distributed acoustic sensing with voxnet michael allen¹, lewis girod², ryan newton², samuel...

Distributed Acoustic Distributed Acoustic Sensing Sensing

with VoxNetwith VoxNet

Michael AllenMichael Allen¹¹, Lewis Girod, Lewis Girod²², Ryan Newton, Ryan Newton²², Samuel , Samuel MaddenMadden²², ,

Travis CollierTravis Collier³³, Daniel Blumstein, Daniel Blumstein³³, Deborah Estrin, Deborah Estrin³³

¹¹Coventry University Coventry University ²CSAIL, MIT²CSAIL, MIT ³³CENS, CENS, UCLAUCLA

24/6/2008 2WiSiG Webinar

What is distributed acoustic What is distributed acoustic sensing?sensing?

Driven by acoustics-based Driven by acoustics-based applicationsapplications

Embedded devices deployed over a Embedded devices deployed over a spacespace

Typically employ wireless Typically employ wireless communicationcommunication


What is distributed acoustic What is distributed acoustic sensing?sensing?

Driven by acoustics-based Driven by acoustics-based applicationsapplications

Embedded devices deployed over a Embedded devices deployed over a spacespace

Typically employ wireless Typically employ wireless communicationcommunication

Wireless sensor networks for acoustics applicationsWireless sensor networks for acoustics applications


Applications and Applications and Challenges of Distributed Challenges of Distributed

Acoustic SensingAcoustic Sensing



Acoustic SensingAcoustic Sensing Has traditional WSN Has traditional WSN

complexities, in complexities, in addition:addition:

High data rate = no High data rate = no streaming to sinkstreaming to sink

Forces local, in Forces local, in network processingnetwork processing



Acoustic SensingAcoustic Sensing Has traditional WSN Has traditional WSN

complexities, in complexities, in addition:addition:

High data rate = no High data rate = no streaming to sinkstreaming to sink

Forces local, in Forces local, in network processingnetwork processing

* Distributed processing properties* Distributed processing properties* Develop applications using a high level language * Develop applications using a high level language

* Easily push new applications into the network* Easily push new applications into the networkWithout sacrificing performanceWithout sacrificing performance


VoxNetVoxNet

VoxNet: integrated hardware and software platform for distributed acoustic sensing

Captures, integrates previous experience in acoustic sensing networks

AudioInput

Detect

Server SideAML DOA

Send RawData

Buffer>3sec?

Run LocalAML DOA

N

Send AMLOutput

Y

Sensor Node

Server Side

Eventassociation

sync4

Network OperatorsSensor sideServer side


How we got to VoxNetHow we got to VoxNet

Acoustic ENSBox (UCLA)Proof of concept (SenSys 2006)

Source localization of marmots (UCLA)

Proof of concept (IPSN 2007)

Wavescope (MIT)(High level, signal-oriented stream processing system)

VoxNetVoxNet


VoxNet architectureVoxNet architecture

In-field PDAIn-field PDA

GatewayGateway

Mesh Network of Deployed NodesMesh Network of Deployed Nodes

Control ConsoleControl Console


VoxNet architectureVoxNet architecture

In-field PDAIn-field PDA

GatewayGateway

Mesh Network of Deployed NodesMesh Network of Deployed Nodes

On-line operationOn-line operation Off-line operation and storageOff-line operation and storage

Compute ServerCompute Server

Storage ServerStorage Server

Internet orInternet orSneakernetSneakernet

Control ConsoleControl Console


RoadmapRoadmap

VoxNet platformVoxNet platform How it’s usedHow it’s used How it’s programmedHow it’s programmed

Performance resultsPerformance results Network latencyNetwork latency Runtime dynamicsRuntime dynamics

Ongoing workOngoing work ConclusionsConclusions


Current VoxNet node: Current VoxNet node: ENSBox V2ENSBox V2

Based on Acoustic ENSBox (SenSys Based on Acoustic ENSBox (SenSys 2006)2006) 4 channel mic. array at 48KHz, 802.11b4 channel mic. array at 48KHz, 802.11b Linux, 400 MHz ARM/64MB/8GBLinux, 400 MHz ARM/64MB/8GB Smaller form factor, Internal batterySmaller form factor, Internal battery GPS, 3-axis accelerometerGPS, 3-axis accelerometer Always-on mote for duty cyclingAlways-on mote for duty cycling

Software support (SenSys 2006)Software support (SenSys 2006) Time sync, self-localizationTime sync, self-localization

Rapidly deployable!Rapidly deployable! Field tested over several monthsField tested over several months ……in the rainforest (Chajul, Mexico)in the rainforest (Chajul, Mexico) ……and the mountains (Gothic, CO)and the mountains (Gothic, CO)With thanks to Travis CollierWith thanks to Travis Collier


VoxNet on-line usage VoxNet on-line usage modelmodel

Write program

// acquire data from source, assign to four streams(ch1, ch2 ch3, ch4) = VoxNetAudio(44100)// calculate energyfreq = fft(hanning(rewindow(ch1, 32)))bpfiltered = bandpass(freq, 2500, 4500)energy = calcEnergy(bpfiltered)



Write program

Node-side part

Sink-side part

Optimizingcompiler




Write program

Node-side part

Sink-side part

Optimizingcompiler

Disseminateto nodes




Write program

Node-side part

Sink-side part

Run program

Optimizingcompiler

Disseminateto nodes




Write program

Node-side part

Sink-side part

Run program

Optimizingcompiler

Disseminateto nodes


Development cycle Development cycle happens in-field, happens in-field,

interactivelyinteractively


Programming VoxNetProgramming VoxNet Programming language: WavescriptProgramming language: Wavescript

High level, stream-oriented macroprogramming languageHigh level, stream-oriented macroprogramming language Compiles down to a directed, graph of communicating Compiles down to a directed, graph of communicating

‘stream operators’ which data flow through (source to ‘stream operators’ which data flow through (source to endpoint)endpoint)

Operates on stored OR streaming dataOperates on stored OR streaming data User writes a script connecting operators User writes a script connecting operators

Writes both node side + sink side separatelyWrites both node side + sink side separately User decides where processing occurs (node, sink)User decides where processing occurs (node, sink)

Explicit, not automated processing partitioningExplicit, not automated processing partitioning

Source

Source

Source

Endpoint


Example – energy Example – energy calculationcalculation

// acquire data from source, assign to four streams(ch1, ch2 ch3, ch4) = VoxNetAudio(44100)

// window ch1 data stream into 32 sample chunks, // passing through hanning then fft operatorsfreq = fft(hanning(rewindow(ch1, 32)))

// apply bandpass filter to freqbpfiltered = bandpass(freq, 2500, 4500)

// calculate energy in bandpassed dataenergy = calcEnergy(bpfiltered)

VoxNetAudiorewindow hanning fft

ch1


Splitting up a logical Splitting up a logical programprogram

// acquire data from source, assign to four streams(ch1, ch2 ch3, ch4) = VoxNetAudio(44100)

freq = fft(hanning(rewindow(ch1, 32)))

//send data to sinktoNet(“frequencies”,freq)

// receive data from node streamfreq2 = fromNet(“frequencies”)

// apply bandpass filter to freqbpfiltered = bandpass(freq2, 2500, 4500)

// calculate energy in bandpassed dataenergy = calcEnergy(bpfiltered)

freq toNet(“frequencies”) fromNet(“frequencies”)

send(“frequencies”) arrived(“frequencies”)

Sink

Node

bandpass


RoadmapRoadmap


Validating VoxNetValidating VoxNet Network latencyNetwork latency Runtime dynamicsRuntime dynamics



Validating VoxNetValidating VoxNet

Implementation of indicative Implementation of indicative application (Marmot localization)application (Marmot localization) Distributed event detection and position Distributed event detection and position

estimationestimation Resource usageResource usage

Hand coded C vs. high level WavescopeHand coded C vs. high level Wavescope Network trade-offNetwork trade-off

Process locally or send raw data to Process locally or send raw data to sink?sink?


Example VoxNet Example VoxNet applicationapplication

Detect and determine location of marmotsDetect and determine location of marmots Crossing of DoA estimates Crossing of DoA estimates Obtain results on-line (scientist interaction)Obtain results on-line (scientist interaction)

Event detection

DoA processing and position estimation

X

Send 32KBper node,per detection

NODES SINK


Hand-coded C vs. Hand-coded C vs. WavescriptWavescript

100%

Hand-coded C Wavescript

EVENT DETECTORDATA ACQUISITION



30% less CPU30% less CPU


100%




Extra resources mean that data can be Extra resources mean that data can be archived to disk as well as processed archived to disk as well as processed (‘spill to disk’, where local stream is (‘spill to disk’, where local stream is pushed to storage co-processor)pushed to storage co-processor)


‘SPILL TO DISK’

100%



Detection data Detection data transmission latencytransmission latency

Deployed network in Gothic, Deployed network in Gothic, COCO Request all nodes to transmit Request all nodes to transmit

data simultaneouslydata simultaneously Emulates the ‘worst case’ when Emulates the ‘worst case’ when

all nodes detect the acoustic all nodes detect the acoustic eventevent

Measure latency to transmit Measure latency to transmit raw detection or processed raw detection or processed data (32KB vs. 800B/node)data (32KB vs. 800B/node) Gathered single and multi-hop Gathered single and multi-hop

datadata Up to three hopsUp to three hops Used single hop 800B data to Used single hop 800B data to

help predict missing 800B multi-help predict missing 800B multi-hop datahop data


Detection data transfer Detection data transfer latencylatency

1 HOP 2 HOPS 3 HOPS12


Detection data transfer Detection data transfer latencylatency

Network latency will become a problem Network latency will become a problem if scientist wants results in <5 seconds if scientist wants results in <5 seconds (otherwise animal might move position)(otherwise animal might move position)

1 HOP 2 HOPS 3 HOPS12


Processing trade-offProcessing trade-off

Sending raw data to sinkSending raw data to sink DoA processing takes a short time (0.04s)DoA processing takes a short time (0.04s) Sending data takes a long time Sending data takes a long time

(32KB, up to 12s in expt.)(32KB, up to 12s in expt.) Sending processed data to sinkSending processed data to sink

DoA processing takes a long time (~2.2s)DoA processing takes a long time (~2.2s) Sending data takes a short time (800B, Sending data takes a short time (800B,

<1s)<1s) Which is best to do to reduce overall Which is best to do to reduce overall

position estimation latency?position estimation latency?


Local vs. sink processing Local vs. sink processing trade-offtrade-off

DoA PROCESSING TIMENETWORK LATENCY

Send raw data, process Send raw data, process at sinkat sink

DoA processing




Process locally, send Process locally, send 800B800B

DoA processing




As hops from sink increases, benefit of As hops from sink increases, benefit of processing DoA locally is clearly seenprocessing DoA locally is clearly seen


Applying the trade-off at Applying the trade-off at run-timerun-time

Aim: process raw data locally when possibleAim: process raw data locally when possible Node has limited buffer space for data samplesNode has limited buffer space for data samples Event detection can happen faster than real-time, so can catch Event detection can happen faster than real-time, so can catch

upup

Wavescript makes this easy to implementWavescript makes this easy to implement Trivial, natural to split and merge multiple streamsTrivial, natural to split and merge multiple streams Same on-node and sink DoA implementationsSame on-node and sink DoA implementations

AML DOASend Raw

DataBuffer>3sec?

AML DOA

N

Send AMLOutputY

Node Sink

Merge2.2s

0.04sx

y


RoadmapRoadmap


Performance resultsPerformance results Network latencyNetwork latency Runtime dynamicsRuntime dynamics



Ongoing workOngoing work VoxNet Platform DevelopmentVoxNet Platform Development

NSF Funded UCLA/MIT collaboration (2008-NSF Funded UCLA/MIT collaboration (2008-2010) 2010)

Aiming for 10x improvement on lifetime Aiming for 10x improvement on lifetime Make platform smaller, lighter, cheaperMake platform smaller, lighter, cheaper

Develop VoxNet application portfolio furtherDevelop VoxNet application portfolio further Add classification, census to bioacoustics apps.Add classification, census to bioacoustics apps. New applications from different domains:New applications from different domains:

Increases generality, validates applicabilityIncreases generality, validates applicability Ongoing development of Wavescript Ongoing development of Wavescript

compilercompiler


ConclusionsConclusions

VoxNet hardware is easy to deployVoxNet hardware is easy to deploy Experience is invaluable in this respectExperience is invaluable in this respect

Wavescript simplifies developmentWavescript simplifies development Allows on-line development in the fieldAllows on-line development in the field

Provides comparable operating Provides comparable operating performanceperformance Despite being high level languageDespite being high level language

Easy to implement network dynamicsEasy to implement network dynamics Such as local processing adaptationSuch as local processing adaptation


For more informationFor more information

My contact details:My contact details:email: email: [email protected]@coventry.ac.ukweb: web: http://cogentee.coventry.ac.uk/~allehttp://cogentee.coventry.ac.uk/~allenmnm

Wavescope:Wavescope:http://http://wavescope.csail.mit.edu/doku.phpwavescope.csail.mit.edu/doku.php

The IPSN 2008 VoxNet paper:The IPSN 2008 VoxNet paper:

Allen, M., Girod, L., Newton, R., Madden, S., Blumstein, D., Estrin, D., Allen, M., Girod, L., Newton, R., Madden, S., Blumstein, D., Estrin, D., "VoxNet: An Interactive, Rapidly-Deployable Acoustic Monitoring Platform","VoxNet: An Interactive, Rapidly-Deployable Acoustic Monitoring Platform", Proceedings of IPSN 2008Proceedings of IPSN 2008


Backup slide: WavescopeBackup slide: Wavescope ““Wavescope is a system for developing Wavescope is a system for developing

distributed, high-rate applications that distributed, high-rate applications that need to process streams of data from need to process streams of data from various sources (e.g., sensors) using a various sources (e.g., sensors) using a combination of signal processing and combination of signal processing and database (event stream processing) database (event stream processing) operations.operations.

The execution environment for these The execution environment for these applications ranges from embedded sensor applications ranges from embedded sensor nodes to multicore/multiprocessor nodes to multicore/multiprocessor servers.”servers.”

distributed acoustic sensing with voxnet michael allen¹, lewis girod², ryan newton², samuel...

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