Database Approach to Spur Wireless Devices Raises Coordination Questions
GENEVA -- Differences have emerged in ITU-R over how to respond to a proposal for a new International Special Committee on Radio Interference (CISPR) database that would be used to set emissions limits on electronic devices, according to letters between the two organizations. Past CISPR work on power line telecommunications (PLT), which a representative recently said resulted in no solution after 10 years of work, does not inspire confidence, said John Shaw, chairman of the reporting group on PLT issues in the ITU-R study group on the broadcasting service.
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CISPR identified the need to set up a database covering characteristics of radio services that have to be considered when setting limits for disturbance emissions from electric and electronic gear, systems and installations, it said in a May letter to ITU-R groups dealing with spectrum management. The CISPR subcommittee on limits for the protection of radio services is developing the database.
The database will contain generic electro-magnetic compatibility (EMC) emission limits for electric products for the protection of radio services, said participants of the ITU-R working party on the land mobile service above 30 MHz, wireless access in the fixed service, amateur and amateur-satellite services in a letter. The letter was also sent to satellite groups, which were not included in letters between CISPR and groups on spectrum management.
Participants in the ITU-R study group on spectrum management “support development” of the CISPR database to cover the “characteristics of radio services which have to be considered for the setting of limits for disturbance emissions” from devices, systems and installations, participants of the group on spectrum management said in the letter. The study group will coordinate ITU-R inputs to the database, the letter said.
The ITU-R working party on the land mobile service is concerned about the approach, participants said in a letter. An alternative approach, based on ITU-R recommendations and reports, with regularly-updated protection criteria for services, would be publicly available free of charge, it said. Documentation from CISPR, and its parent body the International Electrotechnical Commission, is not publicly available free of charge, Shaw said.
The worry revolves around why CISPR wants a quantity and level of data that would normally be used in sharing studies between radiocommunication services, Shaw said. The CISPR group’s remit for general protection of radio spectrum and individual radiocommunication services revolves around setting acceptable limits on conducted and radiated emissions, while accounting for receiver performance, background noise and other general radiocommunication needs, he said.
Protection of individual radiocommunication services could involve some sort of coordination approach, whereby the EMC emission limits vary across frequency bands according to the individual needs of the various services and how receivers are distributed in normal operation, Shaw said.
One danger is that EMC emission limits from electronic and electrical devices would be raised to the maximum allowed to ensure compatibility between the various radiocommunication services themselves, Shaw said. Normally, interference from sources with no status in the Radio Regulations would have to be at least 20 dB below what could be considered in a sharing situation between co-primary services, he said. The concern is a “cumulative ramping effect” that increases interference and background noise, he said.
Providing detailed information for an ITU database that would then be coordinated with the CISPR database “will create an additional process that would be inherently risky,” the ITU-R working party on the land mobile and other services said in the letter. Errors may be introduced in the database development and update process, the letter said. Data might be misinterpreted without information from corresponding ITU-R recommendations, it said. The database would have to be updated with each revision of a related ITU-R recommendation, it said.
The CISPR group circulated a “reporting form” for inputs from ITU-R. It has categories for the name of the radio system, system specifications, receiving frequency band, field strength to protect, receiving antenna gain and bandwidth, estimated number of units, whether it’s a safety-related service, usage area and others.
Some of the categories proposed to be incorporated in the CISPR database are not relevant to address the protection of radiocommunication services from disturbance emissions from electric and/or electronic equipment, systems and installations, the ITU-R working party on the land mobile and other services said in the letter. The issue will be raised next year in the ITU-R study group on spectrum management, Shaw said. Satellite groups may push it forward before then, he said.