Digipeater Data

AprsNetSpy will actively build a list of digipeaters, and stations using them.

The display is divided into several areas.

The Menu

There is only one menu selection, Preferences. If you click it, this dialog appears:

The box at the top sets what data will appear in the Digi Data Screen's far right frame. Either Nodes and the aliases used to access them, or stations and their aliases.

The write to file section allows you to tailor the export of information to the "Cross_Ref" file discussed below.

Stations and their aliases do NOT print out to the Cross_Ref file. However, that data is available in the Station Summary Spreadsheet which can be manually or automatically generated. Node data is added to the report if you place a checkmark beside that option.

Top of the Screen

The total number of digipeaters, stations and either Aliases or Nodes as seen on the network are displayed on the top line.

Below that, a count of the number of digipeaters, stations and stations with aliases or nodes actually heard direct via RF.

Bottom of the Screen

At the bottom of the screen the total number of digipeated packets and number of stations for a selected digipeater is displayed. Also, the last packet received by the selected station is shown. This packet may or may not contain the some of the digis associated with the selected callsign.

In the Middle

The three frames in the middle of the page show data on digipeaters and stations.

The Digipeater frame to the left is a listing of all the digipeaters heard directly by your station. If you click on one of these digis then the column immediately to the right labeled "xx Stations Repeated By" will add the callsign you have selected above the list and fill that list with all the stations that have passed packet traffic through that digipeater. The "xx" will be replaced by the number of stations.

The Stations frame in the middle is a listing of all the stations the program has heard regardless of their direct reception or a receipt of a packet via a digipeater. Stations heard direct are marked with asterisks. If you click on a station in the Stations Heard list the program will then display in the column labeled "xx Digipeaters Used By", all the digipeaters that station has used to pass along traffic. The "xx" will be replaced by the number of digis. This is a complete list of all the digipeaters ANS believes the station has digipeated through regardless of those actually heard directly by the ANS.

The frame marked "Stations and Their Aliases" can display two different types of information. Either data on Nodes detected or station alias information detected. You select which type from the preferences dialog box opened from the menu at the top of the screen. When Aliases is selected, the program will display a list of callsigns for which it has detected alias information. This is primarily done by seeing the KPC3 ID string:

N0KKZ>ID,WIDE2-1:N0KKZ/R RELAY/D KKZBOX/B

However a few other types of identification can trigger recognition of different types of aliases.

If you have selected (via Preferences) to display Node information instead, then the far left box will show a list of Nodes. A node is either a plain node or a gateway.

If you click on a station in the Nodes (or Station) list in this frame then the Aliases associated with that callsign are displayed.

When you click on any station in the left hand frame under "Stations Repeated By" or in the center frame under "Stations Heard By", ANS will attempt to find the callsign in the frames to the right of our selection and if a match is found, it is highlighted and the data is displayed. As an example, I simply clicked on the highlighted callsign in the left hand frame's Repeated by column and the program found a match in the Stations Heard frame and highlighted it and displayed all the digipeaters used by that station and further, the program found a match in the right hand frame's station's heard list and highlighted it and displayed all the Aliases for that station.

There is a limit of 10 digipeaters for each station. I originally thought this might be overkill. But, during testing I have discovered some stations turning up with as many as 9 digipeaters. I may have to extend that to 15. In the mean time the program saves the digipeaters in the order they were first discovered. If an eleventh digi is detected then the first one for that station is tossed and the 11th is added to the end of the list. First in, First out.

Digis in Digis Heard and Digis Used don't Match

In the example above, note that in the right hand column of the center frame of "Digipeaters Used By ??" there is a listing for a digipeater that does NOT appear in the first column on the left. That digipeater was not heard by ANS and so does not appear in the "Digis Heard" list to the left. However, because of its location in one of the unproto paths, ANS can determine that the selected station MUST have been digipeated by the digipeater listed. The "??" above simply means the station indicated in the screen shot above. I've been working on the program and regenerated this screen shot several times and had to change specific callsign information in this paragraph. So, I've gone generic. :-)

Run the program for a while and you will get a pretty good idea of the local digi network and which stations utilize which digipeaters.

Initially I had this screen automatically updating with each received packet. However, when new data arrives, it interrupts your selection process and causes havoc. So, I've made the form semi-active. The totals at the top of the form are updated in real-time. The background color of the "Refresh Lists" button is normally the same as the background color of the window. However, whenever any new data arrives the totals are updated and this button is highlighted in red, as shown above, to indicate that a refresh is needed to display all the current data. The rate of packet arrival at my home generally means that this button is almost always red. Within a second or two of clicking it a new packet arrives and makes the data slightly obsolete.

The only data that is "old" is that contained in the "Digis Heard" and "Stations Heard" lists. You can still click on any of these and the resulting display of data (stations digipeated, digipeaters used and aliases) will show current information.

This digipeater data has been added to the Network Summary Spread Sheet and the Station Summary Spread Sheet files.

If your home station is acting as a digipeater then ANS would normally never See it in the actively heard digipeater list. If you have entered your callsign (the one active in the TNC or on the net) on the Setup screen then when ANS first starts, it adds you to the list of Active Digis. In this way, the program will always display your call in the digipeaters heard list making it easier for you to see which stations are using your system.

In order for this to work you must be using a TNC that does call sign substitution (UIDIGI in a Kantronics KPC3Plus) if you are using an alias. If your TNC received a digi request for the alias RELAY and doesn't transmit that packet out substituting your callsign for RELAY then when that packet is repeated again by a Wide, ANS won't recognize the digipeated packet as coming from your station and simply add the station to the RELAY "digipeater" category. If the alias appears at the end of the unproto path then that packet will not be repeated again after you transmit it. So, even if you are using call sign substitution ANS won't be able to capture that particular station and add it to the list of stations you have digipeated.

Most folks other than WIDEs will be relaying the packets on for further distribution. So, this problem shouldn't be too onerous. The only way around it would be for me to write up a full packet engine and drop the TNC into Kiss mode and control the entire process. I'm NOT going to attempt that at this stage of the game.

If you don't use an alias, then your call will always appear in the unproto path of the originator of the packet to be digipeated and this issue will not arise. Your station is also the ONLY callsign that should ever have an empty list of stations if you click on it. Because the program simply adds it on startup, there may be no stations that have used you as a digipeater. ALL OTHER DIGIPEATERS are detected during an actual digi event and so, they all will have a minimum of one callsign associated with them.

Cross Reference Text File

Cross reference file names are automatically generated in the format:

Digi_CrossRef_YY_MM_DD_HH_NN.txt

	YY = Year
	MM= Month
	DD = Day
	HH = Hour
	NN = Minute

For example:

Digi_CrossRef_05_01_07_02_43.txt

This file was written on January 7th, 2005 at 02:43 am computer time (local in my case).

Click the "Write Cross Ref File" button and all this data will be written to a text file.

At the top of the file will be a listing of every digipeater seen in every path on the APRS network.

Towards the bottom of the file, every station heard will be shown with a list of the digipeaters it has used. There is a limit of 10 digipeaters as described above.

Click HERE to see a sample printout.

You should be aware, there may be several digipeaters in the report that show as having not digipeated any stations. How, you ask, is this possible? Well, first of all, you have the option in the Preferences dialog box set to "Include All Digipeaters" not "Only Digipeaters that have repeated packets". Still, how can a digipeater be listed with no associated callsigns?

N0KKZ>APRS,CALLSIGN1,CALLSIGN2,CALLSIGN3*,CALLSIGN4:Hi

Had the above packet arrived at ANS's portal, then the program would know that.

1. N0KKZ has transmitted a packet addressed or directed to APRS.

2. The text of the message is Hi.

3. The packet is intended to follow the path indicated but ...

4. ANS knows the packet was digipeated by CALLSIGN1, CALLSIGN2 and the last transmission came direct from CALLSIGN3. That's what the asterisk indicates.

ANS can be sure this is true because of the nature of the way traffic flows through the network. CALLSIGN3 could NOT transmit the packet before it sees that it has already been transmitted by the station preceding it in the path. Likewise CALLSIGN2, won't transmit the packet until CALLSIGN1 has sent a digipeated copy on the way.

What ANS can NOT know from this packet is whether or not CALLSIGN4 exists. It's "now" up to CALLSIGN4 to digipeat the packet. And until it does AND the program sees that digipeated packet, ANS will not be able to tell if it actually exists.

So, in the digipeater report you will see CALLSIGN4 but the report will indicate that no stations were seen digipeating through it.

That's how a digipeater might come up showing no digipeated stations. This is assuming that CALLSIGN4 actually exists but is out of range of direct reception of your station.


Webmaster: Rick von Glahn <<rick@vonglahn.com>>