Cable testing
From Mycomputer Notes
In this chapter will discribe all the issues related to testing of the media used by the Physical Layer. In order for a LAN or WAN to properly work the physical layer medium must meet the industry standards. The Standard specified the data rate used to trasmit over Ethernet(10, 100, 1000 or 10,000 Mbps) In this chapter we will encounter the term signal, and it refers to the data signal that moves from the transmitter to the receiver. We know based on previous chapter that what travel as a signal is an electrical current. As the signal travels thorgh the physical media this signals [attenuates] however, the receiver must still be able to clearly determine the state of each bit (1 or 0) of data.
Analog signals have a continuously varying voltage-versus-time graph Digital signals have a square wave with instant transitions from low to high voltage states (0 to 1). Networks Use Digital Signaling Bits are represented by either no voltage (0) or +3 to +6 Volts (1). A Signal Reference Ground attached close to a computer’s digital circuits establishes the baseline for no voltage. Bits must arrive at the destination undistorted in order to be properly interpreted.
