xample of binary coding, the Continuous A-law Piecewise linear A-law Without companding Signal power of sine wave (dBm0) Figure 3.13 Companding performance. Introduction to Telecommunications Network Engineering structure of the eight-bit binary word in the case of European PCM coding, the A-law, is defined in the following way: Bit 1, the most significant bit (MSB): The MSB is the first bit and it reveals the polarity of the sample. Value 1 represents positive polarity and 0 represents negative polarity. The sample value zero may create two different code words depending on whether it has a positive or negative polarity. Bits 2, 3, and 4: These bits define the segment where the sample value is located. Segments 000 and 001 together form a linear curve for low-level positive or negative samples. Thus an A-law curve has 13 linear sections as shown in Figure 3.14. Bits 5, 6, 7, and 8: These are the least significant bits (LSBs) and they reveal the quantized value of the sample inside one of the segments. Thus each segment is divided in a linear fashion into 16 values (quan- tum levels). The structure of the encoded binary word together with the nonlin- ear relationship between signal values and binary words is shown in Figure 3.14 [1]. Note that both the previously described nonlinear com- pression and linear coding are combined in the same figure. The verti- cal axis is linear and each binary word corresponds to one of the quantum levels at equal distance from each other, and linear quantizing is per- formed for a compressed signal. For compression, the vertical and horizon- tal axes have a logarithmic relationship according to (3.9). We see, for example, that half of the quantum level is used for signal levels smaller than 6.25% (1/16) of its maximum value to reduce quantizing noise at low sig- nal levels. Finally, after this encoding process, every other bit of the code words is inverted before multiplexing. This inversion was specified to "mix" the digi- tal signal for easier timing of line systems and equipmen