Final Project Review Team Vibraid April 2014

Vibraid Michael Balanov (Mike) EE Spyridon Baltsavias (Spiros) EE Reona Otsuka (Leo) EE Andrew Woo (Andy) EE

Previous Block Diagram switch signal variable resistance 5 different modules Processing done in software, everything else in hardware

Current Block Diagram Processing block absorbs Filtering module Filtering done digitally!

Reason behind Digital Filtering Analog filters attenuated input signal Extra amplification was required Physical space limitation 3 filters per microphone = total of 12 filter circuits Additional space for extra amplification/active filter Digital advantages Ideal band cutoffs No attenuation Allows for easy combination of filters

Arduino Processing Changes Optimized through low level coding to increase sampling rate From 2.5kHz to around 14kHz rate for each microphone Implemented an optimized FFT to determine frequencies received by the microphones If fundamental frequency is inside desired band, pass signal for comparison Block low-pass noise that was observed Due to limited analog inputs, the Motor strength knob has been changed to a Motor strength switch

Final Comparator Logic Design Decided to implement SPL (amplitude) comparison instead of Time Delay estimation Time Delay could not be improved enough to meet the required specs SPL comparison met specs after purchasing better directional microphones

FPR Requirements SpecificationValueMet? Max Detection radius for 70dB to 120dB within frequency range >3m (10ft)Yes Frequency Detection Range100Hz – 10kHzYes, in most cases Belt Circumference75cm – 105cm (small – large)Yes Belt Width<10cmYes Belt Thickness<5cmYes Product Weight<1kgYes Detection Directionality4 DirectionsYes Vibration Response Time<0.5sYes Vibration DirectionalityVibration to alert user in one quadrant Yes Vibration to Corresponding Detection 99% of timeYes Tunable SensitivityBlock all till Pass allYes Tunable Frequency Detection4 modes: full, low, mid, highYes Tunable Motor StrengthNo vibration to Max supplyNo (2 levels of intensity instead) Battery Life>12hYes

Demo Outline Frequency filtering demo Wearing the device – 4 way directionality

Frequency Filtering 3 switches: High, Mid, Low (-pass) Low band: 100Hz to ~300Hz Mid band: ~300Hz to 600Hz High band: ~600Hz to ~7000Hz Combination of bands possible

Q&A

Digital Filtering Disadvantages Sampling rate needs to be high enough (Nyquist rate) Adds to processing time