1. iTalk 5000b ENEE 408G Group 4 FALL 2002 SEMESTER Josh Merti Pall Kunchai Vijay Kumar

2. Screenshots Server Client

3. Introduction and Background Walkie-Talkie Interface for the Pocket PC (IPAQ) Walkie-Talkie Interface for the Pocket PC (IPAQ) Functions across Wireless Internet Connection/Wireless Local Area Network Functions across Wireless Internet Connection/Wireless Local Area Network Half-Duplex Audio Transfer Half-Duplex Audio Transfer File Transfer Capability File Transfer Capability Secure and Encrypted Transmission Secure and Encrypted Transmission

4. Networking and Transfer Protocol Implementation Client iPAQ Server

5. Client/Server Responsibilities Server Server Provide Static IP for iPAQ Connection Provide Static IP for iPAQ Connection Serve as central connection point for the communications channel Serve as central connection point for the communications channel Generate and Transmit Encryption Key Generate and Transmit Encryption Key Client iPAQ’s Client iPAQ’s Record and Play Audio File of RIFF.WAV Format Record and Play Audio File of RIFF.WAV Format Data Encryption/Decryption Data Encryption/Decryption File Transfer Protocol Implementation File Transfer Protocol Implementation Audio Processing (TBI) Audio Processing (TBI)

6. Benefits of Desktop Server Static IP eliminates unknown IP connection with iPAQs Static IP eliminates unknown IP connection with iPAQs Centralized source for connections eliminates the need to designate an iPAQ either client or server Centralized source for connections eliminates the need to designate an iPAQ either client or server Increased stability of Desktop system makes a system crash much less likely Increased stability of Desktop system makes a system crash much less likely Future Program Versions are flexible to have multiple (2+) clients log into a central server Future Program Versions are flexible to have multiple (2+) clients log into a central server

7. Drawbacks of Desktop Server Transmission speed suffers due to need for “double transmission” Transmission speed suffers due to need for “double transmission” If Server crashes, it must be restarted locally If Server crashes, it must be restarted locally

8. Program Organization (Sender) User Input Create Send Record Get and Store Mic Input Send Audio File Get Filename From Edit Box Open and Read Data From File Create Socket Connect To Server Receive Encryption Key Encrypt Data and Send If(!EOF) Encrypt Audio File

9. Program Organization (Receiver) User Input Connect to Server Download Encryption Key Receive Transmission Type Data File Audio File Open File for Writing Receive, Decrypt, and Write Data Buffer Check for EOF No Close File Yes Close File and Play Audio Create Socket

10. PLACEHOLDER FOR FILE TRANSFER

11. Audio Handler and Voice Recording/Playback Programmed Standard Pocket PC microphone as the audio input Programmed Standard Pocket PC microphone as the audio input Microphone takes raw audio data and records to a “.wav” file Microphone takes raw audio data and records to a “.wav” file Audio Format of Data is as follows: Audio Format of Data is as follows: PCM Audio Format 8 Bit Audio Sample Size 1 Channel (Mono) 11.025 KHz Sampling Rate 88.2 KBits/second

12. Audio Handler and Voice Recording/Playback (Cont) Minimization of wave size while still maintaining audible quality of the recording Minimization of wave size while still maintaining audible quality of the recording Addition of header bits in the wave file prior to the raw data (see following slide) Addition of header bits in the wave file prior to the raw data (see following slide) This allows implementation of standard PlaySound Function (EVC) upon receive by opposite end-user This allows implementation of standard PlaySound Function (EVC) upon receive by opposite end-user

13. WAVE PCM Sound-file Header Format http://ccrma-www.stanford.edu/CCRMA/Courses/422/projects/WaveFormat/

14. Encryption/Decryption and Security of Transmission Unencrypted Data:[ 0 1 2 3 4 ][ 5 6 7 8 9 ] Sample Data Stream:[ 9 8 1 4 5 6 2 8 9 4 2 3 0 7 2 8 ] Encrypted Data Stream: [ 4 0 6 9 3 1 7 0 4 9 7 5 8 2 7 0 ] Transmit Decrypted Data Stream: [ 9 8 1 4 5 6 2 8 9 4 2 3 0 7 2 8 ] Encrypted Data:[ 8 6 7 5 9 ][ 3 1 2 0 4 ]

15. Future Initiatives and Version Possibilities Multiple Client communication through central server Multiple Client communication through central server Implementation of Full-Duplex Communication Implementation of Full-Duplex Communication Server Programmed as an intelligent router Server Programmed as an intelligent router Isolation of a secure socket (end to end) for optimal transmission speeds Isolation of a secure socket (end to end) for optimal transmission speeds Voice-Recognition Keys for increased security Voice-Recognition Keys for increased security Video-Transmission Video-Transmission Hands-free implementation/voice activation Hands-free implementation/voice activation

16. Conclusion A response to costly wireless services A response to costly wireless services A secure transmission and communication link A secure transmission and communication link An expansion of the scope and function of your Pocket PC An expansion of the scope and function of your Pocket PC Open ended application for implementation of further signal processing concepts Open ended application for implementation of further signal processing concepts A simple design and project for further additions by future semester students within the course A simple design and project for further additions by future semester students within the course

17. THANK YOU! Acknowledgements Acknowledgements On to the demo… On to the demo…