New Jersey Transit Debate Continues with Questions About Emission Mask Requirements (7/24/12)
By Michelle Zilis
Several entities weighed in on the debate surrounding the use of TETRA-modified equipment in public-safety spectrum. Following a Harris petition for a rulemaking regarding emissions mask requirements in 800 MHz public-safety spectrum, PowerTrunk, Alcatel-Lucent and Nielson Communications came out in opposition to the request. Harris and the National Public-Safety Telecommunications Council (NPSTC) filed comments supporting the request. Motorola Solutions said the issues deserve the FCC’s consideration, but questioned whether a rulemaking proceeding was necessary.
The proposed rulemaking requested that the FCC restrict digital devices used in the public-safety spectrum to only H-Mask certified devices. Harris said allowing operation of lower emission devices, particularly B-Mask certified devices, could cause system interference to others operating on the spectrum.
In addition, Harris asked that pending the final FCC resolution, the commission prohibit any digital technology not meeting the H-Mask emissions requirement from operating in the spectrum, essentially asking for a freeze of all non-H-Mask devices operating in the 800 MHz spectrum. The third part of the request asked the FCC to “adopt equipment certification ‘technical’ mandates for operations on the mutual aid channels designated in §90.203(i) and §90.203(j)(1).” All commenters, aside from Harris, disagreed with the second two requests.
The emissions mask debate was spurred after New Jersey Transit (NJT) in March awarded a contract to Alcatel-Lucent for a system that included PowerTrunk’s Digital Land Mobile Radio (D-LMR) equipment. The equipment, which some referred to as “modified TETRA,” is a digital technology that meets the B-Mask emissions certification, rather than the H-Mask. Harris argued that use of the lower classification could lead to harmful interference in the public-safety spectrum.
In Section 90.210 of the FCC rules, devices operating in these frequencies must be compliant with the H-Mask if no audio low-pass filter is used, the Motorola Solutions filing said. However, if an audio low-pass filter is used, the device may show compliance with the emission limits specified as the B-Mask, the filing stated.
The FCC-certified PowerTrunk technology contains an audio low-pass filter, which PowerTrunk argued makes the digital technology suitable for use in the spectrum. The D-LMR equipment was awarded type acceptance for Part 90 in July 2010. “In the staff’s response, the chief of the equipment authorization branch agreed, after consultations with the Wireless Bureau, that it was appropriate to certify PowerTrunk’s equipment using the Mask B precisely because it has such a filter,” the filing said.
On May 18, the FCC granted a license to NJT that included 800 MHz public-safety spectrum. NJT asked to reconfigure its 800 MHz system to frequencies in the interleaved portion of the 800 MHz band in lieu of reconfiguration to frequencies in the new National Public Safety Planning Advisory Committee (NPSPAC) band.
Further, PowerTrunk asserted that once technology is certified by the FCC, the regional planning committees (RPCs) are in place to determine, with certainty, that no interference will occur among systems in an area. The Region 28 (New Jersey) RPC held a meeting earlier this month where both PowerTrunk and Harris were scheduled to present. The New York RPC is scheduled for Aug. 28.
When Region 28 was asked for comment, Chairman Mark Grubb said, “It is not up to Region 28 to make such a decision. RPCs coordinate frequency use once frequencies have been requested. Nothing has been requested from Region 28 and therefore no decisions will be necessary.”
Emission Mask Comments
In the Alcatel-Lucent opposition filing, the company stated that the FCC already confirmed the NJT proposed operations comply with the rules by authorizing NJT to operate the PowerTrunk equipment (certified under B-Mask) on the 800 MHz frequencies. The company asked the FCC to decline the request for rulemaking.
The NJT comments echoed the opposition, and said the rulemaking “should not be considered as it is unnecessary and it promotes a commercial barrier to well-established, spectrally efficient, affordable digital radio technology.” The RPC is designed as an additional layer of protection to ensure public-safety system operators within respective regions operate without interference, the NJT filing said.
NJT conducted a pilot of TETRA-type technology certified using a B-Mask for four months without any indication that nearby adjacent system operators experienced any interference, the filing said. Neilson Communications also submitted a comment that the company’s TETRA system in Green Bay, Wis., had not encountered any interference.
However, Harris is not the only proponent of requiring only H-Mask operation in the public-safety spectrum. In comments filed July 13, NPSTC stated that its primary interest is the prevention of interference. The equipment deployed in the NPSPAC spectrum under the pre-existing adjacent channel separations have a high potential to increase adjacent channel interference. “Given this environment, NPSTC supports application for the tighter ‘H-Mask’ in the NPSPAC channels,” the filing said.
Motorola’s filing said the FCC “should assess the potential benefits and risks of requiring the H-Mask for digital emissions for future deployments in the band, regardless of whether audio filtering is done or not.”
However, Motorola did not support the request to freeze devices not meeting the H-Mask during the assessment. NPSTC, PowerTrunk, Alcatel-Lucent and the NJT all also oppose the freeze.
“Harris’ proposal that the commission implement rules solely to fulfill Harris’ view of interoperability, including an immediate freeze on future certification, is inconsistent with the established interoperability requirements implemented at the federal and state level and lacks any merit,” the PowerTrunk filing said.
Mutual Aid Requirements
The third part of the Harris request is for technical requirements for mutual aid channels. Five mutual aid interoperability channels were established as part of the commission rules for the NPSPAC portion of the 800 MHz band. Mutual aid is based on common technology and requires providing analog voice capability, the Harris comments said.
Both Motorola and NPSTC said the FCC rules are already clear and should continue to be applied to all devices operating on the channels.
PowerTrunk said there is no merit to the request for a mandated modulation scheme for mutual aid channels because the “IQ modulation (used by PowerTrunk) is capable of generating analog FM signals,” thus meeting the current requirement.
However, in the Harris reply comments filed July 17, the vendor said that, “despite the assurance of [PowerTrunk’s] D-LMR equipment ‘capacity,’ of analog FM operation, it does not currently generate analog FM signals, and standard TETRA radios do not have the TIA-603 analog FM mode included in them.”
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