The students were assigned to repair a faulty BPSK trainer kit that was not generating proper outputs. After troubleshooting, they found faults in the modulator circuit and replaced faulty ICs and components. This resolved the issues and the kit then produced the correct outputs. The document describes the circuit diagram of the BPSK kit, which includes a power supply, carrier generator, data generator, BPSK modulator, and demodulator. It explains the working of each block. BPSK modulation is robust and used in wireless technologies for its ability to withstand channel conditions.

1. Minor Project Presentation on
BPSK Modulator & Demodulator
SUBMITTED TO SUBMITTED BY
ECE Department ASHISH CHIROTE
RAHUL MAHAJAN
SHUBHAM WAGH

2.  Project Objective.
 Result Before the work.
 Fault Detection & Removal in BPSK Kit.
 Result After the work.
 Introduction of Digital Modulation.
 Block Diagram of BPSK.
 Circuit Diagram of BPSK.
 Applications of BPSK.

3.  From a period of time faculties and students
of our department were constantaly
observing that some practical trainer kits of
labs were not giving proper results, so we
student had taken this as opportunity and
project assignment as well to repair and
maintain those kits.
 Our group was given BPSK Trainer Kit for
detecting its malfunctioning and
troubleshooting its outcome.

4.  When we started working on this kit we found
many faults in this kit, the outputs was not
coming properly.

5.  When we start working with this trainer kit
than we will found that the Modulator is not
generate output properly.
 So we change I.C 4051 & some component.
 After changing the component we get correct
output from the trainer kit.

6.  Then after detecting the faults and working
on circuit and changing some components we
found following outputs from kit.

7.  In digital modulation, an analog carrier signal
is modulated by a discrete signal.
 Digital modulation methods can be
considered as digital-to-analog conversion,
and the corresponding demodulation or
detection as analog-to-digital conversion.
 The changes in the carrier signal are chosen
from a finite number of M alternative symbols

8.  ASK-In this technique the digital data
modulates amplitude of the carrier.
 FSK-In this technique the digital data
modulates frequency of the carrier.
 PSK-In this technique the digital data
modulates Phase of the carrier.

10.  BPSK-In this technique the Binary data
modulates Phase of the carrier.
 The BPSK signal can be generated by applying
NRZ signal & carrier signal to the balance
modulator.

11.  The BPSK demodulator consist square law
device,Bandpass filter, frequency devider by
2,synchronous multiplier, integrator and bit
synchronizer.

12. The circuit diagram of BPSK kit contain
following parts-
 Regulated Power supply of 5v & 12v.
 Carrier generator.
 Data generator.
 BPSK Modulator.
 BPSK Demodulator.

13.  We know that the many of electronic circuit need D.C POWER so we
used regulated power supply of 5v(7805) and 12v(7812) in BPSK
circuit.
 This ckt. Contain the bridge rectifier, filter and voltage regulator.
In our kit the 5v used for drive the data generator ,modulator &
demodulator.
 The 12v power supply is used for drive carrier generator.

14.  The carrier generator is used ic 8038.
 I.C 8038 is generate 3 waveforms in its
outputs i.e. sine wave(used as carrier),digital
pulse(used as i/p of data generator),and
triangular wave.

16.  The data generator is used ic 7490.
 The 7490 is a simple counter, i.e. it can count from 0 to 9 cyclically
in its natural mode.
 It counts the input pulses and the output is received as a 4-bit
binary number through pins QA, QB, QC and QD.
 The binary output is reset to 0000 at every tenth pulse and count
starts from 0 again.
 The chip can count up to other maximum numbers and return to
zero by changing the modes of 7490. These modes are set by
changing the connection of reset pins R1 - R4.
 For example, if either R1 & R2 are high or R3 & R4 are low, then it
will reset QA, QB, QC and QD to 0.

18.  The BPSK modulator is a simple multiplier which multiplies the data
signal and carrier signal.
 The BPSK modulator is used IC 4051.
 This I.C is a 8:1analog and digital multiplexer.

20.  The BPSK Modulator is used coherent detection technique.
 The BPSK Demodulator consist I.C 7486(ex or gate) and I.C TL 084
(op-amp).
 When we applied carrier & BPSK modulated output then it is process
and generate the digital pulse.

21.  I.C 7486 is a EX-OR gate .
 The output is HIGH when one OR the other input is HIGH, but
NOT both. If both inputs are high output will be LOW.

22.  The BPSK modulation is a very basic technique used
in various wireless standards such as CDMA, WiMAX,
WLAN, Satellite, DVB, Cable modem etc.
 It is considered to be more robust among all the
modulation types due to difference of 180 degree
between two constellation points. Hence it can
withstand severe amount of channel conditions or
channel fading. It is used in FDMA to modulate the
pilot subcarriers used for channel estimation and
equalization. As we know different channels are used
for specific data transmission in cellular systems. The
channels used to transmit system related
informations which are very essential are modulated
using BPSK modulation.