Modulation and Deconvolution

In each case, the full derivations of the expressions used in the more practical exposition above will be given. The discussion will also look more closely at some of the simplifying assumptions and the problems that arise when these no longer apply. Before this some comments are made on alternative modulations and deconvolution methods. 

It is possible to use multiple sine waves [10] and so extract as a Fourier series (or other deconvolution procedure) the response to several frequencies simultaneously, as illustrated in Chapter 4. An extension of this is the use of saw-tooth temperature modulations [20]. These can be considered to be a combination of an infinite series of sine waves (though only a limited range will be available in practice). A symmetric saw-tooth (same heating and cooling rate) only has odd harmonics, but an asymmetric saw-tooth (different heating and cooling rates) is equivalent to a broad range of frequencies. 

The use of averaging combined with a Fourier transform is by no means the only possible deconvolution procedure [17]. Details of a linear fitting 

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