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  #11  
Old 07-10-2018, 06:32 AM
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Quote:
Originally Posted by Sam Buchanan View Post
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.
When I look at other trackers on the same system I do not see the odd heading anomalies.

One reliable diagnostic is to decode the raw beacons.

One example: https://aprs.fi/#!mt=roadmap&z=7&cal...3600&tail=3600
Another example: https://aprs.fi/#!call=a%2FKD0CVN-1&...3600&tail=3600

Perhaps there is an issue with the tracker firmware or it's configuration?

Addendum: is it possible the GPS is spewing erroneous headings?
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RV-8 FP IFR | Track my RV-8 | 53VG

Last edited by humptybump : 07-10-2018 at 06:51 AM.
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  #12  
Old 07-10-2018, 12:00 PM
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Location: NC25
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Quote:
Originally Posted by humptybump View Post
When I look at other trackers on the same system I do not see the odd heading anomalies.

One reliable diagnostic is to decode the raw beacons.

One example: https://aprs.fi/#!mt=roadmap&z=7&cal...3600&tail=3600
Another example: https://aprs.fi/#!call=a%2FKD0CVN-1&...3600&tail=3600

Perhaps there is an issue with the tracker firmware or it's configuration?

Addendum: is it possible the GPS is spewing erroneous headings?
My assumption at this time is that the Garmin G5 GPS is either giving me erroneous heading info OR (requires more investigation) a bit may be getting dropped in the data stream. I have a shielded twisted pair wire run for the data.
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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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  #13  
Old 07-10-2018, 05:48 PM
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Gary, there is definitely something messy within the beacons.

https://aprs.fi/?c=raw&call=N157GS&l...0&view=decoded

The above link shows the decoded details of your packets and the "course" is constantly changing. The rest of the data looks good. I'm not sure if the issue is in the tracker of the GPS data going into the tracker, or a wiring connection, or ... well, it's all speculation without further details.
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Last edited by humptybump : 07-11-2018 at 04:39 AM.
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  #14  
Old 07-10-2018, 09:22 PM
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Quote:
Originally Posted by humptybump View Post
Gary, there is definitely something messy within the braces.

https://aprs.fi/?c=raw&call=N157GS&l...0&view=decoded

The above link shows the decoded details of your packets and the "course" is constantly changing. The rest of the data looks good. I'm not sure if the issue is in the tracker of the GPS data going into the tracker, or a wiring connection, or ... well, it's all speculation without further details.
Tracker programming is as shipped from Byonics. I did read the program so as to make sure how it was received.

I was surprised that the Tracker would not read GPS data at 9600 baud but does at 4800. Documentation says it should work at both.

Byonics shipped me one of their GPS units today. Should have it to test before I depart for AirVenture. I ordered it just in case the Garmin G5 does not work. So far, the only thing about the G5 GPS I do not like is the heading.
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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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  #15  
Old 07-13-2018, 09:49 AM
VHS VHS is offline
 
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Default GPS Baud Rates, I-gates, etc.

Gentlemen,

I guess I will have to check your page more diligently! First, the RTG is perfectly happy to accept 4800 or 9600 Baud, but you have to select which one you want to use in configuration. It does not auto-detect the Baud rate. It still needs to me standard NMEA format. If you have a programming cable, it's easy enough to change, or I can reconfigure it for you.

The Internet knows the IP address of an I-Gate, but its actual location can be anywhere, and there is no special reason that the APRS-IS has to know or announce where it is...it can be a Ghost-Gate.

An I-Gate may receive signals directly, or bounced off multiple digipeaters. Irritatingly enough, a Digipeater can also be a ghost, with no position showing, or a bad position, like a string of zeros ( You would not want to live on the place on the planet with all zeros in its lat-long, you could step off he edge and seriously hurt yourself) A Digipeater can also be an I-Gate, without respect to whether there is another I-Gate 300 feet away. This can and will result in the same tracker's packet being sent to the APRS-IS (Internet) from two different I-Gates, not necessarily at the same time, and the packet may still be digipeated again, to weasel itself into some other unsuspecting I-Gate and confuse the poor mapping software at aprs.is, etc.

This is of course, democracy in action. The "system" ( Really a voluntary association of free-agents, often with contradictory goals) generally tolerates this kind of redundancy. Some Digipeaters just decide all on their own to receive packets, and just sit on them for awhile before transmitting. You may have seen a course track that suddenly shows a backtrack in a course that you know did not actually happen.

If you experience errata in mapping ( Call Hessu in Finland, not me! ) You should open aprs.fi, click on your station so that everyone else disappears, and over on the right hand side of the screen, use the button to display "Raw Data". If the right hand of that box is filled with all kinds of dire comments, like "Delayed Or Unsupported Packet" "Out of Sequence" or allegations of illegal time-travel and they have decided to disown you, there may be a problem with your local system. ( There is always a problem with local systems, fret not) Go back to your area of interest, pick a random tracker, and try that test again. If they have a Raw Data page filled with red text, you have one or more cranky digipeaters. ( These are best fixed with a hammer, or a shotgun, or at least reconfiguration.)

Information about range and bearing to stations is inferred by the mapping program (aprs.fi, etc) I would not rely on that piece of info to fly a course home, or call in an artillery strike.

Our TT4-based products, like the MTT4B, calculate range and bearing to a target (Dare I use that word? I dare, I dare!) from the tracker-end, and you can display that on our optional LCD display, but again, we only really know where the target claims to be, not where it really is. Schrodinger's Cat got out.

73,

Allen AF6OF
VHS/BYONICS
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  #16  
Old 07-14-2018, 08:00 AM
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Default Different GPS

Appears the track / heading was being reported incorrectly like Glen and I both thought. Not liking what I was seeing track wise, I figured spend a few bucks and get one of Byonics GPS units and see if it makes a difference.

The track / heading now appears to be reporting correctly. Now sure why the Garmin G5 NMEA 4800 baud data reports an incorrect value for direction but has good altitude and speed.

There are two G5s and a MGU-11 tied together on the CAN bus. They appear to work well together and always gives the correct Ground Speed. Will talk to Garmin at AirVenture 2018 and see if they have any idea. Easy enough to swap connectors between the two GPS units.

Need to get back in the airplane and route / secure the Byonics GPS5 cable to make the system ready to fly to AirVenture 2018 next week.
__________________
Gary A. Sobek
NC25 RV-6
Flying
3,300+ hours
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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