09 Adding Static Objects to APRS

APRS Article 9

January-February 2001

Adding Static Objects to APRS

By Jeff Robbins

VE3JTR (Voice Call)

VA3JTR (APRS Call)

I’m baaack! Sorry about the one issue sabbatical, but I was so pressed for time a couple of months ago, I just couldn’t get into writing mode. I took an issue off in order to juggle work commitments and quite a few night school classes last fall, so I didn’t had a lot of time to put pen to paper. Yes, you got me, I don’t actually write, I type into this computer. I have also been off the air for a couple of months as we rearrange the house, and as of this writing, I am just getting the APRS station wired up and back on the map. So I look forward to getting to know everyone in the APRS world, again.

Before I get into the meat and potatoes of this article, I want to share an email I received from John VE3CJB. John writes: Hi Jeff. I don't know if this is a first. As you can see I have my callsign on my car license and asked MOT for a second car. Since I run this one as an APRS tracker I asked for -9.First they said it would alter my callsign, but I explained it was when I run APRS with an SSID of -9. It was accepted as you can see. 73..John

I have included John’s photo of his new car with his callsign license plate with the SSID of 9. Kind of sharp I must say! As you can see, Ontario has started issuing vanity plates with seven and eight characters, so John may just be starting a new trend in the APRS ham community!

The real power of APRS lies in its ability to track live, moving objects on a map. However, there may be times when adding static objects to APRS could be valuable. You can add a static object to your map by selecting an icon, giving it coordinates and a name, and the object will be transmitted out into the APRS network, and it will show up on every computer screen in the network. Static objects are meant to be for temporary use, and can be removed from the network when the need has passed. Such uses include advising the location of a hurricane, locating hospitals or fire stations, and even for placing hamfests on the map.

As an example, let’s imagine a scenario where some sort of disaster has occurred, and your ARES Emergency Response Team is up and running with APRS. You rush over to the temporary shelter where you have been asked to setup communications, and using the power of APRS, direct the APRS tracker equipped Red Cross vehicles to various points around your city (OK, maybe I am stretching a little, but perhaps it won’t be long before a well established ARES group accomplishes this). In order to give accurate and timely directions to the nearest police or fire station, we need to see their locations on our city map along with our moving vehicles.

Now we could easily place a radio, TNC, and computer in each desired facility, setup your favorite flavor of APRS, and you would have your fire stations on the map. The trouble is, this would obviously be fiscally impossible to accomplish on what is usually a shoestring budget, and wouldn’t add any value to our APRS network anyhow. If anything, they would just add more congestion to the APRS frequency. However, we can use static objects to place markers on your maps for each fire station, police station, hospital, and what ever else you can think of. These are probably not items you would want cluttering up your map for day-to-day activities, but during an emergency, being able to quickly locate those buildings on your map could be vital. By adding those locations as static objects, one person could easily add any additional objects as necessary, and remove them from the network once the emergency has passed. Once the person deletes an object he has created, that particular object will eventually expire and disappear from each computer screen (depending, of course, on how each APRS session is configured).

Some homework would be required to accomplish this feat. Someone in the ARES organization would have to take on the task of determining in advance what facilities need to be highlighted on the maps, take a handheld GPS to each facility and record the coordinates (not entirely necessary, as you could click on the screen map to find out the approximate coordinates, not as accurate though), and make this list available to the person responsible for populating the network during an emergency. This activity will fit nicely into your ARES Pre-Planning sessions.

In order to add objects to dosAPRS, hit I for Input and then A for Add object. You will be prompted for information regarding the object, including coordinates. When complete the new object will be added to your map, and transmitted out into the network. Hint: Your current cursor position on the map will be pre-filled when prompted for the coordinates, you can leave the defaults as is, assuming your cursor is in the correct place.

In order to add objects to WinAPRS or MacAPRS, from the Edit dropdown menu, select Edit/Add Object/Station. As with dosAPRS, the last place you clicked on the map will be the default coordinates in the Add Object window. If the location is correct, you can leave them be, or change them to the correct coordinates.

Hint time: Read the documentation for your particular flavor of APRS. I discovered that using WinAPRS, I needed to check the Active Object box in the Add Object window in order to transmit the fire station out into the network. The default is Inactive, and if left as default, the object will only reside on your own computer.

Now I would like to conduct a test. As a few of you know, in addition to my other activities, I am also a Firefighter. My fire hall is located just east of my residence, at 44° 7’ 23” N and 77° 28’ 44” W. I invite you to try out adding my fire station to the APRS network, using the appropriate icon for a fire station. I will monitor my screen at home about once a day, and if I see you add the fire station to my map, I will contact you via APRS or email, and I will send you one of my new Firefighter QSL cards. If you are too far away for the RF hops to reach my computer, just send me an email advising how you did it, and I will send the card to you anyway. I will publish a list of successful APRS hams in a future issue.

That’s all for this issue. Like I said before, sorry for my brief absence, but I am glad to be back ON THE MAP!