a. What is the size of a frame in bits?
b. What is the frame rate?
c. What is the duration of a frame?
d. What is the data rate?
22.
Answer the following questions about a T-1 line:
a. What is the duration of a frame?
b. What is the overhead (number of extra bits per second)?
23.
Show the contents of the five output frames for a synchronous TDM multiplexer that
combines four sources sending the following characters. Note that the characters are sent in the
same order that they are typed. The third source is silent.
a. Source 1 message: HELLO
b. Source 2 message: HI
c. Source 3 message:
d. Source 4 message: BYE
Ans:
TDM multiplexar: 4 input

7 |
P a g e
M D . S a i d u r R a h m a n K o h i n o o R
24.
Figure shows a multiplexer in a synchronous TDM system. Each output slot is only 10 bits
long (3 bits taken from each input plus 1 framing bit). What is the output stream? The bits arrive
at the multiplexer as shown by the arrows.
Ans:
.
25.
Figure 6.35 shows a demultiplexer in a synchronous TDM. If the input slot is 16 bits long (no
framing bits), what is the bit stream in each output? The bits arrive at the demultiplexer as shown
by the arrows.
Ans:
26.
Answer the following questions about the digital hierarchy in Figure 6.23:
a. What is the overhead (number of extra bits) in the DS-l service?
b. What is the overhead (number of extra bits) in the DS-2 service?

27. What is the minimum number of bits in a PN sequence if we use FHSS with a channel bandwidth of B =4 KHz and Bss =100 KHz?
28.
An FHSS system uses a 4-bit PN sequence. If the bit rate of the PN is 64 bits per second,
answer the following questions:
a. What is the total number of possible hops?
b. What is the time needed to finish a complete cycle of PN?
29.
A pseudorandom number generator uses the following formula to create a random series:
N
i+1
=(5 +7N
i
) mod 17-1
In which Nj defines the current random number and Nj +1 defines the next random number. The
term mod means the value of the remainder when dividing (5 + 7N
j
) by 17.
Ans:
30. We have a digital medium with a data rate of 10 Mbps. How many 64-kbps voice channels can be carried by this medium if we use DSSS with the Barker sequence?

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- Spring '14
- Hooks
- Frame, Frame rate, Time-division multiplexing, Multiplexing