Search Results
The search returned 1,243 publication(s) on its.ntia.gov.
Values of required signal-to-noise ratios are estimated for the following HF communication systems: amplitude-modulation (AM) voice communications systems, noncoherent frequency-shift-keying (NCFSK) radioteletypewriter systems, composite voice and t...
The report describes a series of computer routines for analyzing HF radio propagation in an arbitrary ionosphere - in particular, the echoes obtained in ionospherically propagated ground backscatter experiments. With the aid of a plotting routine t...
Simulcast is a system of broadcasting in which several carriers, each containing the same information and having equal frequencies, are used. In such a system, transmitter frequency drift, random phase between transmitters, and other factors will cau...
A multiple transmitter system, where transmitters at different locations send the same message simultaneously, was tested in the laboratory under simulated typical conditions. The results agreed very closely with those obtained theoretically and sho...
Laboratory and field tests were performed to investigate the nature of interference fading from multiple sources. Fading frequency, rates, and depths were measured, and conditions expected at actual sites common to several paths were investigated. T...
This paper poses, and attempts to answer, some of the questions involved when a UHF antenna is buried in the ground. A description of the basic theory is given, together with illustrative calculations for many situations of interest. Graphs are prese...
This report reviews antenna configurations for use on an ocean data buoy platform. Both electrical and mechanical requirements are considered. A sleeve dipole antenna appears most suitable for small buoys. For large buoys. a discone antenna should b...
The effects of multipath arising when a signal transmitted from a User satellite is scattered by the earth before reaching a tracking and delay relay satellite (TRDS) in stationary orbit are considered. An upper bound for the probability of the scatt...
A numerical method for calculating the scattering and diffraction at an antenna site to be used in a sky-wave communication link is derived. The method of physical optics is used to treat the scattering by the terrain surrounding the antenna site. ...
An estimate of the existing HF electromagnetic interference environment was made for the U. S. Navy receiving antenna area in Bremerhaven, Germany. The estimate was based on land use in the area and measurements of man-made radio noise from various...
An algorithm is presented which permits calculation of the transmitter power required to achieve a given value of circuit reliability or service probability and time availability on high-frequency ionospheric telecommunication systems. The accuracy ...
Continuous wave signals at 9. 6 GHz were propagated over a 97 -KM overwater path extending from 80 m to 3000 IT) above mean sea level. Variations in phase of arrival of the signals received by antennas having 1. 2 and 5* beam widths were recorded sim...
The results of three research projects for the period January 1968 through December 1968 are reviewed. The first was to develop a program (ALLMODES) that presents circuit data for the 7 most probable ionospheric sky-wave transmission modes. The secon...
This memorandum describes FORTRAN routines for printer-plotting distribution functions on a normally scaled graph. Included are related routines for handling distribution functions.
Based on trends of recent ionospheric and solar data, the IPR series of Semimonthly Revision Factors for ITS Ionospheric Predictions provides corrections to the monthly ITS Ionospheric Predictions for F2-layer MUF. Accuracy of the IPR revision factor...
An evaluation of three refractivity variables in terms of their value in correcting microwave slant-range data for atmospheric effects is described. Experiments were conducted in Hawaii in 1967 on a fixed, 65 km overwater propagation path. The data o...
A hypothetical aircraft-to-ground communication channel is examined for frequencies in the 2 -30 MHz band, and in the 200 -400 band. The channel is characterized by its correlation function and scatter function. Particular attention is given to the e...
An investigation of radar microwave relay outages resulting from excessive fading on the line-of-sight microwave relay system indicated that most were caused by multipath propagation which resulted in phase interference fading. Rain attenuation was a...
The ESSA/ITS HF system performance prediction program has been modified and adapted to operate on a time-share computer. The problems and solutions of implementation are discussed. A description is given of the routines used in the prediction program...
This report describes an experiment in which some computations are compared with available field strength data. Several models are proposed which compute an effective height by using a least squares fit to various sections of the terrain profile. Als...