A source machine is connected to a destination machine by a $40-$meter optical fiber link. The source machine is sending data at a bit rate of $2Mbps.$ The velocity of propagation in optical fibers is about $2{10}^8\frac{m}{s}.$ Each frame sent by the source is of size $4000$ bits. If we send frames continuously over $24$ hours, the probability of receiving $1$ bit in error is:

a$.6\mathrm{.}94{10}^{-7}$

b$.1\mathrm{.}157{10}^{-8}$

c$.2\mathrm{.}89{10}^{-12}$

d$)$ None of the above

A communication system uses delta modulation $($DM$)$ to produce a staircase function corresponding to a certain analog signal. DM produced $360$ samples within $2$ minutes. The final output stream of bits will be having a bit duration of:

a$.0\mathrm{.}333s$

b$.0\mathrm{.}5s$

c$.5\mathrm{.}55$msec

d$.$ None of the above

An analog signal having a bandwidth that extends from $500Hz$ to $6000Hz$ is modulated using amplitude modulation $($AM$).$ The carrier signal has a frequency of $10kHz.$ The resulting AM signal will have its upper side band extending from:

a$.10\mathrm{.}5kHz$ to $16kHz$

b$.4kHz$ to $9\mathrm{.}5kHz$

c$.500Hz$ to $10kHz$

d$.10kHz$ to $6kHz$

Two machines use the sliding$-$window control protocol for flow control. Assume that the window size is $5$ and that each frame has a $3-$bit field for the frame sequence number. The source machine sent frames F$0,$ F$1,$ F$2,$ and F$3$ and received RR$4.$ Then, the source machine sent F$4$ and F$5$ and received RR$6.$ The source machine can then send:

a$.$ F$6,$ F$7,$ and F$0$ only

b$.$ F$6$ and F$7$ only

c$.$ F$6,$ F$7,$ F$0,$ F$1,$ and F$2$

d$.$ None of the above