On Mon, Oct 12, 2009 at 3:09 PM, Keith VE7GDH <[email protected]> wrote: > Scott N1VG wrote... > >> I'm not seeing it on the site - the only link I see is for the forums.
It's tough to know what they are up to without knowing the callsigns used... I see AF6IM-7 around the Byron Airport on Sept 19th and 20th. This station was using a path of RELAY,WIDE3-3. That would make it effectively a zero hop path unless some stations around were mis-configured. > The forum makes a mention of WIDE3-3 but also mentions some alternate > frequencies as well as 144.390. I understand they are using either a T2 > or OT2m so they could vary the path and beacon rate based on altitude. > It would be nice to use a short path (or no path) while at 24,000 feet, > but something like a two hop WIDE2-2 below a few thousand feet. The > last post indicates they will be on 144.330, so no path would be needed > unless they set their own digis up. Regardless of the frequency, I can > see that recovering the payload would be of prime importance! Everyone has to go through the same process... 10,000 feet of antenna height and 3 hops paths, and still seeing holes in the tracking, so the next obvious step is to take an amplifier up to get more power... maybe a 13 element yagi too! For a project like this, in an area of dense APRS activity, you HAVE to move off 144.390. Zero hop paths work just fine. With a low altitude drop like this, and a manned payload that is going to be actively returning to the drop zone, a zero hop path is the logical choice. If there should be an issue with an incapacitated skydiver, then your recovery teams should be already deployed down range into the anticipated recovery area. As they have suggested, if they are going to be moving to a separate frequency, then they will need to provide their own receive stations, and if desired i-gates. It is pretty easy to set up a mobile i-gate on any frequency using a cellular telephone with a data plan, and a laptop connected to your receive equipment. The open trackers could easily be set up on a single simplex frequency with a 5 second reporting rate each, and use time slotting to keep from clobbering each other. I would not plan on using the APRS-IS as my main source of data recording, and especially not for tracking and recovery of manned payloads. If those involved in this project are interested, we have a similar project happening around here that we are involved in. We are doing experiments with high altitude balloons using unmanned payloads, with the BEAR and SABLE projects, but will be primary tracking and recovery crews for Le Grand Saut, a manned expedition to 40 km (131,000 feet) above the earth with a world record skydive/parachute recovery jump. Of the many tracking systems on board, only one will be on 144.390. Critical telemetry from Michel which includes physiological sensors will be done on a licensed frequency. Other trackers for the 1 ton of balloon, and 1 ton of gondola will be on distinct frequencies as well. Le Grand Saut has been many years in planning, and attempts to get off the ground, and hopefully next May will see a successful launch and recovery. Le Grand Saut http://www.legrandsaut.org/ BEAR http://bear.sbszoo.com/ SABLE http://bear.sbszoo.com/sable/ We're always more than happy to share experiences and lessons learned with others. I know I can't afford to make all the mistakes made by others again... I'm happy to learn from others and modify my experiments to suit. James VE6SRV
