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APRS

I know that a few people were trying APRS a while back. Today I ran across a site that has an open-source implementation that would be easy to build:

http://www.ringolake.com/pic_proj/gps_trak/freetrak202.html

Suitable GPS modules are readily available for £20 or less.

73

Richard
G3CWI

In reply to G3CWI:

Looks similar to the OpenTracker, but has a PIC chip instead of Motorola. The OT has open-source code too, though very few read it or try to compile it.

73, Jaakko OH7BF/F5VGL

In reply to G3CWI:

Thanks for sharing the information Richard, it looks very interesting.

I built a tracker using a Byonics TinyTrak 3 PIC plus a PCB and case from VU2FD (FoxTrak). The PCB and it’s case was only $2!

My tracker works well, it has all the features of the TT3, but it has better RF performance. I use a puck GPS which cost me £22 (BR-355).

I use APRS to let my XYL keep up to date with my progress. I’ve been quite suprised by the coverage, I’ve been picked up even in the valleys.

73
Colin
M0CGH

In reply to G3CWI: Are you going to build this, Richard? It looks simple as you say but it uses an OP196 op-amp which is unobtainium.

I’ve just been testing the GPS receiver module I got from Hong Kong using Visual GPS software (nice free diagnostic utility.). It works if I take the laptop out into the open but the receiver doesn’t seem sensitive enough to pick up a fix indoors which is going to be a bind when I want to test anything.

Julian, G4ILO

In reply to G4ILO:

OP196 op-amp which is unobtainium.

Am OpAmp is an OpAmp is an OpAmp. There will be a brazillion suitable replacements. But not a (probably) a 741 :wink:

Andy
MM0FMF

In reply to MM0FMF:

In reply to G4ILO:

OP196 op-amp which is unobtainium.

Am OpAmp is an OpAmp is an OpAmp.

Only nearly true but as you say almost anything reasonable will work just fine.

In reply to G3CWI:

It’s a single rail, micropower op-amp. There’ll be loads and loads that are drop in replacements, some may need the power rail limiting. The biggest problem will be getting PDIP packages instead of SOIC, TSSOP etc.

The nice thing about the Ringolake software is that it is not only free but well written and easy to understand. Take it from someone who’s been bashing out assembler since 1978, that is no mean feat.

Andy
MM0FMF

In reply to MM0FMF:

Looks to be acting as a buffer anyway so doubt it’s a critical component

Rick.

I did not manage to program the PIC for some reason so I kludged together some code for the Parallax Propellor and amazingly it works. GPRS for next to nothing. Way cool.

http://forums.parallax.com/showthread.php?138341-APRS&p=1079117#post1079117

73

Richard
G3CWI

So, now it’s working I have no idea what use it is? Is APRS actually of any use for SOTA? Do people bother to look where activators are? Is the APRS2SOTA gateway of any use (it has a nice website)?

None of these things matter much to me though. I have enjoyed the coding, understanding NMEA strings and the packet protocols.

73

Richard
G3CWI

In reply to G3CWI:

I suppose that in the event of an accident it would help Mountain Rescue locate the victim. I prefer not to be a victim!

73

Brian G8ADD

In reply to G8ADD:

I note that two SOTA-APRS exponents are activating at the moment and as far as I can tell, neither is using it today. Perhaps that’s the clue?

73

Richard
G3CWI

In reply to G3CWI:
Hi Richard,
I wonder if its just because there are other easier alternatives to get started with APRS. I use Hamtracker on my IPhone. Ok, it depends on having a mobile signal but for my use in Snowdonia it suffices.

http://www.kramstuff.com/Ham_Tracker.html

All interesting stuff though.

73
Roger MW0IDX

In reply to MW0IDX:

Hi Roger,

I have that app and did experiment with it. My current foray is more of an academic exercise to help me learn embedded programming. I have always shyed away from buying any APRS gear as I could not really see much point in it. I can recall it being used by N2YTF (?) in the early days of SOTA USA - then it was quite interesting but now it seems a bit pointless. Happy to be proved wrong though.

73

Richard
G3CWI

In reply to G3CWI:

Hi Richard,

your project sounds very interesting. My limited experience with APRS for SOTA using SMS messaging suggests that while it works very well when there is a signal path to a cell-phone base station, summits and the valleys leading to them are generally rather problematic in this regard. Often one only gets a connection once one is near the top of the hill. At this point it is just as easy to use Andy’s SMS spotting service as it is to start broadcasting APRS fixes. Thus while APRS over VHF/UHF is fine from, say, a light aircraft or within a built up area it is not so useful when out and about in the dales.

In my opinion what is needed is some sort of system based upon 30m or possibly NVIS on a lower frequency band that would allow activators to self spot reliably from any summit (or nearby valley) perhaps exploying some sort of QRPP NVIS system. Hans Summers’ work with 30m QRPp QRSS beacons

www.hanssummers.com

suggests this should be possible even with a compromise portable/temporary antenna.

73

Rick

In reply to G3CWI:

Richard, the point is becoming more clear in NA now. VA2IEI, N7NZ and a half-dozen others use APRS from the moment they leave the house…first in the car and then on foot. Here, where activations are sparse and trips are long, it gives us a way to estimate when to come back to the shack for the chase. Their speed is indicated. Even more useful, we can see their elevation and compare it to the summit elevation. On APRS.FI, we can change from map to satellite view and zoom in on the listed LAT-LON of the summit to see what’s on top and see them closing in. They can leave messages for us in the little map tack balloon. What hath God wrought, and what will she give us next?

Elliott, K6ILM
Chaser Clown

In reply to G3CWI:

So, now it’s working I have no idea what use it is?

It adds more entertainment to the entertainment. Plus the packets can be used for VHF propagation monitoring.

73, Jaakko OH7BF/F5VGL

In reply to F5VGL:

Thanks all. I have concluded that in most cases APRS is a novelty of little real value - but can, of course, be fun! In more embryonic Associations it has much more utility.

I can see why the novelty soon wears off - more gear to carry. I shall push on with my project though - the technical challenges of a roll-your-own solution are interesting. I’m just glad I didn’t buy any hardware.

73

Richard
G3CWI

In reply to G3CWI: Richard, I can send you a PIC programmed with FreeTrak if you are having trouble doing that.

Over here in the Lakes when I was still able to get out on the fells I always took APRS gear and it always added an extra dimension of radio interest. Many of the keenest SOTA and WOTA chasers around the area run APRS gateways or at least use APRS software. I have had messages from chasers enquiring where I was off to. There have even been cases where APRS has been used to guide an activator on to the correct path for the summit!

In the last few months we have benefited from a new digipeater, MB7UQ, co-sited with the GB3DG repeater, which should mean for those activating in the north and west of the district that you don’t have to be up on a ridge or summit before your APRS signals get gated.

Julian, G4ILO

In reply to G4ILO:

Hi Richard.

I would also echo Julian’s and Elliot’s comments.

Here in the Lake District, several of us that activate for WOTA and SOTA use APRS to track each others progress, use the messaging system and also use it to query summits.

The latter is great for when the better weather comes and you find yourself a little ahead of schedule or with time to add another summit to your days events. Send out the query option and you get back the nearest 10 summits.

With WOTA we have set up the QRU and spot direct on APRS-fi via ?APRS summit reference. This also alerts others to activations that may not have been placed on alerts and places the icon direct on APRS.fi

On a couple of occasions it has also helped to guide activators off of fells in adverse weather conditions over the air when they were unsure of their direction, despite having gps and map etc. Sometimes the extra reassurance is a godsend when the weather disorientates you.

From a personal point of view, it also helps my partner to track my progress and vice-versa when operating alone.

As to carrying extra equipment, most people have phones capable of using APRS these days and many radios now have GPS and APRs options.

For those using older Windows phones there is also an APRS app by Lynn W Deffenbaugh as well as several android ones.

Lynn’s software allows for stallite tracking and whole host of other functions.

Here is a good starting point for that one:

http://aprsisce.wikidot.com/ along with the suuport group on Yahoo
http://groups.yahoo.com/group/aprsisce/

73

Liz