Publications

Abstract: The total radio frequency (RF) field strength is the sum of all signals incident at a given location. These signals can originate from many directions and have various polarizations. This complicates the measurement of the total RF field since commonly used antennas (dipoles, whips, etc.) respond to signals coming from a specific direction and with a specific polarization. This paper describes a prototype antenna constructed from three crossed dipole elements.

Abstract: This report describes one of three free-field radio frequency (RF) measurement systems that are currently being developed by engineers at the Institute for Telecommunication Sciences (NTIA/ITS). The objective is to provide estimates of the electrical properties of the ground (permittivity and conductivity) over which the measurement systems are deployed. This measurement system uses transmission loss measurements between two monopoles placed close to the ground at specific separation distances.

Abstract: When radiofrequency pulse envelopes are observed away from their fundamental frequency their shapes differ from those at their fundamental frequency. Off-fundamental pulse envelopes tend to exhibit spikes at their rising and falling edges with lower-amplitude energy between the spikes. This phenomenon, called the rabbit ears effect, is described in this NTIA Report. Examples of rabbit ears pulse envelopes are provided in a mathematical simulation and from measurements of off-fundamental pulse envelopes of two models of 5 GHz weather radars.

Abstract: Measured power levels for radio frequency (RF) pulses that are frequency modulated (chirped) vary as a function of the bandwidth in which the measurement is performed; if chirped pulses cause RF interference, the power levels of the pulses in victim receivers will likewise vary as a function of receiver bandwidth. This report provides both heuristic and rigorous derivations of the relationships among chirped pulse parameters and the measured peak and average power levels of chirped pulses as a function of measurement bandwidth.

Abstract: We provide detailed descriptions of recent measurements conducted by the National Telecommunications and Information Administration Institute for Telecommunication Sciences in Boulder, Colorado. ITS engineers performed a comprehensive series of both conducted and radiated emission measurements of the Shore-Line-intrusion-Monitoring System (SLiMS). The SLiMS system is currently being developed by Time Domain® under the sponsorship of the Naval Facilities Engineering Command.

Abstract: This report describes speech intelligibility testing conducted on the Adaptive Multi-Rate (AMR) speech coder in several different environments simulating emergency response conditions and especially fireground conditions. The intelligibility testing protocol was the Modified Rhyme Test (MRT). Conditions included background noises of various types, as well as a mask associated with a self-contained breathing apparatus. Analog FM radio transmission and Project 25 digital radio transmission were also included in the test as reference points.

Nicholas DeMinco, Paul M. McKenna, Robert T. Johnk, Chriss A. Hammerschmidt, J. Wayde Allen, Linh P. Vu

Abstract: This report describes a modified rhyme test (MRT) conducted to characterize the behavior of digital and analog communication in the presence of background noise and moderate RF channel degradation. This is done through the use of reference systems to provide a manufacturer-independent perspective on this issue.

Abstract: NTIA is responsible for managing the Federal Government’s use of the radio spectrum. In discharging this responsibility, NTIA uses the Radio Spectrum Measurement Sciences system to collect spectrum occupancy data for radio frequency assessments. This report shows measured frequency data spanning spectrum from 108 MHz to 10 GHz in the vicinity of Denver, Colorado, during the month of June 2011.

Report re-issued with six corrected images in March 2014.