HERNDON, Va. — HawkEye 360 in Herndon, Va., has used space-based radio frequency (RF) data to locate an environmental transmitter that had continued operating for years without a confirmed physical location. The work helped restore an uplink position in NOAA's Geostationary Operational Environmental Satellites (GOES) Data Collection System.

More than 600 organizations across 42 countries use the system to transmit environmental and hazard-monitoring data. The equipment's location remained unknown, meaning operators cannot verify it or free the uplink position for another authorized user.position for another authorized user. NOAA worked with HawkEye 360 to determine where the signal originated.

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GOES system collects environmental data

The GOES Data Collection System provides a communications link for remote monitoring equipment across the Western Hemisphere. Environmental sensors use the system to send measurements through GOES satellites for applications such as flood forecasting, volcanic monitoring and tsunami alerts.

Those sensors rely on assigned uplink positions to transmit their information. If a transmitter keeps broadcasting but no one knows where it is, operators can't easily inspect the equipment or reassign its uplink position.

In this case, the transmitter occupied an uplink position even though its physical location could not be confirmed. HawkEye 360 approached the problem from orbit. The company's satellites collect RF emissions, while its analytics determine where signals originate on Earth. NOAA used that capability to investigate the transmitter without first knowing where to look for the equipment on the ground.

Short transmissions complicate the search

The transmitter gave HawkEye 360 a small window to work with. It broadcast for only 1.9 seconds at a time over a narrow 1.5-kilohertz channel. Other devices were transmitting at the same time, making the target signal harder to isolate.

Despite those conditions, HawkEye 360 geolocated the signal and provided its position to NOAA. The information allowed the operator to find the equipment, verify it and remove it.

Removing the transmitter made the uplink position fully available again and brought the operator back into compliance with federal regulations. The search also led to another discovery. Once the operator knew where the first transmitter was located, it used that information to find a second device without HawkEye 360's assistance. The effort ultimately led to the recovery of multiple non-functioning transmitters that had remained undetected for years.

Those devices can now be refurbished and repurposed for future environmental monitoring, according to HawkEye 360.

Space-based RF supports network troubleshooting

The mission adds to previous work between HawkEye 360 and NOAA involving interference within the GOES Data Collection System. In an earlier case, HawkEye 360 helped identify a persistent ultra-high frequency (UHF) uplink interferer that was affecting environmental data delivery across more than 50 countries. The company also geolocated a disruptive transmitter near Quito, Ecuador. That information allowed Ecuador's telecommunications authority to find and remove an outdated device on the slopes of the Guagua Pichincha volcano.

The work also shows how space-based RF sensing can serve purposes outside traditional defense and intelligence missions. Instead of using RF data to track activity for military operations, NOAA applied it to troubleshoot communications infrastructure that supports environmental monitoring.

"This mission demonstrates how our space-based signals intelligence can directly support the continuity of essential civil systems," said Todd Probert, chief operating officer at HawkEye 360. "Working with NOAA, we were able to pinpoint a transmitter that had been missing for years and return valuable spectrum to the organizations that depend on it for environmental monitoring and public safety."