mple by looking at the dotted line of Figure 4.32 at sample time 1. At this sample time, the pre- dicted value (which equals the previous output value) is 8. Because in this case the input value is bigger than the predicted value, increase the output by 8. This is shown in the solid line of Figure 4.32 (see the line labeled 3). Since the output value doesn't change until the next input sample arrives, draw the output as constant over that time, as seen in Figure 4.32 (see the line labeled 4). Figure 4.32 Graphical evaluation of input-output relationship of DM Chapter Four Continuing to do this for all other sample times leads to the input-output relation- ship seen in Figure 4.32. We see from this figure that the output X follows the input x (t) with a staircase-type waveform, increasing and decreasing by 8 to try to keep up with the changes in x(t). Example 4.6 Determine the output of a delta modulator with a=1 and 8=1, when the input shown in Figure E4.8 is sampled at a rate of one sample per second. Solution: To deter- mine the output, we return to the prophetic words uttered in Section 4.4.5: "if the input value is larger than the predicted Figure E4.8 Input to the DM value, increase the output by 8; if the input value is smaller than the predicted output x(t) value, then decrease the output by 8." Figure E4.9 shows you how to apply the rule and the output that pops out when you input value input value predicted predicted value value Figure E4.9 Output of the DM Source Coding and Decoding: Making it Digital 4.4.6 Overload and Granular Noise Telecommunication engineers saw some interesting things going on in the input-output relationship of a DM, and they made up some words to describe what they saw. The first interesting things they saw were at times when the input is hardly changing. Let's consider an input that's near constant at the value 0.5. We'll assume that the output is initially 0, and we'll assume d = 1, as shown in Figure 4.33(a). What's happening is this: at time 0, the output increases to d = 1; 