Pascucci_Michael_Poster.ppt - Engineering

							                                         Senior Project – Computer Engineering - 2005
    Analog Communication over Wireless Networks
                                               By: Michael Pascucci
                                             Advisor: Professor Spinelli
Purpose:
-Voice-over-Internet-Protocol (VoIP) currently exists as a free
telephone alternative. PCs connected over the Internet can access
telephones using phone numbers converted to IP addresses.
- My project allows for portable VoIP, using Microcontrollers
(“cell phones”) connected over a wireless Internet network addresses.
- Please note: Wireless RS-232 was used, not Wireless Internet

Constraints:
- Telephone  Quality Audio
……~ Sample 8000 sample/sec (8 KHz) with 8 bits/sample
……~ Output at > 8 KHz (in 2n KHz increments) …… …… ……
                                                                                                                Wireless VoIP Cell Phone
- Minimal Propagation Delay (< 200 ms) …… ……
- Serial RS232 protocol-transmission
…… ~ 115200 baud rate (bits/second) to prevent data loss …… …… …
… ~ 8-n-1 transmission format (8 data bits, no parity, 1 start/stop bit)
- 8 bit Analog-to-Digital Converter (ADC) / 12 bit Digital-to-Analog (DAC)


                                    Interpolating the signal on output allows a more accurate reproduction
                                                    without increasing the input Sample Rate
                          Input signal – 8 KHz sample rate
                                                                                             Output signal – interpolation at 16 KHz
                                                                 Output signal – no interpolation




                Functional Diagram                                      System Schematic                       Dedicated Serial-to-Wireless Devices
                                                                                                        (replace with Serial-to-WiFi for use with the Internet)


  Analog voice to Digital           Digital to Analog voice


 Digital Data to Serial Port            IP Packets from
       as IP Packets               Serial Port to Digital Data                                      Microcontrollers


     Serial to Wireless                Wireless to Serial




        To Internet                      From Internet
                               …


                                                                          Mic to ADC        Headphone to DAC           Mic to ADC         Headphone to DAC