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MANUAL
ANALOG COMMUNICATION
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The analog
communication blocks are described:
ANALOG COMMUNICATION BLOCKS |
|
Block Name |
Description |
|
Generates the several types
signal functions as a message signal for analog communications |
|
Modulates the message signal
with DSB-SC AM method |
|
Modulates the message signal
with a conventional AM method |
|
Modulates the message signal
with a single side-band AM method |
|
Modulates the message signal
with a frequency modulation method |
|
Modulates the message signal
with a phase modulation method |
|
Corrupts the transmitted signal
with channel noise |
|
Envelope Detector to demodulate
the message signal |
|
Multiply the transmitted signal
with the carrier signal having an estimated carrier phase |
|
Low-pass filtering the transmitted
signal to demodulate the message signal |
|
Computes the output SNR at the
receiver |
·
Cont. SigGen.
Description: This
block generates several different signal functions such as a sinusoidal signal,
a rectangular signal, a triangular signal, a sinc signal, and so on. The
generated signal can be used for analog communication blocks as a message
signal. Several parameter options in its dialog window are required to be
defined by users to generate output signal.
Input: No signal
Output: Output
signal
Diagram:
Dialog Window:
·
DSB-SC AM
Description: This
block modulates the message signal with double-sideband suppressed carrier
amplitude modulation method. Several parameter options in its dialog window are
required to be defined by users to generate output signal. It plots the
spectrum of the modulated signal, U(f), the modulated signal in time domain,
the magnitude of the message signal, and the carrier signal in time domain.
Input: Input
signal 
Output: Output
signal 
Equations implemented:
Message
signal: 
Carrier
signal: 
Modulated
signal:
where 
is the amplitude of the carrier signal, 
is the carrier
frequency, and 
is the carrier phase.
If we assume that the phase of
carrier signal is zero, we obtain:
where 
is the spectrum of
the modulated signal, 
is the spectrum of
the message signal.
Diagram:
Dialog Window:
·
Conv AM
Description: This
block modulates the message signal with a conventional amplitude modulation
method. Several parameter options in its dialog window are required to be
defined by users to generate output signal. It plots the spectrum of the
modulated signal, U(f), the modulated signal in time domain, the magnitude of
the message signal, and the carrier signal in time domain.
Input: Input
signal 
Output: Output
signal 
Equations implemented:
Message
signal: 
Carrier
signal: 
Modulated
signal:
where 
,
: modulation
index. 
is chosen.
If 
> 1, overmodulated. 
.
is the amplitude of the carrier signal, 
is the carrier
frequency, and 
is the carrier phase.
Diagram:
Dialog Window:
·
SSB AM
Description: This
block modulates the message signal with a single-sideband amplitude modulation
method. Several parameter options in its dialog window are required to be
defined by users to generate output signal. It plots the spectrum of the
modulated signal, U(f), the modulated signal in time domain, the magnitude of
the message signal, and the carrier signal in time domain.
Input: Input
signal 
Output: Output
signal 
Equations implemented:
Message
signal: 
Carrier
signal: 
Modulated
signal:
where the minus sign determines
USB-AM and the plus sign determines LSB-AM. 
is the Hilbert
transform of m(t), denoted by 
. 
is the amplitude of the carrier signal, 
is the carrier
frequency, and 
is the carrier phase.
Diagram:
Dialog Window:
·
FM
Description: This
block modulates the message signal with a frequency modulation method. Several
parameter options in its dialog window are required to be defined by users to
generate output signal. It plots the spectrum of the modulated signal, U(f),
the modulated signal in time domain, the magnitude of the message signal, and
the carrier signal in time domain.
Input: Input
signal 
Output: Output
signal 
Equations implemented:
Message
signal: 
Carrier
signal: 
Modulated
signal:
where 
, 
is frequency
deviation constant, 
is the amplitude of the carrier signal, and
is the carrier frequency.
Diagram:
Dialog Window:
·
PM
Description: This
block modulates the message signal with a phase modulation method. Several
parameter options in its dialog window are required to be defined by users to
generate output signal. It plots the spectrum of the modulated signal, U(f),
the modulated signal in time domain, the magnitude of the message signal, and
the carrier signal in time domain.
Input: Input
signal 
Output: Output
signal 
Equations implemented:
Message
signal: 
Carrier
signal: 
Modulated
signal:
where 
and 
is phase deviation
constant,
is the amplitude of the carrier signal, and 
is the carrier
frequency.
Diagram:
Dialog Window:
·
Channel.
Description: This
block corrupts the transmitted signal with channel noise. Additive white
Gaussian noise is used as channel noise. Noise power is defined in its dialog
window by users.
Input: Input
signal 
Output: Output
signal 
Equations implemented:
where 
is channel noise.
Diagram:
Dialog Window:
·
Envelope Detec.
Description: This
block is used to demodulate the message signal from the received signal through
channel. Envelope detector is composed of RC circuits. A time constant, RC, is
defined in its dialog window by users. In practice a time constant is chosen
with values between 1/fc and 1/W. It plots the demodulated message signal in
both time domain and frequency domain.
Input: Input
signal 
Output: Output
signal 
Diagram:
Dialog Window:
·
Coherent Detec.
Description: This
block multiplies the received signal through channel with the carrier signal
having an estimated carrier phase.
An estimated carrier phase is
defined by users.
Input: Input
signal 
Output: Output
signal 
Equations implemented:
=
where
is the carrier frequency, and 
is the estimated
carrier phase.
Diagram:
Dialog Window:
·
Demod
Description: This
block uses low-pass filter to demodulate the message signal from the input
signal coming from Coherent Detec. block. Bandwidth of
low-pass filter is defined by users. After low-pass filtering, the magnitude of
the demodulated signal is half the magnitude of the transmitted signal.
Therefore, the output signal of LPF is multiplied by the factor of 2.
Input: Input
signal 
Output: Output
signal 
Diagram:
Dialog Window:
·
SNR_o
Description: This
block computes the output signal to noise power ratio between signals.
Reference signal is given as input
to the upper pin of diagram.
Input: Input
signal 
Output: Output
signal 
Diagram:
Dialog Window:
