TDWR Antenna Pedestal Operating Requirements For the Market Survey to Replace the TDWR Antenna Pedestal Drive System

TDWR Antenna Pedestal Operating Requirements For the Market Survey to Replace the TDWR Antenna Pedestal Drive System

1.0 Mission Statement

1.1 Intent.  The intent of this document is to define what the TDWR antenna pedestal motor and drive requirements are and what the minimum expectations are of a replacement antenna pedestal motor and drive system.  This document is also intended to provide enough information for a prospective company/vendor to decide whether or not they may be capable of providing a replacement antenna pedestal motor and drive system within the confines of the present environment.

1.2 Expectations.  The replacement pedestal motor and drive system will be expected to meet or exceed the specifications and capabilities of the present pedestal drive system.  The replacement pedestal motor and drive system will be designed around a brushless drive motor/tachometer system to minimize maintenance and to increase the reliability of the TDWR antenna pedestal.

1.3 Facilities.  The numbers of TDWR facilities that are requiring this antenna pedestal motor and drive system retrofit are 47.  Spare parts will be required for each facility and spared parts will also need to be located at the central depot located in Oklahoma City.

The TDWR antenna tower heights vary in 5-meter increments and range from 5 meters to 30 meters in height.

1.4 Mission of TDWR

1.4.1 Primary Mission of TDWR.  The primary mission of the TDWR is to enhance the safety of air travel through the timely detection and reporting of hazardous wind shear in and near the terminal approach and departure zones of an airport.  Specific sources of the hazardous wind shear that are to be detected are microbursts and gust fonts.

1.4.2 Secondary Mission.  The secondary mission of the TDWR is to improve the management of air traffic in the terminal area through the forecast of gust front induced wind shifts at the airport, detection of precipitation and reporting of storm motion.

1.4.3 Operational Environment.  The TDWR is deployed at an unmanned location, visited only for preventive and corrective maintenance.  As such, the TDWR is expected to meet full functional requirements in all operational modes as an unattended system.  TDWR operates 24 hours a day, 7 days a week, except when shut down for corrective or preventive maintenance.  Operator interaction is from the FAA Remote Maintenance Monitoring Subsystem (RMMS).  Routine measurements and adjustments are accomplished remotely through the Remote Monitoring System (RMS).  Local control is through the Maintenance Data Terminal (MDT), also via the RMS.  In the event of a failure, Built-In-Test Equipment and Built-In-Tests (BITE/BIT) will be used to identify the probable location of the fault and report the probable location of the fault to the RMS MDT so that a maintenance specialist can bring the appropriate Line Replaceable Units (LRUs) to the site.  The same BITE/BIT used to identify a fault will also be used to verify the system repair.  Defective LRUs will be sent to a central Government depot for repair.  Additionally, the RMS controls the execution of certification tests to validate that a system is ready to be returned to operational status.

2.0 Requirements

2.1 Contents.  This document contains specifications of the current TDWR antenna pedestal drive system.  Titles to reference documentation to these specifications can be found in the Applicable Documents section at the end of this document.  Contained within the current requirements stated here are also modifications to the existing system that are necessary to obtain a better performing system.

2.2 Performance Requirements

2.2.1 Antenna Pedestal Positioning Resolution.  The resolutions of the antenna pedestal position measurements are 0.012 degrees or better.

2.2.2 Antenna Pedestal Position Repeatability.  The antenna pedestal positioning response to an angle input command is repeatable to within +/- 0.024 degrees of any previous identical angle input command.

2.2.3 Antenna Pedestal Elevation Drive.  The pedestal elevation drive has a controllable velocity of 0 to 15 degrees per second in steps no greater than 1 degree per second with an accuracy +/- 0.5 degrees per second.  The elevation drive positions and holds the antenna with +/- 0.05 degrees of the selected elevation angle when commanded.

2.2.4 Antenna Pedestal Azimuth Drive.  The pedestal azimuth drive shall have a controllable velocity of 0 to 30 degrees per second in steps no greater than 1 degree per second with an accuracy of +/- 0.5 degrees per second.  The azimuth drive positions and holds the antenna within +/- 0.05 degrees of the selected azimuth angle when commanded.  In normal operation, antenna rotation is in the clockwise direction.

2.2.5 Acceleration/Deceleration.  Both the elevation and azimuth drives are capable of accelerating and decelerating the specified antenna load from 0 degrees per second squared to 15 degrees per second squared maximum about their respective axis.  Acceleration of the elevation and azimuth drives is controllable to the thousandth of a degree per second squared.

2.3 Physical Requirements

2.3.1 Antenna Pedestal Drive Limits.  The pedestal shall operate using all the TDWR scanning strategies.  These strategies include 360-degree azimuth scans in either direction, sector scans, and Range Height Indicator (RHI) scans from -1 to +60 degrees in elevation.

2.3.2 Duty Cycle.  The pedestal shall have a 100 percent duty cycle 24 hours per day for 20 years.  The pedestal shall operate continuously with any or all of the scan strategies in the scan strategy algorithm.

2.3.4 Power Fail.  In the event of the unexpected loss of prime electrical power or in the event of servo drive failure, the moving pedestal shall be brought to a safe stop within 6 degrees for the elevation axis without the moving structures (including motors, etc.) or the pedestal drive electronics sustaining any damage.

2.3.5 Antenna Braking System.  There is no requirement for motor braking.  Motor brakes shall not be included in the servo motor design.  Electrical limits, mechanical stops, and hydraulic buffers are currently provided to prevent damage to the antenna and its support structure.

3.0 Maintenance Requirements

3.1 Periodic Maintenance.   The antenna pedestal motors will be maintained in accordance with manufacturers' recommendations.  It is expected that drive motor periodic maintenance will consist of listening for worn or deteriorating bearings only.  Based upon the bearing life determined by the manufacturer, motors will be periodically changed at scheduled intervals to prevent unscheduled outages of the TDWR system.  There will be no other periodic maintenance.
faaco.faa.gov/.../TDWR_Antenna_Requirements.doc - Estados Unidos

Maria Gabriela Medina Maldonado

C.I. 16779553

CRF