This file gives some hints on setting up the ABPP for pulsar observations and taking data. Note that a full document will eventually appear. The purpose here is to get early users going with their experiments.
If you are testing and can't get on the telescope directly, then forget this section! If you are observing, fire up AOCONTROL, by typing
at the "observer%" prompt from the observer workstation and follow the standard steps to choose your receiver and source.
The input IF frequency expected by the ABPP is 440 MHz for L-band and S-band, and 330 MHz for 430 Dome and Carriage House. This is taken care of in the IFLO.tcl file that is sourced when you fire up aocontrol, so you need not worry about it. ABPP will always choose the largest bandwidth possible given the RF and the DM of the pulsar. The limits are:
1) In Polarimetry (4 stokes mode) no more than 28.8 MHz overall bandwidth is available.
2) The dispersion smearing across a channel cannot be larger than the channel bandwidth. In practice, for example, for a low DM pulsar such at 1855+09 (DM of 13) this means that at L-band you'll have 56 MHz overall bandwidth and at S-band you'll have the full 112 MHz bandwidth. For 1937+21 (DM of 70) at L-band you'll have 45 MHz, S-band you'll have 56 MHz, and C-band you'll have the full 112 MHz bandwidth.
Any center frequency is possible at any of the receivers. In practice it does you no good to shift off of 430 MHz center frequency since ABPP uses the entire available bandwidth of that receiver (both Gregorian and Carriage House).
The iflo.tcl script has been configured for the Gregorian receivers so that a ABPP-compatible IF is coming down from Amplifier number THREE, this gets passed directly to the machine which is located in the backend room. No cabling is required to run the machine which should always be switched on.
The simplest way to control the WAPP datataking program is via tha datataking GUI shown below.
The ABPPGUI is started by clicking on the ABPP button on the pulsar observer's widget.
Once you have started the abpppgui - - you'll see that it's fairly simply laid out. Once you have chosen a source and a center frequency on the main aocontrol gui you can just hit the button "TAKE DATA!":
to begin taking 10 scans of 180 seconds each, which is the standard. The orange "DATATAKING NOT ACTIVE":
will immediately turn into a pink "SETTING UP MACHINE":
and you will see a series of tasks scrolling by in the "Execution Status Window". After about 30 seconds, the command "dataloop -c .." will be left on in the Execution Status window. This is the main datataking command and means that the PC has _probably_ begun taking data. As soon as the PC echos back to the gui in the ABPP LOG, that it is, in fact, taking data, you will see this reflected in the gui by the pink "SETTING UP MACHINE" being replaced by a green "DATATAKING ACTIVE". :
Now press the "Plot Every New Scan" button:
and wait an integration time and as soon as a scan gets written to disk the gui will display it. This is a very useful sanity check. You may also turn off "Plot Every New Scan" and just hit "Disp Last" to display the last scan whenever the mood strikes.
This button automatically turns on the 25 Hz cal (you can see it do this at the VXworks prompt), and takes 2 30-second scans folded at 25 Hz. The cal gets turned off until the next time you say "TAKE DATA!". If you wish to turn it off sooner merely use the 25 Hz cal toggler on the master gui.
If you'd like to end your datataking before you've done all the scans you originally intended to do, press
to stop at the end of the current scan or
to end (relatively) immediately (it may take 10 seconds).
These buttons both work during "SETTING UP MACHINE" as well.