…
Download
1 / 12

Wireless Audio Effects Processor - PowerPoint PPT Presentation


  • 405 Views
  • Updated On :

…. * Wireless * Audio Effects Processor. Lohith Kini Rahul Shroff Spyros Zoumpoulis April 30 th , 2007 6.111 Project Presentation. Our Model: AirTunes®. Audio input from source Compressed Wirelessly transmitted Decompressed Equalizer & Audio Effects. Decompression. Compression.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Wireless Audio Effects Processor' - Philip


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

Wireless audio effects processor l.jpg

* Wireless* Audio Effects Processor

Lohith Kini

Rahul Shroff

Spyros Zoumpoulis

April 30th, 2007

6.111 Project Presentation


Our model airtunes l.jpg
Our Model: AirTunes®

  • Audio input from source

  • Compressed

  • Wirelessly transmitted

  • Decompressed

  • Equalizer & Audio Effects


Top level block diagram l.jpg

Decompression

Compression

IMDCT

MDCT

FSM

SRAM

SRAM

Top Level Block Diagram

IFFT

AC97

Controller

AC97

Codec

Equalizer

Transmission

FFT

Equalization

FSM

Reception


Compression of audio l.jpg
Compression of Audio

  • MP3, MPEG-4, AAC

    • Modified Discrete Cosine Transform

      • Lapped : Map 2N discrete points into N discrete points

MDCT


Slide6 l.jpg

WIRELESS MEMORY

WE

10

18

8-pt.

address

Data_Out

ac97_sdata_in

ac97_synch

Compression

FSM

AC97 Controller

AC97

AC97 FSM

ac97_sdata_out

16-pt.

18

Data

WR

ac97_bit_clock

(global)

FIFO

RD

Data_Out

DA

CLK

16-pt.

18

RFD

1D MDCT

ND

Data_Out

RDY

CLK

Data

Compression

8-pt.

18

RESET


Wireless cc2420dbk rf transceiver l.jpg
Wireless CC2420DBK RF Transceiver

  • CC2420 radio

  • 2.4 GHz frequency band

  • Atmel Atmega128L AVR microcontroller

  • 2x32 kBytes external RAM

  • PCB antenna

  • Joystick, buttons, LEDs (visual user application interface)


Wireless big picture l.jpg
Wireless Big Picture

Block

Memory

(wireless)

TX Control Unit

Encoder (FEC)

FPGA

Packet Transmitter

Packet Receiver

Block

Memory

(wireless)

Decoder (FEC)

RX Control Unit

FPGA


Wireless transmission algorithm l.jpg
Wireless Transmission Algorithm

  • Error Correction Algorithm

    • Forward Error Correction (FEC)

      • sender adds redundant data to its messages

      • allows receiver to detect errors

  • Reed Solomon Code

    • Key idea:

      • data is encoded as a polynomial

      • any k distinct points uniquely determine a polynomial of degree at most k-1

    • Polynomial is then “encoded” by its evaluation at various points, and these values are what is actually sent

    • Transmission: some of these values may become corrupted

    • More than k points are actually sent

    • Receiver decodes the original data

    • Total number of m-bit symbols in the encoded block is n = 2m - 1

  • Example: m = 8, Code Rate 223/255

    • (In each block 223 symbols are formed from the encoder input and 32 parity symbols are added.)

    • Capable of correcting up to 16 symbols per block


Equalization l.jpg
Equalization

  • Use FFT to convert audio signal into frequency spectrum

  • Add desired effects as required by the user

  • Take IFFT of resulting signal

  • Transmit processed audio to AC-97 output line


Audio effects the big picture l.jpg

Mult_re

18

IFFT

Multiplier

Module

real_inv

Mult_im

LPF

18

8

ifft_enable

to_ac97_data

AC-97

Equalizer

FFT_real

18

1024-pt.

FFT

18

Bucketizer

FFT_img

18

10

FFT_index

Decompression

Memory

Audio Effects: The BIG Picture



ad