A clever system designer claims that the
depicted
transmitter has, despite its complexity,
advantages over the usual amplitude modulation system.The message signal
is bandlimited to
Hz, and
the carrier frequency
. The channel attenuates the transmitted signal
and adds white noise of spectral height
.
The transfer function
is given by
Find an expression for the spectrum of
.
Sketch your answer.
Show that the usual coherent receiver
demodulates this signal.
Find the signal-to-noise ratio that results
when this receiver is used.
Find a superior receiver (one that yields a
better signal-to-noise ratio), and analyze itsperformance.
Multi-tone digital communication
In a so-called multi-tone system, several bits are
gathered together and transmitted simultaneously ondifferent carrier frequencies during a
second interval. For
example,
bits would be
transmitted according to
Here,
is the frequency offset for each bit and it is
harmonically related to the bit interval
. The value of
is either
or
.
Find a receiver for this transmission scheme.
An ELEC 241 almuni likes digital systems so much
that he decides to produce a discrete-time version. Hesamples the received signal (sampling interval
). How should
be related to
, the number of
simultaneously transmitted bits?
The alumni wants to find a simple form for the
receiver so that his software implementation runs as
efficiently as possible. How
would you recommend he implement thereceiver?
City radio channels
In addition to additive white noise, metropolitan
cellular radio channels also contain multipath: theattenuated signal and a delayed, further attenuated
signal are received superimposed. As shown in
[link] , multipath occurs
because the buildings reflect the signal and thereflected path length between transmitter and receiver
is longer than the direct path.
Assume that the length of the direct path is
meters and the
reflected path is 1.5 times as long. What is themodel for the channel, including the multipath and the
additive noise?
Assume
is 1 km.
Find and sketch the magnitude of the transfer functionfor the multipath component of the channel. How would
you characterize this transfer function?
Would the multipath affect AM radio? If not, why
not; if so, how so? Would analog cellular telephone,which operates at much higher carrier frequencies (800
MHz vs. 1 MHz for radio), be affected or not? Analogcellular telephone uses amplitude modulation to
transmit voice.
How would the usual AM receiver be modified tominimize multipath effects? Express your modified
receiver as a block diagram.
Downlink signal sets
In digital cellular telephone systems, the base station
(transmitter) needs to relay different voice signals toseveral telephones at the same time. Rather than send
signals at different frequencies, a clever Rice engineersuggests using a different signal set for each data
stream. For example, for two simultaneous data streams,she suggests BPSK signal sets that have the
depicted basic
signals .
Bacteria doesn't produce energy they are dependent upon their substrate in case of lack of nutrients they are able to make spores which helps them to sustain in harsh environments
_Adnan
But not all bacteria make spores, l mean Eukaryotic cells have Mitochondria which acts as powerhouse for them, since bacteria don't have it, what is the substitution for it?
Assimilatory nitrate reduction is a process that occurs in some microorganisms, such as bacteria and archaea, in which nitrate (NO3-) is reduced to nitrite (NO2-), and then further reduced to ammonia (NH3).
Elkana
This process is called assimilatory nitrate reduction because the nitrogen that is produced is incorporated in the cells of microorganisms where it can be used in the synthesis of amino acids and other nitrogen products
There are nothing like emergency disease but there are some common medical emergency which can occur simultaneously like Bleeding,heart attack,Breathing difficulties,severe pain heart stock.Hope you will get my point .Have a nice day ❣️
_Adnan
define infection ,prevention and control
Innocent
I think infection prevention and control is the avoidance of all things we do that gives out break of infections and promotion of health practices that promote life