6.11 : satellite systems

Question 1

what does GPS stand for ?

Answer 1

• Global positioning System

Question 2

Explain why do we use GPS ?

Answer 2

• it is used to determine the exact location of a number of modes of transport . cars usually refer to GPS as satellite navigation system

Question 3

explain how does the GPS work to determine the position of a vehicle ?

Answer 3

• satellites surrounding the earth will transmit signals to the surface of earth , then the computer installed on board of these modes will receive and interpret this signals , each satellite transmits data indicating its position and time , that is why they will need very accurate clock , that is why they use atomic clocks which are accurate the the billionth of a second per day . the computer on board of these modes will need signals from at least 3 satellite to calculate its position accuartly.

Question 4

how does this (to the last card) translates when working in cars ?

Answer 4

• the onboard satnav system will contain stored road maps , when combined with the satellite positioning data the cars exact location can be shown on the map and the driver can also be given verbal instructions , such as after 100 meters turn onto this or that street , a screen on the satnav device will also show the car’s position in relation to the road network .

Question 5

What are the advantages of GPS and satnav ?

Answer 5

• the driver does not have to consult paper , so it is far safer
• it removes errors , for example ( closed streets , one-way streets )
• can estimate the time of arrival
• it can program the fastest route
• it can give useful information such as petrol station locations

Question 6

Disadvantages of GPS and Satnav

Answer 6

• if the maps are not up-to-date , the system can give wrong instruction
• if the system is not sophisticated then , road closures due to accidents or roadworks can cause a problem
• loss of satellite signals can be a problem
• if incorrect starting-point or ending-point is keyed in then the system will give incorrect information

Question 7

what does GIS stand for ?

Answer 7

• Geographic information system

Question 8

Explain what is GIS ?

Answer 8

is a computer system that allows us to map , model , query and analyze large amounts of data according to their location

Question 9

what does GIS allow the users ?

Answer 9

• GIS allows the users to create interactive queries , edit maps and analyze spatial information ( spatial refers to how objects fit together in a space ) The technology combines the maps with computer graphics and databases.

Question 10

What does GIS enables ?

Answer 10

• amalgamation of information into easily understood maps
• performance of complex analytical calculations and then the presentation of the results in the form of maps , tables or graphics ( or the combination of all three )
• geographers, scientists and engineers use it to see the data in several different ways in order to see relationships and patterns
• anything that can be placed1 on a map is a candidate of GIS.

Question 11

what happens when you carry out queries on the GIS system ?

Answer 11

• it will find data that matches the query , then this data will be displayed in the form of maps , diagrams or sets of tables by zooming into the map you can find the finer details about the layering of the data

Question 12

where do we use GIS ?

Answer 12

• it is used by the emergency services to send out the closest personnel to the location
• it is used by biologists and environmentalists to protect animal life and plants in certain vulnerable areas ( after it met a certain criteria when a search has been carried out in the database)
• teachers can use it in their geography , science and engineering lessons
• it can be used for crime mapping in a certain region or country
• it can be used in route monitoring ( used in junctions alongside the scheduling software)
• used in management of agriculture crops data
• used to address public health risks , as it was used during the covid-19 pandemic it was used to see how the virus spread differently in different parts of the world and to combine data such as ( age groups , ethnic groups , density of a population and so on ) to have a unique insight on how the virus was spreading
• it can map of wildfire risks ( it was used in 2019 with the Australian fire outbreaks , it was used to see how and where the fire was spreading )

Question 13

Advantages of GIS ?

Answer 13

• it allows geographical and thematic data of any kind to be combined in a way which shows how they are connected
• it allows the handling and exploration of huge amounts of data ( massive number crunching)
• it allows data to be integrated from a wide range of very different ` sources ( which at first appear they are totally unconnected )

Question 14

Disadvantages of GIS ?

Answer 14

• the learning curve on GIS can be very long
• GIS software is very expensive
• it requires large amounts of data ( thus increasing the chance of errors)
• it is difficult to make GIS user-friendly and be fast at the same time as it needs very complex command languages to work properly

Question 15

what does communication media refers to ?

Answer 15

• it refers to a method of delivering / receiving data / information using telecommunications

Question 16

give examples of methods of sending and receiving information ?

Answer 16

• fibre optics
• copper cable
• wi-fi

Question 17

Explain how does satellites work to receive and send data ?

Answer 17

• satellites contain antenna and transponders (to receive and send data) , and solar panels (for power from the sun) , and contains propulsion ( to ensure correct path of orbiting around earth) , signals are converted to ( analogue ) if necessary then the beamed to the satellite from a satellite dish from earth then the signals are sent as waves and they are sent through a carrier which is radio waves , each wave has it’s own frequency and bandwidth ( the larger the bandwidth the more data it can hold) , once the data reaches the satellite the satellite re-boosts it and sends it back most of the times the frequency is changed so , people don’t get mixed up between the one that has been sent and the one received

Question 18

in what are satellites used ?

Answer 18

• satellite systems are used to transfer data from one part of the world to another , due to the great distances , cables would be too expensive , and there is also the problem of signal deterioration in cables over big distances

Question 19

what are the example of data sent through satellites ?

Answer 19

• television
• internet
• telephones
  all over the world

Question 20

what are the advantages of media communication system ?

Answer 20

• they have good global coverage as they cover most of the earth surface
• they are cheaper , faster and safer from laying cables in difficult or treacherous terrain
• they have high bandwidth
• they are easier to expand ( a lot of companies now produce satellites)
• they are more secure as the sender and the receiver should have a decoding equipment as the signal will be coded for security
• in emergency situations they are more easy to move compared to cables , also satellites in space can change direction of orbit through a booster installed in them
• the receiver can be portable , enabling telephones to have mobile data and phone calls
• they are well-suited for broadcasting , as there can be more than one receiver on earth

Question 21

Disadvantages of media communication systems ?

Answer 21

• there may be a delay when having a even half a second would be noticeable and Disrubt the call as the video and audio are not synchronised or there may be an echo in the sound this delay could be even on fibre optics if there is long distances
• the signals received is affected by bad weather ( such as rain or hailstones ) and is also affected by obstruction ( such as tree branches) and whether the satellite dish has been correctly oriented
• sunspot activity can affect the performance of a satellite
• if they are not in a fixed position relative to earth then they need to be monitored and controlled on a regular basis to ensure that they remain in the correct orbit