Chapter 3 Transmission Basics and Networking Media

Transmission Basics and Networking Media

In any type of communication we have a transmitter and a receiver. Mediums like the book we are using to understand the networking material for this class, is transmitting the information to the reader (receiver). After reading each chapter there are review questions and projects to ensure the message was delivered and understood. These questions acting as a transceiver, asking questions to get a response to acknowledge the user has received the message. Ultimately the class final or certification test will let us know if these mediums transferred the knowledge to the user/node.

Like hand signals the OK sign, the Peace sign or Flipping of the bird, networking has its own type of signaling.

Analog and Digital signal both use electronic current as their source to travel over the medium wire.

Analog is a waveform made up of the following four properties: amplitude, frequency, wavelength, and phase. One of the drawbacks to analog signals is their voltage is varied and imprecise. Analog signals also need to go through technology to modify the signals to make them suitable for carrying data over a communication path.

Digital signal is composed of pulses or precise positive voltages and zero voltages. The positive pulse represents a 1 (one) and a pulse of zero voltage represents a 0 (zero)

Data whether analog or digital is also characterized by the direction it travels over the media (Wire).

Simplex (one way/unidirectional) – Speaker giving a speech and you can’t ask any questions.

Half-duplex (both directions but only one way at a time) – The speaker gives his speech then you can ask a question and the speaker can respond. Still one at a time, people can’t over each other they need to wait.

Full-duplex (bidirectional transmission)–Speaker is giving a speech and hecklers can speak over him blocking his message. Another example would be an argument everyone is talking and not listening.

Now that we can travel in Full-duplex the next thing to do is hold more than one transmission over the same media (wire). This is a technology known as multiplexing which separates the media into smaller sub-channels. An example of this is Voice communications which uses a frequency band of 300-3400 Hz (This is the frequency of human hearing) so they are able to subdivide the band width above 3400 Hz because we are unable to hear the transmissions.

Transmitters and receivers what are their common relationships? Point-to-point transmission is when the sender only transmits data intended for a specific receiver. Point-to-multipoint transmission is still only one sender with multiple receivers. Point-to multipoint is split into two types: broadcast (TV station broadcasting its message) and non-broadcast (Cable TV/pay preview).

Throughput and bandwidth are how we measure the amount/capacity of data transmitted during given time period. Throughput and bandwidth are often interchangeable however the real definition for bandwidth is a measure of the difference between highest and lowest frequencies a medium can transmit.

What is the difference between baseband and broadband transmissions? Baseband transmissions are where digital signals are sent via direct current (DC) requiring exclusive use of one channel. Where broadband transmissions are modulated as radiofrequency analog waves that use different frequency ranges.
Both digital and analog signals have flaws that degrade the signal prior to the signal being received. Noise is any type of undesirable influence degrading or distorting signal. Listed are a few noises that will degrade or distort the signal.

EMI (electromagnetic interference)
RFI (radiofrequency interference)
Cross talk (one signal in a cable infringes on the signal traveling over an adjacent cable)
Environmental influences (Heat, water…)

Another transmission flaw is attenuation the loss of signal’s strength as it travels away from source. There is signal boasting equipment know as an amplifier however, if you have noise on a analog transmission the noise is just going to be amplified creating a bigger issue. With digital signals they use a repeater that regenerates the signal eliminating the noise and increasing the signals strength.

Network cabling and getting it right the first time. Best practices in my experience with cabling along with network gear (switches, routers, firewalls…) and other peripherals is to purchase the latest approved technology following the TIA/EIA standards. Remind decision makers that once we have the infrastructure installed most likely it will not be changing it for ten to 15 years if the latest cabling technologies are used.

Other considerations:
If you are making long runs between two segments of the network, pull two cables at once instead of just one. Therefore if you have issues down the road or need to further expand the segment you have the second cable there without the labor to pull another cable.

When you make a purchase of peripherals (switches, routers, firewalls…) budget to purchase a spare of each therefore in the middle of a day where access to resources are high you are able to repair the issue and keep users working. Many dollars are lost when a network segment is down at 9:00 am in the morning.