On Thu, Apr 29, 2010 at 6:59 AM, Randy Love <[email protected]> wrote:
> Thus, if you have a 3 hop path, and you are in an area where > the 3 hop path can be fulfilled, your packet will go thru 3 > different hops. Please note, this does not necessarily mean > 3 different digipeaters. This means 3 different relays of your > packet expanding outward in all directions! And even that is not accurate. You are telling your packet to go three levels (hops) outwards from your location. If there are only 3 digipeaters that can be accessed in your area, you will get three hops. If there are more, you'll activate more. Let's say you are in an area where three digipeaters can hear you directly, you'll be digipeated by all three (first hop). If each of those are heard by 3 more unique digipeaters, you'll get digipeated by those (second hop). If each of those digipeaters can be heard by 3 more unique digipeaters, you'll get digipeated by those (third hop). Start counting. 3 digipeaters on hop one, 9 on hop two, and 27 on hop three. That's 39 digipeaters total. Obviously this is a simplified mathematical abstraction, and probably doesn't exist anywhere. In some areas, you might only hit one digipeater on the first hop, or maybe 6 or 7... Each digipeater can be heard by a variable number of other digipeaters, which may or may not overlap with other coverage areas. If you want to see what kind of impact you are having, use the aprs.fi info page for your local digipeater, and look at the section that has "Stations heard directly by (your local digi)" copy down all the callsigns of the stations listed there as a digipeater. Do the same for each of those stations, and then once more again. Now, if you're heard by more than one digipeater on the first hop, go back and start all over. You'll probably find many duplicates because the digipeaters usually make a mesh rather than straight lines of propagation, but one thing you'll find out in a hurry, is that the number of digipeaters add up in a big hurry. Then what you need to do, is to figure out just how far each of those digipeaters cover. You can get a bit of an idea of that area by clicking on the "show map" link on the "Stations heard directly" line of the digipeater's info page. You also have to remember that the information collected by aprs.fi is all filtered data. The collected information is only the first packet to make it to the APRS-IS stream, as all the others are discarded. This means that we are only looking at a small subset of the number of packets bouncing around the network. I've asked Hessu (webguru at aprs.fi) to create a routine to automate all of the above for you, so that people could simply click on a link to see "Just how bad am I hammering the network", but Hessu is concerned that instead of people using it to reduce their impact, some would go the other way, and deliberately try to make as large of a splot on the map as possible. James VE6SRV
