Download Loran C Receiver

Loran-C Receiver
Team Deathstar
September 7, 2004
Capstone Fall 2004
Group Members
Matt Anderson (ECE)
 Chris Birschbach (ECE)
 Christy Corner (EE)
 Matt Hayman (EE)
 Erin Mowbray (ECE)

Background: What is Loran-C?
Loran-C is a navigation system that was
developed by the US Coast Guard.
 The system is comprised of transmission
stations located around the world.
 The Loran-C signal is transmitted from
these stations at specified intervals.
 By measuring the time delay between
transmissions a user can determine their
position relative to the towers.

Loran-C Signal
Loran-C Signal continued

The Loran-C
signal is
transmitted on a
100kHz carrier.
Project Purpose

Our group will design a receiver that will
be able to capture and decode the LoranC signal maintained by the United States
Coast Guard.

Our system will consist of three main
parts: the antenna/receiver, processing
unit and personal computer.
Project Funding

Undergraduate Research Opportunities
Program (UROP) Grant.

Amount: $1750
Tentative Budget
Item
Description
Estimated Price
Processor
MC68HC912B32 assembled
$100.00
LCD Display
$75.00
Additional memory
$50.00
A to D converter
$50.00
Antenna Assembly
$100.00
Receiver Enclosure
$100.00
Printed Circuit Board
$200.00
FPGA
Xilinx FPGA Evaluation Kit
$250.00
Filters
3 Butterworth (8th order)
$75.00
RS-232 Interface
Support Electronics
$25.00
Resistors, Caps, switches, sockets, cables
Power Supply
$150.00
$100.00
Student Designed User Manual
Weighted Paper, Binding, Printing Costs
$150.00
Final Project Display
Printed Poster for Engineering Expo
$100.00
Loran C User Handbook
Misc.
$25.00
(Ink Cartridges, Repair parts, Unforeseen Parts
needed, additional reference manuals)
TOTAL:
$200.00
$1,750.00
Project Objectives
Capture a clean copy of the Loran-C
signal
 Determine Time Delays
 Convert to a Latitudinal & Longitudinal
coordinates.

Outline of Approach

The system will consist of the following
subsystems:
 Antenna
Receiver
 Analog-to-digital converter
 Motorola 68K processor
 Memory
 FPGA
 Serial Interface
 PC
 Power
Subsystems Diagram
Processing Unit
Antenna/
Receiver
A/D
Converter
FPGA
RAM
Processor
PC
Antenna Receiver
Subsystem
The antenna/receiver will consist of a loop
antenna with a active Butterworth filter to
capture and amplify the fundamental
signal received by the antenna.
 This segment of the project serves the
main purpose of capturing the Loran-C
signal with minimal noise and preparing it
for processing.

Analog-to-Digital Converter
Subsystem
The A/D converter will sample the analog
signal.
 Sampling rate will be 1MHz.
 The digital data will be sent to the FPGA .

FPGA Subsystem
The FPGA has a state machine for
detecting the third zero crossing of the
Loran-C signal. (Generates an interrupt)
 It functions as a counter to measure the
delay between pulses.
 It includes an interrupt controller for the
processor.

Processor Subsystem
Upon generation of an interrupt, the
processor stores the counter data from the
FPGA into RAM.
 Performs operations on the counter data
to determine time delays and stores the
delays in RAM.
 The microcontroller sends the time delay
data to the serial interface with the PC.

RAM Subsystem

Holds the time delay and counter data for
processing and transmission.
Serial Interface Subsystem
The communication interface between the
PC and the processor.
 Consists of a serial shift register & RS-232
logic level converter.

PC Subsystem
Displays the time delays.
 Performs intensive conversion calculations
to convert data into Latitudinal and
Longitudinal coordinates.
 Displays the Latitudinal and Longitudinal
coordinates.

Power

Transform, rectify, and regulate voltage
from standard 120V/60Hz outlet to
required DC voltages. (Or purchase
power supply)

Include portable power sources (battery or
car adapter) if time permits
Tasks











Antenna Design
Filtering
PCB design
Memory interface
FPGA design
PC programming
PC interface
A/D interface
Processor programming
Power
Users Manual
Schedule
Division of Labor

Matt A




Chris B






Antenna/Filtering
Verilog Design
User’s Manual
Matt H





PC programming
Microprocessor programming
User’s Manual
Christy C


Power
Memory interface
Microprocessor Programming
Antenna/Filtering
PCB
Microprocessor Programming
PC programming
Erin M



Verilog Design
User’s Manual
PC interface
Risks and Backup

Receiving a clean copy of the signal
(Can generate a fake signal)

Baud rate generation for PC/processor
communication
 Buffer

overflow (Sample slower)
Size and complexity of the state machine.
(Can shift tasks from the FPGA to the processor to
compensate.)

RS-232 Communication on PC
(Manually entering data into the conversion program)
Above and Beyond
If time permits we shall include a LCD
display on our receiver that displays the
Loran-C time delays.
 Portable power sources.
 Cup Holders

Questions and Comments