Spectrum Engineering Reports

This report describes a new technique for calculating the spectrum space used by existing frequency assignments.  The Spectrum Use Model (SUM) determines the amount of spectrum used at a given location or the probability that a given location is unavailable for a new assignment.

This report describes analysis models and software packages developed for the assessment of single-entry and aggregate interference from terrestrial emitters into terrestrial or airborne victim receivers. The menu-drive computer programs provide user options for input/output computations, parametric representations, propagations models and emitter distributions. The flexibility in the scenario creation, parameter selection, and computation mode, renders the models applicable to a wide variety of EMC assessments and conditions. Model descriptions, technical formulations, user manuals, and sample runs are provided in this report.

The technical and operating characteristics of meteor burst systems of importance for spectrum management applications are identified. A technical assessment is included which identifies the most appropriate frequency sub-bands within the VHF spectrum to support meteor burst systems. The electromagnetic compatibility of meteor burst systems with other equipment in the VHF spectrum is determined using computerized analysis methods for both ionospheric and groundwave propagation modes. It is shown that meteor burst equipment can cause and are susceptible to groundwave interference from other VHF equipment. The report includes tables of geographical distance separations between meteor burst and other VHF equipment which satisfy interference threshold criteria.

This handbook is intended to provide estimates of radio wave propagation loss between transmitting and receiving antennas of various heights and transmission frequencies above the assumed smooth-earth surface calculated using the NLAMBDA computer model. For many cases involving electromagnetic compatibility analysis, the curves of predicted transmission losses in this report may be used to estimate the transmission losses of the desired and undesired signals. These estimated loss values are given in dB as BASIC MEDIAN TRANSMISSION LOSS for antennas with effective heights up to 5000 meters, operating in the 100-20,000 MHz frequency range, over land or sea, at great circle earth surface distances up to 1000 kilometers.

Since the spectrum is a limited natural resource, the spectrum management community has a major interest in identifying spectrum conservation techniques that will provide more efficient spectrum utilization. Advances in new technology for fixed microwave systems in antennas, modulation schemes and signal processing techniques offer increased efficiency in spectrum utilization. This report analyzes the spectrum conserving properties of the various new technologies for fixed microwave systems applying the concepts in CCIR Report 662-2, and was defined as the spectrum conservation factor (SCF). The report concludes that the SCF technique is an effective indicator of the spectrum conserving properties of technologies which can be used to develop new spectrum standards.

This report is a spectrum resource assessment of the HF band (3-30 MHz). It incudes information on rules, regulations, allocations, technical standards, frequency assignments, system characteristics, and special uses unique to the HF band. The impact on HF services brought about by new technologies is discussed along with potential impacts of HF Over-the-Horizon (OTH) radars and ionospheric sounders. The importance of domestic emergency communications in the HF band is discussed along with new standards for interoperability presently being drafted.

This technical report details a procedure for calculating the mainbeam off-axis power density in the near- and far-field of a parabolic circular reflector antenna. In the report, the on-axis procedures of an earlier report are extended to off-axis analysis. Like its predecessors, it is intended for general use in system planning and evaluation and gives a worst-case estimate for radiation hazard assessment.

Use of Government and non Government flood warning systems in the 162-174 MHz band are growing rapidly in the US. The report investigated ways of improving the spectrum efficiency of these systems to allow for continued growth. Recommendations for narrowing channel widths and allotting certain channels for their use have been adopted.

Interference from high powered weather radars to digital microwave systems is a growing problem in the US. The study identified procedures to avoid these problems. The study was completed in coordination with the FCC and industry. Recommendations dealing with exchange of data bases, coordination procedures and other technical areas have been adopted.