32 Questions
What is the main advantage of parallel transmission over serial transmission?
Increased transfer speed
What is the primary disadvantage of parallel transmission?
Higher cost
What is the purpose of conversion devices in serial transmission?
To convert parallel data to serial and vice versa
What is the main advantage of serial transmission over parallel transmission?
Reduced cost
How many subclasses of serial transmission are there?
3
What is the primary limitation of parallel transmission?
High cost
In parallel transmission, how many bits are sent with each clock tick?
Multiple
What is the primary difference between parallel and serial transmission?
Number of communication lines
What is the main difference between asynchronous and synchronous transmission at the byte level?
Asynchronous transmission sends bits one after another with start and stop bits
What is the purpose of start and stop bits in asynchronous transmission?
To identify the start and end of a byte
How many bits are used to represent a byte in asynchronous transmission?
8 bits
What is the total overhead data bits required for 160000 bit data transmission?
60000 bit
What is the efficiency of 20KB data transmission using asynchronous transmission method?
73%
Which of the following is an advantage of synchronous transmission?
It is faster
What is the responsibility of the receiver in synchronous transmission?
To group the bits into bytes
What is a natural application of asynchronous transmission?
The connection of a keyboard to a computer
What is the main advantage of synchronous transmission over asynchronous transmission?
It is faster
In which layer of the OSI model is byte synchronization accomplished?
Data link layer
What is the total overhead data bits required for 160000 bit data transmission in the given example?
8000 bit
What is the efficiency of the 20KB data transmission using Synchronous transmission method in the given example?
95%
What is the main difference between synchronous and isochronous transmission?
Isochronous transmission has a shorter time interval between blocks
What type of data is collected in isochronous transmission?
Both synchronous and asynchronous data
Why does synchronous transmission fail in real-time audio and video applications?
Due to uneven delays between frames
What is the rate at which TV images are broadcast in the given example?
30 images per second
What is guaranteed by isochronous transmission?
That data arrive at a fixed rate
What is the primary advantage of isochronous transmission in terms of transmission speed?
It is much higher than asynchronous transmission
What is the purpose of a hold circuit in a PCM decoder?
To hold the amplitude value of a pulse till the next pulse arrives
What is the minimum bandwidth required to transmit a 4 kHz low-pass analog signal?
4 kHz
What is the minimum bandwidth required to transmit a digitized 4 kHz low-pass analog signal with 8 bits per sample?
32 kHz
What is the disadvantage of isochronous transmission in terms of error correction?
There is no error correction mechanism
What is the purpose of a low pass filter in a PCM decoder?
To filter out high-frequency noise
What is the advantage of isochronous transmission in terms of character transmission?
There is no need to pause between each character
Study Notes
Transmission Modes
- Data transmission can be accomplished in two modes: parallel and serial
- In parallel mode, multiple bits are sent with each clock tick
- In serial mode, 1 bit is sent with each clock tick
- Serial transmission has three subclasses: asynchronous, synchronous, and isochronous
Parallel Transmission
- Advantage: speed
- Disadvantage: cost
- Requires n communication lines (wires) to transmit the data stream
- Limited to short distances due to high cost
Serial Transmission
- Advantage: cost-effective
- Reduces the cost of transmission over parallel by roughly a factor of n
- Requires conversion devices at the interface between the sender and the line (parallel-to-serial) and between the line and the receiver (serial-to-parallel)
Asynchronous Transmission
- Sends 1 start bit (0) at the beginning and 1 or more stop bits (1s) at the end of each byte
- May have a gap between each byte
- Efficiency calculation example: 20KB data transmission
- Cheap and effective, suitable for low-speed communication, e.g., keyboard to computer connection
Synchronous Transmission
- Bits are sent one after another without start or stop bits or gaps
- Receiver groups the bits
- Bits are usually sent as bytes, and many bytes are grouped in a frame
- Frame is identified with a start and an end byte
- Advantage: speed
- Suitable for high-speed applications, e.g., transmission of data from one computer to another
- Byte synchronization is accomplished in the data link layer
- Efficiency calculation example: 20KB data transmission
Isochronous Transmission
- Similar to synchronous transmission, but with almost zero time interval between blocks
- Collects synchronous and asynchronous data from several devices within a time slot (125 micro-second)
- Guarantees data arrival at a fixed rate
- Suitable for real-time audio and video applications, e.g., TV images broadcast
Advantages and Disadvantages of Isochronous Transmission
- Advantages: high transmission speed, no need to pause between each character, no start and stop bits required
- Disadvantages: requires primary storage device at the sender station, no error correction, and relatively expensive
PCM Decoder
- Recovers an analog signal from a digitized signal through:
- Hold circuit that holds the amplitude value of a pulse till the next pulse arrives
- Low-pass filter with a cutoff frequency equal to the highest frequency in the pre-sampled signal
- The higher the value of L, the less distorted the recovered signal is
This quiz covers the concepts of digital transmission in data communications, including transmission modes and parallel/serial modes.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
