Telephone was the first device to send analog audio signals over long distance through copper wire. Here we are discussing various types of modulations which are the core mechanisms for any telecommunication devices.īefore we start this subject let us go back in the history of telecommunication. Telecommunication is the core subject for sending messages from one place to another place. Video and even digital bits from computer. However in technological point of view these messages can be base-band audio, These are the communication methods between human beings. Q.70.We convey our messages to someone and to the outside world through voice, facial expressions, gestures. Since, the expression for d is same as that for QPSK, the error probability of MSK is same as that of QPSK. Compare error probability for MSK with QPSK. What is the expression for Euclidean distance for MSK ?Īns. So there are no amplitude variations in the transmitted signal.
What is the speciality of MSK in this contest ?Īns. Related with abrupt phase changes, there are always sudden amplitude variations. What is the effect of abrupt phase change on amplitude in QPSK ?Īns. What type of reception technique is used for M-ary FSK ?Īns. A number of correctly tuned filters are required.What are the disadvantages of M-ary FSK ? State the expression for bandwidth of an M-ary FSK. What is the advantage of M-ary FSK over BFSK ?Īns. In orthogonal BFSK, the two carriers u 1(t) and u 2(t) are orthogonal i.e., frequencies f H and f L are integer multiple of f b. Error probability of BFSK is _ as compared to BPSK. What type of receiver is used for BFSK reception?Īns. The bandwidth efficiency of BFSK IS _ as compared to BPSK. State true or false: BFSK signal consists of two BPSK terms.Īns. The frequency of a sinusoidal carrier is switched between two values to represent 0 or 1. How is a message transmitted in BFSK ?Īns. 16-QAM has lower error rate as compared to that of QPSK. Compare 16-QAM with QPSK on the basis of error rates. State the expression for Euclidean distance for 16-QAM system.Īns. The noise immunity of a 16 QAM is _ than 16-ary PSK. Because it gives a better noise performance. Why is amplitude changed along with phase ?Īns. QASK is a system in which amplitude and phase both of a transmitted signal are changed. What is the bandwidth of a 16-ary PSK system ?Īns. What is the relation between M and N ?Īns. BW = 2 f b/N, where N= Number of bits per message Q.45. State the expression for Euclidean distance for M-ary PSK. Represent M-ary PSK signal mathematically.Īns. Probability of error increases as M is increased. Compare error probability of M-ary PSK and QPSK. The reduction in the channel bandwidth decreases with increase in number of messages (M). What is the main advantage of M-ary PSK ?Īns. Bandwidth of QPSK is _ as compared to that of BPSK. The offset between b o(t) and b e(t) is _. What is the phase difference between the adjacent messages in QPSK ?Īns. π/4 radians or 45°. How many phases are transmitted in QPSK ?Īns. The bit rate is _ than baud rate in QPSK. State true or false : Errors occur in pairs in DPSK.Īns. The effect of noise is higher in DPSK than BPSK.Error rate in DPSK is higher than that of BPSK.
Īns. √(2P s) is equal to amplitude A of the carrier.
0 kommentar(er)
