Output-filter section

Designing the output-filter section (refer to Section 3.6)... 

For simplicity of computer implementation, and in almost all practical cases, s(x) can be taken as zero outside some limited range of x. Using filter terminology, we may say that it has a finite impulse response. Let us consider the discrete version. For discretely sampled data, we write the sampled response function as sw. As in Sections V. A. 1-V. A.4, we take its output at the center of the filter. That is, the output corresponds to the Mth finite value, where M is the index at which sm is maximum. Because data are almost always sampled sequentially, we may take the index m as being directly proportional to time. Visualizing the convolution as in Section II.A of Chapter 1, we readily see that the filter s output lags its input by precisely M samples. 

Variants of this basic process are used in other plants. For example, the Comurhex plant at Malvesi [B5] filters the output from the dissolver, uses pulse columns in the extracting section, and dilutes TBP with n-dodecane instead of n-hexane. 

First the core style and material should be selected. This is done in an identical fashion as the single-output filter choke. Either a mopermalloy (MPP) toroid (refer to Section 3.5.5) or a ferrite bobbin core (refer to Section 3.5.2)... 

More windings could be added to the mutually coupled filter choke core, but I highly recommend against this temptation. If the windings are not exact (to the turn), the supply will loose approximately 1 percent in efficiency for each turn in error on each output. Instead, use a mutually coupled filter choke for each complementary set of outputs, and use the output cross-sensing technique described in Section 3.9. 

Designing the output filter choke La) in a forward-mode converter is done first. This simple procedure can be seen in Section 3.5.5. A key design factor is to design the inductor to operate in the continuous current mode. The typical value of peak inductor current is 150 percent of the rated output current. The typical valley (minimum) current is about 50 percent of the rated output current. 

The zero attributed to the output filter capacitor is still present in the control-to-output characteristics. Its location is found in Section B.2.1 and Equation B.9. 

In this connection, it should be carefully noted that, even if X(t) is not a gaussian process, the mean and the autocorrelation function of the output of a linear, time-invariant filter are related to the mean and autocorrelation function of the input process according to Eqs. (3-293) and (3-294).64 This is an important fact of which use will be made in the next section. 

For signals represented approximately by the output of a linear system driven by periodic pulse or noise excitations (e.g., human speech or woodwind instruments), the sine-wave model of the previous section can be refined by imposing a source/filter representation on the sine waves components. Within this framework, the notion of phase coherence [Quatieri and McAulay, 1989] is introduced, becoming the basis... 

Moorer proposed a slightly different structure, shown in figure 3.7, where the late reverb is driven by the output of the early echo FIR filter [Moorer, 1979], Moorer described this as a way of increasing the echo density of the late reverberation. The delays D and D2 can be adjusted so that the first pulse output from the late reverberator corresponds with the last pulse output from the FIR section. The gain g serves to balance the amount of late reverberation with respect to the early echoes. An important feature of this structure, apart from the early echo modeling, is the control... 

However, diode lasers have some negative characteristics that must be overcome for use in Raman spectroscopy. Their broad gain curves permit drift in the output wavelength, and their mode structure is difficult to stabilize. The result is uncertainty in output wavelength and observed Raman shift. Diode lasers of the type shown in Figure 7.5 have high divergence and are less easily filtered and focused than ion or Nd YAG lasers. Modifications to alleviate these problems are described in the next section. 

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