1.  **Mission Statement**

1.1 [Intent]{.underline}. 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]{.underline}. 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]{.underline}. 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.

4.  [Mission of TDWR]{.underline}

1.4.1 [Primary Mission of TDWR]{.underline}. 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]{.underline}. 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]{.underline}. 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]{.underline}. 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]{.underline}

2.2.1 [Antenna Pedestal Positioning Resolution]{.underline}. The
resolutions of the antenna pedestal position measurements are 0.012
degrees or better.

2.2.2 [Antenna Pedestal Position Repeatability]{.underline}. 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]{.underline}. 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]{.underline}. 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]{.underline}. 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]{.underline}

2.3.1 [Antenna Pedestal Drive Limits]{.underline}. 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]{.underline}. 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.]{.underline} 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]{.underline}. 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]{.underline}**.** 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.

# 4.0 Functional Characteristics

Table 4-1. Functional Characteristics of the antenna pedestal system.

+----------------------+-----------------------------------------------+
| Pedestal Assembly    |                                               |
+----------------------+-----------------------------------------------+
| Type                 | Elevation over azimuth axis                   |
+----------------------+-----------------------------------------------+
| Size                 | Height: 133 in. with maintenance platform     |
|                      |                                               |
| Reflector Assembly   | Width: 84 in. with counterweights.            |
|                      |                                               |
| Construction         | Base diameter: 42.5 in.                       |
|                      |                                               |
| Rotation             | Weight: 10,000 lb. (approx) with              |
| Calculations         | counterweights                                |
|                      |                                               |
|                      | Counterweights: 4,000 lb. (approx)            |
|                      |                                               |
|                      | Type: Parabolic reflector, center fed         |
|                      |                                               |
|                      | Diameter: 25 ft.                              |
|                      |                                               |
|                      | Focal Length: 11.25 ft.                       |
|                      |                                               |
|                      | Surface accuracy: 0.025 in. RMS maximum       |
|                      |                                               |
|                      | Weight: 2500 lb. (approx)                     |
|                      |                                               |
|                      | 16 pie-shaped aluminum panels bolted to       |
|                      | aluminum trusses                              |
|                      |                                               |
|                      | 1\. Azimuth mass: Approx 9500 lbs. (4310 kg)  |
|                      |                                               |
|                      | (Includes the Elevation mass + approx ½ the   |
|                      | weight of                                     |
|                      |                                               |
|                      | the pedestal)                                 |
|                      |                                               |
|                      | 2\. The elevation mass: Approx. 7100 lbs.     |
|                      | (3221 kg)                                     |
|                      |                                               |
|                      | (Includes the Reflector + Yokes +             |
|                      | Counterweights)                               |
|                      |                                               |
|                      | 3\. Elevation section is balanced (reflector  |
|                      | to counterweights) to within 40 lbs.          |
+----------------------+-----------------------------------------------+
| Pedestal Drive       | Bull and pinion gear ratio on each axis       |
| Gearing              |                                               |
|                      | Azimuth drive ratio: 629:1                    |
|                      |                                               |
|                      | Elevation drive ratio: 1167:1                 |
+----------------------+-----------------------------------------------+
| Drive motor          | 1\. See TDWR Motor Sizing Documentation,      |
|                      | Revision 2, and dated 29 January 2008 for     |
|                      | motor sizing criteria.                        |
|                      |                                               |
|                      | 2\. Requires a back shaft hand-crank          |
|                      | capability. Hand-crank is maintained separate |
|                      | from motor when not in use. See Figure 1 for  |
|                      | detailed requirements.                        |
|                      |                                               |
|                      | 3\. Requires 2-pole resolver feedback for     |
|                      | motor velocity data.                          |
|                      |                                               |
|                      | 4\. Requires that the motor length be no      |
|                      | greater than 13.25 inches.                    |
|                      |                                               |
|                      | 5\. Requires that the motor technology used   |
|                      | to be brushless.                              |
|                      |                                               |
|                      | 6\. Requires that the motor output shaft      |
|                      | comply with Figure 2.                         |
+----------------------+-----------------------------------------------+
| Drive motor control  | Continuous in azimuth: 30 degrees/sec max     |
| scan                 |                                               |
|                      | Elevation: -1.0 to +60 degrees, 15            |
|                      | degrees/sec max                               |
|                      |                                               |
|                      | Limit switches: -2 degrees and +63 degrees    |
|                      |                                               |
|                      | Hydraulic dampers: -2 and +63 degrees         |
|                      |                                               |
|                      | Position feedback, gear driven, dual-speed    |
|                      | synchros                                      |
|                      |                                               |
|                      | each axis: 1X and 28.125X                     |
+----------------------+-----------------------------------------------+
| Positioning accuracy | Static pointing, within 0.05 degrees          |
|                      |                                               |
|                      | Repeatability deviation, less than 0.024      |
|                      | degrees                                       |
+----------------------+-----------------------------------------------+
| Power input          | 208 V, 3 phase, 60 Hz delta with ground       |
+----------------------+-----------------------------------------------+
| Motor Drive          | 1\. Inrush current at turn-on must be no      |
| Amplifier            | greater than 110 Amperes per drive on any     |
|                      | phase, and shall last no longer than 16       |
|                      | milliseconds.                                 |
|                      |                                               |
|                      | 2\. Drive system provides a minimum of two    |
|                      | programmable bipolar analog outputs using, as |
|                      | a minimum, a 12-bit D/A Converter. One analog |
|                      | output must provide a simulated motor         |
|                      | tachometer output (+/- 10 VDC @ +/- 3200      |
|                      | RPM).                                         |
|                      |                                               |
|                      | The second analog output must be configured   |
|                      | to represent actual motor current (scalable). |
|                      |                                               |
|                      | 3\. Required to accept external rate commands |
|                      | from external controller (+/- 10 VDC) with    |
|                      | adjustable scaling.                           |
|                      |                                               |
|                      | 4\. Drive system capable of providing a       |
|                      | simulated TTL quadrature encoder output for   |
|                      | diagnostics and integration.                  |
|                      |                                               |
|                      | 5\. Drive system provides a serial port for   |
|                      | access to drive software package.             |
|                      |                                               |
|                      | 6\. Software package to have oscilloscope     |
|                      | functionality capable of measuring (a).       |
|                      | Actual position. (b) Commanded position. (c). |
|                      | Actual velocity. (d) Commanded velocity. (e)  |
|                      | Actual current. (f) commanded current. (g)    |
|                      | Internal bus voltage.                         |
|                      |                                               |
|                      | 7\. Drive system capable of running closed    |
|                      | loop operation of both position and velocity  |
|                      | modes (utilized during diagnostics and        |
|                      | integration).                                 |
|                      |                                               |
|                      | 8\. Drive system must be capable of operation |
|                      | in torque mode (normal operation in this      |
|                      | application).                                 |
+----------------------+-----------------------------------------------+

Table 4-2. Environmental Characteristics of the antenna pedestal

and its drive system (SCU).

+----------------------+-----------------------------------------------+
| ####                 |                                               |
| # Servo Control Unit |                                               |
+----------------------+-----------------------------------------------+
| Operating            | 0 degrees C to +50 degrees C                  |
| Temperature          |                                               |
+----------------------+-----------------------------------------------+
| Storage Temperature  | -50 degrees C to +70 degrees C                |
+----------------------+-----------------------------------------------+
| Humidity             |                                               |
+----------------------+-----------------------------------------------+
| Non-operating        | 5 to 90%                                      |
+----------------------+-----------------------------------------------+
| Operating            | Up to 100%                                    |
+----------------------+-----------------------------------------------+
| ##### Motors         | Will be located in an enclosed aluminum       |
|                      | housing which is rain tight but not sealed    |
|                      | from the environment. The motor must meet all |
|                      | its functional and performance requirements   |
|                      | under the following conditions (for 20 year   |
|                      | life)                                         |
+----------------------+-----------------------------------------------+
| Temperature          | -50 degrees C to +55 degrees C                |
+----------------------+-----------------------------------------------+
| Relative Humidity    | 5% to 100% (above 40 degrees the relative     |
|                      | humidity shall be based upon a dew point of   |
|                      | 40 degrees C)                                 |
+----------------------+-----------------------------------------------+
| Altitude             | 0 to 10,000 ft. above MSL                     |
+----------------------+-----------------------------------------------+
| Fungus               | No fungus nutrients allowed                   |
+----------------------+-----------------------------------------------+
| Non-operating        |                                               |
+----------------------+-----------------------------------------------+
| Temperature          | -50 degrees C to +70 degrees C                |
+----------------------+-----------------------------------------------+
| Humidity             | Up to 100%                                    |
+----------------------+-----------------------------------------------+
| Altitude             | 0 to 50,000 ft above MSL                      |
+----------------------+-----------------------------------------------+
| Requirements for     | All access locations (connectors, caps, and   |
| salt fog             | covers) to motor shall be sealed with         |
|                      | gaskets/o-rings.                              |
+----------------------+-----------------------------------------------+
| Useful Life          | 20 years (with maintenance)                   |
+----------------------+-----------------------------------------------+
| Mounting             | Able to be mounted in any position. Able to   |
|                      | mount on present gearbox. Able to be safely   |
|                      | installed and removed in existing antenna     |
|                      | pedestal housing by one person.               |
+----------------------+-----------------------------------------------+

# 5.0 Physical Hardware Requirements

5.1 [Replacement Antenna Azimuth and Elevation Motors]{.underline}. The
replacement drive motors for the antenna pedestal system shall be
directly compatible with the gear boxes that are currently installed in
the antenna pedestal azimuth and elevation compartments. The drive
motors must be able to be installed into and removed from the antenna
azimuth and elevation drive compartments. The physical size of each
motor that is currently installed within these two compartments is
approx. 13.25 inches in length with a diameter of approx. 4 inches.
Motor mounting flange dimensions are 4.75 inches x 4.75 inches x 0.5
inches. Mounting holes: 4X .406 thru on a 5.500 BC. Custom motor output
shaft keyway. Drive motor connections to be made through D3899/20WE6PN
(Motor Power Connector) and D3899/20WB35PN (Motor Feedback) that
incorporate EMI shielding. Pin arrangements to be defined after
qualification.

5.2 [Servo Control Unit (SCU)]{.underline}. Replacement antenna servo
amplifiers and associated electronics (drives) should be no larger than
15 x 12 x 14 inches (HWD) and weigh no more than 50 pounds on a
per-motor basis. All drive electronics must be capable of operating in
the torque mode and accept analog current command inputs from the
existing TDWR Motion Controller. Servo Amplifier input power connectors
to be made through Mil-style pin contact connectors with a current
rating no less than 115 % of rated input current of the amplifier. Servo
amplifier motor power connectors to be made through Mil-style socket
contact connectors with contact rating sized appropriately to the motor
current requirements. Servo amplifier regen resistor output connectors
to be made through Mil-style socket contact connectors with contact
ratings sized appropriately to the regen resistor current requirements.
All connectors to include EMI shielding.

# 6.0 Reliability

6.1 [MTBF]{.underline}. The antenna pedestal drive system shall achieve,
as a goal, a specified mean-time-between-failure (MTBF) of not less than
10,000 hours in the specified environment.

6.2 [Servo Control Unit (Controlled Environment)]{.underline}.

> Temp (C): 0 to +50

#### Rel. Humidity (%): 5 to 90\*

> Altitude (ft. above sea level) 0 to 10,000
>
> \* Above 40 degrees C, the relative humidity shall be based upon a dew
> point of 40 degrees C.

6.3 [Pedestal Drive (Uncontrolled Environment)]{.underline}.

> [Altitude (ft above sea level)]{.underline} 0 to 10,000
>
> [Rel. Humidity (%)]{.underline} 5 to 100 (above 40 degrees C based on
> a dew point of 40 degrees C).
>
> [Temperature (C)]{.underline} -50 to +70
>
> [Fungus]{.underline} -- The pedestal drive shall be in accordance with
> FAA-G-2100G.
>
> [Salt Fog]{.underline} -- The pedestal drive shall operate in a
> salt-laden atmosphere without degradation of material surfaces or
> performance.

**7.0 Rights to Data**

7.1 The FAA shall be given the rights to use, maintain, modify, and
upgrade the software, hardware and technical data and other
documentation that is supplied and formally delivered by the vendor. FAA
shall be able to share the data with other local, state, federal, and
international government agencies without restriction by the vendor. If
any restrictions apply to sharing of the data with other public or
educational institutions, commercial companies and the like, those
restrictions need to be (1) clearly stated by the vendor and (2) not in
conflict with the preceding requirements. The data and hardware
delivered shall not bear any markings or statements that conflict with
the requirements of this paragraph.

**8.0 [Applicable Documents]{.underline}:**

This document contains requirements as stated in the FAA-E-2806/1, TDWR
System Specification, and last updated 7/25/94. This document also
contains excerpts pertaining to the antenna from the System/Segment
Design Document (S/SDD) G551597 Rev. C dated 11/01/94, and excerpts from
the Prime Item Development Specification Antenna Group CDRL Sequence No.
B003-4 (Type B-1). Further parameters originate from TI 6315.6, Antenna
Group Technical Instruction Book.

![](media/image1.png){width="5.997916666666667in"
height="4.572222222222222in"}

**FIGURE 1**

![](media/image2.png){width="4.679861111111111in"
height="3.9305555555555554in"}

![](media/image3.png){width="4.651388888888889in" height="4.1375in"}

**FIGURE 2**

**9.0 [Abbreviations]{.underline}:**

## A/D Analog-to-Digital

ANT Antenna Control Software (CSCI-8)

ACP Antenna Change Pulse

ARP Antenna Reference Pulse

AZ Azimuth

BIT Built-in Test

BITE Built-in Test Equipment

CDRL Contract Data Requirements List

DEU Digital Electronics Unit

IP Ingress Protection

LRU Line Replaceable Unit

MDT Maintenance Data Terminal

PA Power Amplifier

PSF Program Support Facility

RHI Range Height Indicator

RMS Remote Monitoring System Software (CSCI-3)

SCU Servo Control Unit

S/SDD System/Segment Design Document

TDWR Terminal Doppler Weather Radar