Quick fix for DAS baseline errors

  If you get bad baselines which are clearly caused by the DAS, ie one subband has a clear slope or offset, try loading a different configuration, then go back to the old config. If the baseline errors remain, then it may be possible to circumvent the problem by loading a equivalent non-standard configuration that has two subsystems covering the same frequency range. This will give the observer two copies of the spectrum; the bad one can be ignored, and the other good one used (see section 7 for more details). The files are called NS_125X2, NS_250X2 and NS_500X2. These will be read into the X and Y registers of specx. The spectral resolution will be half of the original, but usually this will be acceptable. Note that wider bandwidth options are not currently set up for this dual-subsystem mode.