Types of transmission media including; twisted pair, fibre optic, satellite, microwave cellular, wireless
- A computer can be used to send or receive information.
- It is the network that does this.
- no network = no internet
- Movement of data by upload or download is called transmission of data.
- For this data to move, it needs to go through the air or through cables.
Wired twisted pair - ethernet cable
- Contains 4 pairs of wires
- Is set on the 802.3 standard
- Twisted every cm in a tight twist to minimize electrical interference
- Sometimes shielded completely in aluminium foil to prevent electrical interference (shielded twisted pair)
- Has an rj-45 male connector on each end
- Plugs into an rj-45 female connector wall
- Data speed on a category 5 (cat5) cable less than 90 metres is capable of 100 Mbps
- Data speed on a category 6 (cat6) cable less than 90 metres is capable of 1000 Mbps
- For 100 Mbps 2 wires are commonly used.
- For 1000 Mbps all 4 pairs of wires are commonly used
- Optical fibre cabling has very long strands of glass inside a cable
- Data travels inside the strands of glass as pulses of light
- The size of the strand of glass = the size of a human hair
- Data = light
- Each optic fibre cable can carry 1 or more strands of glass
- Centre part of the optic fibre cable is the strands of glass
- Outside of this is a cladding to reflect the light back into the cable
- Outside of this is buffer coating to protect the cable
- Disadvantages; expensive, difficult to join
- Advantages; fast, no interference
- A communication satellite receives a radio wave signal from a ground station on earth, then bounces the signal back down to a different ground station on earth.
- The satellite not only bounces it back down, but is like a repeater in that it amplifies the signal, so it can keep going further.
- This means that a radio wave can go much further in distance than just 'line of sight' on the ground.
- Remote areas often use satellites to get communications because it is costly with other choices.
- Commonly used to extend TV and/or telephone calls into country or remote areas.
- Has a series of large towers following a path from one town/location to the next.
- The signal goes from one tower, is amplified, and sent on to the next. About 20-50kms away.
- It is 'line of sight' and can't go through mountains or major forests.
- Commonly used for telephone systems.
- Works on a network or collection of cells, each having base station and mast.
- Phone calls travel back and forth along these cells.
- You can see these masts in your big cities.
- Cellular doesn't work in most remote areas as there are no cells available.
- Sometimes the masts are owned by companies, so if you are with company A, you may or may not get a signal.
- For example in the north west of Western Australia, if you are with Telstra - you get signal, if with another company you may not.
- Uses radio waves on the frequency range of 2.4 Ghz or 5 Ghz
- Must have a transmitter to send data and a receiver to receive data.
- Standard 802.11 provides details on set up of wireless. egs 802.11a, 802.11b, 802.11g, 802.11n
- Must be configured prior to working, usually a network name, username and password
- The working range indoors is up to 20 metres depending on wall construction and type of wireless setup
- The working range outdoors is up to 100 metres, depending on the type of wireless setup
Wireless - bluetooth
- Used for short distances up to 10 metres
- Uses short range radio waves around the 2.45 Ghz frequency. Wikipedia states between 2.400 and 2.483
- It is a small microchip that can transmit and receive data
- It is very common in mobile devices
- The bluetooth controller is the Link Manager (LM)
- The Link Manager identifies other bluetooth devices, creates links, sends and receive data
- The Link Manager also controls the operation mode, eg standby (wake each 2 secs to listen), master/slave (initiating link=master), inquiry (causes devices to ID), park (wakes at intervals, listens syncs), hold (power saving, but discoverable)
For You To Do
- Locate the wireless access points in your school. Draw a rough map of these wireless access point locations.
- Make up some advantages and disadvantages for the wired and wireless systems.
- Explain types of wired networking in your own words.
- Explain types of wireless networking in your own words.
Found an error or enhancement? Please fill out this contact us form.