Aprs Net Spy

Aprs Net Spy (ANS) will monitor the local APRS packet network and provide some detail about activities on the frequency.

This program might be of casual interest to anyone, but folks who are deeply into APRS might gain useful insights into their local RF area using it.

The program isn't intended to measure actual load on the system. It just gives a snapshot overview of how many of various different kinds of APRS packets are visible to the program. True network wide analysis would have to be performed from numerous, possibly all, wide digi stations, comparing frequency usage, analysis of received data at all stations for possible collision analysis, etc. ANS is just supposed to be a means to see how the system is running from a particular user's location.

Recently comments appeared concerning this program and its "counts per minute" as a source of information regarding network usability. As stated above, this figure is only meaningful for the receiving station. It has no relationship to the actual network load. And it appears some feel that a higher number of packets per minute equate with possible network saturation. That isn't the case. Consider 100 stations all tightly coordinated to UTC. They all beacon out one packet every minute at exactly the top of the hour. Consider further that they are all located in deep valleys and can't see each other but they can all see a single WIDE station. The result: instead of seeing 100 packets at the top of the hour you'd see NONE. All those stations would be deaf to each other and unaware they were transmitting colliding packets at the WIDE site. The wide site would just hear a surge of noise, unless one station had a significantly stronger signal and could capture the WIDE's receiver.

A more in depth discussion of an APRS network  is offered by Bob Bruninga WB4APR, the creator of APRS, at his website. See the Aloha Concept section for a quick primer on network loading.

Previously the internet connected TCP/IP system wasn't handling the load on full live feeds. In working with another of my programs, I managed to learn all about filtered feeds from Tier 2 servers. I think you will find that the program is actually useful now that you can log into these filtered ports. Details on how to set this up are on the TCP/IP Comm setup screen.

Don't think of this as an APRS program per se, even if it does some of the same stuff. APRS-Plus, UI-View, WinAPRS, APRS-Point and DOS APRS all link you to the APRS network with flair. And it isn't really the "domain" of a local area RF analyzer like this.

Instead, think of this program as a way to look at how APRS functions at your home location. You can develop some interesting information that may be of help when using other APRS program. For instance, running the program for a while you can determine which digipeaters in your area are capable of being used directly from your station.

The program will log any stations you wish to keep track of. These LOG files can be either ASCII delimited text files for use in spread sheet programs or just plain text files of data received from the station via the TNC.

Screen shots and descriptions of the various screens are available in the links to the left.

You can download the program from the download page.

Information on the latest release is available on the Version Page.