QUESTIONS:

1. Is the detection of errors caused by noise or other impairments during transmission from the transmitter to the receiver? ERROR DETECTION

2. Error detection and correction are implemented either at the _____ or the _____ of the OSI model. DATA LINK LAYER AND TRANSPORT LAYER

3. The term _____ means that two or more bits in the data unit have changed from 1 to 0 or from 0 to 1. BURST ERROR

4. Is the detection of errors and reconstruction of the original, error-free data? ERROR CORRECTION

5. Scheme corrects errors by requiring the retransmission of bad blocks? ARQ6. VRC is another name for: PARITY7. The initials ARQ stands for: AUTOMATIC REQUEST FOR RETRANSMISSION8. ARQ is used to? CORRECT BIT ERRORS

9 - 10. Four types of redundancy checks used in data communications VRC,LRC,CRC,CHECKSUM

11. It involves the addition of one extra bit to the bits that encode characters. VRC

12. Is an extension of parity that can provide some error detection as well as detection? LRC

13. Another error detection method consist of adding together all the data words in a block

CHECKSUM

14. Is a set of error-correction code s that can be used to detect and correct bit errors that can occur when computer data is moved or stored. HAMMING CODE

15. Errors are due to ____ in the channel. NOISE

16. FSK stands for: FREQUENCY-SHIFT KEYING

17. It is the transmittal of digitally modulated analog carriers between two or more points in a communications system. DIGITAL RADIO

18. Is the process of changing one of the characteristics of an analog signal based on the information in digital data. DIGITAL-TO-ANALOG CONVERSION

19. It represents the number of independent symbols that can be carried through the system in a given unit of time. INFORMATION CAPACITY

20. It is a quantitative body of knowledge which has been established about “information” to enable system designers & users to use the channels allocated to them efficiently as possible. INFORMATION THEORY

21. States that information capacity is directly proportional to the bandwidth of the system and the number of possible states per symbol. SHANNON-HARTLEY THEOREM

22. The simplest digital modulation technique, where a binary information signal directly modulates the amplitude of an analog carrier. AMPLITUDE-SHIFT KEYING (ASK)

23. Is a form of constant-amplitude angle modulation similar to conventional frequency modulation (FM) except that the modulating signal is binary signal that varies between two discrete voltage levels? BINARY FSK

24. In the equation I = ktB, I is measured in? BITS

25. Number of signal units per second that are required to represent that bit. BAUD RATE

26. States that information capacity is a function of bandwidth and signal-to-noise ratio of the system. SHANNON’S LIMIT FOR INFORMATION CAPACITY

27. States that information capacity is directly proportional to bandwidth and transmission time of the system. HARTLEY’S LAW

28. QAM stands for: QUADRATURE AMPLITUDE MODULATION

29. Number of bits transmitted during one second. BITS

30. Sometimes called as Digital Amplitude Modulation. AMPLITUDE-SHIFT KEYING (ASK)

PROBLEM SOLVING:

1. An analog signal carries 8 bits in each signal element. If 1000 signal elements are sent per second, find the Baud Rate and Bit Rate?

Baud Rate =1000 bauds/second

Bit Rate = 8000 bps

2. Find minimum bandwidth required for an ASK signal at 8000 bps.

BW = 8000 Hz

3. Determine the minimum bandwidth and baud for a binary FSK signal with a mark freq. of 50kHz, a space freq. of 54kHz, and an input bit rate of 4 kbps.

Baud Rate = 4 kilobaud

BW =

4. How many hamming bits are required for a block length of 25 message bits?5 hamming bits

5. How many hamming bits are required for a block length of 10 message bits?

4 hamming bits