What We Do
The Institute for Telecommunication Sciences (ITS) performs cutting-edge telecommunications research and engineering with both federal government and private sector partners. As its research and engineering laboratory, ITS supports NTIA by performing the research and engineering that enables the U.S. Government, national and international standards organizations, and many aspects of private industry to manage the radio spectrum and ensure that innovative, new technologies are recognized and effective. ITS also serves as a principal Federal resource for solving the telecommunications concerns of other Federal agencies, state and local Governments, private corporations and associations, and international organizations. The FY 2015 Technical Progress Report describes research performed in the past fiscal year.
ITS at MILCOM November 1-3
ITS hosted an NTIA booth at MILCOM 2016 November 1-3. On November 1, ITS engineer Chriss Hammerschmidt presented a paper on “Extracting Clutter Metrics From Mobile Propagation Measurements in the 1755-1780 MHz Band” that describes spectrum measurements ITS took during 2015 to inform and validate new radio wave propagation prediction models. ITS has been working to better understand how to factor in the effects of clutter (man-made structures and vegetation) when analyzing and predicting the behavior of radio waves—read about that in the NTIA blog "Understanding Spectrum Clutter—It’s Not About Neatness!" ITS and its predecessor labs within the Department of Commerce have been developing and improving propagation models since about 1909. These mathematical algorithms predict the behavior of radio waves, and they are an essential enabler for spectrum sharing. But increased demand for spectrum, advances in technology, and the tremendous increase in the everyday spectrum usage (sometimes referred to as the “noise floor”), mean that there are tremendous potential benefits from more research and testing to improve the accuracy of existing propagation models. The topic is of special interest to military communications professionals because frequency bands where they operate many critical communications systems are now being opened to sharing. ITS Director Keith Gremban moderated a Technical Panel on Spectrum Sharing - Issues and Approaches on November 2nd where some of the challenges of federal/non-federal spectrum sharing were discussed. Keith also chaired a Technical Paper Session on November 1 on MIMO and Directional Networking, techniques that can help to prevent interference among communications services sharing spectrum.
Research Spotlight: Speech Intelligibility
Speech intelligibility is one of the primary requirements the National Public Safety Telecommunications Council (NPTSC) Broadband Working Group defined for mission critical voice services like those to be delivered over the new nation-wide public safety broadband network that the First Responder Network Authority (FirstNet) is charged with deploying. The NPSTC requirements begin with “The listener MUST be able to understand [what is being said] without repetition.”
For years ITS has conducted various types of subjective testing in tightly-controlled laboratory conditions to sort through myriads of emerging telecom options to find those that sound better or work better in some respect. Where this work was directed towards intelligibility, it has been done through ITS’s participation in the Public Safety Communications Research (PSCR) program, a joint effort with the National Institute of Standards and Technology (NIST), and with the involvement of those who are directly affected—the public safety practitioners. A particular focus has been intelligibility in the presence of background noise to provide comparative intelligibility results for new digital speech and audio codecs, but now the work has expanded to include the condition of the communication network itself.
A new report issued this month describes comparative intelligibility results for new digital speech and audio codecs under different conditions of radio access network (RAN) degradation. Characterizing the relationship between the condition of the RAN and intelligibility is particularly important for mission critical voice because the events that stress the RAN may very well be events that also have critical intelligibility requirements.
One public safety related example would be an event that is escalating, requiring additional personnel to report to the scene. As more and more first responders share radio resources on the scene, those resources will be stressed more and more. As they are stressed, the voice data stream can be corrupted and packets or frames of data can be lost. Voice codecs use various mechanisms to compensate for packet loss or frame erasure—the more successfully they do this, the more “robust” they are and the more likely it is that the listener will be able to understand the message.
The test results published in NTIA Technical Report TR-17-522: Intelligibility of Selected Speech Codecs in Frame-Erasure Conditions can inform codec selection for mission critical voice applications, as well as the design, provisioning, and adaptation of these services and the underlying network. Most importantly, these results can allow those engineering activities to be driven by the critical user experience factor—speech intelligibility.
NTIA Technical Report TR-17-522: Intelligibility of Selected Speech Codecs in Frame-Erasure Conditions
November 2016, Andrew A. Catellier; Stephen D. Voran.
We describe the design, implementation, and analysis of a speech intelligibility test. The test included five codec modes, four frame-erasure rates, and two background noise environments, for a total ...
Conference Paper : Extracting Clutter Metrics From Mobile Propagation Measurements in the 1755-1780 MHz Band
November 2016, Chriss A. Hammerschmidt; Robert T. Johnk.
This paper discusses mobile propagation measurement campaigns in San Diego, CA; Denver, CO; and Washington, D.C. These measurements were made to inform possible clutter models in the 1755-1780 MHz ban...
This Month in ITS History
December 1901: First Radio Transmission Across the Atlantic
On December 11, 1901 Guillermo Marconi demonstrated that radio signals could be sent across the Atlantic. Marconi left a team at Poldhu in Cornwall, England, to transmit the signal, while he made his way to Signal Point in Newfoundland. Marconi set up his receiver and used a kite to raise his antenna. At the appointed time his staff in England sent three Morse code “dots” (S). The shortwave (1.6–30 MHz) radio signals reflected off the atmosphere to the receiver and Marconi heard the “S.” Because Marconi knew the signal to be transmitted ahead of time and when it was scheduled, some questioned his methods and even if he really heard the signal. However, repeated tests proved that the connection between Newfoundland and Cornwall was feasible. Within a year the Marconi Company was connecting ships up to 2,000 miles at sea to land based radio-telegraphs. Although Marconi had proved empirically that this method of reflecting radio waves beyond the earth’s horizon made radio viable for international messages, the principles of ionospheric reflection that allowed the feat were not well understood at the time. The use of shortwave communications by both commercial and amateur operators grew rapidly, while researchers rushed to explain it. The study of “skywave propagation” became a key focus of National Bureau of Standards radio research. Researchers began to map the ionosphere and perform extensive radio propagation measurements to understand how, when, and how far reflected radio signals could travel. In 1939 the first maps of the ionosphere were published in NBS reports, and in 1942 the Interservice Radio Propagation Laboratory (a predecessor to ITS) began providing the military with quarterly ionospheric propagation prediction reports. Changes in ionospheric conditions and solar flares strongly impact ionospheric propagation, but with improved understanding of the physics, better forecasting methods, and more sophisticated equipment, short wave radio is still used today, primarily for long range broadcasting, amateur radio, and over-the-horizon radar.