People, listen up. This is a wild theory here, but it makes sense to me. For those who have played the ArmA II campaign, they would know that Chernarus was invaded by the US, thus the US weaponry and such lying about. And evidently they also took control of the Green Mountain facility. It would be very possible that the US conducted experiments on Chernarus' citizens involving biochemical warfare agents. Now, what would happen if something went wrong right here? What if the quarantine was broken and the subjects were set free. Some of the initial call-out numbers could be prisoner numbers and the Morse code could be the last piece of transmission from US forces at Green Mountain, set on a loop if any US forces were to come nearby. Now, the US is gone from Chernarus, indicating that their mission was done there, but still, there are US soldiers in the mainland. Thus this brings me to this: The Infection started while the US was still in Chernarus. What if the mission failed due to the infection? Soldiers became infected, warnings were sent out, yet still the camps were raided by the undead. This would cause the carrier battlegroup to evacuate as well as they could. This is where Green Mountain kicks in again. The message was put on a loop and the battlegroup pulled out, leaving people to fend for themselves. And as the message is tied to Green Mountain, this could indicate issues with the antenna, leading to that the message was never broadcasted outside the mountain, this would explain why there still are so many military bodies in Chernarus, they didn't know it was coming. And now if Green Mountain was the facility where the infection started, could it not be possible that the very same biochemical agent came with the carriers back to the US? Then about the grid locations, indeed, there are deerstands there, but what about the hunting towers? People said they had radios and military grade equipment, possibly showcasing that the towers were occupied by military forces and used as transmitting beacons, who knows what other places we might find? /Theoretical stuff over. Either way, that's how I think of it. This kind of stuff really gets me up! Go Day Z and Rocket, I love these eastereggs! Also, I have a request for the community. Would it be possible for someone to head down to some of the islands in the south and try to find a signal there? If so, thank you!