National Weather ServiceNational Weather ServiceROC WSR-88DROC WSR-88D

Radar Pedestal SimulatorRadar Pedestal Simulatorforfor

Capt. Colin JohnstonCapt. Colin Johnston

Group 1A

Patrick Macklin - Project Manager

Jeff Myers - Financial Officer

Osama Alkhouli - Configuration Manager

Ryan Jones - Correspondent

Project Problem Statementfor

The National Weather Service Radar Operations Center Captain Colin M. Johnston

• The goal of the WSR-88D Capstone Project is to implement a higher order model to more closely simulate actual radar movement, velocity and acceleration and still return data packets to the command module at the required frequency.

Project Compliance

• 2nd order simulation of radar movement

– Both Elevation and Azimuth

– Meets Specifications

• Rise Time < 1 second

• Settle Time < 2 seconds

• Steady State error < 5%

– Accommodates physical limitation of radar dish

• Maximum speed ± 6 rad/s ≈ ± 36°/second

• Elevation Range -2° to + 60°

– Elevation hard stops eventually cause errors

MAINControl Loop

Functional Block Diagram

RDAData Acquisition

Computer

XMITTransmission

Subroutine

SCIRSerial

CommunicationsInterrupt Routine

PARITY FORMAT

CALCCalculationController

R_TO_PRate Interpreter

SIMRate and Position

Calculations

Simulator Development Steps

• 8th order transfer function

• 2nd order system• State Space

Representation– Position– Speed

• Discrete system– Sampling time 45

ms

1 .00045 0( )

0.1089 0.9718 0.1089

( 1) ( 1)

( 1) ( 1)d n

n n

n n

1 .00045 0( )

0.0908 0.9761 0.0908

( 1) ( )

( 1) ( )d n

n n

n n

Simulation Model Structure

• 16-bit• 16-by-16 bit multiplication• Unsigned subtraction

TTω2

1-2ξTω

Rate response

Position response

+

-Input

Position Command

Z-1

Σ

Z-1

Σ Σ

Current Rate

System PerformanceAzimuth Step Response

System Response to 22.5 Degree StepRed – PedSim response from MicrocontrollerBlue – 2nd order model response simulated in MatLabGreen – 8th order model response simulated in MatLab

System PerformanceElevation Step Response

System Response to 22.5 Degree StepRed – PedSim response from MicrocontrollerBlue – 2nd order model response simulated in MatLabGreen – 8th order model response simulated in MatLab

System PerformanceAzimuth Ramp Response

Position and Rate

0

5

10

15

20

25

Time

Deg

rees

RateCommand(degrees)

PositionResponse(degrees)

RateResponse(degrees/second)

Expenses

Budgeted Actual

Processor $200 $73.50

PLCC IC Extractors $30.00

$3.95

DB9M-DB9F $4.49

Shipping $20.00 $31.95

Total $250 $113.89

Labor Cost

• Actual hours worked – 353.5• Budget Hours - 312

Labor Cost

• Estimated 194 Total Man Hours

– Total labor cost - $9490• For weekly breakdown of hrs worked refer to

Table 1- Team 1A Budget

The Test Environment

Simulation EnvironmentIssues

• Latency in the Labview VI

• Elevation rate command issues