FCC Grants Waiver to Allow Operation of Metrom Ultra-Wideband PTC System
Friday, October 16, 2020 | Comments

The FCC granted a request from Metrom Rail to waive sections of its rules to allow for the certification and operation of ultrawideband (UWB) devices that will be used to enhance the safety and reliability of transit rail operations.

Specifically, the FCC waived the requirement that devices must be handheld while operating and allowed Metrom’s directional antenna system to employ an additional 6 dB of gain to produce an effective isotropic radiated power (EIRP) of up to -35.3 dBm/MHz. Metrom’s operations under the waiver are limited to the 3.248 – 4.99 GHz frequency range.

Metrom designed a UWB-based positive train control (PTC) system, marketed as the AURA system, to operate on an unlicensed basis. The system is designed to prevent collisions between trains, over-speed derailments and unauthorized train movement in work zones, as well as minimize human error. The system is designed to be used as fixed wireless infrastructure but would operate under the handheld UWB device rules. The AURA system is modular, and the wayside modules include UWB anchors that determine operational characteristics such as train speed, position, directions and track ID by interacting with UWB equipment on-board rail cars to collect information necessary for train spacing and control functions.

The Metrom system will employ modules with two different antenna types. One module uses an omnidirectional antenna and does not require a waiver, and the other uses a directional and requires a waiver to operate because it will operate at a higher radiated power than the FCC’s rules permit.

The FCC determined that granting Metrom’s request would deliver strong public interest benefits. The higher emission level would increase range, reduce deployment costs and will not increase the potential for causing harmful interference to authorized users, the FCC said. Because the AURA system relies on relatively low-cost unlicensed UWB devices, it will enable PTC technology to be implemented significantly faster and at lower cost than other solutions.

For example, the FCC said, modernizing the New York City subway signal system using current technology is estimated by the city to take between 40 and 50 years at a cost of tens of billions of dollars, while use of the AURA system could reduce both the installation time and cost.

Metrom provided the FCC with documentation to show that the system is designed to withstand interference from licensed services in the band without affecting the robustness and reliability of its service.

“This is significant because unlicensed operations must accept interference that may be caused by the operation of an authorized radio station; by another intentional or unintentional radiator; by industrial, scientific and medical (ISM) equipment; or by an incidental radiator,” the FCC said.

The FCC also said that with appropriate operational and technical restrictions to prevent harmful interference to authorized services, granting the request would not undermine the purpose of the FCC’s rules.

Find the full order here.

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