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  #51  
Old 01-10-2012, 03:45 PM
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humptybump humptybump is offline
 
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Location: Eastern Shore of Virginia
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Default iGate "soon"

It's been an interesting journey setting up my iGate. (it's not yet up full time or in its final configuration) I have been bouncing back and forth between a Windows PC setup and a Linux setup. I'll do a write-up when it is done.

In the mean time I thought it interesting the percentage of packets that the AGWPE Soundcard modem hears vs decodes. It's much lower than I would have thought. I'd say only about 10% of APRS transmissions that my rig is picking up are actually complete and decode-able - aka checksum verified. Now that I have a decent antenna and cable, I feel the audio getting to the Soundcard is as good as it will be. To be honest, I suspect a dedicated hardware TNC would be doing about the same.

What all of this tells me is that APRS in an interesting hobby but users should not be assuming it is anything more than that. Put another way, if I want a rescue tracker in my plane, I'll install a SPOT or similar satellite tracker.

Don't get me wrong, I think it is cool having an APRS tracker in my plane and I often look for other pilots whom I know have trackers. I will just remember that it's a hobby.
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  #52  
Old 01-10-2012, 04:26 PM
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Sam Buchanan Sam Buchanan is offline
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Quote:
Originally Posted by humptybump View Post
It's been an interesting journey setting up my iGate. (it's not yet up full time or in its final configuration) I have been bouncing back and forth between a Windows PC setup and a Linux setup. I'll do a write-up when it is done.

In the mean time I thought it interesting the percentage of packets that the AGWPE Soundcard modem hears vs decodes. It's much lower than I would have thought. I'd say only about 10% of APRS transmissions that my rig is picking up are actually complete and decode-able - aka checksum verified. Now that I have a decent antenna and cable, I feel the audio getting to the Soundcard is as good as it will be. To be honest, I suspect a dedicated hardware TNC would be doing about the same.

What all of this tells me is that APRS in an interesting hobby but users should not be assuming it is anything more than that. Put another way, if I want a rescue tracker in my plane, I'll install a SPOT or similar satellite tracker.

Don't get me wrong, I think it is cool having an APRS tracker in my plane and I often look for other pilots whom I know have trackers. I will just remember that it's a hobby.
Keep in mind that packets your iGate may not be decoding are most likely being ported through an iGate that is closer to the tracker than your station. The non-decoded packets may be from trackers a great distance from your iGate.

Yes, APRS is indeed a hobby endeavor, but I continue to be amazed at the accuracy and consistency of the tracks I've watched my tracker generate over the past few years. In areas that have decent iGate population I have much greater confidence in a search being successful due to APRS tracks than an ELT or possible even a SPOT with its less frequent transmission interval. The density of iGates is the primary factor for the useability of APRS, some areas of the country are better than others.
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Last edited by Sam Buchanan : 01-10-2012 at 04:29 PM.
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  #53  
Old 01-10-2012, 05:04 PM
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I left SPOT because I felt that I couldn't trust it. There was one area that I traveled frequently and SPOT consistently lost me for about an hour. Maybe that was a small sample to make a decision on, but IMHO it was enough to lose me as a customer.

APRS has been amazing to me. As long as you have someone that cares watching you, it is likely to be more accurate. Personally, this group with support from people like Sam, made it possible for me to fulfill a lifelong dream of having a Ham license.

There is no perfect solution, but this is as you say at the very least an interesting technical exercise.

The problem for you Glen, is you live where there are way more crabs and waterfowl than iGates.
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  #54  
Old 01-10-2012, 06:01 PM
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Originally Posted by Sam Buchanan View Post
Keep in mind that packets your iGate may not be decoding are most likely being ported through an iGate that is closer to the tracker than your station.
Sam, first my many thanks for all you've contributed to VAF and to the APRS thread.

In my case, I was testing raw decoding and not gating the messages. I used a tool that let me see messages and toggle the checksum. I have also listened to the radio over periods of time.

One thing interesting is how many digipeters in my extended (100+ mile radius) and how few gates. Hence, I hope to add a gate for my geography.

In general "someone" is watching my flights which makes APRS all the more interesting and useful. I'm definitely an APRS proponent
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  #55  
Old 01-10-2012, 06:27 PM
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Sam Buchanan Sam Buchanan is offline
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Quote:
Originally Posted by humptybump View Post
Sam, first my many thanks for all you've contributed to VAF and to the APRS thread.

In my case, I was testing raw decoding and not gating the messages. I used a tool that let me see messages and toggle the checksum. I have also listened to the radio over periods of time.

One thing interesting is how many digipeters in my extended (100+ mile radius) and how few gates. Hence, I hope to add a gate for my geography.

In general "someone" is watching my flights which makes APRS all the more interesting and useful. I'm definitely an APRS proponent
My experience with iGates is limited but it seems some soundcards are much better at decoding than others. The audio line level also has a large impact on decoding. I must have gotten lucky with an APRS-friendly soundcard (desktop computer) because it appeared my iGate was decoding a good percentage of the beacons it heard.

Glad to hear you are adding an iGate, it will certainly add APRS coverage in your area.
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  #56  
Old 01-10-2012, 07:09 PM
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Glen tell us when it's set and we will come to test it.
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