SPD - Spectra Display for ATNF Correlators
Description
SPD displays data from the correlator, either in the lag domain - the
correlation function as measured directly by the correlator - or in the
frequency domain - the spectrum which results from the Fourier transform
of the correlation function. The user can select which of the products
contained within the correlator configuration to display and in what
form to display them.
Note: The correlation function is always present for both
positive and negative lags. If only positive lags are measured, as is normally
the case in an autocorrelation function, the positive lag measurements are
mirrored into the negative lags.
Commands
Type the following commands - minimum match - in response to the prompt >
General Commands
>mode
Defines the mode in which the select command operates in selecting products to display.
>mode v - selection by variable or product number.
>mode b - selection by baseline/polarisation.
>select
Selects which products to display.
1. Selection by product number ( mode v ):
In the following examples, the letters refer to the type of display. viz.
- l - The lag spectrum, i.e. correlation function.
- a - The amplitude of the frequency spectrum.
- r - The real part of the frequency spectrum.
- i - The imaginary part of the frequency spectrum.
- p - The phase of the frequency spectrum.
- d - The amplitude difference of the frequency spectrum, using a previously stored reference.
The numbers refer to the product numbers
in the order they appear in the correlator configuration.
Examples:
>select l1 a1 - displays lag and frequency spectra of product 1 on separate plot panels.
[For versions before 27 Oct 2000]
>select a1+2 - displays frequency spectrum of products 1 & 2 on one plot panel.
>select a1+2 a3+4 - displays frequency spectra in two panels, each containing two products.
[For versions after 27 Oct 2000]
>select a1&2 - displays frequency spectrum of products 1 & 2 on one plot panel.
>select a1&2 a3&4 - displays frequency spectra in two panels, each containing two products.
>select a2-1 - displays the difference frequency spectrum between two products.
>select 1-2 4+5 - displays difference and sum frequency spectra in two panels, using the
global display type (see below).
Special Multibeam Selection:
>select mbN - displays lag or frequency spectra of N beams, two polarisations per
plot panel, in the multibeam layout.
2. Selection by baseline/polarisation ( mode b ):
A new plot panel is created for each baseline and frequency selected.
Examples:
>select 1aa - displays all baselines with antenna 1, polarisation AA, frequency 1.
>select 12ba - displays baseline 1*2, polarisation BA, frequency 1.
>select 14cc - displays baseline 1*4, polarisation AA, frequency 2.
>select cd - displays all baselines, polarisation AB, frequency 2.
>select 24 - displays baseline 2*4, all polarisations.
Then use one of the following commands to select the display type.
>l or >a or >p or >d or >r or >i
Sets the global display type and changes all current panels to this display type.
>x
For frequency domain plots, toggles the X axis units from/to frequency to/from channel number.
>array
In baseline mode, defines the currently active antennas.
Examples:
>array 1346 - antenna 1,3,4,6 active, antennas 2,5 inactive.
>array - print out the currently active antennas.
>bins
In baseline mode, and when pulsar binning is active, defines the currently selected time bins.
Examples:
>bins 1-5 10-16 - selects bins 1 to 5 for frequency one, 10 to 16 for frequency 2.
>bins 1.3.5 10.11 - selects bins 1,3 & 5 for frequency one, 10 & 11 for frequency 2.
>bins - print out currently selected bins.
>on OR >off
In baseline mode, when operating with the LBA Correlator, defines which product types are included
in the selection process. In the LBA Correlator there are four product types. The SIN and COS products
are actually formed in the correlator, whilst the SSB1(+) and SSB2(-) products are formed from a phased
combination of the SIN and COS products. The SSB1(+) products form the final data which are archived.
The SSB2(-) products should contain only noise. Note that the SSB products exist only in the
frequency domain. A correlation function display of these products is not possible.
Examples:
>on sc - turn on display of both SIN and COS products.
>on sc+- - turn on display of all types.
>off sc- - turn off all but the SSB1(+) products.
>off - display which types are currently off.
>scale
Allows the plots to be scaled on the Y axis. The default is auto-scaling.
Examples:
>scale l -0.01 0.01 - scale lag plots to cover the range -0.01 to 0.01
>scale a - return to auto-scaling for amplitude plots.
>channels
Allows a selection of a range of frequency channels to plot. The default is all channels.
Examples:
>channels [f1] 100 200 - display channel range 100 to 200 in frequency band 1.
>channels f2 200 500 - display channel range 200 to 500 in frequency band 2.
>channels - reset channel selections to defaults.
>lags
Allows a selection of a range of lag channels to plot. The default is all channels.
Examples:
>lags -800 100 - display lag channel range -800 to 100
>lags - reset channel selections to default.
>avg
When the next data arrives, resets the averaging buffers and starts a vector averaging in
time of the frequency spectra.
>noavg
When the next data arrives, reverts to non-averaging mode.
>save
Saves the current frequency spectra in a stored reference area.
>layout
Controls the layout of plot panels. The default layout is the smallest square (NxN) layout
which will contain the number of plot panels, with the exception that a two panel layout defaults
to 1x2, representing :
(number of panels in X) x (number of panels in Y).
Examples:
>layout 3x4 - 3 panels in X by 4 panels in Y.
>layout 0x0 - revert to default layout.
>layout - prints out current layout.
>quit
Exits the program.
Last updated: Warwick Wilson 28 February 2000
wwilson@atnf.csiro.au