Difference between revisions of "Communication Methods"
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https://www.youtube.com/watch?v=6KsEiwCZi4g&list=PLCiOXwirraUAVO2FCJUdKRM6hYj9teHVe | https://www.youtube.com/watch?v=6KsEiwCZi4g&list=PLCiOXwirraUAVO2FCJUdKRM6hYj9teHVe | ||
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==Parallel Vs Serial== | ==Parallel Vs Serial== | ||
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=Revision Questions= | =Revision Questions= | ||
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<quiz display=simple> | <quiz display=simple> | ||
+ | { Define the term "bit rate". | ||
+ | | type="()" } | ||
+ | + The number of bits transmitted per second. | ||
+ | || Epic. | ||
+ | - The number of bits transmitted in a year. | ||
+ | ||Remember it is per second. | ||
+ | - The amount of bits a computer can store. | ||
+ | ||Bit rate is the number of bits transmitted per second. | ||
+ | - The frequency that signals may change. | ||
+ | ||Bit rate is the number of bits transmitted per second. | ||
+ | |||
+ | { Define the term "baud rate". | ||
+ | | type="()" } | ||
+ | + The frequency at which signals may change. | ||
+ | || Epic. | ||
+ | - The number of bits transmitted in a second. | ||
+ | ||Remember that it is the frequency at which signals may change. | ||
+ | - How fast the computer can process. | ||
+ | ||Remember that it is the frequency at which signals may change. | ||
+ | - The bandwidth. | ||
+ | ||Remember that it is the frequency at which signals may change. | ||
{ What is the difference between bit rate and baud rate? | { What is the difference between bit rate and baud rate? | ||
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||try harder | ||try harder | ||
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{Select the following answers which need to be agreed upon in a protocol | {Select the following answers which need to be agreed upon in a protocol | ||
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-Frequency | -Frequency | ||
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{ What is Latency? | { What is Latency? | ||
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- FALSE. | - FALSE. | ||
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{ Parallel transmission is when (select one or more): | { Parallel transmission is when (select one or more): | ||
| type = "[]" } | | type = "[]" } | ||
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|| Correct answer | || Correct answer | ||
- One bit is sent per second | - One bit is sent per second | ||
+ | |||
+ | { select all that applies to parallel transmission | ||
+ | | type="[]" } | ||
+ | - It is over a single wire | ||
+ | || this is serial | ||
+ | + Multiple bits are sent at the same time | ||
+ | || this is true | ||
+ | + It is sent over multiple wires | ||
+ | || this is true | ||
+ | + It can be affected by skew | ||
+ | || this is true | ||
+ | - It is good for long distance | ||
+ | || this is only applicable to serial | ||
+ | |||
+ | { Select all that are advantages of parallel transmission. | ||
+ | |type="[]" } | ||
+ | - Capable of sending data over long distances | ||
+ | ||This is incorrect, parallel transmission suffers from skew over longer distances | ||
+ | + Data is sent as multiple bits per pulse. | ||
+ | ||This is correct, as it makes it more efficient than one bit at a time. | ||
+ | + High speed data transfer over a short distance | ||
+ | ||This is correct, as it is used mainly in the internal circuitry of a computer | ||
+ | - It uses a single wire to send and a single wire to receive | ||
+ | ||This is incorrect, serial transmission uses a send and a receive wire to achieve full duplex communication | ||
+ | |||
+ | { What potential issue may arise using parallel transmission? | ||
+ | | type="[]" } | ||
+ | + Data may arrive in the wrong order over distance. | ||
+ | ||Correct, this is called skew and may occur because data is sent on different cables; it is possible that one cable is shorter than the rest resulting in data arriving sooner than it should. | ||
+ | -Data is more prone to degradation. | ||
+ | ||All methods of transmitting data are prone to degradation, this is not exclusive to parallel | ||
+ | +It is more expensive and time consuming to lay down the cables over a long distance. | ||
+ | ||Correct, because parallel transmission uses several cables to send data, it becomes incredibly costly over a longer distance as opposed to series, also if the wires are not the same length then skewing can occur so it must be ensured that the wires would also be the same length. | ||
{ What is Bandwidth measured in: | { What is Bandwidth measured in: | ||
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+ Mhz | + Mhz | ||
|| Correct answer | || Correct answer | ||
− | - | + | - Db |
|| Incorrect answer | || Incorrect answer | ||
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|| propagation Latency | || propagation Latency | ||
− | + | { Define the term processing latency: | |
+ | | type = "()" } | ||
+ | - Time taken to pass through a medium | ||
+ | || Transmission Latency | ||
+ | + Time taken to pass around a network | ||
+ | || Processing Latency | ||
+ | - Time taken to pass through a logic gate | ||
+ | || propagation Latency | ||
+ | |||
+ | { Define the term transmission latency: | ||
+ | | type = "()" } | ||
+ | + Time taken to pass through a medium | ||
+ | || Transmission Latency | ||
+ | - Time taken to pass around a network | ||
+ | || Processing Latency | ||
+ | - Time taken to pass through a logic gate | ||
+ | || propagation Latency | ||
+ | |||
+ | {What type of latency is the time taken to pass through a logic gate? | ||
+ | | type="()" } | ||
+ | |||
+ | + Propagation Latency | ||
+ | || Correct answer | ||
+ | - Transmission Latency | ||
+ | || Wrong answer, it was Propagation Latency | ||
+ | - Processing Latency | ||
+ | || Wrong answer, it was Propagation Latency | ||
+ | |||
+ | {What type of latency is the time taken to pass through a medium? | ||
+ | | type="()" } | ||
+ | |||
+ | + Transmission Latency | ||
+ | || Correct answer | ||
+ | - Propagation Latency | ||
+ | || Wrong answer, it was Transmission Latency | ||
+ | - Processing Latency | ||
+ | || Wrong answer, it was Transmission Latency | ||
− | + | {What type of latency is the time taken to pass around a network? | |
− | + | | type="()" } | |
− | { What | ||
− | | type=" | ||
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− | + | - Transmission Latency | |
− | + | || Correct answer | |
− | + | - Propagation Latency | |
− | + | || Wrong answer, it was Transmission Latency | |
− | + | + Processing Latency | |
− | || | + | || Wrong answer, it was Transmission Latency |
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{ Define the term "protocol". | { Define the term "protocol". | ||
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- The delay of transmission. | - The delay of transmission. | ||
||It is a set of rules on how computers communicate. | ||It is a set of rules on how computers communicate. | ||
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{ What is half-duplex? | { What is half-duplex? | ||
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+ Data being sent in one direction so requires multiple wires. | + Data being sent in one direction so requires multiple wires. | ||
|| This is full-duplex. | || This is full-duplex. | ||
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|| correct | || correct | ||
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{ Explain in the context of networking, why parallel transmission might be preferred to serial transmission (Multiple Answers) | { Explain in the context of networking, why parallel transmission might be preferred to serial transmission (Multiple Answers) | ||
| type="[]" } | | type="[]" } | ||
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+ Easier to send large amounts of data | + Easier to send large amounts of data | ||
- It's less costly overall | - It's less costly overall | ||
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</quiz> | </quiz> |
Latest revision as of 07:15, 23 August 2023
Contents
Overview
CraigNDave
https://www.youtube.com/watch?v=6KsEiwCZi4g&list=PLCiOXwirraUAVO2FCJUdKRM6hYj9teHVe
Parallel Vs Serial
Computer Science Tutor
https://www.youtube.com/watch?v=CGulJriYNSI&list=PL04uZ7242_M6O_6ITD6ncf7EonVHyBeCm&index=25
Serial Data Transmission
In serial data transmission each bit is sent one after another by varying the line voltage between 0 & 5 volts for each bit, for two way communication a return wire is required. Serial Data Transmission is commonly used in USB and crossover cables.
Uses
Long distance communication
Advantages
Only need one signal path per way, can be used to route over telecommunications, saves cost of cabling
Disadvantages
Signal strength degrades over distance, so repeaters and so on required
Parallel Data Transmission
Each binary word is transmitted as one, with a signal path for each bit, additional signal paths for Return, Ready/Busy, & one strobe wire are required Ready/Busy is the status of the receiver, strobe wire used after signal placed onto wires on Strobe receiver will set Busy & read after read the receiver sets Ready.
Uses
Short distance data communication
Advantages
Offers faster transmission when compared to Serial
Disadvantages
Skew can easily affect data transmission, leading to errors. This is a result of distance, some bits may arrive at slightly different times. Reading the value could be inaccurate if you read before all bits have arrived.
Synchronous vs Asynchronous
Computer Science Tutor
https://www.youtube.com/watch?v=SLjjgjp2bAA&list=PL04uZ7242_M6O_6ITD6ncf7EonVHyBeCm&index=26
Synchronous means at the same time
- 2 devices will synchronise their transmission signals (based on system clock)
- Sending device will control transmission rate to match receiving device
- Once synchronised data can be sent with no other information
- If devices aren’t synchronised data will be lost
Asynchronous is simply transmission between 2 devices that don’t share a common clock signal.
Asynchronous Transmission
one character is transmitted at a time using start and stop bits to identify the beginning and the end of the character. A parity bit is usually sent to allow for checking for errors during the transmission. It is suitable for relatively small amounts of data.
Start & Stop Bits
- Arrival of data signaled by start bit
- Arrival can’t be predicted so it wakes receiver
- Clock & timing must match on both machines
- End of transmission is signaled by a stop bit
- Each unit of data is transmitted separately with start & stop bits
Baud Rate - Bit Rate - Bandwidth - Latency
CraigNDave
https://www.youtube.com/watch?v=I4dSIZM7Qdk&list=PLCiOXwirraUAVO2FCJUdKRM6hYj9teHVe&index=2
Computer Science Tutor
https://www.youtube.com/watch?v=8wm0QlbW9cQ&list=PL04uZ7242_M6O_6ITD6ncf7EonVHyBeCm&index=27
Baud Rate
Frequency at which a signal can change (ie from 0 to 5 volt), a baud signal of one changes once per second
Bit Rate
Number of bits transmitted per second, bit rate does not equal Baud rate if more than one bit is sent per time, 2 bits can be sent each time with more voltage levels.
Bandwidth
How fast data can be transmitted over a transmission media without significant reduction in strength greater bandwidth means greater the data rate can be sent there is a direct relationship between bit rate and bandwidth. The greater the bandwidth of the transmission system, the higher is the bit rate that can be transmitted over that system. On a cable, bandwidth is measured in Mhz, network Cable has 500 Mhz bandwidth which means 500 million cycles per second more cycles = more data.
Latency
It is the time delay between initiation and the first effect, WAN latency due to distance eg: between ground stations and satellites
Propagation Latency
Time taken to pass through a logic gate
Transmission Latency
Time taken to pass through a medium
Processing Latency
Time taken to pass around a network
Protocols
Is a set of agreed:
- Rules
- Codes
- Signals
That allow the transfer of data from one system to another And consists of:
- Handshake
- Message
- Goodbye
There are multiple commonly used protocols:
TCP/IP and UDP
Sending and receiving data over a network
HTTP and HTTPS
Retrieve pages from the world wide web
FTP
Transfer and upload files, often anonymously
TELNET, SSH
To connect to and manage a server
POP3 and SMTP
Send and receive email
Handshaking
Handshaking sets several variables required for the data transmission:
- Communication protocol
- Pre-agreed signal, codes, rules to ensure successful transmission
Sender checks receiver is connected & ready Sender waits for response Sender signals it will start sending data Receiver signals ready, and sender sends data Receiver indicates data received & ready
Communication protocol Pre-agreed signal, codes, rules to ensure successful transmission Handshaking protocol - Exchange of signals to establish a connection Sender checks receiver is connected & ready Sender waits for response Sender signals it will start sending data Receiver signals ready, and sender sends data Receiver indicates data received & ready