 The secondary advantage is that since the on-time channel experiences less noise power than the sum channel of Figure 2.24 does, it should serve as a better demodulation reference for the difference channel signal. In fact, in view of this, the mean-squared tracking jitter of Figure 2.25 should ideally be smaller than that of the traditional DLL of Figure 2.1 or the SD DLL of Figure 2.24. Here we allow the two phase detectors to have different gains, which we shall further assume represent all the contributions to gain in the two DLL arms. ni(i) c(t-71-8) c(t-f,+8) c(+--8) c(+-,+8) FILTER PN CODE CLOCK GENERATOR (VCC) Figure 2.24. A non-coherent DLL. The Modified Code Tracking Loop Indeed the above turns out to be the case, as will be quantitatively demonstrated shortly. Before doing so, however, and also before discussing other behavioral characteristics of the MCTL and its shortcomings, we point out that the implementation of Figure 2.25 can be reconfigured to more closely resemble that of Figure 2.24 and thereby achieve a further reduc- tion in hardware required. In particular, the difference channel signal can be generated as per the dashed lines in Figure 2.25, thus eliminating one mixer. Note, however, that in this alternate mechanization, the reference sig- nal formed from the difference of the early and late PN codes is not a con- stant envelope waveform which therefore places strict linearity requirements on the single remainining mixer. This constraint also applies to the DLL of Figure 2.24, which conceptually could also be imple- mented, analogous to Figure 2.25, by forming the sum and difference sig- nals after the input mixers. Having derived the loop model and discussed the performance of the DLL in great detail, we shall be extremely brief in the analogous presentation for the MCTL, merely presenting the key results in summary form. In fact, to highlight the similarities between the two code tracking loops and allow easy comparison of their differences, we shall use the same equation numbers as in