PUPPI Observing in Search (Incoherent) Mode

(13 September 2012 -- P. Demorest and J. Deneva)

Here are some brief notes on observing with PUPPI in search (incoherent) mode. The Basic How-To section is a step-by-step guide for new users. Subsequent sections give more details and are written mainly for those who have done this sort of thing with GUPPI before.

Basic Info

Basic How-To

IF/LO setup

Several PUPPI-friendly CIMA config files are available in the p2624 (NANOGrav) project area. These are:

Setting up the PUPPI HW

Setting up the hardware (loading FPGA designs, changing clock rate, etc) is done via the guppi> prompt. Just run 'guppi' on puppimaster to open it up. At the guppi> prompt, run the following commands to set up or change modes:

Once you have done the above steps, you can check that the input power levels are ok by running guppi_adc_hist at the puppimaster command line. Important: Do not run guppi_adc_hist while recording data!

PUPPI has programmable attenuators that can be used to tweak the input power levels via the program puppi_atten. Attenuation for pol A and B can be adjusted separately from 0 to 15.5 dB in 0.5 dB steps. puppi_atten with no arguments will return the current settings. To give new attenuator settings, use -A and/or -B, e.g.:

Running an observation (taking data)

The script puppi_observe will run a coherent fold-mode observation or incoherent search-mode observation. The script takes one argument, which is the par file to use for folding or just to get the source name from. The full path should be used to specify the par file, eg:

The script also accepts the following options (as well as -h for usage info):

By default, this script assumes you have set up the PUPPI hardware and IF/LO settings such that:

To stop an observation before the specified scan length finishes, run puppi_stop.

Plotting/checking data

For incoherent mode, the data are recorded on puppimaster, in /data/puppi/[project ID], where "project ID" is what you give to the -P option of puppi_observe. The data is recorded as 8-bit PSRFITS and can be plotted using the standard Presto, PSRCHIVE, or SIGPROC codes.