Biomedical Engineering Reference
In-Depth Information
Hardware
The major network hardware components are the media and network electronics, as described here.
Media
At the lowest level of the hardware infrastructure is the media used to connect the workstations,
sequencing machines, and microarray readers in a network. The most common media are coaxial
cable, twisted pair wiring, fiber optics, and, for wireless networks, the ether (see
Figure 3-10
).
Figure 3-10. Media Characteristics. Bandwidth, cost, security, flexibility,
and range reflect the innate physical characteristics of the media as well as
the current state of the art in the associated electronics. In this example,
ether refers to wireless LAN signals; satellite and point-to-point microwave
communications links provide the bandwidth comparable to that of fiber
and coaxial cable.
Coaxial Cable.
Coaxial cable is popular as a medium for LANs because it's inexpensive and provides
the greatest flexibility in installation; it can be folded and kinked with minimal signal loss. The coaxial
design, where the center conductor is shielded by a copper or aluminum mesh or foil, provides a
relatively secure connection and a high bandwidth. However, from a security perspective, it's virtually
impossible to determine if an eavesdropper has tapped a run of coaxial cable. In addition, unlike
fiber, it's possible for someone with a sensitive receiver and antenna to remotely pick up signals
traveling through coaxial cable, amplify them, and decode the digital stream. This is especially true in
coaxial cable designs in which the outer shield is formed by a copper or aluminum wire mesh, which
provides incomplete shielding of the inner wire compared to cable made with a solid foil outer shield.
