Routine positioning for hams

Reading all the posts about the Kims, PLBs and trip route planning, it occurs to me to bring up APRS, or Automatic Position Reporting System as a trip safety tool. This is an Amateur Radio method of sending short packets of data that usually include GPS position data. This allows people to see where you are on a reasonably continuous basis, depending on the area.

Many operators have this in their cars, boats, planes, where it transmits positions routinely (between 3 and 30 minutes). Usually these packets are received and injected into the internet (via APRS-IS) where they can be viewed worldwide. Internet APRS traffic can be viewed using inexpensive software or for free using the www.findu.com gateway.

Most often APRS is transmitted over VHF to ground stations; however, VHF transmissions can be picked up by several satellites or the International Space Station, and relayed to the APRS-IS. Alternately, APRS packets can be transmitted over long distances over HF to internet gateways.

A simple, transmit only APRS system can be put together for $100 or less, with more complex systems costing more. In many cases, the same equipment can be used with a laptop to send email thru public gateways using a system called Winlink 2000.

http://web.ew.usna.edu/~bruninga/aprs.html
http://www.aprs-is.net/
http://www.findu.com/
http://www.winlink.org/

Interesting notion for hikers and bikers in repeater range.

It's been a while since I've read part 97, but I think the idea of putting together a transmit only version is contrary to the FCC rules for amateurs.

Some broadcast transmissions, such as those from W1AW for code practice or bulletins are OK, but I believe that most other one way transmissions are not allowed.

It's not. Believe me, it's been hashed out. It's not considered a transmission of general interest. Last time I looked, there were over 40k stations worldwide.

You can rig something up for $100? How?

The cheapest 2M radios are about $150 after rebate. A decent antenn and an NMO mount will be close to $100. The GPS itself will run at least $50 used. You also need a TNC, which I have not priced lately.

With all that being said, I would be perfectly happy with a simple GPS, and a 2M with enough guts to hit some nearby repeaters.

For that matter, if the SAR team knew that you were a ham when looking for you, I would imagine that they would try to get you on 146.520. If they get within five miles of you in an aircraft, you should be able to work them.

I have been using APRS for many years. Mostly so family and friends can see where we are We are nomads and seldom plan our future. To see our present location, click the following url. Then click the Satellite view. Shows our location superimposed on as satellite photograph (not real time, it uses a stock photo). Accurate to about 15 feet.

I have one system in the 5th wheel and one in the truck. There is a mode of operation called "EMERGENCY", which when enabled, will cause all other systems online to sound an alarm and display my coordinates and a text message. There are VERY few false alarms. You can check emergency messages by clicking the "Emergency Beacons" link on the left of the page.


Our current location.

Man, your paying WAY too much for your 2m rigs

Go, buy yourself a GE MVS and a RIB, or get someone to program them - or an old Phoenix. add a TinyTrackIII...

I typically buy used 2m rigs for APRS/PACKET/dedicated use for less than $40. Heck, a few months ago, I was offered 20 rigs for FREE - they ended up in the trash

Did a completed item search on ebay - they typically go for around $25. A TinyTrackIII runs $27 without a case. A Built, tested TinytrackPLUS is $47, and he'll sell it to you with a GPS for $108

$160 should totally set you up with a APRS box with out breaking a sweat

Should have offered them up here to the first 20 replies.
I'm starting to look at those and see new 2M around $200 locally.

KC2IXE is right. I said you could get into APRS for around $100, but to do it, you've got to be willing to hunt for parts and do some of your own assembly. Around here we've seen retired business radios for about $30. Add a TinyTrak or OpenTracker for between $20 and $30, and a OEM GPS board for about $25, and you are set.

http://www.byonics.com/ (TinyTrak)
http://n1vg.net/opentracker/ (Opentracker)

On the other hand, if you have a laptop, you can put together a radio to sound card interface cable and skip the TNC all together.

Exactly!

Thanks for bringing this to our attention, John. Very interesting concept. I skimmed some of the links provided. Did I understand correctly that APRS also supports two-way messaging? So, for example, in the "lost in the wildnerness" scenario, the emergency mode would broadcast your position, and would you actually be able to converse with someone? For example, to get medical advice for a buddy who was seriously injured out in the field?

Can someone explain what this is and what this does in terms someone with zero experience on this subject can understand? Is this like an Amateur Radio based PLB?

That's basically correct, but let me clarify just a bit. An APRS station runs all the time in normal operation, and can be seen by everybody. There is an emergency code you can set in the encoder, which can raise an additional alert for those people who are watching.

If you have the right equipment, there is a capacity to send short messages. No more than 256 characters, I think. These can be sent as regular email, as long as you are in range of an internet gateway. Winlink over HF really shines for email. I went to Mississippi after Katrina, convoying with another guy who had a new HF Winlink installation. He was able to send and receive email all during the trip.

Sure. Think of it more as a fleet vehicle location system, where your location can be tracked all the time. If you were to run into an emergency, such as the Kims' where you were stranded in the woods, the internet portion of the system would retain a trail of your last positions that rescuers could use as a starting point.

However, with a ham license and the right equipment, you could have the flexibility of transmitting your position over long distances using HF radio or by transmitting to any of the available satellites.

Well, I would have had to travel to get the rigs - plus they were BIG heavy out of date rigs that I would have had to prevail on a friend to program (commercial rigs - GE Rangrs for those in the know) - plus 110watts .

Forgot to add - heavy enough that the shipping would cost more than what you could buy a smaller, newer rig on eBay for. I called around to local hams - got rid of 2 or 3 that way. There was a point a few years back (before I knew the guy) - he threw out 200 of them in ONE day. And yeah, he's a ham. Around here - you want to run commecial rigs as a ham, he's a GOOD man to know

Actually, I believe I could build a nice 5 watt Hf rig set to 2182 Khz with an automated repeating SOS on CW that would run for about 12 hours or so. Someone is always listening on that frequency, and you would be DF'd with a fairly tight fix after the first hour or so of transmitting. Get into trouble? No problem, just flip the switch and let the little black box do the job from just about anywhere in the world. Try finding a good PLB for $50 these days.

You could do the same on 500 Khz, but I think the ERP at 2182 Khz is going to be better from a pocket portable device. I'd probably try and scavenge a bar mag antenna from an AM portable receiver and see if I could get a decent Z at frequency with a Hi-Q disc cap or some such.

Ahh, those kind <img src="/images/graemlins/smile.gif" alt="" /> I was given some old train radios when I was a kid, made nice panels to build a pretend spaceship in the closet with.
I'm trying to find inexepnsive handhelds to play with and add t my bob.

I believe that transitters for that frequency have to undergo certification testing per FCC part 80 or 87 depending whether it's a maritime or aviation application.

I also read that the modulation is limited to J3E (single sideband suppressed carrier) or H3E (single side band full carrier). This means that the modulating signal must be analog telephony.

Part 80 (maritime) requires that the minimum PEP be 60 W, I didn't check part 87 aviation to see what the minimum power requirement is there.

So I'm guessing that while this is something that could be put together and used in an emergency, it's not a viable option for wide spread use.

Around here the OMs tend to convert retired portable tranceivers to APRS stations. If the mike is still operable they may be able to establish full two way communication.
I got a TH7F (not retired yet) and a cable for TinyTrack. So I could send my APRS data when I want to.

I clicked on this link thinking about Christmas hams and wondering why they would be discussed on this forum. BTW, I think my wife routinely positions our ham in the center of the oven, and turns it around about half way through because the back of the oven gets slightly hotter.

> It's been a while since I've read part 97, but I think the idea of
> putting together a transmit only version is contrary to the FCC
> rules for amateurs.

From part 97:

In english for everyone else.. is that the rule that says 'screw all the FCC rules and save your bacon if you need to' rule?

Pretty much. Its the "if its really an emergency then use any means of communications you have license or not and we'll waive the fines until after your found" <img src="/images/graemlins/smile.gif" alt="" />

:-)

Hey, the way I hear it, words mean something!

Not only has it been a while since I'd read part 97, I've apparently not be following the whole APRS craze - neat stuff <img src="/images/graemlins/smile.gif" alt="" />

After looking at the rules a bit last night, APRS, though not specifically mentioned, seems to fall under telemetry which is an acceptable use of one-way transmissions.

Still, there's a difference between what you can do in an emergency and what you can do for routine operation.

For now, I'll stick with letting people know where I'm going and carry my cell and dual band HT with me. I hope to soon add a PLB to the gear I carry.

If it comes down to a nasty situation, and I can't get out on my own, then I'd hope to be able to use the cell phone, then HT, and finally the PLB as a last resort to call in for help.

I'm all for using Amateur radio to the fullest extent, but in the end I'd rather spend the extra bucks on a PLB than rely on a APRS setup that I've cobbled together and then hope someone can hear the transmissions. With a PLB, the satellite's always up there listening <img src="/images/graemlins/wink.gif" alt="" />

For one thing, I hope they wouldn't be able to fine you unless your found.. for another, I'd hope that if it was a real emergency, that rule would protect you from being fined..


Words do mean something, and often the ones that you use every day and think you know what they mean, you do not... Do you know all 179 definitions of the word Run? Did you even know there were that many definitions of the word run? What other words do you think that you know that have more definitions then you think they do?

Its when all these words are strung together in haltingly unfamiiar ways that it requires trained personell to sift through which definition is to be used in each sentence that is ment to be very precise and easy to understand, but ultimately is just very confusing, yet still precise.

All that is beside the point of the statment that 'words mean something', which is, when you say something, that something that you said has meaning.. for instance, when my estranged wife said 'I do', it Should have ment that she would follow the list of things that she said 'I do' to, instead she abandons her daughter and husband and runs off with someone that can abandon his wife and 10 (yes, thats TEN) children.. yah, he is going to take care of her.. they deserve eachother.