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iGate Receiving Question

dahugo

Member
So now that I am finally up and running in N40BY, I set up an Igate station at my house, KJ5SZ. It all works fine as I was in contact with another ham buddy who has had an Igate for quite some time (K5VAS).

Anyway, I noticed that even when my path of flight takes me closer to my Igate station at my house than other receiving stations, sometimes it is a more distant station that picks up and reports the location of my aircraft.

Dont' get me wrong--I dont' care so long as it is received. However, seems to me that it would be picked up and logged by the closest receiving station. Can anyone tell me why it is not always the nearest station that receives the signal and broadcasts it on the internet?

HUGO
KJ5SZ
 
Hugo,

I get the same thing happen with my iGate. I think it might be the fact that my APRS antenna in the airplane is in the wingtip and not the best signal in the direction of my station at all times. Or perhaps the other iGate stations have a lot better antenna or better internet connection than I have. So whoever gets my position to the internet first wins.
 
It could be the server you are using, some are faster than others. It is actually a race to get your position to the internet by various iGates, the one with the fastest internet connection will win. You might try some of the other server options in the iGate software. Another factor could be antenna gain, but I doubt it in this case because you said you were close to your iGate.
 
There are two common situations where a more distant igate will relay a packet compared to your on closer igate.

Case 1 - some igates are just faster to post to the Internet. If two or more igates relay the Sam message, the first one wins and all the duplicates are not logged.

Case 2 - weak signals or poorly tuned TNC will result in a corrupt message. I is possible for a closer igate to not get a perfect transformation of the audio whine a larger station or one with a well tuned TNC transforms the message completely.

My igate suffers from case #1. When I first set it up, I was gating about 6000 message per month. A new "bigger better" igate went up about 60 miles north of me and now most traffic gates thru it.
 
I've not used a KPC3 but there are typically three things that affect a TNC's ability to "make good data".

  1. the volume of the audio from the radio to the TNC
  2. the modulation of the audio from the radio to the TNC
  3. the amount of background noise in the audio

All of the above is optimized 'by ear'. Prior to connecting the radio to the TNC, you can listen to the audio to evaluate both the volume and the background noise. A good antenna is part of getting a good solid signal and thus a good solid sound.

Then, it depends on what level of audio signal is expected by the TNC. Some configurations need a speaker level audio signal while others need a line-level signal. The old "attenuated patch cord" was used to go from speaker to line level but this still required getting the volume correct for optimal data.

Finally, the squelch on the radio comes into play. Too much squelch and the audio gets clipped. I've seen a number of configurations of 'receive only' iGates which called for the squelch to be wide open.

All of the above is just to get good data. After that, it is up to your iGate software to get the data to the Internet APRS site.
 
There are two common situations where a more distant igate will relay a packet compared to your on closer igate.

Case 1 - some igates are just faster to post to the Internet. If two or more igates relay the Sam message, the first one wins and all the duplicates are not logged.

Case 2 - weak signals or poorly tuned TNC will result in a corrupt message. I is possible for a closer igate to not get a perfect transformation of the audio whine a larger station or one with a well tuned TNC transforms the message completely.

My igate suffers from case #1. When I first set it up, I was gating about 6000 message per month. A new "bigger better" igate went up about 60 miles north of me and now most traffic gates thru it.


What ever you are doing, it seems to work well. You were picking up tests from my car this morning 137 miles away. There are several stations much closer to me.
 
Thanks Keith. Just so other understand, APRS is an "amateur" activity and so iGates and Digipeaters can come and go without notice. I know this first hand because my traffic jumped a couple months back with an iGate went off-line and a new Digipeater came on line. The result is I'm gating about 25,000 each month and in a race with another on this forum for volume :)
 
Traffic

How does one tell how much traffic is passing thru their I-Gate?

Do you only rely on the info from APRS.FI or is there another method?

Below is what I see for my I-Gate N1FLY-1 on aprs.fi

Position packets heard directly: 439 on radio path Position packets sent to APRS-IS: 552 ? show map
 
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