New Off Road Project Help

[djthumper]

I am actually surprised that are hams aren't using APRS also. Some of the places I have been SPOT didn't work very well but I had good coverage with APRS.

[Mooseknuckle]

some people think different. do what you want first. I personally try not to go alone i dont have a winch...yet. A second set of eyes and someone to pull you out is definitely key. Dont get me wrong recovery equipment is a must but so are friends with the same interest that can help ya out as well. I went the lift route first with a small amount of recovery equipment. I'm not Bill Burke so I'm gonna ease into it. When i go out alone it's in a small area. Knowing it is basically a recon. Anyway,do what you feel is the most important first. You wont be wrong no matter what you do.

[Trail X]

My understanding is that APRS is an amateur radio sorta thing?

SPOT is a subscription based service... if you need assistance, press the SOS, and they will get help to you no matter what.

Where have you not had SPOT service?... the only thing I can imagine is inside a canyon or in the satellite shadow of a large mountain.

[The Roadie]

SPOT technology is one-way only, so the personal beacon can't confirm that messages got to the satellite group and received. That's why there's dropouts sometimes in a tracking session, and why emergency messages are set to auto-repeat for some amount of time, like an hour IIRC. There's an LED that tells the operator if the unit's getting a good GPS lock, and I've seen that be a rare problem in slot canyons. Is that what you mean by SPOT "not working well"?

APRS depends on messaging support in the radio. Greg's has it, but mine doesn't. It might be useful to keep track of a spread-out group, but if you have APRS messaging capability, you can also talk by voice and exchange GPS coordinates and meet up that way.

[KE7WOX]

You need a pretty good radio $400+ to get APRS capabilities. Most lower end radios won't do it.

The main thing about APRS is that you also depend on coverage, and for that matter, satellite is better. As Roadie said, if you're traveling in a spread out group then it works, but for emergency tracking I'd go for Spot (or even both, just in case). Some GPS units (mostly the old ones) have a hard time getting signals in cloudy weather or inside vehicles, but then again, technology should have improved (I'm still using a 6 year old Garmin eTrex, coverage in areas with dense foliage or dense clouds sucks, and it won't pick up signal unless it's sitting by the windshield (I suspect that my heavy window tinting does act as a faraday cage for the GPS). The advantage of Spot is, IIRC, you don't depend on vehicle power for transmitting.

[The Roadie]

And as I just kicked myself for neglecting ... you can put the SPOT in your pocket/belt/bug-out vest when you leave the vehicle for a short hike, fall down, break your glasses and potentially break something else so you can't get back to the vehicle and your SPOT. Just like when Teebes and I LOST our two parked vehicles and went on a 2-3 mile 90 degree hike around a hill to rediscover them. If you have a hand-held GPS, make a waypoint for the vehicle if you ever leave it, and then carry the GPS and enough water for more than 10 minutes.

[djthumper]

Yeah APRS is amateur radio. I was just curious since I know Roadie and a few others are hams also. I see advantages of both. Where I had problems with SPOT was in canyons and close in areas, it had a GPS signal but could not send out a report. Several of us were doing some testing for Baker to Vegas race that we support.

Roadie, APRS isn't just for a short spread out group where you are close enough to talk on radio. with digipeaters and igates the signal can go for hundreds of miles. Yes they have radios out there with APRS built-in but not required. You can a TNC and connect to your present laptop and work APRS also.

Just yesterday I put a tracker on a bicyclist that was doing a sweep of a trail that we could not send vehicles up. I was able to do live tracking in my vehicle but the track can been seen on the internet as well. Click http://aprs.fi/?call=SAG&dt=1272672000&mt=m&z=11&timerange=86400 this was done with a one way tracker but in an emergency I set it up to beacon ever 90 seconds so that we could send help. The tracker is only $260 http://www.byonics.com/microtrak/mtaio.php.

I didn't mean to hijack the thread but I was curious of the APRS usage and now hopefully gave a little better understanding of it.

[Saxis]

How much better is the signal from SPOT than say, XM radio? Satellite, cell and radio signals are pretty much worthless anywhere there is a trail here. I don't get very good reception from SAT or cell on the highway half the time. Sometimes you can find service on the tall hills if they are clear-cut, but if you're stuck or injured, you're pretty much fokkered...

[Trail X]

Hard to tell what the signal strength is... remember it's in reverse. The SPOT is the one sending the signal to the satellite. It's GPS signal is as good as any other GPS system, it uses the same GPS signal.

For SPOT's claimed signal service: http://www.findmespot.com/en/index.php?cid=109
They claim 99% signal success rate in the CON US.

[djthumper]

The GPS receiver in the spot is very sensitive and only has to receive small packets of information. so it is a lot different from XM radio.

[Zero]

Ive never had my sat radio lose service unless i am in underground parking. Even deep in the canyons of the badlands in the dessert with Roadie I had no problems.

Maybe you have an old system or an old antenna? I use sirius by the way

[Saxis]

Ive never had my sat radio lose service unless i am in underground parking. Even deep in the canyons of the badlands in the dessert with Roadie I had no problems.

Maybe you have an old system or an old antenna? I use sirius by the way

Not sure how old it could be on a 2008. It's the factory XM antenna/tuner connected to the BLOSE stereo though, which I've heard don't receive as well as an external.

[janesy86]

Not sure how old it could be on a 2008. It's the factory XM antenna/tuner connected to the BLOSE stereo though, which I've heard don't receive as well as an external.

My reception goes in and out when I'm in the sticks... not offroad just in smaller towns with more trees.

[fishsticks]

Keep in mind XM has terrestrial backup (ie FM) in many areas. So you aren't ALWAYS feeding from the satellite.

[Zero]

Sounds like the only way to fix your problem is to switch to Sirius, or get an external antenna.

[Saxis]

:Iagree: My reception goes in and out when I'm in the sticks... not offroad just in smaller towns with more trees.

I'll lose reception about 10 times on my 22 mile commute to work, mostly on a 12 mile stretch of highway surrounded by trees and hills though.

[Saxis]

Keep in mind XM has terrestrial backup (ie FM) in many areas. So you aren't ALWAYS feeding from the satellite.

Why wouldn't I also lose FM service in those same areas then?

[Trail X]

Keep in mind XM has terrestrial backup (ie FM) in many areas. So you aren't ALWAYS feeding from the satellite.

I believe Sirius does too. Who cares, its the same company anyways.

[fishsticks]

Keep in mind XM has terrestrial backup (ie FM) in many areas. So you aren't ALWAYS feeding from the satellite.

Why wouldn't I also lose FM service in those same areas then?

Different frequency. Also a digital carrier vs standard radio's analog carrier.




JD's right as well.

[djthumper]

FM runs on higher power then XM. The satellites run at a lower power output and the trees absorb RF. You are already running on an external antenna, they combined the XM and On-Star antennas starting in 06, from what I have read.