  When simulating full-disc helioseismic data, instrumental noise has
traditionally been treated as time-independent. However, in reality,
instrumental noise will often vary to some degree over time due to line of
sight velocity variations and possibly degrading hardware.
  Here we present a new technique for simulating Birmingham Solar Oscillations
Network (BiSON) helioseismic data with a more realistic analogue for
instrumental noise. This is achieved by simulating the potassium solar
Fraunhoffer line as observed by the BiSON instruments. Intensity measurements
in the red and blue wing of the line can then be simulated and appropriate
time-dependent instrumental noise can be added. The simulated time-series can
then be formed in the same way as with real data. Here we present the
simulation method and the first generation of a BiSON-like instrumental noise
time series.
