GPS Tracking

Been having a play around with my Iphone GPS and came across an interesting app called Instamapper.
It can be used for tracking your GPS location, best accuracy ive had in the town is 55ft but im sure it could be better out on a hill top.
You can use their API on your own webpage, facebook page or simply send a link to your map on
Thought this could be handy with SOTA, 1 for Chasers to know your location to give an idea how long till your QRV, but 2 as a saftey feature in case of needing rescue. The API tracks your last 50 gps data packets so you can see a route.
The only limitations are battery life and a phone signal. But even without the phone signal you can still read the co-ordinates off the phone screen.

You can check my webpage if you wish to see what ive done so far. You can see my route home from work today :slight_smile:

73 2M0ETR (i know i need to change my login name)

In reply to MM6ADR:



In reply to MM0FMF:

Hi andy, i dont have aprs on any of my rigs.

Hi Adrian,

I use a Tiny Trak3+ APRS/GPS Encoder, got it from for $42. I connect it to my FT-817 together with a GPS receiver and it sends my position every 2mins. See

I tend to use it on most of my activations, to give chasers an idea of my whereabouts on the summits. That’s if i’m within range of a digipeater.



Hi Robert
This is a topic I am very interested in, and also very green. Could we take this discussion off line for a few questions please?



tim AT


In reply to G4YTD:

Why not carry it on here Tim? I am sure that others are interested - me for one!



In reply to MM6ADR:

OK Adrian, fine on not having APRS now. The problem we have in amateur radio is there is a lot of fragmentation of ideas. Sometimes because the people involved disagree and decided to run similar ideas in parallel and sometimes for commercial reasons. The result is we often end up poorer because instead of having one universal solution we have many competing for ideas, funding and people to do something.

This was raised by Bob Bruninga, the guy who original proposed APRS. He pointed out on his website and in QST that there are over 20 “messaging” systems available to hams, all of which are incompatible and most of which aren’t interlinked. See Global APRS Messaging Initiative

This iPhone app isn’t designed for hams per se it’s just another thing we can use. What would be better would be if it could send the posit information to the existing APRS network. That means either getting the app author to mod the software, which (s)he may be prepared to do. Or more sensibly, setup a gateway using the published API which allows any iPhone running the app to post posits to the server and the server translates them into APRS-speak and then sends them into the existing internet linked APRS nodes. That way we don’t fragment APRS further and anyone wanting to track Hams-on-Hills ™ only needs to run the normal APRS software on their PC or whatever.


In reply to G4YTD:

I’m more than happy to share the ideas I had about APRS on here if anyone is interested.


In reply to MM0FMF:

Go for it Andy.

Mike G4BLH

Ok, at great risk of hi-jacking a thread (sorry) here go’s.
I bought a copy of Bob’s APRS book, read it, digested the facts and decided that:
a) It was too expensive to set up
b) Was not well established in the UK
c) Required more time than I had available to make it work

As a result the project was binned some years ago.

I was under the impression that to make the system work efficiently a shiny new hand held was probably needed as a minimum requirement. Kenwood and Yaesu both produce rugged units with GPS, and APRS capability, with equally rugged price tags to boot. Reading your post Rob, and visiting the link, it looks like things have moved on quite a bit and I don’t need a raft of equipment or a huge wallet to be up and running.

Can anybody in SOTA land help me get going with portable APRS for a Yorkshire investment (read small, almost free…)?

Is there a plain language web site I can visit to understand the APRS situation in the UK?

How do I do what you are doing Rob – showing a moving icon on a web based map, preferably of me walking up hills?

I do have a mobile radio in my car that could be pushed into service as a repeater if that is the way it is done.

Over to you boys and girls.

Ho ho ho merry Christmas and all that festive stuff


In reply to G4YTD:
Setting an APRS digipeater is very cheap to do. I run the local digi in my area. I built it with an old MFJ TNC (or any TNC2 clone) and a spare 2M mobile radio. All you do is replace the firmware (one Eprom) in the TNC with UIDIGI. If you do a google search you can find info on the UIDIGI digipeater firmware. You should also be able to find someone to burn the Eprom for free.
Once it’s running it’s a set and forget deal.

Robert is right in saying the Byonics TT3 or ArgentData’s tracker’s are cheap and can be interfaced to any radio.
The really nice feature of the Kenwood & Yaesu HT’s that have APRS built in… is the ability to post your status messages … ie operating frequency in real time.
In the W2 area … mobile cell service is patchy at best… but once I’m on the top I can usually hit a APRS digi.
I know APRS is not as numerous in the UK, but it would not be hard to build. And as long as the digi’s can get back to an igate (internet gateway) you’ll be able to see that status worldwide.
You could also setup a temporary digi in your car while activating to use the higher power of the mobile radio to ‘repeat’ your signal into the nearest digipeater.

Lots of cheap possibilities and I think a good addition to APRS … does sending and receiving an APRS message on a SOTA summit qualify for points ?? hmm


In reply to G4YTD:

You can do APRS quite cheaply but in order for it to be any good you need the network infrastructure. You need to have that network running 24hrs/day to hear the posits you send. And, of course, you need the gear you will carry.

The easy bit is the carried gear. You need a GPS receiver (filth cheap now), an 1200bps APRS encoder and a transmiter. You could buy a 2nd hand Kenwood TH-D7 which has everything for APRS except the GPS or you can make your own tracker. Making the tracker appeals to me and if you build on Veroboard you should be able to build the GPS interface/packet encoder for around £15 (less depending on your junk box contents). You could use the GPS many of us carry when walking or use a small embeddable GPS which cost around £30 in small quantities. Finally you need a transmitter. Again most of have a handy with us when walking or you could use the main activation rig. Personally and from a convenience point of view, a tracker comprising a small GPS module, the encoder and a link to the handy would be the most convenient. Irrespective of what is used you need to ensure you have sufficient batteries for the activation if some of the activation equipment is used to send APRS information when walking to and from the startpoint.

That’s the easy bit because designs exist and are available on the net or kits/ready built gizmos can be bought. The only downsides are how much it weighs, how much it costs and how many more batteries (cost and weight) you need.

Oh and a network to connect to! :frowning:

The network is the APRS problem. In the UK it’s, at best, patchy. Sure there are people doing APRS in the UK but you may find that you can only get your APRS packets into the network when you get to the top of the hill and that rather defeats the point of being tracked as you climb! If you want to be trackable from the base of a remote mountain to the summit then you have an APRS network that can hear you. Thin of how amazing the mobile phone network coverage is in the UK. Even in remote parts of Scotland the coverage is pretty damn fantastic. Now just how many cell towers are there in the UK? 5000? 10000? So it’s a reasonable assumption that we’re never going to get an amateur network that big. You could use the mobile phone networks to carry the APRS messages to a gateway but that’s a naff solution because it costs money for each byte sent. I don’t want to pay!

The alternative is to use the free repeater in the sky to get the APRS info from the base of any hill into the APRS network. Yes use the ionosphere. Now I’m not suggesting we get into Sean’s interest and run HF pedestrian mobile APRS systems but we could. No the obvious solution to me is to use 2m/70cms from the walker and place a 2m/HF gateway in your car in the car park. Most of use never walk that far from the carpark and I can think of loads of activations I’ve done where I could see the carpark from the summit. From the car, 30m will be ideal to get to the gateways that exist in mainland Europe. Once at a gateway you can be sent into the internet connected APRS systems and then pop back out locally in the UK on RF if needed.

The equipment needed is a 2m/70cms receiver and HF transmitter, a TNC to receive the APRS transmissions from the walker and another encoder to drive the HF transmitter at 300bps rather than 1200bps used on VHF. The newly revised licence in the UK allows you to remote control a station so there’s no problem having an HF transmitter running from your car. You do need to ensure that only you can control the remote system and that’s done by having it only retransmit APRS messages that contain your own callsign.

So some ballpark costs assuming buying everything new, cases, leads etc. £70 for the tracker+GPS+batteries. On top of that you need a 2m/70cms radio (handy) and rucksack mounted antenna (cue Richard G3CWI). In the car for the VHF>HF gateway you’re looking at £30 for the 1200bps APRS decoder/300bps APRS encoder and you need a VHF receiver and HF transmitter, aerials and a battery. These don’t need to be expensive, FT290s change hands for often less than £50 at rallies and you only need it to RX. The HF transmitter won’t cost the earth either. I picked up a brand new Codan 2-18MHz 125W SSB set for £80 on eBay and there are lots of beat up rigs about cheap because they don’t do all the modern magic.

So it’s possible and legal in the UK to run a remote VHF>HF gateway and use that to get APRS spots out to the network. Have gateway, can connect!


Just an observation - for your car or if you want to set up a digi at home, why waste a good 2 metre rig, just buy a 2nd hand PMR since you only need one channel 144.800MHz. Such rigs can be had for peanuts these days.

Next time you’re out on your favourite hill, listen on 144.800 for a minute or two. If you hear bursts of data, there’s a fair chance one of them is a digi. If you happen to have a netbook with you, you could always decode the data…


P.S. Typed this before Andy’s post above appeared - cool idea Andy!

In reply to MM0FMF:

This iPhone app isn’t designed for hams per se it’s just another thing
we can use. What would be better would be if it could send the posit
information to the existing APRS network.

The iBCNU app does this. Works a treat.

In reply to MM0FMF:

From the car, 30m will
be ideal to get to the gateways that exist in mainland Europe. Once at
a gateway you can be sent into the internet connected APRS systems and
then pop back out locally in the UK on RF if needed.

The IARU Region 1 Band Plan (2009) states:

“Automatically controlled data stations (unattended) should avoid the use of the 10 MHz band.”

The IARU has agreed that only CW and narrow band modes with a bandwidth of no more than 500 Hz should use the 30m band.

Walt (G3NYY)

In reply to G3NYY:

I’ll go with the FCC mandated bandplan on this Walt which happily allows digimodes above 10.140. Which is just as well as the worldwide de facto APRS frequencies for mark and space are 10149.2kHz & 10149.4kHz and has a bandwidth of 400Hz if I did the maths right. And it’s not automatic unattended in this case, it’s remotely controlled, a significant difference.

See that’s the nice thing about standards, there’s so many of them you can pick and choose the bits that you agree with and ignore the rest :wink:


In reply to MM0FMF:

I’ll go with the FCC mandated bandplan on this Walt which happily allows
digimodes above 10.140.

Of course, as I’m sure you are aware, the FCC has no jurisdiction outside the USA and its territories.

See that’s the nice thing about standards, there’s so many of them you
can pick and choose the bits that you agree with and ignore the rest

Indeed. And this is exemplified by the current situation on the 40m band. The Region 1 Band Plan (w.e.f. April 2009) says 7000 - 7040 kHz should be CW only and digimodes should be above 7040 kHz. However, the segment 7035 - 7040 kHz continues to be awash with PSK31 signals, to the exclusion of all CW activity.

Walt (G3NYY)

In reply to G3NYY:

Well it’s hardly surprising that people haven’t moved on to the preferred part of the band on 40m when the Edinburgh AM mob are still on 145.800 setting such a fine example! :slight_smile: However, we’re lucky in that bandplans are advisory in EU and in general work at keeping conflicting signals separate. 300bps APRS has been running right at the top of 30m for 15years without causing grief to other band users so it’s hardly an issue. It takes time for things to adjust and at least CW is the Martini mode, anytime, anyplace, anywhere. 60m, just above the beacons would probably be a better frequency to use as then the signals would be audible in the UK directly rather than banging them 1500km+ to Central EU and beyond only to send them back. But with 60m being NOVed and currently about to expire in 6 months that might not be the best choice long term without going into the availablity or performance of small mobile antennas for that band.

The simple fact remains if you want to be tracked on APRS you either need an APRS network that can hear you or you need to bring your own network access point to where you can be heard.


In reply to MM0FMF:

There is a considerable amount of interest in the QRP world at the moment in the WSPR mode i.e. using very low power QRSS modes on HF to reliably span continental distances. Very low tech transmitters are used together with a network of monitors providing reception reports in real time over the internet.

I can’t help thinking that something similar to this might provide an alternative to VHF/UHF systems. Perhaps something could be put together using say a 500mW transmitter on 20m, a pic16 and a serial interface to a GPS?

One problem might perhaps be that such narrow bandwidth modes rely upon accurate frequency control which is harder but not impossible to achieve with a portable setup. On the plus side the use of HF means that relatively few monitoring stations would be required to give excellent coverage.


Back on line again now, dont you just hate Christmas cover!!

Thanks for all the APRS info, and the epic response from Andy…

Reading through the threads confirms some of the doubts I have had around using APRS, namely the lack of VHF relays, and whilst the cost of the individual components is quite small, when added together still represents quite an investment (full blown mobile gateway and portable VHF system). The other factor to consider with a HF repeat system sitting in the car is the added interest given by those of smash and grab persuasion (I know having had it happen to me in Patterdale). As Andy typed, the systems are only as good as the infrastructure. In my part of the World, leaving a 2m radio scanning the simplex and repeater channels turns up a QSO every couple of days (I can work stations to a radius of around 75 miles on the vertical too). Thanks again for all the information, I will continue to watch the technology with interest, and hope to jump in at some point.

Until then, Happy Christmas from snow covered Yorkshire.