audio networking

Audio Networking : 

Audio Networking Presented By Manish jain VIII Sem. CP

About audio networking : 

About audio networking Is audio networking a new concept? Traditional uses of sound in computing Phone line modems Under water communications Speech recognition/synthesis Why is audio networking ignored? Computer systems basically aim at long distance transmission at high speed. There are some limitations associated with sound Low data transfer rates. Low penetration power. Sound may annoy people.

Why audio networking now? : 

Why audio networking now? Availability of sound hardware at lost cost. Faster CPU’s Acoustic modems can be implemented fully into software. Range of pervasive devices like.. PDA Mobile Lap Top etc.

Advantages of using sound : 

Advantages of using sound Sound does not penetrate through walls Security Less interference in transmission Fine grain control over range of transmission Unlike infrared waves sound does not need line of sight and so can go around corners. Low cost hardware

Design criteria for audio network : 

Design criteria for audio network Message should be acceptable to people who are concerned with transmitted data. Message should be imperceptible to the person who are not concerned with transmission. System should be developed using ordinary hardware to avoid extra cost.

Audio networking : 

Audio networking Encoding Modulation FFT Demodulation Decoding Message Message

Encoding : 

Encoding eliminate 011101110011110 13 the 0010 13 prosody 0000001 0110 10000100100111110 46 011011110010011001 but 00110010 13 keep 001110100100 13 the 0010 13 words 001100110010 13 Total 102 bits 124 bits Huffman Word General

Modulation techniques : 

Modulation techniques Amplitude shift key (ASK) BASK (On/Off Keying) Frequency shift key (FSK) Dual tone multi-frequency Frequency hoping Melodious transformation Inaudible transmission

Binary amplitude shift key : 

Binary amplitude shift key Time Time Message 0 1 0 1 0 0 1 0 Signal

Dual tone multi-frequency : 

Dual tone multi-frequency * 697 770 852 941 1209 1336 1447

Melodious transmission : 

Melodious transmission 0011 0011 = 3 Scales used: 00 01 10 11

Inaudible transmission : 

Inaudible transmission Human hearing frequency range is approximately 20-20,000 Hz Transmit data over a >20,000 Hz carrier We can produce sounds in normal hardware in the 20,000 ~ 22,000 Hz range (max. is app. 22,000 Hz because normal hardware samples at 44.1 KHz)

Applications of audio networking : 

Applications of audio networking Applications that don’t require higher data bit rates Authentication Steganography Transmissions of URL Locality information Pick and drop interface Audio watermarking Underwater communication

Limitations of audio networking : 

Limitations of audio networking The channel (micro-phone + speaker + air) is far from idle. Existing hardware is usually non-uniform with respect to frequency response. Higher bit rate means less acceptable sound. Error due to surrounding sound. Microphone quality.

References : 

References Cristina Videira Lopes ,Pedro M.Q. Aguir: Acoustic Modems for Ubiquitous Computing . IEEE cs and IEEE ComSoc, Sept-2003 www.recoil.org/audio/ Cristina Videira Lopes, Anshuman Chadha: A 40 bps Speech Coding Scheme. Published in proceedings of the Symposium on Signal Processing for Communication IEEE Globecom, San Francisco, CA, Dec. 2003 Anil Madhavapeddy, David Scott, Richard Sharp: Context-Aware Computing with Sound. University of Cambridge.