Trying to remove the 1400 Mhz resonance in software



    On 21nov08 project s2425 did the following experiment:
Resonances in polA and B showed up between 1395 and 1400. Pol B is located at the lower frequency and pol A at the higher. The resonances made the bandpass bad enough that no statement could be made about the existence of the galaxy.

    After the fact an attempt was made to remove the resonances from the recorded data. This was done for polA to see how well it worked.

The contributions to the system temperature can be broken down into:

Tsys= (Tsky*g1 + Tomt*g2 + Tcal + Trcv)*g3

Steps in removing the resonances

    The steps to remove the resonance are:
  1. make a model of the resonance from the Off source data.
  2. fit    this model to the on source data
  3. subtract the resonance from each
  4. compute posOn/posoff .
  5. Do this for the avg spectra of each  onoff pair.

The model:

    A damped harmonic oscillator was used as the model for the resonance:

Plots showing the results:

    The first set of plots shows the results for each 2min on, off pair (.pdf).
    The 2nd set of plots is the on/offsource average for the 14 on/off pairs (28 minutes on) (.ps) (.pdf):


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