Mobile Coherent Doppler LIDAR: Proposed Technologies for

Scanning, Security and Wireless CommunicationsGSFC at GISS

Motivation: The use of Coherent Doppler LIDAR (CDL) for wind sensing

applications has been increasing over the past few years.

CDL are used for:1. Wind energy operations2. Wind shear3. Weather predictions4. Urban environmental forecasting

Current CDL have a high cost - this design is an all-fiber based CDL using a 1.5µm laser to reduce its cost and increase its reliability for various environmental conditions.

Measure aerosol concentration and wind velocities while being

eye-safe, autonomous, low-cost and portable.System Configuration:

System Overview:

Laser Source:

CW Laser source is used to produce the local oscillator and to seed an optical amplifier

Acousto-Optic Modulator/RF Circuit Driver/Optical Amplifier:

Electronic circuits drive the AOMs producing a train of 200 ns pulses shifted in frequency by 84 MHz and at a rep rate of 20 kHz.

These laser pulses are amplified and then transmitted through an optical circulator.

Optical Circulator:

Directs outgoing or incoming signal.

Heterodyne Detector:

Local oscillator and backscattered signals are mixed through an optical coupler.

A/D FPGA:

Analog to digital converter card which is equipped with an on-board field programmable gate array to allow for real time signal processing.

PC/Signal Processing:

Processes data using Matlab software.

Coherent Doppler LIDAR configuration at City College Of New York in research vehicle.

System Data:

Direct LIDAR data:

Coherent Doppler LIDAR data:

Security/Communications:

Goals:

Devise a way to enable remote data transfer.

Monitor temperature, A/C power supply; to prevent theft and vandalism.

Solutions:

Wireless Ethernet Bridge can send and receive data up to 4 miles (line of sight) at speeds of 300 mbps while

Monitors temperature, A/C power failure. And unauthorized entry.

Alarm system sends text messages, e-mails and app alerts.

Automated Scanner:

Goal:

To develop an instrument that can provide a 3-D model of wind velocity and aerosol volume.

Solution:

Rotary actuator will provide horizontal movement.

Rotary motor will provide vertical movement.

Will be able to create a 3-D conical model of aerosol path and volume.

A/C Power, Communication, and Alarm System Diagram

Range corrected returns vs. time for the direct LIDAR system

Signal intensity vs. time for coherent Doppler LIDAR system

Vertical Wind velocity vs. time for coherent Doppler LIDAR system

Scanner Calculations:

Where I is max permissible torque; m is the mass of the object; and r is the radius)

Maximum angular acceleration:

Where α is angular acceleration; T is the max permissible torque; and I is the moment of inertia Maximum angular acceleration is 3.29 rad/sec2

Minimum time required to turn 45o:

Where t is time; θ is the angle; and α angular acceleration.

Minimum required time to move 45o is 0.69 seconds.

Conclusion/Future Work:

The wireless Ethernet bridge will be installed to provide: I. Remote access to the Coherent Doppler LIDAR system.II. Transmit data from the mobile research lab to the host computer in

the optical remote sensing lab in City College.III. Enable communication for the alarm system.

The alarm system will be installed to provide monitoring of:I. TemperatureII. A/C power failureIII. Unauthorized entry

The scanner is currently being designed using two motors with controllers, and two six inch mirrors.

The scanner will be synchronized with the Coherent Doppler LIDAR system using MATLAB to send the commands to the controller serially.

To represent the horizontal wind speed the motor controller and signal pre-processor will be synchronized to sample the atmosphere at three different angles; zenith and +/- 20o from zenith.

Acknowledgements:

This internship was supported by City College; National Oceanic and Atmospheric Administration- Cooperative Remote Sensing Science and Technology Center (NOAA-CREST); NASA Curriculum Improvements Partnership Award for the Integration of Research (NASA CIPAIR);NASA New York City Research Initiative (NYCRI); and NASA Goddard Institute for Scientific Studies (NASA-GISS). I would also like to thank Miguel Lopez Ph. D. student, Dr. Mark Arend, and Dr. Fred Moshary for their support and guidance. I would also like to thank the staff at Hostos Community College who nominated me and worked hard so that I could receive this internship.

I

T

2mrI

2

t

Object Mass (Kg) Radius (m) Moment of Inertia (Kg*m2)First T-pipe 9.07185 0.123825 0.139095325Second T-pipe 9.07185 0.32385 0.951444946First mirror 1.13 0.0762 0.006561277Second mirror 1.13 0.32385 0.118513069Base 13.5 0.4572 2.82192984First mirror holder 4.82 0.0889 0.038093472Second mirror holder 4.82 0.32385 0.505515924Second motor 2.26796 0.3302 0.247280305Window 1.13 0.32385 0.118513069Window holder 2.13 0.32385 0.223391892First pipe cover 2.8 0.123825 0.042931366Second motor holder 0.4104 0.4318 0.076519589Connector ring 0.907185 0.0381 0.001316879Counter balance 53.189245 0.4318 9.917200685Total 106.37849 15.20830764Max torque (N*m) 50

Proposed Scanner Diagram

Kane Vinson, Miguel Lopez Ph.D. Student, Dr. Mark Arend, Dr. Fred Moshary