SENIOR PROJECTS LABORATORY

ECE 4773

Team 5B: Side Lobe Canceller

Micah Nelson Rafael Mendoza Kari Gammons

Michael Lee

• PROJECT• Sidelobe Canceller for a 915 MHz Atmospheric

Radar

• MENTOR(S)• Dr. Bob Palmer• Dr. Tian Yu• Chad Kidder

• OBJECTIVE• Research, design, and build a sidelobe canceller,

SLC, which will receive interference, known as clutter, caused by sidelobes from the LAP-3000 RADAR system

Design Approach

• Design was developed to be compatible with the LAP-3000 radar

• Design of receiver based on the LAP-3000 receiver design

Vaisala LAP-3000 RADAR

• Lower Atmosphere Doppler Wind Profiler

• Used for weather applications

Clutter Screen is Absent

Specs

• Measurement height– Min = 100 m for wind– Min = 100 m for temp– Max = 2 to 5 km for winds– Max = 1 to 2 km for Temp

• Min Vertical Resolution– 60 m for wind– 60 m for temp

• Radar Frequency– 915 MHz

Sidelobes

• Side lobes are part of the radiation pattern from the radar that are not the main beam. The power of the side lobes is normally much less than the power of the main beam of the radar.

http://en.wikipedia.org

Configuration

LAP3000RADAR

RECEIVER

RECEIVERRECEIVER

RECEIVER

ReceiverBox

IndoorBox

DCAC

ANTENNA

60 MHz

855 MHz

60 MHz

855 MHz

I Q I Q

Inside Structure

915 MHz

+ +_ _

100’

15’

IF 60 MHz

System Block Diagram

10 dBm

36 V DC 2 A

Baseband

Receiver Block Diagram

915 MHz

PREAMPLIMITER BANDPASSFILTER

MIXER

AMP

LOCALOSCILLATOR

AMP

BANDPASSFILTER

QUADRATUREDETECTOR

IF/Detector

LOWPASSFILTER

I Q

855 MHz

60 MHz

Baseband

Dual Matched Bessel Filters

60 MHz

LOWPASSFILTER

Recommended

Schedule

Action Items

ACTION WHO DUE DONE

Pick Parts and Specifications Michael/Rafael/Micah 1-Mar  X

Purchase Micah/Michael/Rafael 2-Mar X

Measure Backscatter Kari/Micah/Michael/Rafael 4-Mar X

Measure Signal Strength Kari/Micah/Michael/Rafael 4-Mar X

Measure Power loss in 100 ft. SMA Rafael/Micah/Michael/Kari 10-Mar X 

Prepare Materials Kari 10-Mar X 

Organize Schedule Micah/Kari 10-Mar X 

Construct Circuit Rafael 14-Apr X 

Cost Comparison Analysis

Cost Allowance $3000.00

Initial Target $2500.00

Initial Cost Estimate $2200.00

Final Cost $2239.65

Schedule Comparison Analysis

Estimated Work Hours

Actual Work Hours

Difference %Expended

Kari 186 173 -13 93%

Rafael 243 234 -9 96%

Micah 216 168 -48 78%

Michael 225 246 21 109%

Total Hours 870 821 -49 94%

Recommendations

• Baseband may be amplified as needed• Digital accounting for difference in magnitude of

I and Q output signals may be done• A limiter may need to be added to the design

immediately after the antenna for added protection

• System gain can be reduced to remedy Intermodulation that may occur at higher dBm ranges such as signals greater than -40 dBm

• Variable attenuators may have better results for future use as a replacement for fixed attenuators