SKA Dishes, SEEG Meeting Cape Town 17-19 September 2013 SKA Dish Verification Antenna #1 – Test Plan Gary Hovey, DVA-1 Project Manger Astronomy Technology

SKA Dishes, SEEG Meeting Cape Town 17-19 September 2013

SKA Dish Verification Antenna #1 – Test Plan

Gary Hovey, DVA-1 Project Manger

Astronomy Technology Program – Penticton

SEEG Meeting, Cape Town19 September 2013


DVA1 Test Plan

• Unit/Sub-assembly Tests• Assembly/Integration Tests• Qualification Tests• Single-dish Tests

• Outline Specification for the DVA-1 Dish(WP2-020-045-020-RS-001)

• DVA-1 Test Requirements for the SKA (WP2-020-030-020-TN-001)

Overview

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DVA1 Test Plan

• Verify components are properly manufactured• Measure performance of units and system.• Compare with Requirements• Check readiness for a subsequent test phase.

• Key performance aspects of DVA1 to be confirmed:– Shape of composite surface(s)– Performance of RIM-supported structure– Performance of foundation and light-weight mount– Performance of Shaped offset-Gregorian-feed-high optics

Test Objectives

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DVA1 Test Plan

• Transitory (Pretty much only one shot at it.)• Chance to understand performance of individual pieces.• Primarily metrology based (Laser tracker / Photogrammetry)• Load/no load tests.• Key components

– Foundation– Mount– Power– Drives– Reflector surfaces

Unit/sub-Assembly Tests

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DVA1 Test Plan

• Tests– Deflections under load– Check for stability and

evidence of rocking

• Equipment required– Laser tracker– Hiab crane– Test load

Foundation

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DVA1 Test Plan

• Control via pendent• Tests

– Safety logic responds as planned– Fail-safe brake and E-stop– Speed and range of motion– No load power usage

• Pre-requisites– AC Power– Cabinet

Basic Drive System

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DVA1 Test Plan

• Tests– Electrical Power lockouts – E-stop and limits switches– Range of motion– Tower deflection vs

moment– Motor torque vs speed– Encoder linearity

• Equipment needed– Basic drive system– Laser tracker– Hiab crane– Tilt meters & Data logger

Mount

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DVA1 Test Plan

• Measure surface– Static shape– Shape changes with

temperature (and perhaps load)

• Equipment– Laser tracker– Photogrammetry

• Other tests– RF reflectivity– Material coupon tests

Reflectors

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DVA1 Test Plan

• Initial Tests– Safety logic and fail safe

brake– Basic motion– Range of motion– Full drive operation

• Tracking• Slewing• logging• Host computer control

• These will be done initially without the feed support and sub-reflector.

Initial Qualification Tests

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DVA1 Test Plan

• Measure changes in shape and position over gravity, temperature, wind, and time– Pedestal– Primary and sub-reflectors– Feed support

Mechanical Performance Tests

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DVA1 Test Plan

• Ku band receiver tests– Adjust feed– Check receiver and backend– Check pointing

RF Qualification Tests

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DVA1 Test Plan

• Holography• Pointing modeling

– Tracking precision repeatability testing• Tipping curves• Antenna radiation patterns and efficiency• System power and dynamic effects over environment.

Single Dish Testing

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DVA1 Test Plan

Pointing Model

The pointing model will continue to be refined and updated. Any evolution of the pointing model will be noted and analyzed.

We are considering using an optical telescope securely mounted in the focal region to use for optical pointing. This is more accurate and can look at dynamic effects.

A source will be tracked at the 3dB point for more accurate measurement of the RF pointing

Tipping curves

Tipping curves will be measured to determine the effect of ground spillover as a function of elevation (and azimuth, depending on the horizon variability). This is a direct measurement of the spillover, and can be useful in looking at various baffle structures. Note that the standard “signal” for tipping curves (the atmosphere) will be removed to leave the residual ground-coupling.

Single Dish Testing

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DVA1 Test Plan 14 of 23


DVA1 Test Plan

Holography• With the inclusion of a small reference antenna and a

prepackaged microwave holography system.

Antenna patterns/efficiency• Wide-angle pattern cuts will be measured (primarily using

satellites) to measure beam-shape and side-lobe structure etc. This will be done at different frequencies (as available) and in the presence of varying solar insolation, wind and elevation.

Power consumption• Drive system can relay motor power and torque, as well as tilt

and gear train torque to host computer.

Single Dish Testing

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DVA1 Test Plan

Polarization • Polarization will be investigated by looking at:

– highly polarized satellite downlinks and mapping dual-linear polarization patterns

– natural sources with reference antenna– Both use a reference antenna + correlator– Mechanically rotate by 90o

Single Dish Testing

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DVA1 Test Plan

• Antenna designed for wide-angle UWB feeds• Could reduce the canonical “5-feed” arrangement to 1,2 or 3• Modeling shows ground-spillover limits Ae/Tsys

– Is there a baffle arrangement to mitigate?• Multiple versions:

– ATA, QSC, Quad-ridge, 11 feed, …• Might make most sense at low frequencies:

– 0.5-5.0, (0.7-1.4), 5-10– 0.5-3.0, (0.7-1.4), 3-6

Wide-band Feed Testing

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DVA1 Test Plan

• Outside scope (for N>2)• Outlined in“DVA-1 Test Requirements for the SKA” WP2-020-

030-020-TN-001. • Use to characterize beam with multiple reference antennas

(closure relations)• Internet based VLBI?• Leave in hooks as possible to use with ST

Interferometric Testing

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DVA1 Test Plan

Sources: Satellites

Ku-band: e.g. DirecTV, DISH

S-band: e.g. XM radio, Sirius

C-band: e.g. Anik, ABS

L-band: GPS, iridium

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DVA1 Test Plan

• We have a holography receiver.• Lynn Baker has designed a Ku band holography feed and is

designing an L-band feed.• Need receivers for other bands• MeerKat receiver would be useful for L-band testing.

Receivers

Backend

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DVA1 Test Plan

• Sep 25 Mount arrives• Oct 25 Begin foundation/mount/drive testing• Nov 4 Back-structure attached to Reflector• Nov 6 Begin reflector unit testing• Nov 13Install reflector on mount• Nov 18 Begin Qualification testing• Dec 3 Secondary and feed support Installed• Dec 20Non RF testing mainly complete

Key reflector and mount performance characteristics known

Schedule/Milestones (Pre-single dish tests)

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DVA1 Test Plan

• Jan 6 Begin RF qualification testing• Jan 20 Being Holography testing• Feb 3 Install and qualify L-band feed (MeerKat)• Feb 17 Begin pointing modeling• Mar 10 Begin measuring tipping curves• Mar 24 Measure antenna pattern and efficiency• Apr 14 Investigate polarization performance• May 2014

Initial DVA1 single dish testing complete

• Summer 2014 Testing of other bands

Schedule/Milestones:RF Single Dish Testing

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DVA1 Test Plan

Questions? Comments?

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Documents

SKA Dishes, SEEG Meeting Cape Town 17-19 September 2013 SKA Dish Verification Antenna #1 – Test Plan Gary Hovey, DVA-1 Project Manger Astronomy Technology