September 12th, day Ten, AA6DY

Today’s location information was more difficult to decode. When things are going well, we get two packets of information – message 1 and message 2 every 10 minutes. We think of the two different packets as the main packet and the supplemental packet. Today we received only one packet the entire day – and it was a supplemental message 2 packet. It was received on 05:14 UTC at Grid NN36QW North China, Kazakhstan to the west, Mongolia to the east and Russia to the north. We went to sleep on September 11th just east of the Caspian Sea near Uzbekstan on the bottom left of the map.

Our tracker sends out one message on the 2’s (02, 12, 22, 32, 42, 52 after the hour), and one on the 4’s. Any ham station that hears our signal will post the message to a database over the internet. To be able to piece together all the information to accurately locate the balloon, we need both messages. If we just receive the message sent on the 2’s (first packet), we can estimate our balloons location somewhere within a 7,000 square mile grid, and an altitude within 1,200 meters. If we also receive the message sent on the 4’s, we can locate our balloon to a 15 square mile grid and an altitude within 320 feet. The first message has a ham call included in the packet, but to save space in the packet, the second only has a hint of its sender.

Today we received only a single packet – and it was a message 2, meaning we received one packet that has only a hint of the identity of its sender. Based on its location and two ID characters we purposefully encode in message 2, we think it’s ours.

We’ve been getting regular reports on the 1st packet at 13,000 meters. The 2nd packet has been giving us around 670-910 additional meters. When I report our altitude at 13,910 or 13,670 meters that’s with both packets received. If you happen to be monitoring the APRS site you may only see an altitude of 2,197 feet, we’re not on our way down, that’s just the 2nd packet.

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