In a Public Notice (DA 13-801) released Monday, the FCC’s Office of Engineering and Technology invited comments on the Technology Advisory Council white paper and recommendation for improving receiver performance.
As we saw with the LightSquared debacle, receiver performance can impact the use of spectrum outside the band the receiver operates in. The white paper notes that “radio operation has traditionally been regulated solely on the based on using limits on transmitters, with few if any explicit constraints on receivers.”
It notes that: “Receivers can be brought into the policy picture with minimal regulatory intervention by introducing an 'interference limit'” policy; that is, the establishment of ceilings, called harm claim thresholds, on in-band and out-of-band interfering signals that must be exceeded before a radio system can claim that it is experiencing harmful interference. Manufacturers and operators are left to determine whether and how to build receivers that can tolerate such interference, or even determine that they will choose to ignore these limits. Harm claim thresholds thus allow the FCC to provide guidance on the optimization of receiver performance without unduly restricting technical and commercial choice.”
Refer to the white paper for details on how such a scheme could be implemented.
Monday's Public Notice explains, “The TAC white paper sets forth an interference limits policy approach, and suggests that steps should be taken to define the radio environment in which receivers are expected to operate. According to the paper, this approach would make it easier to determine which party bears responsibility for mitigating harmful interference when it occurs, by specifying signal power levels called ‘harm claim thresholds’ that a service would be expected to tolerate from other services before a claim of harmful interference could be made.”
OET seeks specific comment on the white paper, including the actions the FCC should take to implement an interference limits policy, and on the overall interference limits policy approach proposed in the white paper. Information is requested on the practical effects of the various options in the white paper as well as “the method used today relative to receive standards and specifications, the use of multi-stakeholder organizations in the development of interference thresholds, and the role of the FCC.”
While the Public Notice does not describe the impact of such an approach on broadcasting, specifying improved adjacent channel interference rejection in radio or television receivers could potentially allowing closer spacing of broadcast stations.
Doug Lung is one of America's foremost authorities on broadcast RF technology. He has been with NBC since 1985 and is currently vice president of broadcast technology for NBC/Telemundo stations.
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