1. Communication Systems I CPE 313: Micro Processors and Interfacing

2. How can information flow from point A to point B?

3. Morse Code Can you spell your name? See http://morsecode.scphillips.com/jtranslator.html for a live demohttp://morsecode.scphillips.com/jtranslator.html

4. Morse Code in Hollywood 1996 Film

5. Fountain of Bits

6. How to transmit voice? Speaker = Sound reproducer Mic = Sound transducer Max Frequency Range: 20-20,000 Hz Electrical signal in a transmission line

7. How Are Phone Connected?

8. How are phone conversations connected? Traditional Switched Network Each conversation needs a dedicated line. Very expensive to build the network.

9. Using Multiplexing Techniques Frequency Division Multiplexing (FDM) Many connections can be multiplexed through a single line

10. Freqeuncy Channels

11. Traditional Telephone Lines Limit the Sound Frequencies Transmitted 400 – 3,400 Hz The bandwidth of this line is 3kHz Can you think of why?

12. Frequency Channels If the main transmission line has a maximum bandwidth of 1MHz, How many concurrent phone connections can it carry?

13. What if we want to send digital data over the phone line? Can it be done? 010111001010111001

14. Digital to Analog Encoding See http://www.iesmarenostrum.com/informatica/zmaterias/ral/flash/digit_modulation.swf for an interactive demo.http://www.iesmarenostrum.com/informatica/zmaterias/ral/flash/digit_modulation.swf

15. Example: A Traditional Modem Modem Typical Maximum Speed 56Kbps

16. How data is sent with a traditional modem Traditional Modem Telephone Network Home Internet Gateway Destination Phone

17. Example II: ADSL Modem ADSL

18. Why is ADSL much faster? 256 Channels of 4 kHz each

19. But What About the 4K Bandwidth Limitation? Splitter ADSL Modem DSLAM Telephone Network Data Network Home Digital Subscriber Line Access Multiplexer

20. How fast is ADSL? ADSL = 256 x 4 kHz x 8 bits = 8 Mbps ADSL2= 12 Mbps ADSL2+= 25 Mbps *ADSL2+ expands channel frequency from 1.1 to 2.2 MHz

21. Serial vs Parallel Transmission Image © Quatec

22. Example of Serial Comm? Example of Parallel Comm?

23. Which Mode is More Common? Cost. Less cables. Smaller size. Simplicity. Keeping bits aligned in a high- speed parallel line requires more complex electronics. Serial Why?

24. The Need for Speed Speed Mbps

25. Synchronous vs Asynchronous A B A B Synchronous uses a clock line Asynchronous relies on a common clock on each side

26. Playing Catch with a Blind Receiver If you are the blind catcher, which method would you choose? Method 1: Pitcher throws and sends a signal Method 2: Pitcher throws every 10 seconds. No signal. Pitcher Catcher

27. RS-232 (Serial Communication) Baud Rate Data bits Start bit / Stop bits Parity

28. RS-232 Pulses Letter “V” ASCII = 86 (0101 0110 2 ) 9600 bps, 8-N-1 Layout: Start Bit, Data Bits, Parity, Stop Bits * Note: Rs-232 logic pulses are inverted

29. RS-232 Pulses Letter “Y” ASCII = 89 (0101 1001 2 ) 9600 bps, 8-Odd-1 Layout: Start Bit, Data Bits, Parity, Stop Bits * Note: Rs-232 logic pulses are inverted

30. How about ASCII 255? Layout: Start Bit, Data Bits, Parity, Stop Bits The data transmission is unbalanced. Can cause transmission errors. 9600 bps, 8-N-1

31. Manchester Encoding (IEEE 802.3) Bit 1 = Low to High Bit 0 = High to Low

32. Example Image: Wikipedia

33. Data = 255 Manchester Code

34. Encode the following transmissions using the Manchester standard Letter “V” ASCII = 86 (0101 0110 2 ) Letter “Y” ASCII = 89 (0101 1001 2 )