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  #1  
Old 07-08-2018, 07:54 AM
RV6_flyer's Avatar
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Default APRS Bearing or Track

Flew my APRS tracker for its first successful test flight today.

https://aprs.fi/#!mt=roadmap&z=11&ca...3600&tail=3600

http://www.airprs.com/#/tab/flight/num/1531050481
(Yes I know the above has reached End of Life and will go DARK at any time.)

It appears that I am seeing bearing from iGate and not airplane heading or track. Most other tracks I have looked at appear to be heading or track of the aircraft. Wondering if I have something programmed incorrect.

RTG has the program it shipped with. IT looked good to me before install so changed nothing. I am using my Garmin G5 #2 RS-232 at 4800 baud (9600 baud did not work) as my Byonics RTG GPS source.
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  #2  
Old 07-08-2018, 08:16 AM
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Gary, it seems to me this would have to be a problem with the web interface. Your tracker and the G5 don't know the location of the iGate, only the web interface has that info. I would fly the tracker (it is working very nicely!) a few more times and see if the error persists.
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Last edited by Sam Buchanan : 07-08-2018 at 08:20 AM.
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  #3  
Old 07-08-2018, 05:00 PM
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Gary welcome to the APRS TV! It's a cool albeit ancient little device. Now we know where you are

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  #4  
Old 07-08-2018, 05:19 PM
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Just s teachable moment:

The beacon contains the data, including latitude, longitude, altitude, speed, and heading. All of that is computed from the GPS data.

The beacon is received by zero or more stations. These stations may be igates or digipeaters. Eventually the beacon arrives at zero or more igates. The various web interfaces don't bother to do any extensive data crunching to compute the beacon relative the igate which ultimately got credit for submitting to the "big database in the cloud".
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  #5  
Old 07-08-2018, 05:20 PM
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Quote:
Originally Posted by Vlad View Post
Gary welcome to the APRS TV! It's a cool albeit ancient little device. Now we know where you are
Vlad:

Thanks.

My HAM license expired back in the late 70's when I started working full time. Got it back last year and was able to reclaim my old call sign.

Hope you do not mine me STEALING part of your signature and adding it to mine after I customized it.

I have an APRS On / Off switch below the throttle so yes I could do something like you show.
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Gary A. Sobek
NC25 RV-6
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Where is N157GS
Building RV-8 S/N: 80012

To most people, the sky is the limit.
To those who love aviation, the sky is home.
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  #6  
Old 07-08-2018, 09:51 PM
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Quote:
Originally Posted by humptybump View Post
Just s teachable moment:

The beacon contains the data, including latitude, longitude, altitude, speed, and heading. All of that is computed from the GPS data.

The beacon is received by zero or more stations. These stations may be igates or digipeaters. Eventually the beacon arrives at zero or more igates. The various web interfaces don't bother to do any extensive data crunching to compute the beacon relative the igate which ultimately got credit for submitting to the "big database in the cloud".
Glen, not sure I fully follow your reply, but are you saying it was igates that were submitting the "bearing to igate" data to the web interface? I don't look at heading data on my beacons so don't know that I've ever had this bearing to igate "error".
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  #7  
Old 07-09-2018, 05:12 AM
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Quote:
Originally Posted by Sam Buchanan View Post
Glen, not sure I fully follow your reply, but are you saying it was igates that were submitting the "bearing to igate" data to the web interface? I don't look at heading data on my beacons so don't know that I've ever had this bearing to igate "error".
Yeah, my post turned into one home run-on pil of confusion.

The point wanted to make some clarification of the APRS system:
  1. Just because a tracker sends a beacon, doesn't mean it will make it to the internet
  2. It's common that more than one igate will process a given beacon
  3. When multiple igates receive a beacon, "the fastest igate wins"

Specific to the OP, only two points are important:
  1. The data fields displayed on websites are all determined from the GPS data by the tracker and encoded into the beacon
  2. None of the websites [that I have reviewed] perform any computation on beacons beyond what is needed to format the data

Here is a good overview: ftp://www.tapr.org/projects/mic-edev...c-e-proto.html

The protocol allows for additional optional dat to be incorporated into a beacon.
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Last edited by humptybump : 07-09-2018 at 05:22 AM.
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  #8  
Old 07-09-2018, 08:01 AM
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Thanks for the reply, Glen. I still understand the situation to be one where only the website knows the location of the igate, not the tracker. So if heading to igate info appears on the website rendering of beacons, it has to be generated by the interface because the tracker doesn't know the location of igates. We may be seeing igates that are mis-configured and sending unneeded data to the web.

Gary, a call to Allen at Byonics may very well clear all this up. But your tracker is working very nicely....enjoy!
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  #9  
Old 07-09-2018, 12:01 PM
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Quote:
Originally Posted by Sam Buchanan View Post
if heading to igate info appears on the website rendering of beacons, it has to be generated by the interface because the tracker doesn't know the location of igates
That is correct Sam. Do you know of a website that shows "heading to igate"? I've not come across any.
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  #10  
Old 07-09-2018, 07:04 PM
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Quote:
Originally Posted by humptybump View Post
That is correct Sam. Do you know of a website that shows "heading to igate"? I've not come across any.
This entire discussion was prompted by post #1 of this thread. Read it and look at the beacons on Gary's flight. You will see what we are discussing.
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