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APRS stopped working

LettersFromFlyoverCountry

Well Known Member
Hi folks:
After a flight down to Red Wing a couple of weeks ago, my APRS suddenly stopped squawking me.

I've noticed some gaps in the track just prior to that, Oshkosh for example.

But nothing since that Red Wing flight.

We flew through a fair amount of rain on the way back from Cleveland a couple of months ago. And there was a long gap through Indiana.

I took the wingtip off today and verfied that the unit is getting a signal from the GPS -- steady green light -- and that it is transmitting -- red light and a packet burst on the scanner in the hangar.

The antenna was twisted in a few spots as the old Gorilla tape let go but I replaced it all and went for a flight today.

Nothing.

What steps should I take to diagnose this problem?
 
Bob,

Good idea checking the antenna/RF situation but that is definitely not the problem as evidenced by your recent raw packets on aprs.fi. Plenty of packets but alas, not a single legitimate position report in the last 149 packets on August 15. I've never seen anything like this.

Couple of possibilities come to mind: could your GPS settings have been changed so it's no longer outputting $GPGGA or $GPRMC sentences or some other GPS-related malady? (I'm not sure if the steady green LED means the GPS is sending good sentences or only that it has acquired satellites.)

Your TinyTrak3 has switch-selectable primary and secondary operating parameters. Most people skip the switch and used the default (primary) but is it possible you've switched to the secondary parameters and they aren't programmed properly for position reports?

It would be helpful if you would post a screen capture of your TinyTrak3 configuration screen. Perhaps something seemingly innocuous somehow managed to get checked.

--
Joe
 
GPS not likely the culprit, at least in configuration.I'm using the little GPS puck out there, not feeding from the 296 in the cabin.

But, actually I'm using an old Micro Track (since discontinued)

I'll have to pull the unit, rig up the cable and see what the current configuration is.

Since we flew through so much rain coming back from Cleveland, I'm kinda wondering if there's any possibility a static electricity buildup might've had some kind of impact. Of course that was before the Red Wing flight.

I'm inclined to just upgrade the system.
 
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Position Info

Bob,

I looks like your position info is not coming thru. Packets are there on the web, but no data to tell them where to plot it.

If you look at some on my raw data, you can see the position info:

2015-08-11 16:42:36 CDT: KD0CVN-1>APOT21,WIDE2-1,qAR,W0YC-5:!4434.37N/09230.43W'290/129/A=002427-018807.9V 74F
2015-08-11 16:44:21 CDT: KD0CVN-1>APOT21,WIDE2-1,qAR,N9XH-4:!4436.16N/09234.66W'302/119/A=002514+006607.8V 74F
2015-08-11 16:44:57 CDT: KD0CVN-1>APOT21,WIDE2-1,qAR,N0AGI:!4436.84N/09235.95W'314/112/A=002554+005507.9V 75F


Might be a bad connection from the GPS to the microtrak. Give me a call and we can talk thru it.
 
I hadn't seen the packet data before. That certainly answers a lot of questions.

Connections were solid between the gps and MT so I've ordered a new one and I'll swap it out.
 
Pete et al. I swapped out the GPS with a new GPS5 from Byonics. I got a flashing blue LED on the GPS5, signalling a link with the satellites, and I've got a steady green LED on the MicroTrak, signalling it's getting GPS data. Of course I had a steady green with the old GPS too, so there you go.

I haven't taken it up yet to see if it can hit a repeater and send good data.
 
At about that same time, I had a flight from Northern AZ to Colorado, where packets were sent, but no GPS position. Flew again last week and worked perfectly.

My guess would be a temporary problem on the APRS server. GPS seemed to be normal on the EFIS, or I'd suspect a gps outage.
 
HI Bob,

we might want to program the microtrak to not use Mic-e compression, too. I can do that for you with my old laptop.

Send me a message if you are coming to KANE for the AOPA thing.


Pete et al. I swapped out the GPS with a new GPS5 from Byonics. I got a flashing blue LED on the GPS5, signalling a link with the satellites, and I've got a steady green LED on the MicroTrak, signalling it's getting GPS data. Of course I had a steady green with the old GPS too, so there you go.

I haven't taken it up yet to see if it can hit a repeater and send good data.
 
I got my airplane all put back together after getting painted, and now the APRS is no longer working. The Micro Trac is in the left wing tip, and has always performed great. My first thought was I misconnected something during reassembly, so I took off the wing tip again, and everything was fine. GPS puck stuck down on the bottom of the wingtip with some velcro. The J-pole antenna also in place and connected tightly to the unit. The GPS and power is connected and I get the usual red/green LED indications that it is online, and after a few minutes a steady green LED indicates that the GPS has a position lock.

I put the wing tip back on and flew around yesterday, but still no tracks getting broadcast!

Could the paint on the wing tips be blocking the GPS? It does have some amount of metal flake in the paint, but it certainly isn't what I think would be extreme enough to be a problem.

Does anyone here have any other advice on troubleshooting this issue?
 
maybe

metallics in paint are blocking the VHF signal from the Tx rather than the GPS reception. Check VSWR after painting? Might not be easy to do inside the tip, but it's a free suggestion ;)
 
Where did you perform the test flight? If it was sufficiently local, it could be a ground station off-line.

There are a number of plane with metallic paint and trackers so That may not be the [full] problem.

If you know a HAM radio operator and/or can find a radio that will receive 144.39Mhz, you can verify you are transmitting.

he better _be_ a ham operator :p

Clarification (for smarty people): "find a HAM operator with lots of useful tech toys like 2M portable radios, antenna and transmitter testers, etc.
 
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If he's on APRS

he better _be_ a ham operator :p

Good point about verifying tx on 144.39 with an HT or other rig, ideally while watching the status LED's on the tracker to be sure it's _your_ data burst you're hearing.
 
Yes, I'm officially KJ6YRP and I do have a handheld. This weekend I flew up and back from Ramona to Corona, and Ramona to Cable to Long Beach and back. I always have great APRS coverage in the SoCal area.
 
It is back working. I was able to hear the packet bursts from my handheld scanner. Not sure what was the issue during the previous flights. I just opened up the wingtip and made sure all of the connections were OK. Maybe I just had to jiggle the wires a bit?
 
that's happened to me before, Bruce.

More than once. Tracker mysteriously inop at a locale/altitude where I've always hit iGates in the past. No sooner than I check connections it starts working on the next leg of the flight.

I suppose all this will become fairly moot once 2020 gets here and we can be tracked all the time by big brother.
 
update

I'm in the middle of doing my annual condition inspection, so the wing tips were off again. I had disconnected my J Pole antenna and put the APRS antenna that I got with the tracker inside the wing tip back several months ago. The changing of the antenna solved the issue I was experiencing with packets not getting heard. I was back to spitting out packets reliably. When I did this change, I just left the J Pole antenna in the wing tip (figuring I might need to use it again if the other antenna wasn't the solution).

I pulled out the J Pole antenna and found this on the end.

IMG_4980%20%281%29-M.jpg


I don't recall seeing the conducting wires sticking out of the end before.
Maybe this was shorting and causing the intermittent issues?

I did a Google search on J Pole antenna fabrication with TV antenna wire, and some examples have the wires at the end connected and others say not to connect it. I guess it depends on how long the wire is to match the wavelengths of the transmitter. Obviously, this model left them disconnected.

So a question for Pete: Can I just cut off the wires extending from the tip? I have a picture of the J Pole antenna when I originally installed it, but zooming in is a bit blurry. I don't see the wires poking out more than a tiny bit. I'm just wondering how the wires started migrating out of the insulator plastic covering (vibration? heating/cooling?).

Has anyone else seen this happen before?
 
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Antenna

Bruce,

Let me know if your antenna is not repairable, I can dig up one of our V6 ( Center-fed, 1/2 Wave dipole) which is a bit shorter and will get a bit more ERP out of your Micro-Trak. You can E-Mail me directly: [email protected].

73,

Allen AF6OF
VHS/BYONICS
 
The V6 made a big difference in my RV-8 wingtip installation. Thanks to Allen for getting me to change from what you were using. He is very, very good at keeping you up and running IMHO.
 
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