APRS traffic in Baltimore overloaded during Field Day

If you were like many in Baltimore Maryland you may have found it almost impossible to send a packet from one node to another even when that node was across the street on Field Day. While looking at what types of traffic where going over the network on Sunday morning I noticed one item that continued to come up; People were trying to use the WIDE command causing packet collations and network saturations. There simply is no reason to have a WIDE7-7 packet when trying to score points on Field Day. In addition it was apparent that people simply increased their power output in an attempt to get their packet on the network.

In highly populated areas if people could try to follow a few common sense rules the APRS network will be more reliable and less overloaded as it was in Baltimore on Field Day 2003.

Unless you have a very specific reason to broadcast your position more than once every 3 - 5 minutes don't. Most vehicles in highly populated areas are not likely to travel more than 4 miles in 5 minutes. Unless someone is specifically tracking you or you are apart of an activity that is using APRS to keep track of where everyone is, you shouldn't broadcast your information more than needed. Many trackers offer the ability to manually broadcast your position, consider using this especially when stuck in traffic.

Next, if you host a stationary beacon or igate, there really is no need for you to broadcast that fact more than once every 45 - 60 minutes. People use beacons for different reasons, some to broadcast weather information and others use it to help figure about what kind of DX they can expect. I personally enjoy reading weather reports while driving down the road, but in most cases it is not necessary for a weather stations to send out the same report every 15 minutes, instead see if you can limit that broadcast to major changes in the environment such as a 2 - 5 degree temperature change or strong wind change that could affect boaters, aircraft, or other people that rely on weather readings.

Broadcasting at a higher power than required is also another problem. In Baltimore Maryland there are several Digipeaters located in very good locations, such as the N3KTX nodes, which have better coverage than you will ever get from your mag mount at 50 watts. By increasing your power you are simply increasing the possibility that your packet will negate someone else's packet and can cause unnecessary network saturation. Personally I have tested my Kenwood D700 at 50, 25, and 5 watts and I have noticed almost identical responses of positions on www.findu.com.

Another question that many people have is "What should my packet path be?" This is going to be very different from region to region, but while in a highly populated area where there are a lot of ham operators with igates or digipeters that have excellent coverage it is my recommendation that you do not use anything beyond RELAY, WIDE or WIDE2-2, and at most RELAY, WIDE2-2. If your goal is to have your location published on the internet on a page such as www.findu.com than those settings should be able to do it for you. If you are in a more remote location you may want to consider WIDE3-3, but try to be aware of what types of fixed digipeaters are available.

Lastly, being a mobile Digipeter in a highly populated area should be closely considered. If you commute from a remote area to a highly populated area it may be worth having the digipete option turn on, but if you remain within a highly populated area where there is good igate coverage or even digipeters that are already covering the area of your commute, then there may be no point. Some radios, such as the Kenwood D700, have multiple program modes that can allow you to change to different settings as you drive. It is relatively easy to setup two program modes on a D700 which would allow you to easily switch on the digipeter option with the press of a memory mode button. Then when you are downtown, turn the option off, but when you are driving in the country help out your fellow ham by turning it back on.

There really are a lot of things to think about and this article was written from what I experienced on Field Day, which was virtually no way to communicate a simple message from one point to another due to packet network saturation in Baltimore Maryland on 144.39. APRS, as is the rest of Amateur Radio, a community effort and a lot of fun. Set your radio the way you want, but be respectful to the limited amount of data that can actually flow over the airwaves.

Phillip Tompkins

KD7QOT

kd7qot@linuxonly.net