P11210 – WOCCS: RF Test Bench

Michael DeFrancis (CE)Shaheer Khan (EE)

Demetrios Koukouves (ME)Andrew Nosal (EE)

Final Design PresentationFriday, 2/18/10

Project Background

This project is part of the Wireless Open Source / Open Architecture Command and Control System (WOCCS). The project family aims to create a modular system that transmits and receives basic data from a base unit to a remote unit.

Test bench objectives:• Test system level functionality of WOCCS• Capable of interfacing with WOCCS modules

Main deliverables:• Mobile and remote test bench• User manual• Software package & GUIs• Board layout & mechanical drawings for reproduction

Needs and SpecsCN1 High The Test Bench needs to test the system performance.CN4 Medium The Test Procedure needs to be repeatable.CN5 Medium The Test Bench needs to be user friendly.CN6 Medium The Test Bench needs to be mobile.CN7 Low The Test Bench needs to be compatible with future projects.CN8 High The Test Bench needs to be open source and open architecture.CN9 High The Test Bench will function independently of the system.

ES1 CN1 Measurable range for mid range 1 m 10 to 400 0 to 500ES2 CN1 Measurable range for mid range 2 m 10 to 400 0 to 500ES3 CN1 Measurable range for long range m 100 to 4000 0 to 5000

ES4 CN1Measurable Command Data Loss Range % 0.1 to 100 0 to 100

ES5 CN1Measurable Telemetry Data Loss Range % 0.1 to 100 0 to 100

ES6 CN1 Measurable Latency Range s 0.01 to 5 0.001 to 10ES7 CN1 Measurable Data Bandwidth Range kbps 0 to 60 0 to 128

ES8 CN1Measurable Operating Time Range of System hr 0 to 8 0 to 12

ES9 CN2, CN3 User manual and test procedureAverage Score in

% 70 100ES10 CN6, CN9 Test Bench operating time hr 8 12ES11 CN6 Test Bench Weight g 400 300

ES12 CN6 Test Bench Size L x W x H cm7.6 x 12.7 x

12.7 7.6 x 10.2 x

10.2ES13 CN7, CN8 Open Source/Open Architecture Binary Yes Yes

System Architecture

Hardware – Arduino & PCB for Power Testing

• Measures WOCCS system battery voltage and current draw

• Calculates instantaneous system power consumption

• Arduino Uno performs Analog to Digital Conversion, power consumption calculation and USB communication to the PC

PCB Layout

Software – Test Bench Control Station

•GUI automatically detects devices and allows for manual configuration

•Allows the user to upload / download files and perform bandwidth, data loss, and latency tests

•Communicates with WOCCS according to a serial protocol developed by members of each team

Software – Power Meter• Arduino software

streams power calculations over USB

• GUI Reads incoming voltage, current, and power data over the USB serial port and graphs data in real-time

• Toggles between different test modes such as voltage, current and power

Subsystem TestingFor a 222 byte file the calculated bandwidth was 64.571 kbit/s and bandwidth was consistent 9 out of 10 times. We believe there is an issue with how the RF microcontroller calculates bandwidth causing occasional inconsistencies. The data loss test showed a 0% data loss for a file sent over the RF link as expected. To verify that we were correctly calculated data loss, the data was modified after it was received such that it would be 10% incorrect. The data loss test accurately reported a 10% data loss. For a 111 byte file the calculated latency was 182 ms, 204 ms, and 200 ms. For a 202 byte file the latency was 178 ms, 188 ms, and 188 ms. This indicated that the latency test consistently measures latency. The accuracy of the latency test is dependent on accuracy of the time stamps taken on the RF microcontroller.

At the present state, the operating time test is not fully functional due to a complex grounding issue. Under certain, controlled conditions, the operating time test can successfully measure the voltage, current, and power of the WOCCS system and therefore ensure operating time.

Project Successes• Meets majority of specifications• Interfaces with mid range 1 module over USB• Capable of testing of bandwidth, data loss, latency, and range• User manual for testing WOCCS created• Test bench meets a minimum operating time• Mobile• Light weight• Small

Project Failures• Operating time test which includes voltage, current, and power does not

function under all conditions due to a grounding issue• Cannot measure current below 5 mA• Over budget due to an additional PCB order

Budgeting

WOCCS family received $5000.00 from Harris RF

Test bench allocated $500.00 (not including shipping) for base and remote test bench with Arduino microcontrollers, PCBs, enclosure, and software

Total spend by Test Bench team: $538.45

Over budget $38.45 due to need for additional PCBs

Moving Forward/Recommendation

•Triple Check the PCB layout to ensure not only electrical layout, but mechanical tolerances

•Explore designs which would remove the dependency on other devices being designed concurrently

•Redesign the USB communication protocol to allow the transfer of larger files

•Explore possible increase of the data rate over USB

Acknowledgements

• Harris Corporation• Philip Bryan• Leo Farnand• Vince Burolla• Dr. Dorin Patru• Dr. Edward Hensel• Dr. Andreas Savakis• Robert Kraynik