<< Chapter < Page Chapter >> Page >
Implement a spectrogram application in the Native Android environment. Signal processing includes windowing, zero-padding, overlapping, FFT, and working with complex numbers.

Lab overview

In this lab, you will create an Android application that plots the spectrogram of streaming audio, and deploy it on the Google Nexus 7 tablet.

Similar to the previous labs, you will be provided with an existing project with all of the required peripherals already set up. Unlike the previous labs where data was processed sample-by-sample, this lab requires block-based processing.

What is the minimum latency for processing a block of length 256, with an audio sampling rate of 8 kHz?

[link] shows a block diagram of the system you will be implementing. The project is already configured to stream audio and display the processed output to the screen.

System-level block diagram

Audio capture -> Audio buffer -> Preprocessing -> FFT -> Energy calculation -> Display

You will be focusing on the signal processing tasks, which will be implemented in native C code. For those that are interested in the Android Java specifics, we will provide an optional tutorial that shows you how to build the project from scratch, explains the different Android classes that were used, and along the way, provides supplemental links to references and other useful Android tutorials available on the web.

Part 1: getting started with android and eclipse

In this section, you first setup your Android device in development mode, import a skeleton project into Eclipse, and familiarize yourself with the Android project structure and build process.

Setting up the google nexus for development

On the tablet, you must enable the Developer options under Settings :

  1. Go to Settings ,
  2. Click on About tablet ,
  3. Click Build number seven times (yes, 7).

Under Settings>Developer options , enable the Stay awake and USB debugging options.

Setting up eclipse

The development environment you will be using is the Nvidia Tegra Android Development Pack 2.0 . To get started:

  1. Start Cygwin by double-clicking on C:\NvPack\cygwin\cygwin.bat
  2. In the prompt, navigate to the Eclipse folder by typing cd /cygdrive/c/NvPack/eclipse
  3. Launch Eclipse with ./eclipse
Cygwin provides a Linux-like environment for Windows, and launching Eclipse from within Cygwin is required for native C debugging to work correctly.

Choose a new workspace on your U: drive, similar to what you did in Lab 0. This step feels familiar because CCS is actually based on the Eclipse framework.

Importing the project

Once Eclipse opens, select File>Import...

  1. General>Existing Projects into Workspace
  2. V:\ece420\nexus\Lab4\
  3. Check "Copy into Workspace"
Close out of the "Welcome" screen.

Once the project is imported, it will try to build automatically. If you see a build error, you will need to define the $NDKROOT variable in your workspace:

  1. Go to Project>Properties
  2. Expand C/C++ Build>Environment
  3. Add...
  4. Name: NDKROOT, Value: C:\NvPack\android-ndk-r8

Understanding the android project structure

An Android project with Native code support has 4 main components:

  • .\AndroidManifest.xml - contains app-related information, such as project name, activities, and required peripherals (e.g., microphone).
  • .\res\layout\main.xml - describes the layout of the user interface. In our project, we define an ImageView , which is used to display the spectrogram.
  • .\src\ - contains the Java source files.
  • .\jni\ - contains the native C source and Make files.

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Good
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!





Source:  OpenStax, Ece 420 fall 2013. OpenStax CNX. Sep 26, 2013 Download for free at http://cnx.org/content/col11560/1.3
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Ece 420 fall 2013' conversation and receive update notifications?

Ask