Re: RF to IS (Igate Question)

James Ewen


One thing that would help is including your callsign so that we have a chance of helping you understand your local RF environment.

It appears that your email address is your name, and your name is fairly unique (ie not Smith or Jones), so a search on gives me a callsign of KC8WCJ.

It looks like your igate is KC8WCJ-10.!call=a%2FKC9WCJ-10&timerange=3600&tail=3600 is showing that there are 13 other stations gating traffic to the APRS-IS within 40 km of your location. So, you are competing with all those stations in the race to get packets to the APRS-IS first.

But as others have said, putting an APRS infrastructure component on the air isn't a competition. In fact putting APRS infrastructure on the air is something that needs to be done with planning and forethought. Putting a digipeater on the air needs to be thoroughly researched and planned before one should be making the decision to put it  in place. Digipeaters heavily impact the RF network by resending the packets back into the RF network.

I-gates are less of an impact on the RF network due to the fact that they are mostly a listen only device. Only when there are messages destined for a local RF station from a remote station will the i-gate push traffic to RF. Having too many i-gates in an area can cause a bit of traffic congestion when they all try to push the same remote traffic into the overlapping coverage area. But for the most part, there's not a lot of IS-RF messaging happening.

So, if the purpose of putting an i-gate into service is to try and "win", you've got your work cut out for you. Probably the easiest way to "win" is to disable all other i-gates for 50 miles or so. Arson works well, but it is frowned upon. Seriously, you are not alone in wondering why your i-gate isn't gating everyone around you. You have stated that you understand the race conditions, and the anit-dupe filtering, so the issue you are facing is the delay in your station. That is a factor that is contributed to by every component between the RF spectrum and the APRS-IS network. I wouldn't bother trying to tweak every component to try and "win the race". it's not important.

What is important is not the number of packets that you have gated to the APRS-IS, but the fact that you have gated packets to the APRS-IS.

This page can show you all the stations that were "heard" by your i-gate station. The fact that labels this list as "Stations heard directly by KC9WCJ-10"  is perhaps where a lot of people get hung up. It really should say "Stations heard directly by KC9WCJ-10 that managed to get to the APRS-IS first, and therefore not get killed by the APRS-IS duplicate packet filters". You can see another view of the same information here:

You can also look at the graphs of what your station is doing...

You can click on one of the callsigns in the list and have a look at the raw packets from that station to see that your i-gate was able to move those packets to the APRS-IS. You can see all the rest of the stations acting as i-gates as well.

2020-08-22 00:01:24 MDT: KD9OAJ-9>TQUX9Q,WIDE1-1,WIDE2-1,qAO,KC9WCJ-10:`sK7l{M>/`"5v}_%
2020-08-22 00:02:07 MDT: KD9OAJ-9>TQUX6T,WIDE1-1,WIDE2-1,qAO,KC9WCJ-10:`sK4m\|>/`"5x}_%
2020-08-22 00:02:51 MDT: KD9OAJ-9>TQUX6U,WIDE1-1,WIDE2-1,qAR,AB9FX:`sK<0x1d>m 7>/`"5w}_%
2020-08-22 01:14:22 MDT: KD9OAJ-9>TQUX6Y,WIDE1-1,WIDE2-1,qAR,WA9SGF-2:`sK<0x1d>l!`>/`"5D}_%
2020-08-22 02:08:45 MDT: KD9OAJ-9>TQUX6Y,WIDE1-1,WIDE2-1,qAR,WX9O-3:`sK<0x1d>l!#>/`"6)}_%
2020-08-22 08:54:35 MDT: KD9OAJ-9>TQUX6X,WIDE1-1,WIDE2-1,qAR,KD9KAF-1:`sJ~l"q>/`"6C}_%
2020-08-22 08:57:32 MDT: KD9OAJ-9>TQUX6Y,WIDE1-1,WIDE2-1,qAR,KD9KAF-1:`sJ~lI\>/`"5s}_%  

One of the key things you need to keep in mind is that there is probably a lot of competition on the RF network between stations. APRS by it's design does not attempt to eliminate packet collisions. They happen all the time. By having multiple receivers available, you have multiple chances to be able to copy the packets on RF. This station above was on N Nagel Ave, just south of the Kennedy Expressway, not far from your house when you gated these packets. Is that because your station finally won the timing race, or was it because your station was the first station to get a clear copy of his packets? There may have been packet collisions happening that corrupted the packet reception at other local i-gates, but due to proximity and FM capture effect, your station managed to copy the full packet, and was able to gate it to the APRS-IS. Had your i-gate not been operating, it is possible that a local fill-in digipeater would have acted upon the WIDE1-1 path element, and then another i-gate might have copied that packet, and pushed it to the APRS-IS. Just as likely, it may not have happened, and those packets would have never made it to the APRS-IS network. You can't know for sure. We do know for sure however that some combination of events and conditions meant that your i-gate helped these two packets from this station get to the APRS-IS network.

In areas of high APRS traffic, we can see people putting up digipeaters with little regard to the impact they have on the RF network. The "more is better" mentality kicks in when people see that their packets aren't making it to the APRS-IS, when in fact the issue is that there are too many packet collisions happening. Adding another digipeater compounds the issue, by increasing the number of packets on the air. The addition of more i-gates on the other hand can help in a situation like this as they generally are listening and not retransmitting packets. Lots of i-gates end up masking the overcrowded RF network by capturing local RF packets and forwarding them to the APRS-IS. 

Trying to fix an overcrowded APRS RF network is almost impossible. It's like herding cats. You need to educate people, get them to listen, understand the issues at hand, and then finally commit to actively work on correcting the problem. Most of the source of the perceived problem is people not seeing their packets on the APRS-IS. They will increase power, increase path lengths and increase their beaconing rates in an attempt to "fix" the problem. By having a lot of i-gates listening and  gating packets to the APRS-IS, this "fixes" that problem, and perhaps keeps some people from increasing power, increasing path lengths, and increasing beacon rates. If they are shown to be successful with low power, and a short path, perhaps they will back off, and subsequently reduce their impact on the network, which in turn leaves more room for others, and reduces the number of collisions on the RF network.

So while your station might not be winning the race every time, you are still helping to push packets to the APRS-IS.

Say "Hi" to Roger and Steve! That's a pretty busy block for amateur radio!


On Sat, Aug 22, 2020 at 11:41 AM Rich <rich@...> wrote:
I have the dubious distinction of being one of the few igates in this part of NE PA according to  Lots of digipeaters but no igates.  I liken that distinction to being the elephant (big ears) in the room with a bunch of alligators (big mouths, e.g. repeaters.)  I hear most of the digipeater traffic and send it to the internet.   

Ya play the hand you are dealt.  :)

On Sat, Aug 22, 2020 at 11:35 Rob Giuliano via <> wrote:

But that is exactly my point.  I understand wanting to contribute.
Not trying to say this 'isn't contributing".  

The system may work just fine (now) if this (or that) station is removed, but if too many in the area did the same thing, the system would break.  Keeping your igate up is not a bad thing - unless it is also DIGIing and over flowing the RF capability.  It is there to be used when needed.  Add battery backup or other capability that will continue to feed in power outage or something and your backup becomes even more important.

It is also important to look at the network (as I suggest below) to see why.  If your station becomes a backup - good.  If your station is not contributing for another reason, you can dig deeper.  If other igates are closer, you are VERY unlikely to win no matter how high you put your antenna.

Robert Giuliano

On Saturday, August 22, 2020, 11:17:27 AM EDT, Mike Jordan <mjordan@...> wrote:

Hi Robert, for some of us, the reason we set up an APRS station is to be
able to contribute and do something for the ham community. Maybe getting
enjoyment out of being able to provide something for others is old
fashion and out of style, but that is why I do it.  What is the fun of
setting up a station if a few super stations with lots of power, high
antennas, super fast internet speeds, etc., get to do all of the
transferring of APRS information?  That means there really is no need
for my station or any number of stations in my area to even attempt to

So yes, it is natural for some of us to wonder and question if our
stations are even doing any good and if not, is there anything we can do
that will improve our contribution to the APRS system. Ever since I've
set up my station 4 months or so ago, I've looked a number of times to
see if my IGate was doing anything for the APRS community around me. I
think it is, but then they were doing fine before I set up and would do
fine if I take it down... but like the original poster of this thread, I
still wonder if my station is doing any good at all.

We each do this for our own reasons, it's human nature.


On 8/22/2020 7:59 AM, Rob Giuliano via wrote:
> I don't understand the question.
>    There is no reward for providing the most packets to the APRS system.
> Why is it so important to have "your igate" be the one that gets the
> packet posted?
>    The point here is to ensure all packets ARE POSTED. And it appears
> they are.
>      If the packets are being handled, then the system is working.
> If someone else is the one that posts them, there are a number of
> reasons - none are bad!
> 1.  The packet was sent direct over IP, and over over RF
>      Sorry, you will NEVER win!
> 2.  Other igates are closer and receiving the packet before you
>      How many hops have been used before you hear the packet?
>          Any one of those hops may also be an Igate.
> 3. You antenna is higher than everyone else and they et the signal first.
>      Kind of sounds funny to type out.
>      Truth is: that additional height is not likely to make a difference,
>        unless that is another igate right next to yours (like next door).
> If you are really that interested, you can do a little research to see
> how things are working.
> Go to (or other site that gives details) and choose some
> stations near you to see
> who did gate them.  Compare the stations location and distance to that
> igate to that station and
> your location.  If the distance to your station is closer, you can
> consider improvements.  If not,
> then you are just not in an area where APRS stations are transmitting from.
> Robert Giuliano
> On Saturday, August 22, 2020, 1:33:03 AM EDT, timcholdas@...
> <timcholdas@...> wrote:
> Hello All!
> Just downloaded and set up the software for use as an RX/TX Igate. Wow,
> what a wonder program! For as many features as it has, it really works
> so well and is very intuitive.
> I am using Direwolf as a software TNC from my Yaesu radio hooked to a
> vertical at 70 feet. I'm hearing a ton of stations (verified by
> selecting RF only for both the map view and scroll). Unfortunately, I'm
> barely uploading any to the IS per Maybe 1 out of every 100
> received are being uploaded to the IS. From what I understand, if
> packets are duplicated, the first one takes priority and the others that
> are received by servers are disregarded. I'm wondering how/ why the
> other Igates are beating mine in uploading to the IS. Is direwolf slower
> than hardware based TNC's? I tried the rotate.aprs2 server as well as
> noam.aprs2. Everything is working fine per se, just seems to not upload
> nearly as much as it receives.
> How can I "speed it up"?
> I've been a long time APRS user and am wanting to give back to the
> community by adding some coverage.
> 73 all,
> Tim

Rich Hurd / WC3T / DMR: 3142737  
Northampton County RACES, EPA-ARRL Public Information Officer for Scouting
Latitude: 40.761621 Longitude: -75.288988  (40°45.68' N 75°17.33' WGrid: FN20is

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