E-Vest : WIRELESS NON-INVASIVE ECG MONITORING Digital FM Serial transmitter

E-Vest: WIRELESS NON-INVASIVE ECG MONITORINGDigital FM Serial transmitter

Mohammed Alsadah Alexander Wright

Faculty Advisor:Dr. Kamesh Namuduri

Department of Electrical Engineering University of North Texas Denton, Texas

Objectives• Contemporary Issues

• Introduction

• Design Consideration

• Circuit Design

• Hardware/Software

Implementation

• Reception Information

• Testing

• Difficulties

• Standards & Ethics

• Result /Conclusion

• Team Work

• Further Exploration “Work”

• References

Contemporary Issues “ Motivations”

• On March 17th 2014, Carmen, a 16 year old Virginia girl dies moments as soon as she completes the half-marathon.

• This is our potential goal to save lives and prevent sudden Cardiac Arrest

Fall 2013 : Bluetooth • The Bluetooth frequency range is at

2.4 to 2.485 GHz/

• The distance range is only 100 meters

or approximately 328 feet.

• Predefined Standard : FCC approved

• Low power and Low voltage (3.3V)

• Built in Antenna

• Encrypted Connection

Introduction • In order to support remote monitoring of EKG signals we need

the ability to transmit digital information over long distances in a cheap and efficient manner

– We decided to perform FM transmission of digital data through Binary Frequency Shift Keying

– In order to minimize cost and complexity we made use of an LC circuit instead of phase locked loop based oscillator

– This design will have less frequency stability and higher phase noise than a PLL based system

– Goal is to be able to transmit a digital signal at least half mile (805 meters ).

BFSK

• Binary Frequency Shift keying

• Uses two discrete frequencies vs entire continuous variation range used in FM

FM Circuit

Design• Multiple BJT amplification stages some with feedback

• LC Hartley oscillator using hand wound inductors made of enameled

magnet wire.

• LM566 Voltage Controlled oscillator used to generate square waves for

bits through UART connected to an NMOS

Oscillator circuit• Voltage divider of output

square wave

• NTE2932 NMOS used to switch

voltage on pin 5 based on 3.3V

TTL signal input

Circuit design • Circuit in the breadboard for

the original FM transmitter

• Below, the circuit successfully soldered

Hardware/Software Implementation

• Interface control documentation

Reception Information

Software Defined Radio using Realtek RTL2832U chip• http://sdr.osmocom.org/trac/wiki/rtl-sdr

SDR# Software• http://sdrsharp.com/

Testing • Oscilloscope used to verifyTTL to square wave conversion

SDR# used to verify

transmission of square

waves

Reception

• WinFM softwarecreated to decode dataimages show 0’sand 1’s being received

Difficulties • Ordering components

– Lead times, hard to find components

• Soldering circuit– Special thanks to Abraham Hasir for helping us

• Differences between theoretical values and what provided the results we wanted – likely due to breadboard capacitance/resistances

Standards & Ethics• Standard for medical equipment from ISO/IEEE 11073

• IEEE 1284: UART Serial Communication

• UNT Institutional Review Board (IRB) Procedures

Federal Communications Commission • The FCC limits unlicensed FM broadcasts to a maximum signal strength of

250uV/m (microvolts per meter), measured at a distance of 3m--about 10 feet

• limiting both the antennae gain and voltage level of the circuit we can control the field strength of the transmitted signal

• we have both lowered the voltage and completely eliminated the antennae in order to prevent exceeding these limits.

Result/Conclusion• We have successfully transmitted serial TTL level data using

binary frequency shift keying over FM bands using available electronics components.

• We believe this project will assist in the remote monitoring of athletes as they compete toward reaching their goals while remaining safe from abnormal heart conditions.

Further Exploration “ work” • Jarvis Jones and I will be

designing the Antenna

(summer 2014).

• Transmits at a carrier

frequency of 2.75 GHz

using no more than 24

Mhz bandwidth.

Design flow diagram for the Antenna Design

Antenna Design Requirements

Designing The Antenna using the HyperLynx Software

Simulation and Parameter Review

Finished Design and requirements accomplished

Prototype evaluation

Manufacture usable silicone micro strip

antennae

Requirements met?

Yes No

References• "Frequency-shift Keying." Wikipedia. Wikimedia Foundation, 15 Mar.

2014. Web. 21 Mar. 2014. <http://en.wikipedia.org/wiki/Frequency-shift_keying>.

"Headlines." Home. N.p., n.d. Web. 21 Mar. 2014. <https://www.fcc.gov/>. • Kim, Hyoung Soo, Venu Varanasi, Gayatri Mehta, Hualiang Zhang, Tae-Youl

Choi, Kamesh Namuduri, Jakob Vingren, Nandika Anne D'souza, and Robert Kowal. "Circuits, Systems, and Technologies for Detecting the Onset of Sudden Cardiac Death Through EKG Analysis." IEEE Circuits and Systems Magazine 13.4 (2013): 10-25. Print.

• "Virginia Girl, 16, Dies Moments after Finishing Half Marathon ." NY Daily News. Carol Kuruvilla, 17 Mar. 2014. Web. 18 Mar. 2014. <http://www.nydailynews.com/news/national/virginia-teen-16-dies-moments-finishing-marathon-article-1.1725562>.

Questions