UPTEC E 18 010 Examensarbete 30 hp Juni 2018 Wireless electrocardiogram trans- mission based on ultra wideband radio Oskar Flink Abstract Wireless electrocardiogram transmission based on ultra wideband radio Oskar Flink Teknisk- naturvetenskaplig fakultet UTH-enheten Ultra wideband (UWB) communications has been a subject of much discussion over the last decade. The method of UWB has had a hard Besöksadress: time to establish itself among other methods such as Bluetooth and Ångströmlaboratoriet Lägerhyddsvägen 1 WiFi but as internet of things (IoT) gains a foothold in our daily Hus 4, Plan 0 lives, UWB has presented some new application areas. These application areas are, among other things, self driving cars, Postadress: energy efficient data transfer, health care applications, sensor Box 536 751 21 Uppsala networks and real time location systems. Telefon: This project aims to use UWB communications to real-world 018 – 471 30 03 applications, specifically, electrocardiography (ECG) - an Telefax: application in health care in this project, and develop a 018 – 471 30 00 prototype for the application. Hemsida: The prototype consists of two Android smart phones and two UWB http://www.teknat.uu.se/student modules (EVK1000 evaluation kits from DecaWave, Inc). Each smart phone connects a UWB module so that the two smart phones, one as sender and the other as receiver, can communicate directly through UWB radios. This is intended to serve as a proof-of-concept that UWB devices are well suited for short range data transfer applications. The result achieved by the project is an android application along with sending and receiving programs for the development boards by Decawave and additional information regarding UWB and its uses. The results also include a comparison of UWB, Bluetooth and WiFi as of todays standard. The goal of the project is to learn how android applications are programmed, how UWB is used in todays technology and how to program and use development boards presented by companies. The prototype has been built and shown that 12-lead simulated ECG signals from the sender can be transfered to the receiver through the UWB communications. The work includes programming (in C) the two UWB modules for UWB communications, and Java for the android applications (programs) on the smart phones. The Android application is handling transmission of ECG signals to the sending UWB module and then receiving them from the receiving UWB module as well as displaying them on the receiver. The future work to continue the present project is to replace the sending smart phone by an ECG device that sends real ECG signals. Handledare: Håkan Sjörling Ämnesgranskare: Ping Wu Examinator: Tomas Nyberg ISSN: 1654-7616, UPTEC E18 010 Tryckt av: Uppsala Sammanfattning I dagsl¨agetfinns det m˚angaolika s¨attatt skicka information tr˚adl¨ost,de vanligaste s¨atten¨arWiFi och Bluetooth men en mindre utforskad teknik ¨ar Ultra-Wideband, UWB. Det ¨aren teknik som blir mer och mer popul¨aratt anv¨andamellan apparater som inte beh¨over l˚angr¨ackvidd och samtidigt vill s¨andamycket information. En av teknikens st¨orstaf¨ordelar¨aratt den ¨arv¨aldigtenergieffektiv vilket passar bra till portabla applikationer. N˚agraav dessa applikationer ¨arsj¨alvk¨orandebilar, lokaliseringssystem, medicinala l¨osningar och tr˚adl¨osdata¨overf¨oring. I det h¨arprojektet beskrivs hur tekniken f¨orUWB fungerar och vad den kan anv¨andastill. F¨oratt visa anv¨andningenpraktiskt har en prototyp f¨ors¨andningav EKG-signaler mellan telefoner med hj¨alpav UWB har tagits fram. EKG, eller ECG st˚arf¨or electrocardiography och ¨aren sorts hj¨art¨overvakning som l¨akare anv¨ander f¨oratt hitta onormala hj¨artslagoch hj¨artflimmer.Tanken bakom prototypen ¨aratt en patient ska kunna ta ett ECG under l¨angretid. Informationen ska tr˚adl¨ostskickas till en telefon s˚aatt patienten inte ska beh¨ova ta upp l¨akartid och kunna b¨araden utan att vara bunden till en plats. Prototypen best˚ar av tv˚aAndroid smartphones som ¨arkopplade till tv˚aUWB- s¨andare. Kommunikationen mellan telefonerna och s¨andarnaanv¨anderUSB och kom- munikationen mellan s¨andarnaanv¨anderUWB. Detta f¨oratt telefoner inte st¨oderUWB- kommunikation ¨an,vilket g¨oratt en extern s¨andare¨arn¨odv¨andig. S¨andarnasitter p˚a utvecklingskort fr˚anDecawave kallat EVK1000 och dessa sk¨oterall den tr˚adl¨osakom- munikationen. N¨ars¨andningeng¨orsmellan telefonerna simuleras ECG-signaler i ena telefonen, skickas till UWB-s¨andarensom skickar det vidare till mottagaren. Hos mottagaren ritas dessa signaler ut i telefonen och anv¨andaren kan d˚al¨attse hur dessa ser ut. Signalerna simuleras ist¨alletf¨oratt fysiska m¨atningartas p˚agrund av att dessa ¨arsv˚araatt g¨ora. Det kr¨aver v¨alkalibrerad utrustning och utan s˚adanutrustning ¨ardet sv˚artatt fastst¨alla att signalerna kommer fram korrekt. Tanken med projektet ¨aratt visa hur UWB kan anv¨andassom ett s¨andningsmedium och grundligt visa en praktisk applikation till detta. Att anv¨andaUWB inom medicinala l¨osningar¨arett steg till att f˚amer energieffektiva apparater med l¨angrebatteritid och samtidigt ha en s¨aker ¨overf¨oringav information. Detta kan i framtiden str¨acka sig l¨angre ¨anbara ECG och skulle kunna anv¨andastill att skicka vilken data som helst. Resultatet av projektet blev en android-applikation som kan kopplas upp till De- cawaves EVK1000 utvecklingskort. Detta kort har programmerades till att kunna ta hand om informationen som skickas fr˚anandroid-applikationen och hantera meddelanden i som skickas mellan tv˚autvecklingskort. Applikationen inneh˚allermenyer f¨oratt s¨atta upp USB-kommunikationen och hanteringen av denna. Den kan skicka ut ECG signaler ¨over tolv kanaler som sedan ritas upp i tolv olika f¨onsterhos mottagaren. I rapporten tas ¨aven f¨or-och nackdelar om UWB upp och en j¨amnf¨orelsemed Bluetooth och WiFi har genomf¨ortsf¨oratt visa skillnaderna mellan dessa protokoll som motivation till varf¨or just UWB passar bra till detta ¨andam˚al. M˚aletmed projektet och rapporten ¨aratt visa att UWB l¨amparsig f¨orm˚angaolika applikationer, bland annat ECG-signalhantering som anv¨andsinom sjukv˚arden.M˚alen innefattar ¨aven att bygga f¨orst˚aelseinom Androidprogrammering, programmering av utvecklingskort och tr˚adl¨oskommunikation. Den ger ¨aven insikt i hur protokoll anv¨ands, i detta fall IEEE 802.15.4-2011 samt hur projekt likt detta kan l¨aggasupp och hanteras. Projektet har legat som grund till fler andra projekt som p˚abyggnad av ECG-hantering och ¨aven distansm¨atningmed hj¨alpav UWB. ii Acknowledgements I would like to give a special thanks to Ping Wu, H˚akan Sj¨orling,Andreas G¨awerth, Viktor St˚ahl,Maria Toll and Tommy Holmberg for their support during this project. iii Contents 1 Introduction 1 1.1 Background . .1 1.2 Overview . .3 1.3 Objectives . .3 1.4 Tasks and scope . .4 1.4.1 Tasks . .4 1.4.2 Limitations . .4 1.5 Outline . .5 2 Theory 6 2.1 Electrocardiogram . .6 2.2 Ultra wideband (UWB) communications . .7 2.2.1 Signals of UWB, wideband and narrow band . .7 2.2.2 Spectrum . .8 2.2.3 Path loss models . 10 2.2.4 Interference and noise . 10 2.2.5 Modulations . 11 2.2.6 Multiple access . 11 2.2.7 Error correcting . 13 2.2.8 Communications protocols . 15 2.3 UWB Ranging protocol . 19 3 Implementation 20 3.1 System overview . 20 3.2 Hardware . 21 3.2.1 Android devices . 21 3.2.2 EVK1000 evaluation kit . 22 3.3 Software and development tools . 25 3.3.1 Android Studio . 25 3.3.2 CooCox IDE . 25 3.3.3 MATLAB . 26 3.4 Implementation . 27 3.4.1 EVK1000 programming . 27 3.4.2 Android Application . 32 iv 4 Results and discussion 36 4.1 Prototype . 36 4.2 Performance . 36 4.2.1 Data rate . 37 4.2.2 Latency . 37 4.2.3 Energy consumption . 38 4.3 Android application . 38 4.4 Problems and solutions . 38 4.5 Comparison of wide and narrow band communication . 39 5 Conclusion and future work 41 References 43 v Abbreviations and definitions Acronym Definition AB Aktiebolag, corporation ACK Acknowledged frame ADC Analog to Digital converter ALOHA Multi access method ASCII American Standard Code for Information Interchange AWGN Additive White Gaussian Noise b Bit B Byte BLE Bluetooth Low Energy BPM Burst Position Modulation, see PPM. BPSK Binary Phase Shift Keying BT Bluetooth CDMA Code division multi-access CRC Cyclic redundancy check, error detecting code dB Decibel dBm Milli decibel ECC Error correcting code FCC Federal Communications Comission FDMA Frequency Division Multiple Access FEC Forward error correction GUI Graphical User Interface IDE Integrated Development Environment IEEE Institute of Electrical and Electronics Engineers IoT Internet of Things MAC Media Access layer MHR MAC header NACK Not acknowledged OSI Open system interconnection PHR PHY header PHY Physical layer PPM Pulse Position Modulation PRF Pulse repetition frequency RLTS Real Time location systems RS Reed-Solomon error correction code vi SECDED Single-Error-Correct Double-Error-detect SFD delimiter SHR Synchronization header TDMA Time Division Multiple Access USB Universal Serial Bus UWB Ultra Wide Band W Watt WiFi Wireless Network 802.11 standard vii 1 Introduction 1.1 Background Electrocardiography (ECG) is often performed in a hospital. This occupies the doctor and it is also costly to keep patients with long term heart monitoring in hospital care. The idea behind this thesis project is to create a wireless communication solution that would make the ECG device easier to wear for extended periods of time to monitor heart activity. Several sensors are used when performing an ECG meaning that lots of data needs to be sent to a base unit which, in this case, is a smart phone. UWB communications and ranging have attracted lots of interest of academia and industries because it has many advantages: • High time resolution for precise localization • High energy efficiency • Range/bitrate scalability • Robust to interference and multipath • Difficult to intercept (in traditional ways) • Radio suitable for wireless sensors.