U.S. Army Electronic Proving Ground

Abstract Given the rapid increase in the use of operational mesoscale models to satisfy different specialized needs, it is important for the community to share ideas and solutions for meeting the many associated challenges that encompass science, technology, education, and training. As a contribution toward this objective, this paper begins a series that reports on the characteristics and performance of an operational mesogamma-scale weather analysis and forecasting system that has been developed for use by the U.S. Army Test and Evaluation Command. During the more than five years that this four-dimensional weather system has been in use at seven U.S. Army test ranges, valuable experience has been gained about the production and effective use of high-resolution model products for satisfying a variety of needs. This paper serves as a foundation for the rest of the papers in the series by describing the operational requirements for the system, the data assimilation and forecasting system characteristics, and the forecaster training that is required for the finescale products to be used effectively.

Amplitude-probability-distribution (APD) data are presented for ignition emanations from V-8 engines of used motor vehicles. Outputs from both single and multiple engines running at 1500 rpm were measured with an omnidirectional antenna over the frequency range from approximately 20 MHz to 1 GHz. In each case, the antenna was oriented similarly with respect to the vehicle(s)-vertical, height 3 m, distance 10 m. Results are presented on Weibull-distribution sheets and compare favorably with those of Hsu et al. [1] using a different technique. On each sheet, APD distributions are given for various received bandwidths between 1 and 300 kHz. For the larger bandwidths, curves are straight lines with large negative slopes. At narrower bandwidths and for multiple vehicles, slopes are less steep. Major conclusions from the APD results include the following. 1) Although overlapping of successive pulses at a detector becomes more prominent at narrower bandwidths, measurements are still valid and representative for a given bandwidth. 2) Measurements indicate good repeatability. 3) Curve shapes are essentially independent of tuned frequency, but do depend upon bandwidth and number of vehicles. 4) Amplitudes are functions of tuned frequency and number of vehicles.

A four-bar infrared test target has been built to test the feasibility of using perforated ambient temperature plates for the four bars instead of the customary plates operated at temperatures different from ambient. Six different sizes of four-bar arrays provide six different spatial frequencies. Front and back arrays of perforated plates are moved relative to one another by a motor drive to expose more or less of a sky reflector backplate, thereby producing a varying apparent temperature differential between the bars and their interstices. The target system also features a radiometric monitor which mechanically servos the bar patterns to compensate for changes such as dust or clouds. Qualitative tests with infrared imaging systems show satisfactory bar patterns which disappear when the perforations are closed. Quantitative tests show that differential temperature accuracies of about one tenth of a kelvin can be attained.

The use of digital computer techniques has become mandatory in the whole realm of ballistic missile design and guidance. And we are rapidly approaching the era in which computer techniques similarly might well become a necessity in many phases of ground combat. The feasibility of applying these techniques in a tactical warfare environment has been established, and the Department of the Army has a high priority program underway to place a prototype Automatic Data Processing System (ADPS) into its tactical organization within the next four years. This paper will explain the design objectives of this system and the progress to date in the applications area, and describe the extension of several techniques required to make the system function.

A procedure for using the 700-mb dew point temperature as an objective aid for forecasting the occurrence or nonoccurrence of cumuloform showers in southern Arizona is presented with verification data.

This paper discusses the approach used in a proof of concept effort developing data elements and data models for specific applications in the modeling and simulation (M&S) functional areas of research and development, test and evaluation, analysis, and combat development. Specifically, this joint data base elements approach provides the M&S community with a reverse-engineering data modeling procedure using IDEFIX that is compatible with the Department of Defense Corporate Information Management initiative. This approach also includes the development of a data dictionary/directory, containing the data elements and their descriptions, information on M&S data bases, and a repository to support future developments.

This paper presents an anti-jamming Global Positioning System (GPS) receiver antenna testing system. The system is composed of a set of six circular rails with different radii that are installed to emulate GPS satellite orbits, a set of GPS antennas each carried by a trolley that can move on the rails to emulate GPS satellites, a trolley movement controller to emulate the GPS satellite constellation propagation, and a multi-channel GPS simulation system that provides GPS signal and GPS satellite state position information. The GPS receiver antenna under test is at the center of the rails. As the GPS antennas carried by trolleys move on the rail to emulate the GPS satellite constellation propagation, the GPS receiver antenna under test receives the emulated GPS signals. The GPS signals’ arrival direction is almost the same as that coming from real GPS satellites. The anti-jamming GPS receiver antenna testing system can emulate a GPS satellite constellation with multiple GPS satellites; with high emulation accuracy (in both GPS signal phase and satellite angular position with respect to the GPS receiver antenna under test); requiring only a single phase calibration at the beginning of each test; and can support a 4 hours test / emulation.

The U. S. Army Electronic Proving Ground at Fort Huachuca, Arizona has tested a new type of theodolite using pulsed light for ranging and tracking of meteorological balloons. The pulsed-light theodolite (PLT) electronically computes the slant range to an airborne free balloon. The time required for a pulse of light to go to the balloon and back determines the range. By using the slant range and azimuth and elevation angles, the equipment computes the elevation, wind speed and wind direction and automatically prints the data on paper tape. The tests indicate that the PLT system is an accurate and fast method of measuring low-level winds. It could provide wind data without delay to such activities as rocket launchings.

This paper discusses the approach used in a proof of concept effort developing data elements and data models for specific applications in the modeling and simulation (M&S) functional areas of research and development, test and evaluation, analysis, and combat development. Specifically, this joint data base elements approach provides the M&S community with a reverse-engineering data modeling procedure using IDEF 1X that is compatible with the Department of Defense Corporate Information Management initiative. This approach also includes the development of a data diet ionary/di reetory, containing the data elements and their descriptions, information on M&S data bases, and a repository to support future developments.

A number of factors which contributed to the establishment of the Army's Electromagnetic Environmental Test Facility (EETF) at the U. S. Army Electronic Proving Ground are reviewed. Technical planning to date covering the layout, organization and operation of the EETF is summarized. Finally, predictions as to the possible future scientific role and activity of the EETF are made.

The Army for some time has considered the feasibility of transmitting digital information over tactical narrowband FM. This paper presents the results of bit error rate measurements made on narrowband FM links being interfered with by a variety of modulation types. The desired signal is a frequency shift keying signal of 1200 and 2400 Hertz with bit rates of 600 and 1200 bits per second. This signal is transmitted over a 25 kHz FM channel. The interfering signals will be: a. Gaussian noise b. ASK 1200 and 2400 Hertz tones at 600 bits per second c. ASK 1200 and 2400 Hertz tones at 1200 bits per second d. ASK 750 and 1500 Hertz tones at 750 bits per second e. Narrowband voice f. AM noise.

The emphasis in this work has been on maximal utilization under critical conditions, of the operator, lines, and subscribers, in the belief that in combat communications they are extremely important, and limiting factors should be known and understood so that corrective measures can be taken. This is shown by the difference in service between six or more subscribers, and between short and long conversations. Some of the results obtained are as follows. There are load conditions where the addition of a second operator does not improve service, in fact, it can be detrimental. Under some conditions the number of lines is the limiting factor, and with others the operator is the limiting factor. There are heavily loaded conditions where service is not much better with a fast board than with a slow board. A board which is 15 per cent faster may give an improvement of less than 1 per cent under some conditions. There are conditions that require subscribers to spend far more time in waiting and trying than in talking. Operations that take up the operator's time are multiplied to the subscribers, and result in much poorer service than is apparent just from the increase in operator occupancy. Adding a second line to a busy subscriber generally improves service to all subscribers. Dividing a given calling rate between more subscribers (or trunks) always improves service. Increasing the calling rate always makes for poorer service. Reducing message length always improves service. Long conversations are the greatest obstacle to good service. Conference calls can ruin service if prior conversations are allowed to continue without interruption.