APRS – a contribution to Break In, the journal of Amateur Radio in New Zeland

 Sept 2000

- by ZL1AMW

APRS, or "Amateur Packet Reporting System" has been around for a number of years, but until recently has only small take-up in New Zealand. The first widespread publicity I came across in this country was at Flock House Conference, where Basil ZL2UT and Steve ZL2UCX ran an APRS forum.

Next there was considerable interest aroused by an address to the Christchurch Conference in 1999, from Darryl VK2TDS. After that Conference, Darryl travelled throughout the country, giving branch talks, which further increased awareness.

Then in late 1999, a new approach appeared – Roger G4IDE (author of the Winpack programme) produced a new programme called UI-View, which opened out a whole new approach to APRS operation.

At this point I must acknowledge that the APRS programme has some dedicated users in New Zealand, and this provides many amateurs a great deal of operating satisfaction. What is new is that we now have two alternative ways of operating APRS, and in my view, UI-View is the kick-off the mode has needed. With the arrival of UI-View, APRS should be considered a protocol or agreed way of operating, rather than just a computer application. The name UI-View comes from the designator UI, or "Un-numbered Information" which is the type of packet radio frame used by the APRS protocol, and provides a view of station locations.

UI-View - What is it?

UI-View is a computer programme, that will run on any windows computer. The basic function of the programme is to draw maps on your screen, and show stations in their location as icons.

UI-View uses the defined APRS protocol for communicating between stations so is compatible with stations running APRS. This on-air communication uses standard AX-25, best known as packet radio.

The first thing you need to operate UI-View is a set of maps of your local area. The marvellous thing about UI-View is that it uses simple .BMP or .GIF files. These can be created easily by scanning maps with your computer scanner, or making screen saves from any mapping programme. There are also a large number of map files available from the Internet. The one trap is that you need to be able to tell the computer where in the world the map is. You need to know the latitude and longitude of the top left and bottom right corners of each map, and enter them into a small text file for the programme to read. Armed with this information, UI-View will load the best map available to display a selected station, and draw it at the correct location.

The Internet is a marvellous ally to amateur radio. It can provide a source of much information. You can find the home of UI-View on the web at www.ui-view.com, or APRS at www.aprs.net. For New Zealand maps, have a look at ZL2UMF’s collection at www.zl2umf.wallace.net.nz  or my site at www.zl1amw.wallace.net.nz.

A further use of the Internet is to provide a means of inter-linking stations. There are a number of APRS servers on the Internet, and both APRS and UI-View programme users can connect to these, providing a path for their beacons. Stations can set themselves up as Internet gateways, or "IGATE" stations. These then pass location traffic from the Internet server to a local radio channel. The result of this is to provide linking between clusters of APRS activity, and widen the pool of users. In New Zealand there are three basic clusters of activity, in the Waikato/Bay of Plenty, Wellington/Blenheim and Christchurch areas. In each area there is one or more stations set up most evenings as an IGATE, providing a single wide-area ZL network. If you are seeking some activity, but there are no other APRS stations in your area, try connecting your UI-View or APRS to aprs.moffatt.nu:14490 [ - Note: - now: aprs.net.au:10153].

There are a large number of APRS servers, on the Internet. These are interesting as they can provide clusters of stations in different areas throughout the world. The best known is at aprs.net:23, however be careful, this server is VERY busy – usually over 1000 stations simultaneously operating. My Pentium 166 is stopped dead in its tracks if connected to this server, it is just too busy to allow the computer to process all the beacons.

To operate as an IGATE, amateurs need to obtain a special validation number, which is matched against their callsign. This is used whenever logging on to an APRS server, thus provides some protection against non-amateurs passing traffic to and from radio frequencies. UI-View’s one restriction is that unless you have registered your shareware, you are unable to enter a validation number into your programme. This is a further small protection against non-amateur traffic, as it is unlikely that non-amateurs will go to the trouble of registering this amateur radio programme. Unregistered programme users can still connect to an APRS server, and operate on a radio channel, they just cannot gateway the traffic between Internet and their radio.

 

The APRS protocol uses the standard Packet Radio beacons, with the "VIA" function of level 2 digipeating. Each user sets up a beacon setting that tries to get their location transmissions digipeated through as many hops as possible thus advertising their station to the widest area possible. Most other packet activity, for example BBS operation, is carried out by the user first connecting to the distant station, then carrying out their business, then disconnecting. APRS traffic is simply sent by casting the information to the wind, and allowing as many as possible to pick up the beacon as it passes by. This makes it a very relaxed mode, able to fit in with channel congestion well.

 

GPS – Locators

The programme is designed for using a GPS receiver, to provide for automated location for mobile stations. With a GPS, you can run UI-View on a laptop computer in a moving vehicle, and display your location on the screen, plus have your location transmitted to other local stations.

Having a laptop computer in a moving station can be both fun and a bit of a hassle, the computer is difficult to power, and rather fragile to carry in a moving vehicle. An alternative is to simply connect a GPS to a TNC, plus radio. This will produce a simple tracker, which sends location beacons, and is much more portable. The downside of this simple tracker is that while everyone else then knows where you are, it does not provide you any information in the vehicle on your position.

A GPS is not essential for tracking mobile stations – the programme uses "objects", to mark stations manually. Users can insert a symbol for a vehicle, and this will then be broadcast to everyone in the network. The object can then be moved by either the originator or any other station, and the move is shown on everyone’s station. This then works like an electronic pegboard, where a number of vehicles or parties io a wide area event can be plotted from one location, but monitored from a number of other locations.

Messages

The programme also provides a simple messaging function. Users can type single-line messages to individual stations, or as bulletins to all operators. Messages are available for viewing by all stations on the network, allowing a "round-table" discussion session. This can be ideal for emergency situations where having everyone aware of the overall situation is a good thing.

UI-View32

There are actually two different versions of UI-View. The original programme is a 16 bit, Windows application that will operate under Windows, Windows95, Windows98 or NT4. This programme is shareware and all functions, with the sole exception of validation on an APRS server are available without need of registration.

UI-View32 is a 32-bit version of the programme, and operates on Windows95/98 or NT4/Windows 2000. This is a faster, and in some ways smarter version, which requires registration to operate.

What makes this programme very exciting is that it is still under rapid development. Every few weeks a new version is released, bringing more varied and fascinating features. This development is being applied to both versions of the programme, so both registered and unregistered users can reap the benefits.

The differences

As mentioned, UI-View and APRS use a common on-air protocol, and provide mostly similar functions, so what is the difference?

One significant difference is that while both are shareware, registration of APRS is more costly than UI-View ($US60, compared with 10 UK Pounds). APRS restricts unregistered users from being able to save their settings, which is somewhat frustrating for regular operation, while UI-View allows all radio functions without registering.

Maps are easier to create for UI-View, as it uses basic bit-maps, however the APRS programme use of vector maps allows it to zoom in and out on maps, which UI-View cannot.

APRS is a much more mature programme, having been around for many years, however the dynamic development of new features within UI-View makes it an exciting programme to play with.

What do you need to operate UI-View?

The basic needs are:

Where do you find APRS activity?

There is activity on the following frequencies every day:

Why Do It?

This is a special mode of operation, where you can, at a glance, see who is on-air at the moment in any given area. You can type messages to them at any time, and it will pop up on their screen. Other operators will be able to join in and chat with you both, just like a local repeater, however the other station may be next door, a few hundred, or a few thousand kilometres away.

You can have fun running a mobile station, or track other mobiles on your screen. There are many technical challenges in this mode, including packet modems, portable radios and interfacing computers. This has been a brief run-down of some of the functions of UI-View – there are many more available.

The possibilities for AREC events are tremendous, so having a pool of UI-View or APRS operators in an area is a great asset. Have a go.

For further information, you are welcome to contact the author by email