Question 1: Describe the difference between slow FHSS and fast FHSS.
Question 2: What do you mean by direct sequence spread spectrum?
Question 3: What is the relationship between bit rate of a signal before and after it has been encoded by using DSSS?
Question 4: What do you mean by CDMA?
Question 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?
Question 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?
Question 7: The given table describes the operation of an FHSS system for one complete period of the PN sequence.
![563_operation of FHSS system.jpg](https://secure.tutorsglobe.com/CMSImages/563_operation%20of%20FHSS%20system.jpg)
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.
Question 8: The given table describes the operation of a FHSS system by using the same PN sequence as in the problem above.
![1154_pn sequence.jpg](https://secure.tutorsglobe.com/CMSImages/1154_pn%20sequence.jpg)
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.