The FCC allowed TETRA equipment certification and use in two bands, UHF 450 – 470 MHz and the business/industrial (B/I) land transportation 800 MHz band (809 – 824/854 – 869 MHz) that aren’t in the National Public Safety Planning Advisory Committee (NPSPAC) portion of the 800 MHz spectrum.

The commission said the order “will give private land mobile radio (PLMR) licensees additional equipment alternatives without increasing the potential for interference or other adverse effects on other licensees.”

One of the concerns with TETRA noted in comments filed was the potential for interference. Motorola Solutions provided technical analysis showing interference potential, and the TETRA Association provided technical analysis showing no potential for interference.

“We agree with the methodology utilized by the TETRA Association and do not believe it was necessary to perform this analysis at frequency offsets less than 18.75 kilohertz,” said the order. “We thus conclude that the TETRA Association’s technical analysis accurately represents TETRA systems’ interference potential. … We find that TETRA offers adjacent channel protection that is often better than other narrowband systems currently operating in the LMR bands.”

Regarding system architecture, some commenters voiced concerned that deployment of TETRA technology in low-elevation, cellular-type architecture could cause near-far interference to incumbent high-site systems, “but these commenters do not explain why the use of TETRA technology in a cellular-type system is any more likely to cause such interference than the use of other technologies,” the order said.

Emissions technical rules were also an issue in some comments. “We do not find it necessary, as proposed by Motorola, to incorporate all of the emission limits in the TETRA standard into the rules,” the order said. “While we will require the TETRA limits for emissions close to the carrier, we retain the current limits for emissions more than 75 kilohertz from the carrier to reflect the current rule requirements, which have successfully limited interference in adjacent bands.”

The FCC agreed with commenters who argued against allowing TETRA technology in public-safety spectrum. The FCC said the record supports prohibiting TETRA on the 800 MHz public-safety NPSPAC channels. “We also will not allow TETRA technology to operate in 700 MHz public-safety spectrum,” the order said.

The order follows an FCC ruling in 2011 that green-lighted TETRA for limited use for business, industrial and transport applications. The original order allowed some use of TETRA equipment, while the latest order allows permanent use.

“This is extremely positive news for the TETRA market," said Phil Kidner, CEO of the TETRA + Critical Communications Association (TCCA). "All arguments against the adoption of TETRA in the U.S. appear to have been rejected by the FCC, and we are delighted that critical communications users in the U.S. can now consider TETRA as fully approved.”

Separately, Harris asserted that PowerTrunk’s “low power” TETRA technology will cause interference in the NPSPAC band and filed a separate petition for rulemaking to prohibit reduced-power TETRA in the band. The FCC said that issue is outside the scope of this proceeding and took no action on it.