Developing Low-Cost Radio Receiver: Competency Demonstration Report

This Competency Demonstration Report (CDR) details a student's project focused on developing a low-cost radio receiver for radio detection finding (RDF) applications. The project aimed to create an efficient and affordable RDF system, utilizing techniques like Time Difference of Arrival (TDOA) and pseudo-Doppler methods. The report outlines the project's background, objectives, and the student's responsibilities, including hardware and software development, testing, and analysis. The student faced challenges in integrating the system with APRS software, which was resolved by manually adding the ToA format. The project successfully developed a TDOA prototype, demonstrating its potential for signal source detection. The report highlights the student's contributions, collaborative efforts, and the innovative use of COTS components and APRS packets for data transmission, providing valuable insights into the design and implementation of a low-cost radio receiver.

Competency Demonstration Report (CDR)
Career Episode 1

CE 1.1: Project Introduction
Name of the Project : Developing Low Cost Design of Receiver for Radio
Detection
Geographical Location : [Please Fill]
Project Duration : [Please Fill]
Organization : [Please Fill]
Position in the Project : Team Member
CE 1.2: Project Background
CE 1.2.1: Characteristics of the Project
With the advancement of technology, RDF (Radio Detection Finding) system by rescue
ad search teams for emergency services and detection of victims, emergency personnel and
ambulances. I have observed that the development of these devices requires complex and
expensive infrastructure. The implementation of RDFN (Radio detection Finding Network)
initially require high cost and complexity in production but developing a miniature system would
results in deceasing the cost issue associated with them. Therefore, I took this particular project
for the development and production of low cost and efficient RDFN system that could allow any
persons to use them if required. In this project I have used the technology of GPS (Global
Positioning System), theory and practical implementation of ToA (Time of Arrival), TDOA
(Time Difference of Arrival) and clock drift for the implementation of the radio detection
receiver.
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CE 1.2.2: Objectives developed for project
The significant drawbacks of the existing system and technologies include the complex
architecture for implementation, high cost in production and complexity in using the system for
tracking and detection. Therefore, I have worked in this project with the significant aim of
developing a simple, low cost and reproductive design of receiver for detecting radio signals. For
the process of implementation, I have initially reviewed the techniques and procedure used for
the existing RDF systems and determined the appropriate process that I have undertaken for
completing this project. Therefore, for ensuring the proper completion and standard in tis
particular project, I have prepared the following objectives:
 To develop the system within the budget limit of $500;
 To use the Detection Finding method of Pseudo Doppler and TDOA for improving
the location accuracy within 1 km;
 To implement the network compatibility of receiver with the Automatic Position
Reporting System (TRPS);
 To compare the efficiency and accuracy of the receiver developed by Pseudo Doppler
and TDOA methods;
 To analyze and obtain the results with respect of APRS packet and COTS timing;
CE 1.2.3: My area of work
While working on this project, I was initially associated myself for investigating the
implementation and development of RDF (Radio Detection Finding) for asset tracking and
public services. I have built two significant receivers and conducted relevant tests for ensuring
the accuracy, practicability and functions of the receiver. In order to provide proof of concept for
COTS (commercial off the shelf) components, I have developed the TDOA (time difference of
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arrival) and RDF based pseudo-Doppler receiver. While developing the pseudo-Doppler receiver
I have implemented large antenna, custom hardware that has increased the error regarding weak
signal and multipath. During the TDOA implementation, I have provided low cost and simple
RDFN and used GPS COTS receiver for obtaining accuracy in time synchronization. For the
implementation of the final radio signal detection receiver, I took the advantages of multiple
detection techniques and TDOA hardware for improving the accuracy and operations of radio
signal detection.
CE 1.2.4: Project Group
Figure 1: Team Members Associated with the Project
CE 1.2.5: My responsibilities throughout the project
I had the responsibility of determining the hardware and software requirement required
for the radio detection receiver. I have configured the hardware element and identified the
software requirement for the accurate identification of the source signal. I took more
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responsibility in conducting various test and analysis for ensuring the accuracy of the developed
prototype. Further, I have compared the two prototype model for providing the appropriate,
feasible, and low cost solution for signal source detection.
CE 1.3: Distinctive Activity
CE 1.3.1: Comprehending the Theory of the project
The sources of radio transmission are located with the assistance of RDF. I have used two
processes for developing the RDF, first with developing the module for receiving the signals and
second the module for characterizing the signal obtained through the receiver. I have designed
the receiver appropriately for receiving and determining the modulation type and frequency of
the signal obtained. While on the other hand, I have used ToA, RSSI (Received Signal Strength
Indicator) and signal detection for characterizing the obtained signals. The processing of the
received signal is essential for determining the accurate location of the signal sources. In the
RDFN, the accurate method of FD is used for detecting the accurate location of source signal.
The calculation and identification of the accurate location are done based on automated computer
applications.
CE 1.3.2: Engineering Knowledge and Skills applied in the project
Since the project was developed in a group, I took the responsibility of developing the
prototype model of TDOA receiver. Before starting the practical work for the implementation, I
have developed the block diagram showing the various hardware element and connection
between them.
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Figure: Block Diagram that I have developed for the TDAO Prototype
I have selected Integrated T3-301 VHF data radio, VHF Data transceiver of Friendcom
FC-301/D 5 watt, GPS module and 12 V batteries that has cost me approximately $400 for
hardware. I have used microcontroller for interfacing between the different hardware elements. I
have integrated and ensured the precision and accuracy of the COTS GPS for TDOA. I have
ensured that the timing accuracy for the developed prototype is lesser than 333ns error. In
addition to that, I have validated individual components based on their specifications. I have used
T3-301 APRS Module for controlling the TDOA. I have used 32-bit Coldfire MCF51JM128
processor for ensuring the digipeater and telemetry functionality. With the application of the
software, I have ensured that TDOA receiver gets activated whenever RX frequency signal is
transmitted.
CE 1.3.3: Accomplishment and Task Performed
After the completion of the receiver prototype model, I have engaged myself with the
analysis of the results obtained from the TDOA prototype. I have initially integrated the
hardware component and ensured proper connectivity between them. For ensuring the proper
functionality and operations of the receiver, I have implemented additional software.
CE 1.3.4: Identified Issues and Their Solutions
Issue: In order to provide accuracy and proper functionality of the TDOA receiver, I have
developed the entire network. I have used FM receiver radio as the base station and connected it
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through the sound card for operating with APRD program. I have selected the AGWTracker for
automatic tracking and plotting of the location in computer screen. The vital issue arose when
AGWTracker could not identify the ToA format of the received signal packet.
Solution: In order to overcome the issue, I have studied various books, journals and
communicated with my assistant professor. Assistant Professor had suggested me to manually
add the ToA format within AGWTracker. With the addition of ToA format, I was able to
automatically locate the signal source without any additional need from the need users.
Furthermore I have used timing accuracy 1 μs for the GPS and determined the accuracy of
location detection to 333m.
CE 1.3.5: Plan for producing creative and innovative work
I have conducted the analysis of the prototype system based on the APRS packets and
COTS (commercial off-the-shelf) Timing for providing creativity within the project. While
conducting the analysis based on the APRS packets, I have ensured that the prototype TDOA
system provides immediate responds to traffic and provides packet information with each
transmission. Through the transmission of the packets, I have provided information regarding the
HDOP value, IRQ counter, ADC value, voltage, temperature of system, and packet ID number. I
have provided accuracy in the timing of the signal based on the firmware used in this project. I
have configured the software in such a way that precision of 1 ms have provided me in achieving
accuracy of 1μs from the GPS data.
CE 1.3.6: Collaborative work
I was working with two other team members for the timely completion of the receiver
integration project. I have followed collaborative approach in selecting the hardware element and
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development the plan for conducting the project. In addition to that I have maintained close
collaboration with the team leader and assistance professor who have guided me throughout the
project.
CE 1.4: Project Review
CE 1.4.1: Project Overview
The developed system with TDOA have provided simple and cost efficient solution for
determining signal source. Further, I have observed that the prototype model of TDOA RDF
have provided efficient functionality in the basic level. Further, the application of software
element has provided practical results to the developed model.
CE 1.4.2: My contribution to work
I have provided the architectural needs and requirement for developing the TDAO
prototype model. I was successful in developing the entire prototype and carried out the
appropriate analysis for ensuring the accuracy and functionality. Further, with the application of
my theories and knowledge in the field of engineer, I was able to obtain success in this project.
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