1. Communications Baseband PDR Communications Baseband Project 05500

2. Communications Baseband PDR Members  Advisors:  Dr. Joe Delorenzo  Dr. Eli Saber  Dr. Sohail Dianat  Team Members:  Leland Smith (Team Leader)  Jason Riesbeck (Chief Engineer)  Jonathan Hutton

3. Communications Baseband PDR Introduction  Communications Baseband is a project created by several professors in order to stimulate student’s practical understanding of communication systems.  Sponsor: Rochester Institute of Technology Department of Electrical Engineering

4. Communications Baseband PDR Project Overview  Modulate/Demodulate using Amplitude Modulation, Frequency Modulation, and Pulse Code Modulation  Receive analog or digital transmission approximately a classrooms distance and demodulate  Output original signal to see/hear successful recovery

5. Communications Baseband PDR Team Work Breakdown

6. Communications Baseband PDR Fundamental Design Objectives Specifications Weight Can be completed in allotted time. 10 Communicates AM, FM, and PCM across a classroom 9 Suitable for evaluation in a laboratory 7 Affordable for customer. 6 Easy to Use. 4 Minimal amount of external equipment 4

7. Communications Baseband PDR Concept Analysis

8. Communications Baseband PDR System Development Divided into 12 subsystems Specification developed for each

9. Communications Baseband PDR Feasibility  Assessed at a subsystem level.  Depends on the resources available  To maintain feasibility, subsystems should:  Satisfy design objectives  Economical  Comply with time constraints

10. Communications Baseband PDR FCC Considerations CountryFrequencyNotesStandards US2.400-2.483.5 GHzISM Band 1W802.11/11b 902-928 MHzISM Band (Used by GSM in most countries) 5.800-5.925 GHzISM Band 5.15-5.25 GHzU-NII (Unlicensed - National Information Infrastructure) max. 200 mw EIRP 802.11a 5.25-5.35 GHzU-NII max. 1w EIRP802.11a 5.725-5.825 GHzU-NII max. 4w EIRP802.11a Unlicensed Bands (FCC 15.247.b.4) All other bands 100mW or less Antenna gain can be as much as 6dB.

11. Communications Baseband PDR Audio Subsystem  Block Diagram Input Output

12. Communications Baseband PDR Anti-Aliasing Filter  Specifications:  0-5V Input  Pass-band 20 kHz  Stop-band 22 kHz  Attenuation 20 dB  Elliptical Filter

13. Communications Baseband PDR Anti-Aliasing Filter Schematic: Plot:

14. Communications Baseband PDR Anti-Aliasing Filter  6dB Voltage Level = 3dB Power Level = 1.26V  Output =1.26V @ 20.0 kHz  Attenuation =

15. Communications Baseband PDR AM Subassembly  Block Diagrams

16. Communications Baseband PDR AM Modulation  Carrier  1 MHz Sine Wave  Modulator  Oscillator Input  Audio Input

17. Communications Baseband PDR Carrier Signal  Clock Oscillator  Square Wave  RLC Filter

18. Communications Baseband PDR Carrier Signal

19. Communications Baseband PDR AM Schematic

20. Communications Baseband PDR AM Receiver  AM Receiver  Demodulates Signal  Amplifies the Signal by 18 dB

21. Communications Baseband PDR FM Systems  Complicated to engineer  Could take months in industry Transmitter Receiver

22. Communications Baseband PDR Radio IC’s  A simple and effective solution

23. Communications Baseband PDR Choosing an FM IC ObjectivesWeight Part availability10 Comprehensive design resources8 Application examples7 Performance6 Price5 Low parts count5

24. Communications Baseband PDR Design Documentation  Schematics  Parts Lists  Specification Documents  Interconnection Control Documents  Test Procedures  Printed Circuit Board

25. Communications Baseband PDR Design Issues  PCB Short

26. Communications Baseband PDR Design Issues  PCB Short  Voltage Regulator Pin-Out

27. Communications Baseband PDR Design Issues  PCB Short  Voltage Regulator Pin-Out  Tuning Capacitor

28. Communications Baseband PDR Design Issues  PCB Short  Voltage Regulator Pin-Out  Tuning Capacitor  Audio Distortion

29. Communications Baseband PDR Design Issues  PCB Short  Voltage Regulator Pin-Out  Tuning Capacitor  Audio Distortion  Tuning Inductor

30. Communications Baseband PDR FM Feasibility TaskEstimated Time in Hours Actual time in Hours Schematic Creation15 12 Performance Analysis5 5 Specification Formation13 10 Parts List8 10 General Documentation10 11 Board Layout12 15 Board assembly7 6 Functional Test12 8 Integration4 4 Tweaking and Repair20 10 Total106 91

31. Communications Baseband PDR Finished Product FM Transmitter FM Receiver

32. Communications Baseband PDR FSK Systems  Similar to analog FM systems  Also very complicated

33. Communications Baseband PDR FSK Feasibility Nordic NRF2401 Transmits data at 1Mbps 2.4GHz ISM band

34. Communications Baseband PDR FSK Link Analysis  NRF2401 Specification ○ 0dBm output power ○ -80dBm receiver sensitivity  Link Budget Analysis ○ 60dB of attenuation at 10m (with 0dB antenna gain)

35. Communications Baseband PDR Design Documentation  Schematics  Parts Lists  Specification Documents  Interconnection Control Documents  Test Procedures  Printed Circuit Board  FSK Protocol Information

36. Communications Baseband PDR Time Budget Task Estimated Time in Hours Actual time in Hours Part Research810 Schematic Creation77 Performance Analysis52 Specification Formation85 Parts List87 Timing Information108 Board Layout1215 Board assembly76 Functional Test1312 Integration1520 Tweaking and Repair204 Total113106

37. Communications Baseband PDR Finished Product

38. Communications Baseband PDR PCM and Control Subassembly  Transmit Side  Conversion of Analog to Digital  Apply Protocol to Digital Data  Manage Memory and Data Flow to FSK Chip  Receive Side  Provide Control to FSK Chip  Receive and Manage FSK Chip Data  Control and Send Data to DAC

39. Communications Baseband PDR Interface Specifications  Rail to rail (0-3.3V) analog signal input  Desire >44 kHz Sample Rate  1 Mbps transmit rate to FSK chip  Send samples to Digital to Analog Converter at sample rate

40. Communications Baseband PDR Solutions  PICmicro Microcontroller  Analog Devices DAC  10-bit  No overhead bits  Serial  Up to 20 MHz data rate

41. Communications Baseband PDR Capabilities  PIC offers 10-bit AD  PIC provides I/O ports  USART (Synchronous/Asynchronous Communications), and MSSP (Master Synchronous Serial Port for DAC)  Many I/O Ports for control lines  Provides 1MHz USART  Data storage and management

42. Communications Baseband PDR Chosen Microprocessor  PIC18LF2525  Low voltage at full speed 3.3V @ 32MHz  Internal oscillator up to 32MHz  External interrupts  MSSP  More robust commands

43. Communications Baseband PDR System Diagram

44. Communications Baseband PDR RX FSK-PIC-DAC Interface  Vref = Vdd

45. Communications Baseband PDR Communications Protocol  PIC must manage data from 10-bit samples to exact 1 Mbps output  USART sends 8-bit words and takes care of data rate  The FSK chip offers several protocol options

46. Communications Baseband PDR IN  PIC  OUT  Known: What goes in must come out – and at the same rate.  Therefore: The rate the PIC can sample at is governed by the FSK communications protocol.  Sampling rate must be some integer number of the outgoing packet rate

47. Communications Baseband PDR Protocol Options Protocol TypeFSK Chip Mode SynchronousShockBurst/Direct AsynchronousDirect

48. Communications Baseband PDR Synchronous with Shockburst Option

49. Communications Baseband PDR Asynchronous Option 1

50. Communications Baseband PDR Asynchronous Option 2

51. Communications Baseband PDR Sr. Design I Choice Protocols  Asynchronous – 1 Sample per 2 Frames

52. Communications Baseband PDR Things Not Considered Back Then  The RX FSK chip automatically sends out data in synchronous mode  This makes it more convenient to transmit in synchronous mode because the RX side doesn’t have to eliminate start and stop bits

53. Communications Baseband PDR The Chosen Protocol  Send one AD sample consistently.  Last 6 bits will be meaningless

54. Communications Baseband PDR Timing TX Side  One 10-bit AD conversion takes 14us  USART transmits at 1MHz, 8 bits at a time = 8us  Therefore store one sample ahead of time

55. Communications Baseband PDR Timing RX Side  Receives data at 1MHz  Takes 16us to receive each 10-bit AD sample  MSSP sends data to DAC at 8MHz resulting in no timing issues

56. Communications Baseband PDR

57. FSK Chip Requirements  TX Chip requires a break for 202us every <4ms  202us=13 samples lost every 4ms  TX Chip requires a preamble of ‘01010101’ after each break  Also, the first bit of the second word must be the same as the first bit of the preamble  Solution: send two preambles

58. Communications Baseband PDR Design Issues  Received Preamble is used to synch up RX chip, used as a clock  If RX sampling becomes out of synch with transmitter, it will use the preamble to correct its sampling time

59. Communications Baseband PDR TX Data and RX Data Synch Problem

60. Communications Baseband PDR Solution: Synchronization Word  A 16-bit synchronization word was chosen  Second Problem: How does the RX chip determine when the synch word starts?  RX receiver chip constantly sends a clock to RX PIC  Need to comb through bit by bit to synchronize up with TX words

61. Communications Baseband PDR How to Synch?  Need to make a software shift register  Must use RX receiver chips clock to clock in 1 bit at a time into a register  When input register matches synch word, it knows it is lined up with data words, it starts receiving the USART data

62. Communications Baseband PDR TX Chip and Power Supply

63. Communications Baseband PDR RX Chip and Power Supply

64. Communications Baseband PDR Current Progress FunctionsPercent Complete Microphone Amplifier100 Audio Gain Blocks100 Audio Filter100 AM Transmitter 95 AM Receiver 90 FM Transmitter80 FM Receiver100 FSK Transmitter100 FSK Receiver100 Analog to Digital Conversion100 FSK Transmitter Digital Control100 FSK Transmitter data stream100 FSK Receiver Digital Control100 FSK Receiver Synch Word recognition50

65. Communications Baseband PDR Cost Analysis ItemPrice ($) Board Layout100 FM Transmitter Parts40 FM Receiver Parts30 GFSK Transceiver Parts30 Audio Section parts25 AM Receiver Parts30 AM Transmitter Parts30 PIC Implementations15 Power Supply15 RF Cables30 Misc. Prototype Materials20 Estimated Total365 Actual Cost390 Additional parts110

66. Communications Baseband PDR Future Improvements / Spin-offs  Improve Quality of FM Transmitter  Refine code to make digital transmission more robust (i.e. data encoding, error detection).  Organize systems into student projects, labs, or class curriculums.  Add digital serial transmission using MSSP

67. Communications Baseband PDR  Questions ?