APRS and SPOT

2008 has seen the arrival within the RV community of two fantastic enhancements to aviation safety and enjoyment. Both of these systems rely on GPS and the internet to provide means to track the progress of our flights and the current location of our planes. The safety ramifications of these systems is obvious to all who spend a little time studying them.

Please be assured the purpose of this thread is not to promote any sort of competition between fans of the two tracking systems. It is instead a fast track for pilots just being exposed to APRS and SPOT who are wondering about the features of each system and how they would be of use in personal aircraft. This post is based on personal experience and the experiences posted by users of both systems. In the case of SPOT, detailed info about the mechanics of the system can be found on the company website. In regard to APRS, the details are considerably more scattered since it is hobbyist-based, but the VAF APRS forum is by far the most comprehensive collection of info about APRS in the aviation environment.

SPOT:
1) Reasonable purchase cost of unit ($170)
2) Requires very little knowledge of the system on the part of the user
3) Requires no connection to aircraft systems
4) Has customizable methods of tracking and notification
5) Subscription-based service ($100-150/year)
6) Tracking option uploads beacons to the internet at ten minute intervals but display on the web site can be further delayed
7) Easily removed from plane for terrestrial or marine use
8) Is a commercial venture with phone and web support
9) Dependent on clear view of sky for connection with satellites

APRS
1) Reasonable purchase cost of system components ($120-250)
2) No subscription or access fees for internet tracking
3) Based on hobbyist use of 2-meter Ham radio band
4) Requires possession of Amateur Radio Technician License
5) Requires some degree of geekiness on part of operator
6) Provides practically real-time internet tracking down to ten second intervals
7) Usually is installed with some interconnection with aircraft electrical system
8) Is not easily removed from aircraft for terrestrial use
9) Dependent on population of land-based digipeaters and iGates for coverage

This list can be expanded with further details (and replies will not doubt provide additional info) but should provide an overview of the two systems.

Based on my experience, here are some observations which other users of the systems may or may not share.

1) For the pilot who has no interest in "hobbying" or learning a new interest, SPOT will be more easily added to the aircraft and implemented since the device can be simply "thrown on the dash" of the plane

2) For the pilot who wants to avoid subscription fees, APRS will provide the lowest ongoing cost for tracking service

3) The pilot who wants commercial support in all aspects will probably need to consider SPOT

4) SPOT may guarantee coverage over a wider area as long as the device can "see" the sky. However, field history is demonstrating the APRS network is very good in all but a few isolated locales.

5) If automotive or marine tracking is desired from the same device, SPOT is the more viable option

6) The highest degree of resolution and accuracy of aircraft tracking is available from APRS. SPOT is limited to ten minute tracking intervals which in RV time could be as many as thirty miles between beacons. APRS can beacon every few seconds in maneuvering flight which can pinpoint the location of the aircraft to a very high precision. SPOT does provide the option of sending a discreet beacon if the pilot is capable of doing so.

I hope this discussion is helpful to those exploring tracking options. The benefits of APRS and SPOT tracking are readily apparent and should become more and more popular as they penetrate our aviation community. Both systems were designed with terrestrial use in mind, but I think their greatest value may turn out to be in the aviation world.

Get one or the other

Sam - great list! First of all - Who you calling a Geek?!?

In this day of $10,000+ Electronic Panel Gizmos, one of these really devices should be in most everyone's plane. Great bang for the buck. Ask your spouse if she thinks you should install one.......

For those worried about the black helicopters tracking them down, install it on a switch, right next to your photon disruptors......

4) SPOT may guarantee coverage over a wider area as long as the device can "see" the sky. However, field history is demonstrating the APRS network is very good in all but a few isolated locales.

Very Isolated - Like Western Nebraska - Ugly coverage - Good thing most people (including me) don't fly there much I met some of the nicest airport people ever out there though.

I am not all that impressed with the spot's tracking on the ground. APRS is where I will go with my plane, but I am enjoying playing with the spot after the Oshkosh deal.

PLB?

Seems to me the PLB should be a part of the comparison even though the primary function is a little different..I.e higher purchase price but free for life (however long life maybe in the age of radpidly improving Gizmos).

Of course the PLB doesn't actually track your position it is a single purpose unit.

APRS is useful for in the air tracking but presumably not useful for finding a downed aircraft unless it happens to be in direct line of sight of a digi repeater..Highly unlikely.

Also SPOT presumably has a 5W transmitter like the PLB?

The PLB signal is triangulated using satallites that do not require a clear view of the sky..But GPS units can give markedly improved location if they can download their position.

All have to be manually activated except the SPOT and APARS May already be functioning in the case of emergency..The PLB most certainly will not.

Brief to my Wife "You hear that noise..if it goes bang then silent, hit that button, extend antenna, hold up the sky and pray...I'll be kinda busy"...

Frank

I'm really sold on the SPOT device.

A couple of weeks ago on a backpacking trip in NM with the Boy Scouts, ten sets of parents got to "travel along" as we hiked 10 days at the Philmont Scout Ranch. They all thanked me for the nightly "OK" messages.

On a separate trip with my daughter to Monterey, once we were on the ground I stuck SPOT up in the corner of the dash of the rental car. The Mrs. got to track us as we travelled all over the area.

A couple of months ago as my teenage daughter drove my son to Grandma's house, I made her take SPOT so her Mom and I could know where they were.

I bought it for flying, but that little orange box gets trucked all over the place.

John Allen


A couple of notes:

Those Lithium batteries aren't cheap, but they seem to last forever. I've got 35 hours on the current set.

The SPOT device just doesn't work under a forest canopy.

Great post as usual Sam ...

Fully agree with what was said. (I have both).

One little addition though.

The APRS **can** be packaged so that it can be "thrown in the plane" (any plane) and not be connected to any systems.

For those working on one using the 8000FA, there is a plastic "project box" that is just the right size for the 8000FA + AA (x8) battery holder and the 12 volt regulator. The DB9 connector fits through one end and the SMA antenna connector goes through the other. Sorry I do not have pix handy at the moment.

James
W4JEC

Great Thread!

It's funny you started this today am, because I have been playing with our new Spot for a couple of days now. I have had an ACR PLB on my shoulder for a year (Louise gave it to me for my birthday last September), and I am very comfortable over inhospitable terrain knowing that I can send my GPS coordinates with a push of the button. of course, it cost about $550, and will have to have a new battery every 5 years, and only functions in the case of an emergency.

We got the Spot for Louise, partly for the emergency function, and partly because she is commuting to work in her -6 now, and I'm hoping that the Spot will give me a better idea of when I have to have dinner ready! The tracking function is nice to have in addition to the emergency function. I am pretty confident in the ability of both the PLB and the Spot to transmit their messages to satellites if properly activated, and that those messages will find their way to the appropriate rescue parties.

One thing that I have learned about the Spot however is something pointed out above - in tracking mode, if you go down, and don't touch the unit, ten minute tracking intervals are still going to leave a HUGE area to be searched. Accurate, rapid rescue will only occur if you push the "Help" button on the way down, and/or the unit survives the crash and keeps transmitting (or you activate it on the ground). In this regard, it's reliability in accurate crash-scene location is similar to the PLB in my opinion. The Spot probably has a slight advantage, in that if you have it in tracking mode, and it survives the impact, it will keep transmitting if you didn't do anything on the way down, whereas the PLB will just be a brick if you are unconscious or dead.

The costs are probably a wash - in terms of Aviation Units, a five year span will see similar expenses, with the PLB a little cheaper. But we got the Spot free from Oshkosh, so we're already $150 ahead!

I simply don't have the time to tinker with APRS, but am mighty impressed with what many folks have done with it! I am a little skeptical about it's viability in the real mountainous west, but I'm willing to be convinced.

Paul

I have APRS.

1) It is much cheaper than Spot.
2) If you can build and wire up your airplane then adding APRS is a slam dunk.
3) If you can pass your PPL written then you can pass the HAM exam.
4) I installed a switch for those stealth missions.
5) My location is transmitted every 60 seconds.
6) The display of dots on the map is nicer than those balloon thingys from Spot.

Of course, the original thread addressed aircraft tracking which APRS excels at. Hiking, driving, boating, keeping in touch with loved ones is probably more the realm of Spot. For me, a PLB would be a nice companion to my APRS system if I ever had an off airport landing or had to ditch in the swamps of Georgia. But then, the gators would probably get to me first regardless of what equipment I had.

See what you started, Sam?

frankh said:

APRS is useful for in the air tracking but presumably not useful for finding a downed aircraft unless it happens to be in direct line of sight of a digi repeater..Highly unlikely.

Click to expand...

First. Sam good work AGAIN!

Frank,
I have to disagree with you on this. Here is how I would expect me to be found.... About 2 hours after dinner, wife scratching head..."where's Mike?" S.O.B. better not be flying. HE said he was coming right home...
Wife walks over to computer looks me up on the web... Oh look, S.O.B. did go flying 2 hours ago and ... wait.....went right into the lake right there. #$!@#$@.

Wife calls Mikes pilot buddy in a panic, "looks like Mike went flying and his track stops in the lake"..... Buddy pilot begins doing what buddy pilots know how to do.

Now someone with a clue can continue the operation and they know EXACTLY where to look.

Seems to me that the APRS puts very good accuracy on me and the web tracking means the one person who pretty much knows where I SHOULD be all the time would be the first one scratching head wondering where I was when I was late. The web tracking is the key and the fire and forget (start engine and its on) means its likely to work when I need it.

I have feared that if I ever went in, no one would find me for years. Maybe the fear is unfounded. I dont have that fear with APRS anymore. 99% of my flying is over great coverage areas.

Just imagine how many could have been found if they had one of these running when they went in. Dead or alive, they will find you and even in a crappy coverage area, they will get very close. Between APRS, radar, ELT and so forth, you will get found with APRS. I have never felt that was the case with any other system.

I love the SPOT gismo. But Im a geek and I HATE HATE HATE subsciptions.

My 2 cents and very biased view of APRS since I just got mine installed.

APRS in the Rockies

http://tinyurl.com/64engf

My APRS unit is firmly placed in the bottom of my trash can. I wasted 1 month and nearly $425 trying to get (just 1) packet out of it. It was a complete waste of my time and money.

I ended up buying the Spot and it was running less than 3 minutes after I opened the box. By the way, it runs for 14 days on batteries. That's pretty cool too.

Phil

Kahuna said:

First. Sam good work AGAIN!

Frank,
I have to disagree with you on this. Here is how I would expect me to be found.... About 2 hours after dinner, wife scratching head..."where's Mike?" S.O.B. better not be flying. HE said he was coming right home...
Wife walks over to computer looks me up on the web... Oh look, S.O.B. did go flying 2 hours ago and ... wait.....went right into the lake right there. #$!@#$@.

Wife calls Mikes pilot buddy in a panic, "looks like Mike went flying and his track stops in the lake"..... Buddy pilot begins doing what buddy pilots know how to do.

Now someone with a clue can continue the operation and they know EXACTLY where to look.

Seems to me that the APRS puts very good accuracy on me and the web tracking means the one person who pretty much knows where I SHOULD be all the time would be the first one scratching head wondering where I was when I was late. The web tracking is the key and the fire and forget (start engine and its on) means its likely to work when I need it.

I have feared that if I ever went in, no one would find me for years. Maybe the fear is unfounded. I dont have that fear with APRS anymore. 99% of my flying is over great coverage areas.

Just imagine how many could have been found if they had one of these running when they went in. Dead or alive, they will find you and even in a crappy coverage area, they will get very close. Between APRS, radar, ELT and so forth, you will get found with APRS. I have never felt that was the case with any other system.

I love the SPOT gismo. But Im a geek and I HATE HATE HATE subsciptions.

My 2 cents and very biased view of APRS since I just got mine installed.

Click to expand...

I must admit I loved the writing style and any married man can relate..

I would agree that provided someboday was looking they could probably get a good idea of where you are.

Mind you, did we not lose an RV6 over NM and ATC had a hit on him at 2000AGL?...I seem to remember it took weeks to find him.

Maybe that was just misfortune but I think your argument at least partly depends on the kind of terrain.

I too hate subscriptions and so for me the PLB is the way to go...It has significant disadvantages in itself of course.

Frank

Phil said:

My APRS unit is firmly placed in the bottom of my trash can. I wasted 1 month and nearly $425 trying to get (just 1) packet out of it. It was a complete waste of my time and money.

I ended up buying the Spot and it was running less than 3 minutes after I opened the box. By the way, it runs for 14 days on batteries. That's pretty cool too.

Phil

Click to expand...

Phil, if you don't mind digging your APRS gear out of the trash can and sending it to me, I'll be happy to pay shipping.

(Trying to think through the $425......$180 for the tracker, $60 for a GPS, $25 for an antenna, and.........)

My hangar mate's wife watched the breakfast run this morning from home and has delivered orders for him to install APRS in his plane......now.

I will pay shipping, plus a small admin fee!

Expand APRS

Best thing those of us who have used APRS (and see the potential) can do is try to set up more iGates...I'm gonna put one up on a tower in Independence, OR that will cover much of the Willamette Valley and west to the crest of the Coast Range...
I think we could/should probably buy a few cheapo computers, load in the appropriate software / hook up the scanners and do some real good toward expanding the coverage of the system. As Pete has already done, we should look for "holes" in the coverage and get serious about finding ways to increase coverage in those areas. I don't have the techie skills (or TIME) to get this done, but I'll donate $$ to help anyone who wants to get it started.

FWIW, I too carry an EPRB...but I don't keep it open and unfolded with my finger on the button, there is still time needed to deploy and send the signal. The beauty of the APRS system is the frequency of transmissions...plotted almost real time on the web. I've sent notes to all my family showing them how to "look me up." Even if APRS doesn't save your bacon, it gives peace of mind to family. For sure, some people would have been found if this system was installed in their aircraft.

Cheers from Buenos Aires...

fliier said:

I'm really sold on the SPOT device.

A couple of notes:

Those Lithium batteries aren't cheap, but they seem to last forever. I've got 35 hours on the current set.

The SPOT device just doesn't work under a forest canopy.

Click to expand...

SPOT will work just fine on DURACELLS. Just not as long........