The textual description of each protocol ends with transmission characteristics.
For example, the characteristics for ISO 18000 Part 7 are shown in Figure 3.13. This
declares that in the byte the LSb is ?¬?rst, in the packet the MSB is ?¬?rst, each byte contains
9 bits and one of these bits is a stop bit. Thus, a complete physical layer description ?¬?le
contains a waveform description, preamble description, and a transmission characteristics
description.
3.3.2 Waveform Features Library
The physical layer waveform feature library in Figure 3.3 is a collection of basic hardwarebased
components corresponding to various waveform features. For example, this set
contains a hardware-based edge detector, sampling counter, sampling registers, serial-toparallel
hardware blocks, ?¬?rst-in-?¬?rst-out (FIFO) blocks, and other basic blocks as prede-
?¬?ned components in the library. These components are programmable and designed to ?¬?t
different user-de?¬?ned parameters speci?¬?ed in the textual description from Section 3.3.1.
A hardware-based edge detector, for instance, can be used for detecting only a rising edge,
only a falling edge or either edge. Similarly, a sampling counter can vary based on different
sampling rates corresponding to the different data toggling rates and different duty cycles
of bit data in the description.
T = 9.4 ?µs
1 bit 1/2 bit 1/2 bit 1/2 bit 1/2 bit 1 bit
Bit ???0??™ Bit ???1??™
Bit ???1??™ Bit ???0??™ after bit ???1??™
4 ?µs 4 ?µs
FIGURE 3.
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