2007-08-09 Radios and Emails

I've gotten some surprised commentary about the size of a couple of my emails lately, and thought I should offer some explanation. It's a bit technical, but bear with me. As we explained before, the time on the radio frequency is the limiting factor for each subscriber's use. The Winlink and Sailmail operators are continuously trying to increase speed, to allow more information exchange in that limited time. I spent about $800 just before we left NZ to upgrade our radio modem to the newly developed Pactor 3 code from Pactor 2. In good radio conditions, that will increase maximum transmit speed from about 400 bytes per minute to about 1400. But if radio wave propagation is poor, due to low sunspot activity, or if background noise is high, due to solar flares or human RF activity, the maximum won't be reached. The developers of the system came up with a clever protocol where a segment of information is sent, then the recieving end sends it back. If it comes back right the transmission continues where it left off. If it has errors or holes in it, the bad parts are re transmitted until the return is correct. So, if conditions are bad, data may have to be exchanged up to 5 times to get it right. That slows even Pactor 3 down to under 150 bytes per minute. Learning to get the most out of the system involves learning when the propagation is best and the noise the least on each of the 10 frequencies the Sailmail station at Firefly, Australia moniters. Two things have been improving our use. I've been learning which frequencies work best when, and radio propagation in general has improved in the last week. I was expecting to have to break the longest of those emails into two or three segments, as I did with the reef story. I was astonished to see the transmit speed rising to over 1200 bytes per minute when I sent a short batch of business emails, so as soon as that was finished I posted the big message, and re connected. I love it when it works like that, but we can't count on it. We do get to be dependent on it though.

This morning just at the end of the Rag of the Air radio net, with the wind blowing a low-end gale, Jim heard a big clunk and the radio went dead. His antenna wire had come down from the tree that held it. That meant he couldn't order materials, couldn't contact Kyoko, who has gone to Labasa for the week, couldn't send or recieve information about the licenses and visas we need. But coincidence is a strange thing. Yesterday afternoon a NZ yacht arrived unannounced, and it turns out lorrie is a very competent radio technician and was keen to give us a hand. I went out to the Also 2 on its mooring, and took off the broken HF radio whip antenna that has languished there since the last cyclone 5 months ago. I spliced the break, and Steve (Red Sky) and I devised a mounting for it on a tree up on the hill. Sea Eagle 2 had arrived late last night with Ross and Pauline and their boy Hunter. They and Lorrie set about rewiring the automatic antenna tuner to work in the new system, and we all had a hand in devising and installing a grounding system. Just before dark, the last wire was connected, the system tested, and Sailmail contacted and messages sent. If it was going to break, it could have done it at a MUCH worse time. I've said before, there's a LOT of talent out here sailing around. It's fun to have a team come together like that, from nowhere, and solve a problem. Good, too that everyone's competent boat handlers. The gale force gusts are still blasting off the hills, but no anchors are dragging, everything is sitting nicely here at Also Island. Ted