National Radio Dynamic Zone (NRDZ)

This NSF-funded effort supports (1) the development of an NRDZ concept definition, (2) design and development of prototype advanced spectrum monitor (ASM) devices, and (3) broader impact efforts related to spectrum awareness and spectrum management. This article (2018) appears to be the origin of this idea.

NRDZ Concept Definition:

When we consider precisely what an NRDZ might be, we need to carefully explore how it would potentially be used by various stakeholder communities. While communities and subcommunities have differing use cases, the unifying motivator for all stakeholders that has come through clearly in discussions is increased spectrum access. That is, passive users (radio astronomy and remote sensing) are developing receivers with ever wider bandwidths to increase sensitivity (and reduce observing time), and active users are developing transmitters and receivers that require broader bandwidth for faster throughput of information for an increasing number of wireless-enabled systems.

For all stakeholders, an NRDZ could provide an established location to perform both individual and coordinated experiments that allow them to utilize broader bandwidth. Controlled experiments performed in an NRDZ may have wider applicability if proven there.

There are two fundamentally different NRDZ models that have been discussed, referred to in some stakeholder discussions as (1) a “Coordination Zone” (with various levels of management and enforcement), versus (2) a “Wild West” (with little to no enforcement). Both have advantages and disadvantages, but to be clear, some sort of coordination, management and monitoring will be required in either model. In general, the first model is more appealing to the radio astronomy and remote sensing communities, as careful coordination (manual or automated) will be required for sensitive receivers to function in the coming decades. The second model is more appealing to the active community because it would allow a large amount of freedom in the testing of new equipment, and the testing of new theoretical models of propagation.

Project Director Chris De Pree presents current status of the NRDZ project at AAS 241 (Seattle, WA).

In order for an NRDZ to succeed, all potential users must be able to point to tangible benefits to their community. In stakeholder discussions thus far, this appears to be possible. In an NRDZ, active users would gain managed access to spectrum currently not available. Passive users would gain access to broad bandwidth observing without the need to undertake complex RFI monitoring and mitigation, and potentially the opportunity to test automated coordination systems with next generation wireless transmitters.

Broader Impacts:

The NRDZ Broader Impacts curriculum includes a citizen science project, a high school curriculum, and an undergraduate curriculum, all focused on increasing the number of students and citizens aware of the spectrum as a finite resource for both science and commerce. These curricula will be made available via the Superknova website as they are completed during the 2021-2023 period.

Advanced Spectrum Monitor (ASM):

One of the NRDZ deliverables is to design, develop and oversee the installation of the ASM prototype at the observatories identified as NRDZ test locations. One ASM device will be built and tested at NRAO's CDL facility, then later validated the Green Bank Observatory (GBO) both within the GBO anechoic chamber as well as outside as described in the original NRDZ proposal to the National Science Foundation. This device will be designed and built with the combination of funds designated within the NRDZ project budget. In all, CDL plans to build three (3) devices to be deployed in three (3) locations: one at the VLA, one at GBO, and one in reserve at the CDL at the end of the NRAO-NRDZ project.

Engineering drawing of the ASM-1 Prototype currently under development at the CDL.

The device will be capable of receiving, determining vectors to, and categorizing signals from frequencies of 1 to 120 GHz. Hemispherical coverage is required as potential interferers can be terrestrial or space borne. Frequency, Signal strength, Polarization and Spectral Occupancy will be measured and logged by the device. The ASM will be designed in the form of a cone or tetrahedron with multiple antennas built into the perimeter of the outer shell. This configuration will allow for the device to determine azimuth and elevation of emitters. Each antenna will be sampled individually, allowing for the amplitude measurements to be entered into an algorithm that will determine a two-dimensional vector (azimuth, elevation) to the radiating source.

The Advanced Spectrum Monitor (ASM) device will provide autonomous spectrum monitoring between 1-120 GHz. The first ASM will be delivered to the Green Bank Observatory for testing in late 2022/early 2023. Above is an image of the first high frequency horn (covering 16-120 GHz) taking shape in the Central Development Laboratory (CDL) machine shop. Below, bench testing of the Monitor and Control module and various components that will make up the cylindrical RF insert.

(Below) ASM-1 (Proof of Concept Device) during on site RFI and Field Testing at the Green Bank Observatory. May 2023.

NRDZ LOGOS

These logos are freely available for use by any NRDZ-related projects. If there are different formats needed, please reach out to the NRDZ Project Director, Chris De Pree.