (select a sub selection of the data
channels) before transferring.
- control.pl: Connects all the perl processes together. Mostly used
pass messages between the processes. Can be run on any machine to which
(incoming) network connections can be opened. Generally run on the same
machine as corr.pl
- corr.pl: Receives data from the LBADR recorder at the observatory
and initiates the software correlator. Connects to control.pl.
- ui.pl : A CLI to control system. Used to configure various
parameters such as the number of spectral points and to initiate a
fringe check for a specific time. Connects to control.pl. Multiple
copies can be run simultaneously.
- obs.pl: Runs at the observatory on the LBADR recorder. Sends the
to the software correlator. Connects to control.pl and corr.pl
To run the programs, they need to know the remote host running
the other programs. This can be set on the command line, or preset via
environment variables. In the RtFC directory there is a script
which should be sourced and will setup most of these environment
variables. Before running the RtFC system, the values set in this
script should be checked.
To run the system first start control.pl, then correlator.pl. After
this run obs.pl at each observatory taking part in the fringe check and
finally run ui.pl from any machine which can connect to control.pl.
More than one ui.pl can be
A grab command from ui.pl gets the observatories to
look for the right time code, then they send the data to corr.pl,
it is stored. The program vsipack is used to only send a fraction of a
second and will optionally only send some of the channels (the LBADR
recorder normally records up to 4 data channels).
- Correlator setup
- Observatory Setup
- Running RtFC