Hey Guys, Thanks for all the great info. I understand, and WILL NOT set up the airborne digi.
My aprs setup is documented here : http://www.mnwing.org/ click the powerpoint, skip the geeky LED stuff, and there is an overview of my setup. I fly a lot of rescue dogs and APRS is great for coordinating pickups! Thanks again guys hope you all have a good holiday!! PS there is a big APRS hole over western Nebraska as well! Pete --- In [email protected], James Ewen <ve6...@...> wrote: > > On Wed, Dec 23, 2009 at 7:34 AM, Peter Howell > <pete.how...@...> wrote: > > Hey Keith, Pete's callsign is KD0CVN-1 > > > I have the a Nuvi350/tracker2/Yaesu mobile setup running in my > > experimental airplane. It works great - super tracking - easily > > updated status messages, and the envy of my flying friends - > > the email from 10,000 ft! > > It looks like you might have done some homework... From what I can > see, you are using a single hop path at most. As you have observed, > you can get into the APRS network from an airborne platform very > nicely. > > As you are probably aware, in the realm of VHF communications, antenna > height is where it's at. When you are flying, you have some of the > best antenna height available. Running long paths, or very fast beacon > rates from an airborne platform can cause a lot of problems across the > APRS RF network. With just 500 feet AGL, you're probably going to get > into a LOT of digipeaters for many miles around. The APRS-RF network > can handle getting hit like that, but it's all your earth bound > neighbors that might feel a little miffed by you hogging the network. > > > I'd like to set up the digi function(mini awacs), but I am not well > > versed in how to set up the parameters. Is there a good guide I > > can access? The tracker2 manual makes it seem too easy - > > maybe it is. > > Okay, so... remember how you can hit a whole bunch of digipeaters from > 500 feet AGL? Well, the reverse is true as well, but it's not only the > digipeaters on the ground that you can hear, but every other station > on the ground. If you run an airborne digipeater that acts like a > ground based digipeater, you're going to be causing quite a bit of > noise. Every ground based station asking for a hop from a digipeater > will not only bounce through the regular digipeater network, but will > also be handled by your airborne digipeater. You'll be adding to the > noise factor in areas already covered by digipeaters. Also, due to > your altitude, you will be increasing network loads because you will > be causing stations located well outside the ground based digipeater > footprint to be included in the local digipeater network. > > Think of it this way, if you can hear a station 200 miles away, and > you digipeat him, another digipeater 200 miles the other direction > will most likely hear your digipeated packet. That means that the > original station which is 400 miles away from the ground based > digipeater is now effectively a local station, and will be seen in > that area. Now multiply that by a couple hundred times, to include all > the ground based stations you'll be able to hear... and you thought > that the earth bound peons were grumpy when it was just you making > noise from the sky... > > To get an idea of what traffic you might be bouncing around the local > RF network, try this... > > Go to the page linked below. > > http://aprs.fi/?call=kd0cvn-1&mt=m&z=7&timerange=3600 > > This will show the last hour of packets from your station, from the > last time you were up flying. Now without touching anything else, > click on "Show All" in the upper right side of the screen where it > says Track Callsign: [Clear / Show All] > > Hold on for a bit, and watch all the stations that you could > potentially be digipeating show up on the map. That's quite a few > stations, and an awful lot of airtime being used. > > Now, if you were flying around Saskatoon, Saskatchewan, things might > be a bit different. > > http://aprs.fi/?call=VE5RHF&mt=m&z=7&timerange=3600 > > Again click on the "Show All" link, and you'll see why you wouldn't > cause such grief. > > You can still run an airborne digipeater, as Bob by running it on a > frequency other than 144.390. If there is an alternate experimental > APRS frequency in your area, an airborne digipeater might be welcomed > as an interesting adjunct to the network. The other option is to run a > non-standard digipeater alias. Digipeating on just your callsign, or > an alias such as TEMPn-N would not cause problems, as the ground based > stations would need to specify using your airborne digipeater > explicitly. > > Yes, we are indeed raining on your parade. Think of it this way > though. Would you drag a VHF repeater up in the plane on 146.85 and > run it while flying? Of course not, you would interfere with the > repeater on the east side of St. Paul, and probably a couple others > depending upon how high you were flying. > > The APRS network runs on a single frequency, and there are literally > thousands of people using that resource. While amateur radio is > experimental by nature, we already know what the results of these > types of experiments will produce. > > Now, if you have a special event of some kind that could benefit from > having a long range digipeater available, feel free to fly one, but > just be aware of the issues outlined above. Set up a sked with some > buddies that are far flung, get the plane up at 9000 feet, and see if > they can bounce signals through you using a special digipeater alias. > You can still play and have fun, but you're not going to drag everyone > else in the world into the fray. > > I hope this makes sense to you, and gives some reasoning behind why > you would NOT want a flying digipeater on 144.390 acting upon WIDEn-N > packets. Maybe a little easier to live with than just getting your > fingers slapped and told NO! > > James > VE6SRV >
