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A Royal Australian Air Force (RAAF) Orion aircraft (back) prepares to take off from RAAF Base Pearce near Perth April 6, 2014. Australian Prime Minister Tony Abbott said on Sunday searchers were "hopeful but by no means certain" that a pulse signal reportedly detected by a Chinese ship in the Indian Ocean was related to a Malaysia Airlines jetliner, Flight MH370, missing for four weeks. Seen in front is part of a Royal New Zealand Air Force (RNZAF) Orion aircraft. REUTERS/Richard Polden

Almost a month after Malaysian Airlines flight MH370 went missing over the Gulf of Thailand, searchers are focusing on two areas in the Indian Ocean where they detected possible signals consistent with MH370’s black-box pinger.

The signals were detected by the Australian ship HMS Ocean Shield and the Chinese ship Haixun 01 about 300 nautical miles away from each other.

Searchers are hastening to detect pinger signals because MH370’s black-box pinger battery could expire during the next two weeks. The pinger battery lasts from 30 to 45 days, with April 22 being the latest to find a signal. A confirmed signal would greatly narrow the search area, which is now the size of England.

The Chinese vessel Haixun 01 has reported two signals at the 37.5 kHz frequency. These signals were detected about a mile away from one another with equipment used just below the surface of the water. While not confirmed, the Haixun 01 signals are promising for their consistency, and one signal lasted 90 seconds.

Retired Air Chief Marshal Angus Houston, who is coordinating the massive search effort, calls it the most promising possible evidence so far.

“I think the fact that we’ve had two detections, two acoustic events in that location, provides some promise, which requires a full investigation.”

He went on to stress that there is no confirmation of the origin of the signals, and told journalists, “I urge you to continue to treat (the news) carefully.”

He did say that Chinese search planes detected “white objects” floating on the surface about 55 miles away from where the signals were detected, according to the South China Morning Post.

The British Royal Navy ship HMS Echo is headed to the area where Haixun 01 detected the signal to deploy their listening equipment, which may be able to confirm the signals and possibly identify them. HMS Echo is expected to arrive early Monday morning.

Haixun 01 detected the signals south of where the Royal Australian Navy ship Ocean Shield is investigating signals it detected. Ocean Shield has the most sophisticated search equipment of any ships in the search; its specialized towed pinger locator can detect a black box up to 20,000 feet below the surface. The distance between the Haixun 01 and Ocean Shield signals suggests they came from two different sources.