Start of frequency range.
The ccsSpectrumRequestLowFreq is adjusted slightly to
accurately represent the actual starting point
of the frequency range.
The adjustment is done as follows:
aFactor = (center frequency - ccsSpectrumRequestLowFreq)/12K
ccsSpectrumRequestLowFreq = center frequency - (aFactor * 12K)
where 12K is the FFT's bin size.