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atmosph

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NAME

atmosph - Analyse phase statistics from a uv dataset  

PERSON RESPONSIBLE

mchw  

CATEGORIES

uv analysis  

DESCRIPTION

ATMOSPH computes phase statistics from a uv dataset. Either Structure function, Allan deviation, or Spectra can be calculated.

ATMOSPH does not apply gains, bandpass or polarization corrections. Known instrumental phase fluctuations should be removed, but slow instrumental phase drifts do not make much difference to the fitted phase fluctuations. ATMOSPH code does remove the average, but no other phase variations which may be part of atmospheric fluctuations.

Each baseline and time interval are averaged independently.

  The default calculates the structure function, the output lists:
number of records averaged, time(days), antenna pair, uvdist elevation(radians), [phase_rms*sqrt(sin(elevation)), phase_rms(degrees), flag(*=bad), for i=1,nchan].
  If Allan deviations are calculated, the output lists:
number of records averaged, time(days), antenna pair, sampling_interval, uvdist, [amplitude_deviation, phase_deviation(degrees), flag(*=bad), for i=1,nchan].
  If Spectra are calculated, the output lists:
number of records averaged, time(days), antenna pair, frequency, uvdist, [phase(degrees/Hz, phase(degrees), flag(*=bad), for i=1,nchan].
  The Miriad task ``rmsfit'' can be used to fit power laws to
the output log file.  

PARAMETERS

vis
The input UV dataset name. No default.
select
This selects the data to be processed, using the standard uv-select format. Default is all data.
line
The linetype to be analysed, in the form:
    type,nchan,start,width,step
where type can be `channel' (default), `wide' or `velocity'. The default is channel data, a maximum of 4 channels will be used.
interval
Two values giving the averaging time, and the maximum time interval between samples in minutes. Default averaging time = 10 min. The default maximum interval between samples is the averaging time.
base
Units and reference baseline for uvdist in meters. Default=100m.
options
This gives extra processing options. Several options can be given, each separated by commas. They may be abbreviated to the minimum needed to avoid ambiguity. Possible options are:
   'psf'        Compute the rmspath for each time interval.
   'allan'      Compute Allan deviation for each time interval.
                    sqrt{<[a(i-k)-2a(i)+a(i+k)]**2>}
                where k is the sampling interval. Minimum 10 records.
   'spect'      Compute spectra of phase for each time interval.
   'topo'       Use the topographic baseline length for uvdist.
                Default is to use the projected baseline. 
   'unwrap'     Attempt to extend phases beyond -180 to 180 degrees

Only one of 'psf' 'allan' and spect' can be chosen. The default is the phase structure function 'psf'.

log
The list output file name. The default is the terminal.
device
PGPLOT device to plot PSF. Default is no plot.
xrange
Plot range in the x-direction. 2 values. Default is 10m to self scale.
yrange
Plot range in the y-direction. 2 values. Default is to self scale.


 

Index

NAME
PERSON RESPONSIBLE
CATEGORIES
DESCRIPTION
PARAMETERS

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Time: 18:35:38 GMT, July 05, 2011