ENEE 498c---Fall 2003

1. ENEE 498c---Fall 2003 Project Description: RF Range Finder

2. System Description • Function • Measure the distance between two identical units. • Two operation modes: “Measure” (M) and “Broadcast” (B) • An unique code for each unit; the M unit can be set to look for a specific B unit. • Specifications • 1 m resolution • 255 m range • 1 m ≡ 3.3 nsec (3.3e-9 sec*3e8 m/sec≈1 m) => clock frequency=1/3.3 nsec=300 MHz • 255 m ≡ 8 bits, binary: 8-bit counter

3. System Description: Block Diagram • Control parameters: • Unit’s self ID • Target unit ID if in M mode • Seeker unit ID if in B mode • Operation mode • Calculator: The PIC16F62X • Distance indicator: 7-segment display

4. System Description: Logic Design Signals present on the board: - B / M: “broadcast / measure”. B’=M - TE: “transmit enable” - TRV: “transmission received valid” - S : “send” (for unit in M mode) - C / CS: “count / count stop” TE = (B•TRV) + (M•S) CS = M•TRV C = M•S

5. System Description: Timing C S TEM RF to air RF received TRVB ↑ TRVM ↑ RF received RF to air TEB Board delay CS RX/TX chip and antenna delay Distance delay: Valid for measurement Calibrationrequired: Build-in a delay subtraction after calibration measurements.

6. RF Components • Transmitter: LINX RXD-433-KH • Relevant features: • TE “Transmission Enable” pin • Address pins to give unit unique ID code • Receiver: LINX TXE-433-KH • TRV: “Valid transmission received” pin • Address pins to set the code of the unit to “listen” for • Antenna: LINX planar antennas • On-board integration information: Available in application notes