Introduction

• It is PC based instrument designed using industry standard PIC18F4550 from microchip corp.

• It has idyllic GUI designed using visual C# .net 2005.

• It has 6 different modules.

Modules• Electronic counter.

• Programmable function generator.

• Digital carrier modulation

• Digital Multi-meter.

• Weather station.

• Digital storage oscilloscope. (DSO)

Electronic counterDigital frequency counter

Digital time period measurement

Digital pulse width measurement

Digital duty cycle measurement

Digital phase angle measurement

Digital ratio measurement

Digital frequency counter

Timer

At t = 0sec

Counter Counter

Timer

At t = 1sec

Synchronized SynchronizedCounter & timer start at t = 0sec.

Counter & timer stop at t = 1sec.

timer = 1 sec.

count = frequency

count = 0

timer = 0 sec.

Digital time period measurement

Capture timer

Timer = X

Capture timer

Timer = Y

Time period = Y-X

Time period

Digital pulse width measurement

Capture timer

Timer = X

Capture timer

Timer = Y

Time period = Y-X

Pulse width

Digital phase angle measurement

+

_

+

_

X-OR gateCOMPARATOR

PHA

SE D

IFFR

AN

CE

INPUT WAVE

Digital Multi-meter

• Digital voltmeter • Digital ohmmeter • Digital Capacitance meter

• Digital Inductance meter

Digital voltmeter

A/D converterAnalog voltage Digital voltage

Digital Capacitance meter

+

_

R

c

ΔV=0.693VCC

E=VCC

Q=0 at t=0sec.

COMPARATOR

Putting values in Eq. below

ΔV=E(1-e-t/RC)

Timer start Timer stop

R= constant

C= variable

Digital ohmmeter

+

_

R

c

ΔV=0.693VCC

E=VCC

Q=0 at t=0sec.

COMPARATOR

Timer start Timer stop

C= constant

R= variable

Putting values in Eq. below

ΔV=E(1-e-t/RC)

Weather station

•Temperature measurement

•Humidity measurement

•Atmospheric pressure measurement

Temperature measurement

IC used: SHT11

Range: -40 to 123.8°C

Humidity measurement

IC used: SHT11

Range: 0 to 100%RH

Atmospheric pressure measurement

IC used: MPAX6115A

Range: 15 to 115kPa

Components used and ranges

Digital carrier modulation

Binary Frequency shift keying generator (BFSK)

Binary Phase shift keying generator (BPSK)

Binary amplitude shift keying generator (BASK)

Binary Frequency shift keying generator (BFSK)

Binary Phase shift keying generator (BPSK)

Binary amplitude shift keying generator (BASK)

ΣPHASE-TO-AMPLITUDE

CONVERSION D/A CONVERSION

PHASE REGISTER

TUNING WORD

PHASE

ACCUMULATOR

24 TO 48 BITS

14 TO 16 BITS

Programmable function generatorProgrammable function generator

SYSTEM CLOCK

fc

Working of Programmable function generator

Frequency is determined by the eq.

fOUT = output frequency of the DDSM = binary tuning wordfC = internal reference clock frequency (system clock= 20 MHz)n = length of the phase accumulator, in bits

Amplitude control in Programmable function generator

+

_Rf

R1

R2

Digital potentiometer

By varying input control word we can control output voltage

Digital storage oscilloscope (DSO)

• Single channel digital storage oscilloscope.

• Voltage range: 40V peak-to-peak

• Five User selectable time base.

• Nine user selectable voltage base.

• On screen rise time and total time display.

• On screen peak amplitude display.• Waveform storage capability.

Thank you!