Communciation Lab Report

Communication Laboratory Report

A11MJ0041, A11MJ0051, A11MJ0057

Section 2

Abstract Line coding consists of representing the digital signal to

be transported by an amplitude- and time-discrete signal

that is optimally tuned for the specific properties of the

physical channel. There are two types of line

coding which are Return-to-zero (RZ) & Non-return-to-

zero (NRZ). RZ describes signal drops (returns) to zero

between each pulse. NRZ represents is a binary code in

which 1s are represented by one significant condition &

0s are represented by some other significant condition

TDM is a method of transmitting and receiving

independent signals or waveform via a common signal

path that needed synchronized switches at each end of the

transmission line for signal or waveform appears on the

line in a fraction of time in an alternating pattern. In this

case, The TDM multiplexer and TDM demultiplexer select

certain waveform based on desired needed via a

particular path in a fraction of time.

FDM transmits the signals along the same high speed link

simultaneously with each signal set at a different

frequency.there are two types of FDM which are FDM

Multiplexer and FDM Demultiplexer.

Key Words- Unipolar NRZ Signal Decode, Unipolar

RZ Signal Decode, PCM Demodulator, Discipline, Field,

Subject, Subtopic,FDM Multiplexer, FDM Demultiplexer,

FDM Signal Generator

1. Introduction

A line code decoder is used to retrieve the original line

code which chosen for the used within a communications

system for baseband transmission purposes. The line

coding is normally in digital data transport. A Return-to-

Zero (RZ) System describes a line code which the signal

drops (returns) to zero between each pulse and the signal

is self-clocking. A Non-Return-to-Zero (NRZ) System is

a binary code in which 1s are represented by one positive

voltage and 0s are represented by one negative voltage,

with no other neutral or rest condition. Pulse-code

modulation Demodulator is an electronic circuit system

used to extracting the original information analog signal

from a modulated carried wave which has been digitally

represents. In a PCM stream, the amplitude of the analog

signal is sampled regularly at uniform intervals, and each

sample is quantized to the nearest value within a range of

digital steps. A waveform generator is a piece

of electronic test equipment used to generate

electrical waveforms. These waveforms can be either

repetitive or single-shot which case some kind of

triggering source is required which is either internal or

external. The resulting waveforms can be injected into a

device under test and analyzed as they progress through it,

confirming the proper operation of the device.

Multiplexing is the set of techniques that allows the

simultaneous transmission of multiple signals across a

single data link. Whenever the transmission capacity of a

medium linking two devices is greater than the

transmission needs of the devices, the link can be shared

in order to maximize the utilization of the link, such as

one cable can carry a hundred channels of TV.

Meanwhile, the time-division multiplexing is multiple

transmissions that can occupy a single link by subdividing

them and interleaving the portions. Demultiplexing is any

of several signals was put onto a single carrier, then at the

other end the signals must be separated and each sent to

the appropriate destination. This mean one input the

shared channel is routed to one of several outputs. FDM

will generate signals by each sending device modulates

with different carrier frequencies. These modulated

signals are combined into a single composite signal that

can be transported by the link. The carrier frequencies

have to be different enough to accommodate the

modulation and demodulation signals. In demultiplexing

process, we use filters to decompose the multiplexed

signal into its constituent component signals. Then each

signal is passed to an amplitude demodulation process to

separate the carrier signal from the message signal. Then,

the message signal is sent to the waiting receiver.

2. Methodology

For Experiment 5, the UNI-NRZ encode circuit in Figure

01-1 on EXPERIMENT 01 of GOTT-DCT-6000-01

module was being used.

http://en.wikipedia.org/wiki/Digital_signal

http://en.wikipedia.org/wiki/Pulse_(signal_processing)

http://en.wikipedia.org/wiki/Binary_coding

http://en.wikipedia.org/wiki/Significant_condition

http://en.wikipedia.org/wiki/Electronic_test_equipment

http://en.wikipedia.org/wiki/Waveform

The frequency of the function generator was set to 1kHz

TTL signal and connected to the Data I/P of GOTT-DCT-

6000-01 module. Next, it was connected to the UNI-NRZ

O/P of Figure 01-1 of GOTT-DCT-6000-01 module to the

UNI-NRZ I/P of Figure 02-1 of GOTT-DCT-6000-01

module. After that, the output waveform was observed by

using oscilloscope and the measured results were

recorded in Table 5-1. According to the input signals in

Table 5-1, the step3 was repeated and the measured

results in Table 5-1 were recorded.

For Experiment 6, the UNI-RZ encode circuit in Figure

01-2 on EXPERIMENT 01 of GOTT-DCT-6000-01

module was being used.

The frequency of the function generator was set to 1kHz

TTL signal and connected to the CLK I/P of Figure 01-2,

as well as CLK at the left bottom and CLK I/P of Figure

01-2. Then, the UNI-RZ O/P of the Figure 01-2 was

connected to the UNI-RZ I/P of the Figure 02-2. After

that, the waveforms of UNI-RZ I/P, TP1, TP2, TP3, TP4

and Data O/P were observed by using oscilloscope. The

measured results were recorded in Table 6-1. According

to the input signals in Table 2-3, the step3 was repeated

and the measured results in Table 6-1 were recorded. The

frequency of function generator was set to 2 kHz signal

and connected to the CLK I/P in Figure 01-2. Then, the

other function generator was set to 1kHz TTL signal and

connected to the Data I/P in Figure 01-2. Next, the UNI-

RZ O/P of 01-2 was connected to UNI-RZ I/P of 02-2.

The waveforms of UNI-RZ O/P, TP1,TP2, TP3, TP4,

Data I/P were observed by using oscilloscope, then the

measured results were recorded in Table 6-2. According

to the input signals in Table 6-2, the step5 was repeated

and the measured results in Table 6-2 were recorded.

For Experiment 13, by referring to the Figure 06-1

EXPERIMENT 06 of GOTT-DCT-6000-03 module.

J1 was short circuit and the PCM modulated signal was

generated from the input signal terminal (Audio I/P),

input 250mV amplitude and 500Hz sine wave frequency.

By referring to the circuit diagram in Figure 06-1 of EXP

06 of GOTT-DCT-6000-03 module. The J1 of 06-1 was

short circuit and the output terminal (PCM O/P) of

modulated PCM signal of 5-1 was connected to the input

terminal (PCM I/P) of demodulation PCM signal of 06-1.

The output terminal of buffer (T1), 2048 kHz square wave

generator (T2), 8kHz square wave generator (T3),

demodulated PCM signal output terminal (T4), and signal

output terminal (Audio O/P) were observed by using

oscilloscope and measured results were recorded in in

Table 13-1. According to the input signals in Table 13-1,

the step3 was repeated and the measured results in Table

13-1 were recorded. J2 of 5-1 and 06-1 were short circuit.

From the signal input terminal (Audio I/P) of 5-1, input

250mV and 500Hz sine wave frequency. The output

terminal (PCM O/P) of modulated PCM signal of 5-1 was

connected to the input terminal (PCM I/P) of

demodulation signal of 06-1. The signal waveforms T1,

T2, T3, T4 and Audio O/P were observed by using

oscilloscope. The measured results were recorded in

Table 13-2. According to the input signals in Table 13-2,

the step5 was repeated and the measured results in Table

13-2 were recorded.

For experiment 19, the sinusoidal, triangle and square

wave generator or Figure 09-1 of experiment 09 of

GOTT-TDM Multiplexer and Demultiplexer module is

referred. Then, by using oscilloscope, the output signal

waveform of triangle wave output port (TP1) is observed.

Variable resistor VR3 is adjusted so that the amplitude of

TP1 is maximum without distortion, the output signal

waveform and voltage is recorded at table 19-1.After that,

by using oscilloscope, the output signal waveform of

triangle wave output port(TP2) is observed. Variable

resistor VR1 is adjusted so that the amplitude of TP2 is

maximum without distortion, the output signal waveform

and voltage is recorded at table 19-1.Lastly ,by using

oscilloscope, the output signal waveform of triangle wave

output port(TP3) is observed. Variable resistor VR2 is

adjusted so that the amplitude of TP3 is maximum

without distortion, the output signal waveform and

voltage is recorded at table 19-1.

Experiment 20 is continued, the time generator and

analog switch or Figure 09-1 of experiment 09 of GOTT-

TDM Multiplexer and Demultiplexer module is referred.

Next, the variable resistance is turned to “Clock Adj”

.Left to the end, at this moment, the counter of the clock

is slow. By using CH1 of the oscilloscope, the output is

observed on the output signal waveform of triangle wave

output port (TP4).Then by using CH2 of the oscilloscope,

the output signal of the TDM output port (TDM O/P) is

observed. Initially, the output signal waveform and

voltages is recorded at Table 20-1.Then, by using CH1 of

the oscilloscope, the output is observed on the output

signal waveform of triangle wave output port (TP5).Then

by using CH2 of the oscilloscope, the output signal of the

TDM output port (TDM O/P) is observed. Initially, the

output signal waveform and voltages is recorded at Table

20-1.Lastly, by using CH1 of the oscilloscope, the output

is observed on the output signal waveform of triangle

wave output port (TP6).Then by using CH2 of the

oscilloscope, the output signal of the TDM output port

(TDM O/P) is observed. Initially, the output signal

waveform and voltages is recorded at Table 20-1.

Experiments 21 are referred to the circuit in Figure 21-2

and Figure 21-3 or refer to Figure 10-1 of experiment10

of GOTT-TDM Multiplexer and Demultiplexer module.

Firstly, the output port (TDM O/P) of TDM multiplexer is

connected to the input port (TDM I/P) of TDM

Demultiplexer in Figure 10-1.Then,by using oscilloscope,

the output signal waveform of amplifier (TP1)of

Demultiplexer is observed .The output signal waveform

and voltage is recorded in Table 21-1.The triangle wave

output port (TP4),square wave output port(TP5) and

sinusoidal wave output port (TP6)is connected to the

triangle wave input(TP2),square wave input port(TP3)

and sinusoidal wave input port(TP4)of the TDM

Demultiplexer.Then, by using CH1 of the oscilloscope,

the output signal waveform of the input port(TP2) is

observed. By using CH2 of the oscilloscope, the output

signal waveform of output port (O/PI) of the TDM

Demultiplexer is observed. Finally, the output signal

waveform and voltage is recorded in Table 21-2. Then, by

using CH1 of the oscilloscope, the output signal

waveform of the input port (TP2) is observed. By using

CH2 of the oscilloscope, the output signal waveform of

output port (O/P2) of the TDM Demultiplexer is

observed. Finally, the output signal waveform and voltage

is recorded in Table 21-3. Then, by using CH1 of the

oscilloscope, the output signal waveform of the input port

(TP2) is observed. By using CH2 of the oscilloscope, the

output signal waveform of output port (O/P3) of the TDM

Demultiplexer is observed .Finally, the output signal





output port (O/PI) of the TDM Demultiplexer is observed.

Finally, the output signal waveform and voltage is

recorded in Table 21-5. Then, by using CH1 of the


(TP3) is observed .By using CH2 of the oscilloscope, the


Demultiplexer is observed .Finally, the output signal










output signal waveform of output port (O/PI) of the TDM













waveform and voltage is recorded in Table 21-10.

For experiment 22-1, the EXPERIMENT 11 of GOTT-

FDM Multiplexer and Demultiplexer module was used.

The output signal waveform of audio signal generator

1(TP1) was observed by using the oscilloscope. The

variable resistors "Audio Frequency Adjust 1" and "Audio

Gain Adjust 1" were adjusted so that the output frequency

was 150 HZ and the amplitude was 600 mV The results

were recorded in table 22-1. The output signal waveform

of audio signal generator 2(TP3) was observed by using

the oscilloscope. The variable resistors "Audio Frequency

Adjust 2" and "Audio Gain Adjust 2" were adjusted so

that the output frequency was 800 HZ and the amplitude

was 600 mV. The results were recorded in table 22-1

shows the output signal waveform of audio signal

generator 3(TP7) was observed by using the oscilloscope.

The variable resistors "Audio Frequency Adjust 3" and

"Audio Gain Adjust 3" were adjusted so that the output

frequency was1.2 KHZ and the amplitude was 600 mV.

The results were recorded in table 22-1.

For experiment 22-2, the EXPERIMENT 11 of GOTT-


The output signal waveform of carrier signal generator 1

(TP2) was observed by using the oscilloscope. The

variable resistor "Carrier Gain Adjust 1" was adjusted so

that the amplitude was 600 mV. The results measured

were recorded in table 22-2. The output signal waveform

of carrier signal generator 2 (TP4) was observed by using

the oscilloscope. The variable resistor "Carrier Gain

Adjust 2" was adjusted so that the amplitude was 600 mV.

The results measured were recorded in table 22-2 shows

the output signal waveform of carrier signal generator 3

(TP8) was observed by using the oscilloscope. The

variable resistor "Carrier Gain Adjust 3" was adjusted so

that the amplitude was 600 mV. The results measured

were recorded in table 22-2.

For experiment 24, the EXPERIMENT 11 of GOTT-


The output signal waveform of FDM output port (FDM

O/P) was observed by using the oscilloscope and the

measured results were recorded in table 24-1.

For experiment 25, the EXPERIMENT 11 0f GOTT -

FDM Multiplexer and Demultiplexer was used to produce

the modulated FDM signal source. The output signals

waveform of carrier signal generator 1 (TP1) was

observed by using the oscilloscope. The variable resistors

"Audio Frequency Adjust 1" and "Carrier Gain Adjust 1"

was adjusted so that the output frequency was 500 Hz and

the amplitude was 600 mV. The output signals waveform

of carrier signal generator 2(TP3) was observed by using

the oscilloscope. The variable resistors "Audio Frequency

Adjust 2" and "Carrier Gain Adjust 2" was adjusted so

that the output frequency was 800 Hz and the amplitude

was 600 mV. The output signal waveform of carrier

signal generator 3(TP7) was observed by using the

oscilloscope. The variable resistors "Audio Frequency

Adjust 3" and "Carrier Gain Adjust 3" were adjusted so

that the output frequency was 1.2 kHz and the amplitude

was 600 mV. The output signal waveform of TP5, TP6,

TP9 were observed by using the oscilloscope. The

variable resistors "Mod Adjust 1", "Mod Adjust 2", and

"Mod Adjust 3" were adjusted so that the output signal is

the modulated DSB-SC signal. The modulated FDM

signal (FDM O/P) in figure 11-1 was connected to the

input terminal (FDM I/P) in figure 12-1. The carrier

signal (TP2) in figure 11-1 was connected to the input

terminal 1 of the carrier signal (carrier I/P) in figure 12-1.

The carrier signal (TP4) in figure 11-1 was connected to

the input terminal 3 of the (Carrier I/P) in Figure 12-1.

The output signal waveforms of the audio signal 1(audio

O/P1), audio signal 2(audio O/P2) and audio signal

3(audio O/P3) were observed by using oscilloscope. The

variable resistors "Carrier Adjust 1" and "Gain Adjust 1"

was adjusted for audio O/P1 followed by the "Carrier

Adjust 2" and "Gain Adjust 2" was adjusted for audio

O/P2 and lastly, the " Carrier Adjust 3" and " Gain

Adjust 3" was adjusted for audio O/P3 so that the

amplitudes were maximum without distortion. The results

were recorded in table 25-1.

3. Results and Discussion

Table 5-1 Measured results of UNI-NRZ signal decode

Input Signal

Frequencies

(Data I/P)

Input Signal(Yellow Upper) and

Output Signal (Blue Lower)

Waveforms

1kHz

2kHz

4kHz

Table 5-1 shows that the waveforms between UNI-NRZ

signal and data signal are similar to each other. But, the

amplitude are differ a little. Since, we only need to add a

buffer in front of the decoder circuit, which can recover

the original input data signal which shown at Figure 5-2

above. This is the same for all the Data I/P frequencies

(1kHz, 2kHz, 4kHz). The differences between the inputs

and the outputs results most probably are caused by some

instrumentation noise or distortion.

Table 6-1 Measured results of UNI-RZ signal decode. (fclk

= 1 kHz)

TEST

POINT

OUTPUT

WAVEFORMS

TEST

POINT

OUTPUT

WAVEFORMS

UNI-

RZI/P

TP1

TP2

TP3

TP4

DATA

O/P

Table 6-1 Measured results of UNI-RZ signal decode. (fclk

= 2 kHz)

TEST

POINT

OUTPUT

WAVEFORMS

TEST

POINT

OUTPUT

WAVEFORMS

UNI-

RZI/P

TP1

TP2

TP3

TP4

DATA

O/P

Table 6-2 Measured results of UNI-RZ signal decode.

(fdata = 1 kHz fclk = 2 kHz)

TEST

POINT

OUTPUT

WAVEFORMS

TEST

POINT

OUTPUT

WAVEFORMS

UNI-

RZI/P

TP1

TP2

TP3

TP4

DATA

O/P

Table 6-2 Measured results of UNI-RZ signal decode.

(fdata = 1 kHz fclk = 3 kHz)

TEST

POIN

T

OUTPUT

WAVEFORMS

TEST

POIN

T

OUTPUT

WAVEFORMS

UNI-

RZI/P

TP1

TP2

TP3

TP4

DAT

A O/P

Figure 6-2 shows the circuit diagram of unipolar return-

to-zero (UNI-RZ) decoder. The output of the UNI-RZ

decoder is a NOR-RS flip-flop, which is comprised by

R3, R4 and two NOR gates. TP2 is the “S” terminal and

TP3 is the “R” terminal. From the results shown above,

TP1 is the inverted output of the Clock input. TP2 is the

filtered result of UNI-RZI/P, because of the capacitor C1.

The clock signal will be inverted by a NOT gate which is

comprised by the NOR gate. Then, by using XOR to

operate the inverted clock signal and UNI-RZ signal and

passing through a differentiator which is comprised by C2

and R2, the output will be transformed to pulse wave

which is used for “R” terminal of RS flip-flop. UNI-RZ

signal will pass through a capacitor to the “S” terminal of

RS flip-flop. Finally by sending both UNI-RZ and clock

signals into the RS flip-flop, we can recover the original

input data signal.

Table 13-1 Measured results of PCM demodulator when

J1 short circuit.

Input

Signal of

PCM

Modulator

Output Signal

Waveforms

TP1 TP2

500Hz TP3 TP4

250mV

TP5 AUDIO O/P


J1 short circuit. (continue)

Input Signal

of PCM

Modulator

Output Signal

Waveforms

TP1 TP2

1kHz TP3 TP4

250mV

TP5 AUDIO O/P


J2 short circuit.

Input Signal

of PCM

Modulator

Output Signal

Waveforms

TP1 TP2

500Hz TP3 TP4

250mV

TP5 AUDIO O/P


J2 short circuit. (continue)

Input Signal of

PCM

Modulator

Output Signal

Waveforms

TP1 TP2

1kHz TP3 TP4

250mV

TP5 AUDIO O/P

From the Figure 13-2, FS0 and FS1are the data format

selection of PCM encoder. The data format selection of

PCM encoder can encode the sample to 8-bit µ-law

format, 8-bit A-law format or 16-bit digital data format.

As a result of the FS1 in the encode circuit is grounded,

therefore, the FS1 in the decoder circuit must also be

grounded. The selection of FS0 and FS1 of both the

modulation and demodulation must be same, otherwise,

the demodulated audio signal will be different from the

original audio signal.

In Table 13-1, TP1s are the buffer results of the inputs.

So, it will be quite similar to the inputs. TP2s show the

results of similar to 2048kHz Square Wave Inputs.

Besides that, the TP3s show the results of similar to 8kHz

Square Wave Inputs. Furthermore, TP4s show the high

frequencies noises of the signals. Finally, Audio O/P

results were filtered by the Low Pass Filter where the

results are much better than the TP4s results.

Table 19-1 Measured results of waveform generator

This experiment shows the production of square

waveform, triangular waveform and the sinusoidal

waveform produced when the input is connected to TP1,

TP2 and TP3 respectively. This is because the multiplexer

is consist of the triangle wave and square wave

generators. Then, when the input is connected to those

generator the certain output will be produced. The VR3,

VR1 and VR2 is keep adjusting respectively to obtain the

maximum output of the waveform.

Table 20-1 Measured result of TDM multiplexer

TP4 and TDM

O/P

TP1

TP2

TP3

TP5 and TDM

O/P

TP6 and TDM

O/P

The combination of three waveforms in the time domain

was under control by the set of binary pulses is called

TDM multiplexing. It can be shown in the above picture

that after the pulses are triggered the combination of the

waveform is happened. The variety of shape of the

combination of the waveform happened because of two or

more waveform are sampled at the same rate but at

slightly different times, then waveforms are be added and

interleaved without mutual interaction. The different

connection of TP4, TP5 and TP6 showed that the same

theories is applied to all kind combination of waveform.

Table 21-1 measured result of the input of TDM

demultiplexer.

Table 21-1 Measured result of the output of TDM

demultiplexer

TP2 AND O/P1


demultiplexer

TP2 AND O/P2


demultiplexer

TP2 AND O/P3


demultiplexer

TP3 AND O/P1


demultiplexer

TP3 AND O/P2


demultiplexer

TP3 AND O/P3


demultiplexer


demultiplexer

TP4 AND O/P2


demultiplexer

TP4 AND O/P3

The multiplexer is connected to the Demultiplexer. It is

used to produce a single waveform as the output. Firstly,

TP4 AND O/P1

it can be observed that the combination of the waveforms.

Then, when TP2 is connected, the output at O/P1 show

the square waveform is observed when the pulse is

triggered. The other output at O/P2 and O/P3 show the

waveform and the pulse are not matched. The same

happened when TP3 is connected, but the waveform is

concurrently with the output at O/P2 and did not match

the pulse at the output O/P1 and O/P3.Then when the TP4

is connected, the waveform match the pulse at the output

O/P3 not at the O/P1 and O/P2.This is happened because

the when the input is connected at the TP2,the pulse is

actually readily at the O/P1,so when at O/P1,when there

are pulse, the square waveform is produced. When at the

output of O/P2 and O/P3, it did not match the pulses. The

same happened for TP3 and TP4.

Table 22-1 Measured results of audio signal

TP1

TP3

TP7

For the experiment 22-1, the audio signal generator (ICL

8038) was used. The output signal waveform of audio

signal generator were obtained by adjusting the variable

resistors audio frequency adjust 1 and audio gain adjust 1.

A potentiometer is available to remove distortion in the

FM output of the ICL8038.Using no message signal, a

sinusoidal waveform was observed. If distortion was

present, the potentiometer is varied until the distortion is

minimized. The capacitors were used to decouple the

message and output signals and remove any DC bias.

Table 22-2 Measured results of carrier signal

TP2

TP4

TP6

The Wien Bridge Oscillator is a two-stage RC coupled

amplifier circuit that has good stability at its resonant

frequency, low distortion and is very easy to tune making

it a popular circuit as an audio frequency oscillator It can

generate a large range of frequencies. For the experiment

22-2, the output signal waveform of carrier signal

generator were obtained by adjusting the carrier gain

adjust. Carrier adjust gain was used to reduce the gain so

that the amount of distortion was reduced.

Table 24-1 Measured results of FDM modulated signal

http://www.amazon.co.uk/gp/aws/cart/add.html?ASIN.1=0750631023&Quantity.1=1&AWSAccessKeyId=AKIAIQ6ODJLR27IKQI7Q&AssociateTag=basicelecttut-21

http://en.wikipedia.org/wiki/Frequencies

FDM O/P

Frequency Division Multiplexing works by transmitting

all of the signals along the same high speed link

simultaneously with each signal set at a different

frequency. For FDM to work properly frequency overlap

must be avoided. Therefore, the link must have sufficient

bandwidth to be able to carry the wide range of

frequencies required. The demultiplexor at the receiving

end works by dividing the signals by tuning into the

appropriate frequency.

The advantages of the FDM multiplexing are :

1. The sender can send signals continuously.

2. It also works on analog signals.

3. No dynamic coordination is necessary.

For each frequency channel, an electronic oscillator

generates a carrier signal, which is a steady oscillating

waveform at a single frequency that functions to carry

information. The carrier is much higher in frequency than

the baseband signal. The carrier signal and the baseband

signal are then applied to a modulator circuit. The

modulator then changes some aspect of the carrier signal,

such as its amplitude, frequency or phase.

The carrier center frequency produces sub-frequencies

from the mixing of the modulated baseband. The

information from the modulated signal is carried in the

sidebands each side of the carrier frequency. the sub-band

frequencies of the channel must be far from each other so

that they do not overlap and the sub-bands will not

interfere with each another. The available channel

bandwidth is divided into sub-bands; each can carry a

separate modulated signal.

At the receiving end, a local oscillator mixes with the

carrier frequency, and the resulting baseband signal is

filtered to produce each sub-band to a separate output.

The DSB-SC modulation was used to implement the

FDM multiplexer because both of its upper

sideband and lower sideband were transmitted and the

carrier is suppressed in the mean time. So the efficiency

of the suppressed carrier amplitude modulation is higher

than the DSB-AM.

Table 25-1 Output signal waveforms of audio signal

Audio O/P1

Audio O/P2

Audio O/P3

MC1496B was designed for use where the output voltage

is a product of an input voltage or signal and a switching

function or carrier.

Synchronous detectors are considerably more complex

than simple envelope detectors. They consist of phase

locked loop and multiplier circuits. Demodulation is

performed by multiplying the modulated carrier by a sine

wave that is phase locked to the incoming carrier.

Synchronous detectors are a subset of detectors product..

The advantage of synchronous detection is that it causes

less distortion than envelope detection and works well

with single sideband signals. The synchronous detectors

are phase sensitive. The amplitude of the demodulated

signal is a function of the relative phases of the incoming

carrier and the carrier generated inside the receiver.

A low-pass filter is an electronic circuit that hasa constant

output voltage from dc up to a cutoff frequency. As the

frequency increases above the cutoff frequency, the

output voltage is attenuated.

http://en.wikipedia.org/wiki/Electronic_oscillator

http://en.wikipedia.org/wiki/Carrier_wave

http://en.wikipedia.org/wiki/Frequency

http://en.wikipedia.org/wiki/Modulator

http://en.wikipedia.org/wiki/Amplitude

http://en.wikipedia.org/wiki/Frequency

http://en.wikipedia.org/wiki/Sideband

http://en.wikipedia.org/wiki/Local_oscillator

The advantage of this configuration is that the op-amps

high input impedance prevents excessive loading on the

filters output while its low output impedance prevents the

filters cut-off frequency point from being affected by

changes in the impedance of the load.

4. Conclusions

As a conclusion, A line code decoder is good to retrieve

the original line code which chosen for the used within a

communications system. PCM Demodulator is an

electronic circuit system used to extracting the original

information to digitally representation.

The waveform generator is a device that can be used to

show different type of waveform. By having different

type of waveform the result of experiment of multiplexer

and Demultiplexer can be tested its usage. Multiplexer

allow multiple signals to be subdividing and interleaving

to be occupied as a single link. It is a combination or

addition of several waveforms. Demultiplexer is an

opposition of multiplexer. Its select a waveform from

several waveform of the input as the output. It is triggered

by the pulse or clock. FDM is a technique by which the

total bandwidth available in a communication medium is

divided into a series of non-overlapping frequency sub-

bands, each of which is used to carry a separate signal.

Whereas the FDM Demultiplexer is reverse of the FDM

multiplexer but use filter to decompose the multiplexed

signal into its constituent component signals.

5. References

[1] "Return-to-Zero" - Wikipedia, the Free

Encyclopedia. N.p., n.d. Web. 25. Apr. 2014.

<http:// en.wikipedia.org/wiki/Return-to-zero >.

[2] "Non-Return-to-Zero" - Wikipedia, the Free

Encyclopedia. N.p., n.d. Web. 25. Apr. 2014.

<http:// en.wikipedia.org/wiki/Non-return-to-

zero >.

[3] “FrequencyDivision Multiplexing (FDM)” –

Techopedia. Mon. 28.Apr.2014.

<http://www.techopedia.com/definition/7153/fre

quency-division-multiplexing-fdm>.

[4] "Frequency-division multiplexing" - Wikipedia,

the Free Encyclopedia. N.p., n.d. Web. 25. Apr.

2014. <http:// en.wikipedia.org/wiki/Frequency-

division multiplexing >.

[5] Daenotes.com, (2014). Multiplexing,

Demultiplexing, TDM, FDM. [online] Available

at:

http://www.daenotes.com/electronics/communic

ation-system/multiplexing [Accessed 28 Apr.

2014].

[6] Torres-Company, V. and Chen, L. (2009).

Radio-frequency waveform generator with time-

multiplexing capabilities based on multi-

wavelength pulse compression. Optics Express,

[online] 17(25), pp.22553-22565. Available at:

http://www.opticsinfobase.org/oe/abstract.cfm?u

ri=oe-17-25-22553 [Accessed 28 Apr. 2014].

[7] Zone.ni.com, (2014). Theory of Time Division

Multiplexing - Developer Zone - National

Instruments. [online] Available at:

http://zone.ni.com/devzone/cda/ph/p/id/270

[Accessed 28 Apr. 2014].

http://www.techopedia.com/definition/7153/frequency-division-multiplexing-fdm



Documents

Communciation Lab Report