Single pol/brd spectral line observing with wapps only provides 1 pol

Jan 05


    The spectral line gui allows you to setup the wapps for 1 polarization per board. You can select polA or polB for the first board and the opposite pol for the 2nd board. This allows for more channels per spectra (but uses up more boards). An example would be: The problem is that the gui configures the wapps to provide polA to both boards (actually it could be polB, i'm not really sure... the important thing is that you only get 1 polarization). This problem has been there since at least nov04 and probably all the way back to may04. This problem does not occure when the gui is used in pulsar mode.

    People who have been observing with 1 polarization per board have been losing sqrt(2) in sensitivity since they are not getting both polarization's recorded. The plots show an example of what is happening.:

    The correlation polAxpolB for the single pol/brd is close to one the correlation for the 2 pol/board is centered on 0.

    This problem was reported by chris salter in nov04.  I reported a similar problem on 20may04 and again on 31jul04 stating that the single pol per board header values were incorrect (i mistakenly thought that the data was ok, just the headers were bad).

    The gui continued to allow users to select polA for board 1 and polB for board 2. People have been observing in this mode and have been losing sqrt(2) in sensitivity as well as quoting the wrong sensitivity levels. When we find things like that that may need some time to correct, we should disable the feature in the gui until it can be fixed. This would prevent users from  inadvertently using broken options.

    This problem is scheduled to be fixed on 3feb05.