Data Taking Command Options

simple_getdata (Sets up the spigot to take data):

Options:

-v	verbose mode
-t tickver	1: print tick on skip; 2: print tick on skip & exit; 3: always print tick
-w	if set, don't write ticks in output
-l bufs	number of buffers to read. This sets the time for the observation, with a count of 1 equal to 0.04192 sec (e.g. -l 1500" is one minute)
-o outfile	specifies output filename;
-n scannum	specifies scan number; defaults to next number (starting with 1)
-m mode	specifies mode in Hex; See table for more info.
-b nbits	number of bits in data; defaults to number in mode
-c file	if set, calculates scale & offsets using specified file
-u file	if set, updates the scale & offsets
-r file	if set, reads the scales & offsets
-f freq	center radio frequency of the bandpass (not the power) in MHz, for header info
-d	indicates that a double-Nyquist mode is being used
-pfilename	Write the 0 lag value to the file filename every 0.04 ms. If no file name is given it writes to the file 'spigot_power.dat' in the local directory. Note that if you wish to use the stripchart then you must leave this as the default.
-s 1 or 2	Sampler for calibration: 1 (default) or 2

If you are having trouble calibrating the spigot there are a couple of tricks you can play:

• If you beleive the trouble is due to having too large a range in power levels coming down the system (e.g. lots of RFI) you cam try reducing the width of the 0 lag gaussian distribution using the SIGMA16BIT, SIGMA8BIT, and SIGMA4BIT environment varaibles. The default setting for these are 1000, 28, and 2, respectively. If, for example, you are running in the 8 bit mode, and in a bash shell, and wich to cut the width in half, you would simply type "export SIGMA8BIT=14" (in csh you would type ("setenv SIGMA8BIT 14"). You must run this command before running any of the load_vs A B commands.
• If you are running in a dual polarization mode, you can try calibrating the individual polarizations, and then adding up the results. You do this using the -s option for simple_getdata and the merge_calib routine. That is, you would run something like this:
  load_vs A B
  simple_getdata -t 2 -w -l 10 -m nmode [-d] -f freq -c calib_pol1.fits -s 1
  simple_getdata -t 2 -w -l 10 -m nmode [-d] -f freq -c calib_pol2.fits -s 2
  merge_calib -1 calib_pol1.fits -2 calib_pol2.fits -o calib.fits -O a -S g
  load_calib -r calib.fits
  

merge_calib (Merges the calibration files from the two polarizations):

Options:

-a	arithmetic mean
-g	geometric mean
-1	use value from 1
-2	use value from 2

Example: modify_calib.py -i input.fits -o output.fits -1 0.5 -2 0.5
(Reduces the scale factors by 50%, without re-running the calibration)

Options:

-g x1:x1	Good range (in lags) to get scale factor from
-b x1:x1	Bad range (in lags) to avaoid for scale factor
-1 scaleFactorA	Amount ScaleA is multiplied by
-2 scaleFactorB	Amount ScaleB is multiplied by
-i input.fits	Input fits file, to be modified
-o output.fits	Output file, which has been modified