This page last updated 10/14/2011

 

I-Gates that have been running for an extended period of time

Over time we have seen that some I-Gates start causing QRM to the RF and IS network.  This can usually be seen one of two ways.  The first is latency from when the I-Gate receives a packet to the time it gates it to the internet stream.  The other symptom is gating erroneous objects to RF and the internet stream.  This problem can easily be fixed by shutting down the TNC and restarting it.  It has been suggested that anyone with an I-Gate reset their computers and TNC/radio once every week.

Users of KPC3 Plus TNCs and UIView - There is a serious known bug that plagues KPC3+ TNCs (but not the original KPC3).  After running for several days, a KPC3+ operating in KISS mode will start randomly delaying the passing of received packets to the attached computer, sometimes by several minutes.  (KISS is the preferred mode for UIView and is mandatory for using UIView's digipeater features.) 

Passing such long-delayed packets to the APRS Internet System (or digipeating them) can cause them to appear many minutes AFTER more recent position reports have been processed by other digipeaters and/or IGates.  This causes forward-backward-forward-backward "hyper-jumping" of moving stations on other users' maps.  [The APRS Internet System considers any packet arriving within 30 seconds of the previous one, that contains the identical payload, to be a duplicate, and automatically rejects it. An old packet, even if it is a duplicate, arriving MORE than 30 seconds later WILL be passed.]

This bug affects all firmware revision levels of the KPC3 Plus. It can be temporarily cleared by resetting the TNC or by cycling it's power OFF and then back ON.   In the case of UIView, exiting and than restarting UIView also clears the problem.  You can also set up UIView to restart automatically.  To see how to do this, click here.

 

Setting Up UI-View 32 for I-Gate Operation and General Home Station Information

Are you looking for some help to get your UI-View 32 to work as an I-Gate?  Thanks to Matt N9NMH and Mark N9MEA, here is a word document that should help you.

Here is some more information about setting up your home station as an I-Gate.

One thing that many people overlook both in their home station and in I-Gates is the value of NOT using an omni antenna at their base station if they want to get maximum decoding from all digis in the area. 

It is counter intuitive, but if your home station or I-Gate can hear two or more digis, then you do NOT want to have an omni antenna that can hear them all equally.  If you can only decode two digis direct, then set your antenna on one side of your house so that it hears one of those digis at least 10 dB stronger than the other digi.  If you can decode 3, then set your antenna such that it hears the best one 10 dB better than the second one, and 20 dB better than the third one.  You usually have plenty of dB to play with. 

You do this, because in a collision (happens all the time in APRS by design), you want ONE copy to always be 100% decoded and not destroyed by the other digis.  Yet, you still hear all three digis if they do not collide.  Remember, the design of APRS digis is that they are all supposed to key up on the same packet at the SAME time to minimize channel loading.  If you have not taken this fundamental antenna arrangement, and hear 2 or more digis within a few dB of each other then you are missing a LOT of packets!

You can tell if you are seeing collisions, by watching the S meter and your TNC. First, by ear, you can usually hear them as jumbled audio.  If you see strong RF signals and do NOT decode, then you are hearing collisions and losing most of your packets due to collisions! 

You should certainly fix this problem by taking the necessary effort to assure this anti-collision arrangement of your antenna.  Remember, HIGHEST and BEST is not the optimum for APRS. APRS is a network with a contention based delivery system.  Set up your antenna to match that network characteristic and you will double or triple your station performance. 

This may mean an antenna below the roof line, or on a specific side of your tower, or a small beam, or any combination.  Or just sticking up a 39" reflector rod somewhere within a foot of your existing antenna to change the pattern a bit.

All it takes is 10 dB difference, and that is not much at RF.  Think of it as 2 "S" units.

If your 2 or 3 digis all "pin your S meter" so you cannot see the difference, then simply temporarily insert an attenuator so you can get ALL the levels down into the range of your "S" meter.  Then assess how the 2 or 3 digis compare.  Make your antenna adjustments to get the 2 "S" unit difference between all of them.  Then when you are satisfied, remove the attenuator and you are all set.

 

Home Station Information - Sending out Objects with a UI-View Station

One of the problems with UI-View is that when you send out objects that are created with in UI-View, they go out with the same path you have set in your station setup.  This can be a problem because it floods the network with unwanted packets.  An example would be if you wanted to send out an object for a particular repeater, it will go out with your normal station path (something like WIDE2-2) when it should be kept as a local only object.

There are two ways to accomplish this as a local only object.  The best way is to have it generated right from the local digipeater with a computer running UI-View or directly from the TNC running the digipeater.  At a lot of my sites, this is not a practical option.  The second way is to find someone that can hit the local digipeater direct (no other hops needed) and be sure that they have a Kantronics KPC3 or KPC3+ TNC.  You can program the TNC to send out up to 4 objects with a path using the local digipeater.  This isn't as good as having the digipeater itself send it out, but it is much better then sending it out with the larger path.

The settings are:

LT 1 ;145.370  *111111zDDMM.hhN/DDDMM.hhWr145.370 T114 R30m
LT 2 ;Aspirus  *111111zDDMM.hhN/DDDMM.hhWhAspirus/Wausau Hospital
LT 3 ;Krnwtr FD*111111zDDMM.hhN/DDDMM.hhWdKronenwetter FD
LT 4 ;Krnwtr PD*111111zDDMM.hhN/DDDMM.hhW!Kronenwetter PD
*Be sure to use the correct object icon for the object you are creating.  A list of object symbols is available here.  The maximum length for the object name is 9 characters.  The first LT string send out a repeater icon (the letter r does this) for the 145.370 repeater.  The end of the string again tells us that it is the 145.370 repeater but also tells us that it has a tone of 114.8 (no need to worry about the decimal point and following number, all the tones we use are standard so when everyone sees the T114, they will know to use the tone of 114.8) and has a range of 30 miles.  The other 3 LT strings give us locations of a local hospital (letter h), fire department  (letter d), and police department (!).  The "/" between the lat and long tells the decoding software which table (/ or \) to pick the correct icon from.  For instance, if we use our "h" for the hospital, using the "/" table will make the icon show as the hospital icon , but using the "\" table, it will show up as the ham store icon .  Before creating an object, always check to make sure that the name you want to use isn't already being used.  You can type it in on the APRS Search Engine to the left.  If you are creating Echolink, IRLP, Winlink 2000, or WIRES objects, check out this link to get the correct format.

BLT 1 EVERY 00:10:00 START 00:00:03
BLT 2 EVERY 00:10:00 START 00:00:13
BLT 3 EVERY 00:10:00 START 00:00:23
BLT 4 EVERY 00:10:00 START 00:00:33
*These BLT strings tell the TNC to send out the LT strings every 10 minutes and stagers them so they don't all go out at the same time.

LTP 1 APN383 VIA KC9NW-1
LTP 2 APN383 VIA KC9NW-1
LTP 3 APN383 VIA KC9NW-1
LTP 4 APN383 VIA KC9NW-1
*These LT strings tell the TNC what path to use when sending out the LT strings.  Be sure to substitute in your correct TNC firmware version, these are for a KPC3+ running firmware 8.3.  Also don't forget to substitute in the call of your local digipeater.

This has been test and known to work on Kantronics KPC3 ver 8.2, KPC3+ ver 8.3 and ver 9.1.  It is not known if it works on any other TNCs or firmware versions.  If you try it on something other then those listed above, drop me an email (n9mea[at]wisconsinaprs[dot]net) and let me know if it worked or not.