The
rms (root-mean-square) value of
a periodic signal is defined to be
where
is defined to be the signal's
period :
the smallest positive number such that
.
What is the period of
?
What is the rms value of this signal? How is it
related to the peak value?
What is the period and rms value of the
depictedsquare wave , generically denoted
by
?
By inspecting any device you plug into a wall socket,
you'll see that it is labeled "110 volts AC". What isthe expression for the voltage provided by a wall
socket? What is its rms value?
Modems
The word "modem" is short for "modulator-demodulator."
Modems are used not only for connecting computers totelephone lines, but also for connecting digital
(discrete-valued) sources to generic channels. In thisproblem, we explore a simple kind of modem, in which
binary information is represented by the presence orabsence of a sinusoid (presence representing a "1" and
absence a "0"). Consequently, the modem's transmittedsignal that represents a single bit has the form
Within each bit interval
, the amplitude is either
or zero.
What is the smallest transmission interval that
makes sense with the frequency
?
Assuming that ten cycles of the sinusoid comprise a
single bit's transmission interval, what is thedatarate of this transmission scheme?
Now suppose instead of using "on-off" signaling, we
allow one of several
different values for the amplitude during any transmission
interval. If
amplitude values are used, what is the resulting
datarate?
The classic communications block diagram applies to
the modem. Discuss how the transmitter mustinterface with the message source since the source
is producing letters of the alphabet, not bits.
Advanced modems
To transmit symbols, such as letters of the alphabet, RUcomputer modems use two frequencies (1600 and 1800 Hz)
and several amplitude levels. A transmission is sentfor a period of time
(known as the transmission or baud interval) and equals
the sum of two amplitude-weighted carriers.
We send successive symbols by choosing an appropriate
frequency and amplitude combination, and sending themone after another.
What is the smallest transmission interval that
makes sense to use with the frequencies given above?In other words, what should
be so that an
integer number of cycles of the carrier occurs?
Sketch (using Matlab) the signal that modem produces
over several transmission intervals. Make sure youaxes are labeled.
Using your signal transmission interval, how many
amplitude levels are needed to transmit ASCIIcharacters at a datarate of 3,200 bits/s? Assume use
of the extended (8-bit) ASCII code.
We use a discrete set of values for
and
.
If we have
values for amplitude
,
and
values for
,
we have
possible symbols that can be sent during each
second interval. To
convert this number into bits (the fundamental unit ofinformation engineers use to qualify things), compute
.
Questions & Answers
Ayele, K., 2003. Introductory Economics, 3rd ed., Addis Ababa.
what's the difference between a firm and an industry
Abdul
firm is the unit which transform inputs to output where as industry contain combination of firms with similar production 😅😅
Abdulraufu
Suppose the demand function that a firm faces shifted from
Qd 120 3P
to
Qd 90 3P
and the supply function has shifted from
QS
20 2P
to
QS
10 2P .
a) Find the effect of this change on price and quantity.
b) Which of the changes in demand and supply is higher?
Demand curve shows that how supply and others conditions affect on demand of a particular thing and what percent demand increase whith increase of supply of goods
Israr
Hi Sir please how do u calculate Cross elastic demand and income elastic demand?
Abari
Got questions? Join the online conversation and get instant answers!