On Fri, Oct 30, 2009 at 4:04 AM, n1kcg <[email protected]> wrote: > Use a Nuvi 350, OT2m, and a Kenwood TM-V71. It works and gives > me waypoints of nearby stations, plus puts out beacons of my location, > but also noted it is not super reliable. > Set my beacon interval to 15 seconds, and my power medium. > Seems to work to get some location beacons out. Tried smart beaconing, > but that resulted in less packets transmitted, and a poor breadcrumb > trail plotting on aprs.fi .
You're new to APRS and this forum, huh? You've just done the equivalent of throwing chum into shark infested waters, slicing your wrists, and then going for a swim! 8) BTW, don't try making this same comment on the main APRS forum... The first thing you need to do is to put a radio on 144.390, and turn up the volume... do you hear anything? More to the point, do you hear much in the way of quiet time? Just looking at the APRS map of your area, I have a hard time seeing the map under all the APRS icons. http://aprs.fi/?lat=41.2847&lng=-72.9522&mt=m&z=9&timerange=3600 You have to share the frequency with all those other people out there. If every one of them were to send a packet every 15 seconds, do you think that there would be any chance of decoding anything usable? For simplicity sake, APRS can handle about 40 average users on the channel reliably. Add more users, and something has to give. Usually what happens is that packets start colliding (one station transmitting over another.). This destroys both packets. Boosting your power output might get you into the local digipeater better, but you are simply walking over other stations to win the fight. Sending packets at a faster rate might up the number of packets seen from your station, but it's the equivalent of walking down a crowded sidewalk, and simply swinging your elbows more. You might get more room on the sidewalk, but you're going to piss off a lot of people in the process. If you live in a congested area, you have to live with the fact that you might not be able to get every packet into the network. When it gets busy, the solution is to have everyone slow down their reporting rates. Just like a crowded freeway, more traffic means slower speeds as congestion builds. If you get one guy still driving at full speed, you get a bunch of smashed cars, and then throughput on the freeway stops. So, if you want to check to see if your APRS tracker is working well, I would suggest moving off 144.390, and using an alternate frequency for your testing. Yes, you would need to put another station on the same frequency to monitor the success of your packets. Yes, if you are driving out of range of that station, you'll need a digipeater or two on that frequency as well. In the Seattle area where 144.390 got really crowded, they build another 1200 baud network on a VHF frequency, as well as a couple 9600 baud networks, both on VHF and UHF. I live in a virtual APRS desert, and I would not think of trying to run a 15 second rate on a regular basis, it's totally inappropriate. James VE6SRV
