ITU-R Approves Recommendations on New Propagation Prediction Methods
GENEVA -- ITU-Radiocommunication (ITU-R) study group SG- 3 gave a preliminary nod to 3 draft recommendations aimed at gauging the maximum functional distance between free space optical (FSO) system gear and better modeling of broadcasting network service areas. Development of propagation and interference studies on some new ultrawideband (UWB) applications has stalled for lack of study data. The 3 recommendations will be forwarded to ITU member nations for consideration.
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Two of the recommendations concern calculating interference and propagation for a better idea of the maximum distance between FSO devices in varied environmental conditions, said Alexandre Vassiliev, ITU-R SG-3 counselor. FSO uses optical frequency bands at around 400 terahertz -- infrared and visible frequency bands. Liberated from cables, FSO devices propagate freely through space, but rely on line- of-sight and can be affected by rain and other conditions accounted for in the new calculation method.
The 3rd draft recommendation covers use of digital terrain maps in international spectrum coordination. The 120 countries at last summer’s Regional Radio Conference demanded more precise propagation models for spectrum coordination, Vassiliev said. The recommendation details ways to calculate propagation by using independently created maps, largely for measuring broadcast networks’ coverage and service areas, he said. NTIA played a major role in developing the recommendation, he said.
Propagation prediction methods also are being developed for UWB technologies, but more data are needed, since commercial products are so new. For example, UWB sees use as a kind of radar in vehicles to help drivers keep vehicles apart on the road. Studies have been done on signals less than 20 meters from their sources, but more study is needed on spurious signals when many UWB devices are operating over a greater distance, Vassiliev said. Further, UWB may interfere with other radiocommunication services like meteorological passive sensors or satellite receivers operating in the same frequencies. A business or govt. will have to submit the necessary data for the study group’s work to progress, he said.