Measurements on Wireless transmission of ECG signals

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1 Measurements on Wireless transmission of ECG signals A. Gabrielli a,b, I. Lax a a) INFN Bologna b) Physics Department, University of Bologna, Italy alessandro.gabrielli@bo.infn.it IPRD 3-6 October 2016 Siena Alessandro Gabrielli 1

2 Outline Tests of wireless transmission in the Electronics Lab., INFN Bologna Ultra Wide Band digital protocols: Wireless Transmission Receiver circuit Application to an ElectroCardioGram (ECG) prototype apparatus IPRD 3-6 October 2016 Siena Alessandro Gabrielli 2

3 Transmitter IPRD 3-6 October 2016 Siena Alessandro Gabrielli 3

4 Transmitter circuit Generic Input Voltage - Voltage-Frequency Converter - Digital Modulator - RF Transmitter Synchronous ON-OFF Keying SENSOR VIN S-OOK Digital Modulator TRANSMITTER IPRD 3-6 October 2016 Siena Alessandro Gabrielli 4

First Stage of the Transmitter Circuit Volt 100mV/div 5V/div 200mV/div Here the ramp was created to emulate a general sensor s output The VCO frequency shifts accordingly Time (1ms/div)

5 First Stage of the Transmitter Circuit Volt 100mV/div 5V/div 200mV/div Here the ramp was created to emulate a general sensor s output The VCO frequency shifts accordingly Time (1ms/div) Generic Input Voltage - Voltage-Frequency Converter On every rising edge of the digital waveform a coded-signal (sequence of bits) is transmitted IPRD 3-6 October 2016 Siena Alessandro Gabrielli 5

6 Synchronous ON-OFF Keying S-OOK digital protocol Set of 15 bits - 1 is two RF bursts (Sync + Data) - 0 is one only RF burst (Sync only) -! On-Off Keying (OOK) Protocol! IPRD 3-6 October 2016 Siena Alessandro Gabrielli 6

order of 1 m Measurements of the Ultra Wide Band 350 MHz to 3.

7 Recent tests on transmitted waveforms Tests on the transmission signal on a prototype ASIC (TowerJazz 180nm and UMC 130nm), at a distance of the order of 1 m Measurements of the Ultra Wide Band 350 MHz to 3.2 GHz signal detected by the receiver IPRD 3-6 October 2016 Siena Alessandro Gabrielli 7

8 Recent tests on transmitted waveforms The Ultra Wide Band (UWB) spectrum is visible and the detected power versus distance is measured The power is converted to voltage over a radiation resistance of 50 ohms at the receiver side Amplitude Received Tens of µv IPRD 3-6 October 2016 Siena Alessandro Gabrielli 8

9 Receiver IPRD 3-6 October 2016 Siena Alessandro Gabrielli 9

10 Receiver prototype at 3.2 GHz Band-Pass Filter in the receiver IPRD 3-6 October 2016 Siena Alessandro Gabrielli 10

11 Band-Pass Filter in the receiver Back Side Front Side Entirely parasitic band-pass filter centered at 3.2 GHz IPRD 3-6 October 2016 Siena Alessandro Gabrielli 11

12 Filters in the receiver Wide-Band Commercial RF receivers IPRD 3-6 October 2016 Siena Alessandro Gabrielli 12

13 Antenna and Filters in the receiver IPRD 3-6 October 2016 Siena Alessandro Gabrielli 13

cascaded band-pass filters the Ultra Wide Band signal allows

14 Three cascaded filters in the receiver 0 1 Sequence of 15 bits - 1 is two bursts - 0 is one burst only - On-Off Keying (OOK) Protocol Using three cascaded band-pass filters the Ultra Wide Band signal allows reconstructing the modulating wave IPRD 3-6 October 2016 Siena Alessandro Gabrielli 14

15 Prototypes test without filter (UMC 130nm) Peak at 3.5 GHz Noise over the bursts Received Bursts (carrier at 3.5 GHz) Noise over the bursts IPRD 3-6 October 2016 Siena Alessandro Gabrielli 15

16 Prototypes test with filter (UMC 130nm) Peak at 3.5 GHz Reduced Noise over the bursts Received Bursts (carrier at 3.5 GHz) Reduced Noise over the bursts IPRD 3-6 October 2016 Siena Alessandro Gabrielli 16

17 Bits inside a FPGA in the receiver (Chipscope) IPRD 3-6 October 2016 Siena Alessandro Gabrielli 17

18 ECG Application IPRD 3-6 October 2016 Siena Alessandro Gabrielli 18

19 Application to a ECG waveform Commercial Instrumentation Amplifier INA114 low-frequency signal to the VCO and to the RF Transmitter - very low DC offset - low drift - low noise - very high open-loop gain - very high common-mode rejection ratio - very high input impedances Concept: The PCB card is populated to get to a low-frequency signal used as modulating waveform for our VCO IPRD 3-6 October 2016 Siena Alessandro Gabrielli 19

20 Application to a ECG waveform Commercial Instrumentation Amplifier INA114 Screenshot of a student heart-beat as it is seen on an oscilloscope T/div 200 ms IPRD 3-6 October 2016 Siena Alessandro Gabrielli 20

21 Reproduced ECG waveform through an Arduino circuit ECG signal as created via an Arduino and a DAC Thus we were able to test the entire system: Transmitter + Receiver IPRD 3-6 October 2016 Siena Alessandro Gabrielli 21

22 Reproduced ECG (Arduino) converted to frequency via a VCO The modulating ECG signal is converted to a digital waveform with a frequency inversely dependent on the modulating amplitude. IPRD 3-6 October 2016 Siena Alessandro Gabrielli 22

23 Digital ECG waveform transmitted, acquired on the receiver and reconstructed on a FPGA IPRD 3-6 October 2016 Siena Alessandro Gabrielli 23

24 Real ECG waveform transmitted and reconstructed on the receiver Some studies. There is still something to adjust on the real ECG waveform acquired on the receiver The negative part of the waveform is cut somewhere... But we are working on it! IPRD 3-6 October 2016 Siena Alessandro Gabrielli 24

25 2) S-OOK modulation is added and a 3.2 GHz burst series is transmitted 1) ECG signal is created 3) A series of filters on the receiver eliminates the 3.2 GHz carrier and extract the modulant ECG signal IPRD 3-6 October 2016 Siena Alessandro Gabrielli 4) Eventually a FPGA holds the digitized heart-beat 25

26 Conclusion We started from a generic UWB transmitter-receiver circuit from 350 MHz (TowerJazz 180nm) to 3.3 GHz (UMC 130nm) We studied the S-OOK digital modulation We tested the wireless transmission in the Electronics Lab., INFN Bologna, using parasitic band-pass filters Then we implemented an ECG waveform as modulating signal, via a commercial Instrumentation Amplifier A full demonstrator ECG transmitter-receiver is definitely close to be completed IPRD 3-6 October 2016 Siena Alessandro Gabrielli 26

6.101 Introductory Analog Electronics Laboratory

6.101 Introductory Analog Electronics Laboratory Spring 2015, Instructor Gim Hom Project Proposal Transmitting, Receiving, and Interpreting ECG Waveforms Daniel Moon (dhmoon@mit.edu) Thipok (Ben) Rak-amnouykit