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Predmore Associates

Stellar Solutions to Your Technical Problems

Read Predmore, Ph.D.

413-549-8554

Amherst, Massachusetts

predmore@PredmoreAssociates.com

 

 

Service Areas

Dr. Read Predmore of Predmore Associates is available as an independent consultant or temporary member of a design or project team for universities, manufacturers and design firms. He has more than 30 years of experience in the development and implementation of low-noise millimeter wave receiver and radiometer systems. He is uniquely qualified to manage the design, fabrication and implementation of millimeter systems for communication, remote sensing and radio astronomy applications.

Results of Dr. Predmore’s work include: recommendations, specifications, engineering drawings, reports and custom software. He works primarily in the East Coast of the United States and is available for short-term projects that include travel anywhere in the United States including Hawaii, Western Europe and Japan.

Predmore Associates provides services in the following areas:

Millimeter-wave Antenna and Optics

Antenna Optics

Design, evaluate and measure the optics for microwave and millimeter-wave parabolic antennas. These include primary focus systems and antennas with either Cassegrain or Gregorian secondary reflectors. Perform field-of-view (FOV) calculations in the focal plane. Specify the required surface accuracy and optical alignment tolerance to meet the system performance versus frequency.

Quasioptical Design

Experienced in the design of multiple-element quasioptical systems including focusing mirrors, image sideband rejection, beam splitting, polarization selection components and feed horns.

Case Study: Redesign of millimeter-optics

Dr. Alan Parrish of the Five College Radio Astronomy Observatory (FCRAO) at the University of Massachusetts and Dr. Philip Solomon of the SUNY Stony Brook Stratospheric Research Program required redesign of the millimeter-wave optics for their chlorine monoxide (Cl-O) spectrometer. Chlorine monoxide can destroy the protective ozone layer in earth’s upper atmosphere and is being monitored by spectrometers in Hawaii and Antarctica.

The spectrometer, which operates at 278 GHz, is being used to monitor the upper stratosphere for chlorine monoxide. It is being redesigned to incorporate newer receiver electronics. Some of the elements involved in the redesign are:

  • Simplifying the optics within the vacuum Dewar from four optical elements to none

  • Orienting the output beam at Brewster’s angle to minimize reflections at the vacuum Dewar interface

  • Minimizing the size of the beam at the vacuum Dewar interface to decrease the cryogenic cooling required

  • Fitting the new optics within the volume of the existing optics

  • Preserving the orientation, position and size of the output Gaussian beam to interface with the existing calibration system

The outcomes of this work include:

  • Diagrams of the Gaussian Beam size as it progresses through the optical elements

  • Design parameters for the new ellipsoidal mirrors

  • Engineering drawings for the new ellipsoidal mirrors, which will be used to machine the mirrors

  • Recommendations for the new feed horn

  • Final report on the new optics with a summary of design parameters, calculations and drawings

 

Millimeter-wave Systems

Millimeter-wave Receivers

Design and implement millimeter-wave receivers for communications, remote sensing, and radio astronomy applications. Experienced in the design of heterodyne receiver electronics, both at ambient temperature and cryogenically cooled. Have designed IF processing modules and signal processing systems such as digital correlators and acousto-optical spectrometers (AOS).

Millimeter-wave Radiometers

Evaluate, design and fabricate radiometers for remote sensing and radio astronomy applications. Uses include atmospheric and earth remote sensing from the ground, air and space. Radio astronomy applications include continuum and polarization radiometers .

 

Cryogenic Electronics

Design and implement cryogenically cooled microwave and millimeter-wave receivers, including:

  • Vacuum container design

  • DC & RF feedthroughs

  • Microwave and millimeter-wave vacuum windows from materials such as fused-silica and Teflon

  • Heat radiation shielding

  • Conductive and radiative isolation of low-temperature stages

  • Heat loss calculations for:

    • Coaxial cables

    • Conductive heat load via mechanical structures

    • Radiative heat loading

  • Minimization of radiative heat loads with proper material selection and treatment

  • Choosing high thermal conductivity materials for optimally cooling microwave and millimeter-wave components

 

Precision Metrology

As Chief Metrologist for the Large Millimeter Telescope (LMT), Dr. Predmore was responsible for the overall optical alignment error budget, which included the primary surface panels, secondary reflector, and alignment criteria for the optical elements when subjected to deformation due to gravity, temperature and wind. Dr. Predmore evaluated and recommended various laser metrology systems including the laser ranging system developed for the National Radio Astronomy Observatory’s Green Bank Telescope (GBT), commercial laser trackers, and the LM5 laser measurement system from Automated Precision, Inc. (API). In addition, Dr. Predmore was responsible for the metrology of the LMT surface panels.

Case Study: Metrology of LMT Surface Panels

There are 180 panels required for the LMT 50 meter (165 ft.) diameter parabolic surface. Each panel is about 3 by 5 meters (10 by 16 ft.) and needs to be manufactured with a root-mean-square (rms) surface error of around 15 microns (0.0006 inches). The LMT Project was responsible for providing the panel metrology system. Some of the elements in specifying and selecting this equipment were:

  • Developing LMT panel metrology requirements

  • Researching, investigating and selecting the panel metrology option

  • Developing the environmental control requirements

  • Developing the bid package including requirements, specifications and test procedures

  • Project management

The outcomes of this work were:

  • Specifications for special test artifacts for the LMT Panel Metrology system

  • Environmental control conditions for the metrology process

  • Specifications for environmental monitoring sensors

  • Performance of factory acceptance tests

  • Specifications for software requirements and interfaces between software modules

  • Development of surface fitting software

  • Required metrology procedures including the measurement of the interfaces between the panels and the telescope surface structure


Project Management

Predmore Associates provides project management of technical projects from inception through prototyping to production. Benefits of Dr. Predmore’s project management experience include:

  • Creating spirited and enthusiastic project teams

  • Effectively developing short-term and long-term goals

  • Organizing project structure and establishing time lines and accurate costs

  • Excellent communication, including the ability to give and receive feedback

Project Management Stages

Development of System Requirements

Project management begins with system requirements such as bandwidth of a communication system, Signal-to-Noise-Ratio (S/N or SNR), frequency band and market (for one of a kind or consumer products).

Define System and Component Interfaces and Block Diagrams

Develop Project Plan

Project planning includes capital and personnel resources budgets as well as space and equipment requirements. The project plan will include an estimated timeline and total cost for the project. These estimates will be refined as the project develops and the final system is clarified.

Project Meetings

Effective project management requires regular team meetings (weekly or more often when appropriate) to communicate progress, reveal problem areas and achieve weekly and long-term goals to accomplish final objectives.

Project Management Tools

To foster communication within the project team as well as with management and production personnel, we work with project management tools. Depending on project requirements, we will use Work Breakdown Structures (WBS), PERT and Gantt charts as well as Microsoft Project.


Technical Software

Dr. Predmore has both his undergraduate and Ph. D. degrees in Physics as well as 40 years experience in applied mathematics and technical programming. In addition to 18 years of programming in C, he has three years experience in applying MATLAB to technical problems. Very experienced in regression and optimization techniques for both linear and non-linear systems, Dr. Predmore is also skilled at multiple linear regression analysis for fitting or modeling of experimental data. In addition to knowledge of curve and surface fitting, he is experienced with Fourier analysis, which can be applied to numerous areas such as vibration of structures, digital signal processing and spatial frequency analysis of surface errors.

Dr. Predmore’s imagination, practical experience and technical expertise allow him to apply mathematical techniques across disciplines. For example, he has applied mathematical modeling techniques from computer graphics to the background characterization problem for a millimeter-wave imaging system. Due to his mathematical curiosity, Dr. Predmore is constantly learning new mathematical techniques.

Some examples of technical software that Dr. Predmore has written are:

  • Design of all-pass network for sideband rejection using the simulated annealing optimization technique
  • Correction of STARRS ocean salinity measurements for the effect of astronomical emission from our galaxy
  • Metrology software for the Large Millimeter Telescope (LMT) parabolic surface panels. This software finds the best fit to the desired segment of a parabola and gives the panel surface error as a function of spatial wavelength
  • Multilateration data analysis software for a system of precision tracking laser interferometers
  • Stability characterization of an acousto-optical spectrometer system using the Allan variance analysis technique
 

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