Department of Electrical and Computer Engineering

SDP team Yngvesson

Ioan TiheneaTomas Broka

Dmitriy StupakSergey Derivolkov

IR Communication Channel

Supplemental SWNT Component

Department of Electrical and Computer Engineering

Design OverviewFor our Senior Design Project we were working on creating a communication system that has two computer interface terminals and hardware circuitry components on each end and an Infrared communication channel (transceiver) in the center.

The key component to our SDP project was a Single Walled Carbon Nanotube (SWNT) thin film detector detecting IR radiation. Due to technical issues, the SWNT thin film detector will be simulated with a photosensitive diode.

Department of Electrical and Computer Engineering

System OverviewComputer Interface

Signal Processing

Transceiver

Computer Interface

Signal Processing

Input from keyboard by user CPU

USB Interface

Software

MultiprocessorDigital to

Analog circuit

Focusing Lenses

USB Cable

IR Radiation

2 wire cable

Legend

Bolometer Analog to Digital Circuit

Multiprocessor

USB Interface

CPU Display

Software

System Block Diagram

LED emiter SWNT film Detector

Department of Electrical and Computer Engineering

What happened to the SWNT Thin Film Idea/Theory Materials

• Budget Constraints Process

• First Attempts• Using Different Carbon Nanotubes• Wider Holes on Devices• Following the Literature

Challenges• Quality of Film• Survival of the Acetone Bath

Department of Electrical and Computer Engineering

Circuitry and Program AspectsProgramThe Logic of the ProgramTransmitter End MCUReceiver End MCU

CircuitryTransmitter CircuitryReceiver Circuitry

• Multiple Stage Amplifiers• Flexibility of Design

Department of Electrical and Computer Engineering

Department of Electrical and Computer Engineering

Department of Electrical and Computer Engineering

Department of Electrical and Computer Engineering

Department of Electrical and Computer Engineering

Department of Electrical and Computer Engineering

Signal analysis Using a multimeter we detected a signal in a

range of 0.3 mV to 0.6 mV. When a film that was detecting a signal in the

above range was put on our breadboard, we were not able to detect any signal, the oscilloscope would show only noise.

We shielded the board also used a battery to eliminate 60 Hz noise but signal still couldn’t be detected.

The performance of our circuit couldn’t be determined.

Department of Electrical and Computer Engineering

Signal analysis cont. Replaced the film with a photodiode and the

signal could be detected easily. Using an active probe we were able to detect a

signal of 2mV (in a distance of 200cm between IR LED and the photodiode at a frequency of 500 Hz).

Department of Electrical and Computer Engineering

Signal analysis cont.

Using a passive probe, to measure the signal from our circuit (photodiode connected to amplifier) the lowest signal peak to peak to be detected was 1.6 mV.

Department of Electrical and Computer Engineering

Signal to noise ratio (S/N) S/N is 1.3. S/N needs to be higher than 3 for the circuit to

work properly. We conclude that our signal need to be higher

than 5 mV to be detected by our circuit.

Department of Electrical and Computer Engineering

Demo

Demo Presentation

Department of Electrical and Computer Engineering

Questions

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