The measured position of a photogrammetric camera star image and its true projected position generally do not coincide, indicating the presence of distortion errors. It has been assumed that the r-sidual errors obtained from the solution for distortion coefficients, showing the uncorrelated random character between star images, reflect operator setting error, or emulsion instability. Recent studies conducted at The Aerospace Corporation on the generic AVIOTAR lens used on the Wild BC-4 ballistic camera indicate that errors which were thought to be wholly random may have systematic components caused by lateral chromatic aberration and image distortion. An analysis of the lens was accomplished using The Aerospace Corporation's Polychromatic Program for the Analysis of General Optical Systems. This analysis provides insight into the effects of lateral chromatic aberration and image orientation versus field angle. Lateral chromatic aberration is significant because it produces a spatial position shift of predominantly low-temperature objects when distortion is calibrated with high-temperature stellar sources. The results of the study indicate that these effects must be included in the calibration procedures and data reduction algorithms to obtain high accuracy position data.
The Optical Evaluation Facility (OEF) at White Sands Missile Range (WSMR) has developed and incorporated various test and analysis methods and procedures. The testing may be as simple as examining a point image or as complex as combining weighted interferogram information of three wavelengths to obtain the "white-light" response of the system being tested. The spectral range for testing components and systems varies from 0.45 to 11.0 microns. The varied hardware and facilities capabilities of the OEF will be discussed. The different testing methods used will be examined in detail. New techniques for testing visible and IR systems will be presented.
A comprehensive Discrimination Flow Field and Sensor Simulation model has been prepared for the Ballistic Missile Defense Advanced Technology Center (BMDATC). This model is composed of software packages assembled from in-depth developmental efforts throughout the ballistic missile defense community. The objectives of the model (or set of models) include the capability to predict radar, optical, and laser signatures of threat objects and their plumes or wakes in the flight regimes of low altitude boost, high altitude boost, orbital midcourse, and reentry. The user-oriented model allows instant system studies to be made while the vast amounts of data, required for the production of discrimination signatures, are manipulated by the BMDATC Advanced Research Center's (ARC's) CDC 7600 computer. Visual impact leading to understanding of the underlying phenomenon of the physical system is immediate as spectacular interactive color displays of the system are presented. This paper details the background of the study and gives results for the optical discrimination problem area. An outline is also presented indicating the techniques employed to calculate line-of-sight radiance levels in a high altitude rocket plume.
White Sands Missile Range (WSMR) has developed an Adaptive Prediction Filter (APE) that provides digital servo control for optical instrumentation tracking mounts when operated in a slaved track mode. The APF is a programmable microprocessor based design utilizing both an 8-bit and a 16-bit microprocessor. A wide variety of serial data input formats can be handled and the APE provides Type 11 servo performance, adaptive servo control, and coordinate conversion for input data in a Cartesian coordinate format. The paper covers the design, theory of operation, and test results of the APE when used with an optical tracking mount.
The effects of atmospheric turbulence on imaging systems, and beam projection systems such as laser designators, can be evaluated and the performance predicted in terms of a properly path-weighted value of the turbulence structure constant, Cn2. An operating system for direct field determination of this weighted value with a portable slit scanning telescope and on-line data reduction minicomputer system will be described. This system utilizes a point laser source located in the vicinity of the target and scans the image of that source from the opposite end of the optical path. The on-line computer system combines data, for the system on test, with the data taken on the atmosphere at the instant of test firing, utilizing Fourier and Abel transform techniques, to provide a prediction of behavior of the system on test, or an evaluation of the effects of the atmosphere on that test. The results can be presented in a variety of forms, including immediate hard copy plots of the MTF of the atmosphere, of the overall system being tested, or plots of predicted radial distribution of intensity on target for the system on test. The slit scanning telescope can track a slowly moving target, with internal optical tracking. A gyro platform is under development which can provide operation from shipboard or other unstable platform.
Transmission and meteorological measurements are taken at both ends of a double-ended overwater transmission path. Three radiometer heads are used in connection with visible and blackbody sources to cover the visible, near, mid-, and far infrared spectrum. Measurement of the meteorological parameters of wind speed and direction, temperature, dew point, pressure and precipitation is accomplished from instrumented towers located adjacent to the source and the receiver sites.
There is a need to provide a photo-optical digitizer system to ascertain quickly and accurately, the information required. Many quantitative measurements must also be recorded, compared, stored, and computed in real time. The best feasible solution is a semi-auto-matic system with an open-end output capability, able to digitize the information. The L-W International 110-C Photo-Optical Digitizer System, the "Informer," could solve the dilema. The system will accept an image from projectors with various aperture formats, television monitors, and hard copy. The Digitizer provides for lengths, areas, angles, frame count, and other various features. After digitizing, data can be transmitted to computer peripherals and major computer systems. The "Informer" has a standard EIA-RS232C or Bit Parallel output interface or optional special interfaces.
A new data reduction method is investigated, based on an efficient spline approximation algorithm. It capitalizes on the natural data compression achieved by the processing of the Fourier-Transform of the raw waveform and the further reduction and computational efficiency obtained by the applied spline approximation technique. As a side merit, we obtain a good noise immunity, since the noise present in the raw wave-form or the Fourier Transform will be averaged out by the smoothing action of the method involved.
The tracking techniques employed by the SUPER RADOT system are enabled through automated control by a large mini-digital computer. The operational mode calibration, error determination, designate, acquisition and track functions are mechanized by a modular software package which is integrated and controlled through mode switch and matrix panels located in a control console. The auto-track functions allow collection of atmosphere limited precision target angular position data. The systematic error content of the vehicle position data is determined through definition of tracker error model coefficients by application of star track error determination techniques. The distribution of star data point residuals after correction model fit indicates systematic error sigmas for azimuth and elevation coordinates of less than ±1.0 arc seconds. Sunlit reentry targets have been detected and acquired by the optical-video sensor and auto-tracked by the video processor at slant ranges in excess of 1000 kilometers.
For those of you who are not familiar with the film or video industry, a fluid head is a device which mounts between a camera and a tripod or dolly. The purpose of the device is to move the camera in panning and tilting; in other words, horizontally, vertically or any combination of horizontal and vertical movements.
Designing an installation of a high resolution encoder (19 to 22 bits) on a radar or optical tracker is a technically demanding job. Unfortunately, many designers treat the installation planning of an encoder as a simple bolt-on job and frequently not enough space is left, or mounting surfaces are provided which are not commensurate with the accuracy of the encoder. A further complicating factor is that many encoders must be mounted on structures that were not originally designed to accept a transducer of such high resolution and accuracy. A poor installation causes a tracking error between the system's boresight axis (optical or radar) and the encoder readout angle. This paper will present a thorough review of the mechanical parameters that must be defined and controlled to properly interface a high resolution encoder. The paper will also discuss maintenance techniques that can be used to lower operating costs and improve operating reliability over the life of the equipment.
This paper reviews the equations which characterize direct detection pulsed laser radar performance and illustrates their use for laser wavelengths in the 0.3 to 1.1 micron spectral region. The dependence of laser radar performance on both atmospheric and hardware parameters is discussed. The atmospheric effects include attenuation, scintillation and beam steering and the primary hardware parameters include laser wave-length and detector type. The attenuation analysis for slant paths includes models for two commonly encountered vertical attenuation coefficient profiles. One model assumes an exponential decrease of the attenuation coefficient with altitude and the other simulates temperature inversion-induced haze layers. The analysis is applicable to terrestrial, airborne and ground-to-space applications. The results are presented in a graphical form which permits rapid performance estimates to be made for a variety of common laser wavelengths and atmospheric conditions.
The theoretical performance of laser ranging systems is easily determined with appropriate analysis and the correct ranging link parameters. Few systems achieve this performance in real ranging situations because of unexpected variations in the link parameters. The practical effects of such parameters as pulse modulation, coherent fading, detection error, atmospheric propagation error and calibration techniques on the accuracy of the range measurement will be discussed.
Laser technology has revolutionized range instrumentation by providing methods for gathering precise real time space position data. Current methods are tedious and susceptible to human error in both the data gathering and the subsequent analyses. This paper will discuss typical range instrumentation requirements with a comparison of solutions provided by laser technology and more conventional means. Concrete examples will be provided with the description of an existing laser system which was used as the principal space position test instrument. A movie will be shown demonstrating laser technology applied to determination of space position of aircraft, rockets, ballistics, rocket sleds and other objects. Also, examples of the data gathered with laser systems will be presented.
The conversion of a Contraves cinetheodolite to provide laser derived range data, angular correction and automatic tracking capabilities is described. A variable pulse rate Neodinium YAG laser provides the quasi TEMoo laser pulses which are used to provide both range and angular tracking error data. The cinetheodolite has been modified to provide direct drive torque motor in both elevation and azimuth optical section axes. A separate followup servo is incorporated to drive the base section which supports the major system electronic assemblies and the operator. A micro-processor is utilized to provide active control of most laser and servo functions. Data obtained during acceptance tests and operation of the system at Edwards AFB is also being presented.
Five precision Mobile Optical Mount Systems (MOMS) are being built for the NASA Goddard Space Flight Center. They will be used for laser ranging to satellites with retroreflectors. The MOMS system consists of a precision servoed mount with a 30-inch aperture receiver telescope and 4-inch aperture Coude mirror transmit optics system with the entire system in a 45-foot long trailer which also houses the main laser in a clean room. Design and test data will be presented for major system parameters including optical characteristics, structural resonances, mount geometry, servo system bandwidth, smoothness and accuracy, and the Coude transmit mirror alignment, and monitoring system.
Laser ranging systems development has played a major role in advancing the tracking of spacecraft, as well as obtaining precise measurements for scientific experiments. This paper will describe the application of laser ranging for intercomparison of tracking systems, spacecraft and lunar tracking, and scientific experiments.
Advancements in technology over the past decade have opened doors for accomplishing computational tasks that were not imagined possible at the beginning of that period. Coupled with some recent concepts in pattern recognition and artificial intelligence, optical tracking system configurations with excellent tracking reliability and with the capability to correct for boresight error in real-time are within the scope of current technology. Aspects of the problem and the new supporting technology are discussed in this paper to put these developments into perspective.
TV trackers began evolving from RADAR track-while-scan systems in the late 50's. One of the first was built by Norden, a "boresight Error Measuring Device" for ADTC in 1960. The width and height of its rectangular gate were each adjustable. Detection bias was also manually set. It was reported to track when the target was large enough or strong enough, but its tracking integrators suffered from drift. The operator had to continuously adjust the detection bias. If the contrast of the target changed polarity, the operator had to throw a polarity switch. In 1963, Southern Research Institute delivered to MICOM a TV tracker with a gate that discriminated against background by fitting itself to the contrast contour of the target. After three generations of improvements, the SRI Adaptive Gate Tracker was selected as the baseline concept for the Maverick missile guidance unit. We are now four designs later and still no single tracker incorporates all of the functions known to be desirable in a TV tracker. A general review of Automatic TV Trackers was presented by F. J. Thomas and C. A. Winsor in 1976(1). The present paper discusses problems of pictorial tracking and an approach to their solution.
This paper covers the Optical data Conversion (ODC) Modernization Program at White Sands Missile Range (WSMR). During Phase I, the Telereadex film readers were refurbished using solid-state electronics. The recordex accumulators were replaced by solid-state type and the card punches were replaced by magnetic tape units (MTU's). In Phase II, the capability of reading encoded dials was added to the ODC. Two Contraves AFB-2 readers were purchased to read Contraves Model F type film formats. Each Telereadex was retrofitted with data matrix readers to read Contraves Model F type film formats and Cine-Sextant film formats. Phase III is now in progress. Digital controllers will be retrofitted to the film reading station. The controllers will perform an internal error checking on the data prior to sending it to the data handling system. The data handling system will receive data from all nine of the reading stations. The system will format and store the data until all of the data from a given mission is received. The data will be checked for consistency and will be recorded on magnetic tape which will be used in the data reduction.