Concerns Mount Over Interference by Short-Range Devices
GENEVA -- Meteorologists will press the 2012 World Radiocommunication Conference for more tools to protect their work from short-range device interference and for greater recognition of their needs in national rules, speakers said on Friday at a seminar on radio spectrum use. Satellite interests will press for greater ITU-R involvement, but some intergovernmental organizations are opposing changes to the Radio Regulations. The World Meteorological Organization (WMO) and the ITU held the seminar.
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New frequency management challenges have emerged with technology advances, higher spectrum demand and flexibility, said Philippe Tristant, chairman of the meteorology organization’s Steering Group on Radio Frequency Coordination. He was referring to ultra wide band, software- defined and cognitive radio.
The trends pose great risks for many “public” frequency users, including those in meteorology, said Tristant, Meteo France’s frequency manager. Incumbent radiocommunication services need adequate protection from emissions of short- range devices, Roger Atkinson of Australia’s Bureau of Meteorology said in a summary of WMO positions. Conference studies are focusing on radio frequency identification and other short-range devices, including those using UWB, Atkinson said.
Interference can and does play out in various ways, Tristant said. Some UWB devices transmit in passive bands 10.6 to 10.7 GHz and 1,400 and 1,427 MHz, where none are allowed, Tristant said, citing the Radio Regulations. Frequencies authorized for UWB use in the 6.7 to 7.1 GHz band are also important for passive oceanographic measurements, Tristant said. Radars, science services, meteorological satellite and others use nine bands where UWB devices operate, he said.
Other short-range devices are causing problems, Tristant said. Some radio local area networks at 5 GHz are fixed and have big antennas with lower power, sufficient to provide service over several tens of kilometers, he said. Europe and Japan don’t allow UWB between 5 and 6 GHz, a band used for weather radars, Tristant said. The U.S. and Europe notched out more protection for the 1,400 to 1,427 MHz passive band, he said. But some other administrations are now considering national rules, he said.
UWB devices are regulated nationally or regionally, with no international regulation as far as ITU-R is concerned, Tristant said. Recommendations produced in 2005 cover measurements, impact and regulatory framework guidance. “The problem is now we need to make radio administrations follow these recommendations,” he said.
A group of participants from the International Organization for Standardization and the International Electrotechnical Commission consider short-range device regulation a national matter. No changes are needed in the radio regulations to deal with this conference agenda item, said the group, which concentrates on RFID-related issues.
AsiaSat and participants in an ITU-R group on satellite issues said short-range devices using ultra wide band technology interfered with fixed earth stations using frequencies 3,400 to 4,200 MHz. ITU-R should determine the conditions on how the devices can operate in various frequency bands, AsiaSat said. Studies and field trials show that the emission levels used in devices offered today present “a great potential for interference” into the fixed- satellite and broadcasting-satellite services, Norwegian operator Telenor said.
The potential is real for short-range device and ultra wide band interference from one country to affect another country’s satellite sensors, Tristant said. Radio astronomers are also concerned, he said. Highly sensitive passive sensing applications can get “really harmful interference” in aggregate from other countries, Tristant said. The degradation could affect all weather and climate modeling on a global basis, he said.
Another issue is automotive short-range radars at 24 GHz, which have been one of the more difficult frequency management issues for the passive sensing community, Tristant said. Spurious emissions fall into a passive band at 23.6 to 24 GHz where no emissions are allowed, he said. The band is one of the most important for meteorology, unique in its use for measuring water vapor and cloud liquid water, he said. Car radar proponents tried to keep the spurious level low to avoid problems, but interference still happens, he said. Aggregate global emissions can corrupt measurements for all countries, he said.
Studies for a 2002 U.S. rulemaking to allow car radars didn’t take into account the scattering and reflection of main and side lobe radar signals which “produce, on an aggregate basis, a huge amount of interference that” also affects satellites, Tristant said. The protection criteria used in U.S. studies were outdated, he said referring to a revised ITU-R recommendation that notes the difference. The studies also didn’t take into account other devices in the band, which add to interference totals, he said.