A cow has managed to activate an emergency position-indicating radio beacon (EPIRB), setting in motion a response by Canberra authorities and Northern Territory Police.

About 6:00pm on Saturday, monitors in Canberra detected an EPIRB signal emanating from an area north of the NT township of Adelaide River, about 3,000 kilometres away.

They alerted police officers at Adelaide River, about 113 kilometres from Darwin, who rushed to a paddock on Pell Station.

When NT Police officers got there they could not see anything other than grazing cattle, but as daylight ebbed away, a flashing light on the beacon became visible.

"The beacon was not registered but eventually ownership was traced to a chopper company from Katherine," Superintendent Louise Jorgensen said.

She said the device had fallen from a helicopter in March while the pilot was mustering in the area and had remained there until "activated by the heavy-footed, hungry beasts" which had tried to eat it.

Territory Duty Superintendent Brendan Muldoon urged people to register their emergency beacons.

"This EPIRB was lost some time ago ... it fell out of a helicopter," he said.

"The problem is, if the device had been registered, the owner could have been contacted and we would know it was no longer in use.

"We treat every incident like this as a life-threatening emergency."

Duty Superintendent Muldoon said anytime a device was activated, police threw "everything we've got at it".

In a statement, the Australian Maritime Safety Authority urged all beacon owners to ensure their details were up to date, in the event they sell or loan their device.

"This gives search and rescue officers vital information to assist in genuine search and rescue operations," it said.