ARDUINO MASTER-SLAVE ACOUSTIC COMMUNICATION SYSTEM

(4 points project presentation)

Presenter: Elia Linzky (317608313)

Advisor: Dr. Samuel Kosolapov

Introduction

Motivation:

Universality: Acoustics - an already existing ability to (but not limited to) all cellphones

Immediacy: Doesn’t require pairing. Ideal to transfer small amounts of data, fast.

Solution for private cases like in ships, planes, safe-rooms

Project goal: Examination of short range acoustic communication as a replacement for NFC (IR, WiFi etc.)

Introduction

Arduino development kit as a control unit

Common and cheap – 3$

Slow processor – 16Mhz

C programming language

Two communication methods: Morse Code, SKFK

Symbolic functions implementation: MC – Arithmetic device, SKFK – Temperature measurement

Goertzel Algorithm as frequency detector

Project details:

System Configuration & Behavior

MasterDevice

SlaveDevice I

SlaveDevice II

An optional configuration

Universal devices (M/S)

Device Basic Block Diagram

Control Unit

(Arduino MEGA)

Amplifier )OP(

BPF(Resonance Circuit)

LPF

ADC

Receiver TransmitterUSB to PC

Microphone

Temperature sensor

Speaker

Method I: Morse Code

f=1500[Hz], BR=250[dots per sec]

Easy to implement

Frequency independent

Noise sensitive

Needs additional hardware

Dictionary (from left to right)

0

5

Method I: Morse Code

Dot duration X 3 Dot durationDot duration

Signal Reception process:

Sampling

Control Unit

LPF

ADC

MicrophoneA

B

C

Voff=2.5V

Method II: SKFK

‘Pause’ – 1400Hz BR=25[signs per sec]

‘0’ – 1500Hz

‘1’ – 1600Hz

Decoded by Goertzel filter

0

5

0 PP 1 EOTSOT

Semi binary data transfer

Method II: SKFK

High noise resistance Low error rate

No additional hardware required

Transmitting to/receiving from multiple devices at once is possible

Long processing time

Limited to low frequencies

0

5

0 PP 1 EOTSOT

Electrical Scheme & Hardware Solutions

CU Amp.

BPF

LPF

ADC

Main Scheme:

Thanks for listening!

Additional Context

Neutralizing speaker’s inductive component

Boucherot cell:

Additional Context

Thermistor temperature calculation:

y = 1300.7e-0.038x

0

250

500

750

1000

1250

1500

1750

2000

2250

-20 -10 0 10 20 30 40 50 60 70 80

R[Ω

]

T[̊C]

Thermistor Resistance vs Temperature

Additional Context

Amplifier gain capacitor:

Additional Context

Microphone circuit:

Sensitivity

Additional ContextReceiver: RC LPF:

Vc(t)

charging

discharging

Dotlenght = 4 [mSec]

τ= RC = 0.5 [mSec] = Fast but stable enough

Additional Context

Resonation Xc=Xl

BPF:

Additional Context

Speaker:

Additional Context

Microphone: