problem 1: Describe the difference between slow FHSS and fast FHSS.
problem 2: What do you mean by direct sequence spread spectrum?
problem 3: What is the relationship between bit rate of a signal before and after it has been encoded by using DSSS?
problem 4: What do you mean by CDMA?
problem 5: Suppose that we wish to transmit a 56-kbps data stream by using spread spectrum.
a) Find out the channel bandwidth needed when SNR = 0.1, 0.01 and 0.001.
b) In an ordinary (not spread spectrum) system, a reasonable goal for bandwidth efficiency might be 1 bps/Hz. That is to transmit a data stream of 56 kbps; a bandwidth of 56 kHz is used. In this case, Find out the minimum SNR which can be endured for transmission devoid of appreciable errors? Compare to spread spectrum case?
problem 6: An FHSS system employs a total bandwidth of WS = 400 MHz and an individual channel bandwidth of 100 Hz. Find out the minimum number of PN bits needed for each frequency hop?
problem 7: The given table describes the operation of an FHSS system for one complete period of the PN sequence.
a) Determine the period of PN sequence?
b) The system makes use of a form of FSK. What form of FSK is it?
c) Determine the number of bits per symbol?
d) Determine the number of FSK frequencies?
e) Determine the length of a PN sequence per hop?
f) Is this slow or fast FHSS?
g) Determine the total number of possible hops?
h) Show the variation of the dehopped frequency with time.
problem 8: The given table describes the operation of a FHSS system by using the same PN sequence as in the problem above.
a) Determine the period of PN sequence?
b) The system makes use of a form of FSK. What form of FSK is it?
c) Determine the number of bits per symbol?
d) Determine the number of FSK frequencies?
e) Determine the length of a PN sequence per hop?
f) Is this slow or fast FHSS?
g) Determine the total number of possible hops?
h) Display the variation of the dehopped frequency with time.