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
A golfer on a fairway is 70 m away from the green, which sits below the level of the fairway by 20 m. If the golfer hits the ball at an angle of 40° with an initial speed of 20 m/s, how close to the green does she come?
A mouse of mass 200 g falls 100 m down a vertical mine shaft and lands at the bottom with a speed of 8.0 m/s. During its fall, how much work is done on the mouse by air resistance
Chemistry is a branch of science that deals with the study of matter,it composition,it structure and the changes it undergoes
Adjei
please, I'm a physics student and I need help in physics
Adjanou
chemistry could also be understood like the sexual attraction/repulsion of the male and female elements. the reaction varies depending on the energy differences of each given gender. + masculine -female.
Pedro
A ball is thrown straight up.it passes a 2.0m high window 7.50 m off the ground on it path up and takes 1.30 s to go past the window.what was the ball initial velocity
2. A sled plus passenger with total mass 50 kg is pulled 20 m across the snow (0.20) at constant velocity by a force directed 25° above the horizontal. Calculate (a) the work of the applied force, (b) the work of friction, and (c) the total work.
you have been hired as an espert witness in a court case involving an automobile accident. the accident involved car A of mass 1500kg which crashed into stationary car B of mass 1100kg. the driver of car A applied his brakes 15 m before he skidded and crashed into car B. after the collision, car A s
can someone explain to me, an ignorant high school student, why the trend of the graph doesn't follow the fact that the higher frequency a sound wave is, the more power it is, hence, making me think the phons output would follow this general trend?
Nevermind i just realied that the graph is the phons output for a person with normal hearing and not just the phons output of the sound waves power, I should read the entire thing next time
Joseph
Follow up question, does anyone know where I can find a graph that accuretly depicts the actual relative "power" output of sound over its frequency instead of just humans hearing
Joseph
"Generation of electrical energy from sound energy | IEEE Conference Publication | IEEE Xplore" ***ieeexplore.ieee.org/document/7150687?reload=true
A string is 3.00 m long with a mass of 5.00 g. The string is held taut with a tension of 500.00 N applied to the string. A pulse is sent down the string. How long does it take the pulse to travel the 3.00 m of the string?