LoranC Receiver

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Loran-C Receiver

• Team Deathstar
• September 7, 2004

Capstone Fall 2004
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Group Members

• Matt Anderson (ECE)
• Chris Birschbach (ECE)
• Christy Corner (EE)
• Matt Hayman (EE)
• Erin Mowbray (ECE)

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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.

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Loran-C Signal
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Loran-C Signal continued

• The Loran-C signal is transmitted on a 100kHz
  carrier.

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Project Purpose

• Our group will design a receiver that will be
  able to capture and decode the Loran-C signal
  maintained by the United States Coast Guard.
• Our system will consist of three main parts the
  antenna/receiver, processing unit and personal
  computer.

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Project Funding

• Undergraduate Research Opportunities Program
  (UROP) Grant.
• Amount 1750

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Tentative Budget
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Project Objectives

• Capture a clean copy of the Loran-C signal
• Determine Time Delays
• Convert to a Latitudinal Longitudinal
  coordinates.

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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

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Subsystems Diagram
Processing Unit
A/D Converter
Antenna/Receiver
FPGA
PC
Processor
RAM
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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.

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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 .

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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.

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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.

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RAM Subsystem

• Holds the time delay and counter data for
  processing and transmission.

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Serial Interface Subsystem

• The communication interface between the PC and
  the processor.
• Consists of a serial shift register RS-232
  logic level converter.

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PC Subsystem

• Displays the time delays.
• Performs intensive conversion calculations to
  convert data into Latitudinal and Longitudinal
  coordinates.
• Displays the Latitudinal and Longitudinal
  coordinates.

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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

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Tasks

• Antenna Design
• Filtering
• PCB design
• Memory interface
• FPGA design
• PC programming
• PC interface
• A/D interface
• Processor programming
• Power
• Users Manual

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Schedule
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Division of Labor

• Matt A
• Power
• Memory interface
• Microprocessor Programming
• Chris B
• PC programming
• Microprocessor programming
• Users Manual
• Christy C
• Antenna/Filtering
• Verilog Design
• Users Manual
• Matt H
• Antenna/Filtering
• PCB
• Microprocessor Programming
• PC programming
• Erin M
• Verilog Design

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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)

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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

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Questions and Comments