Featherweight Tracker - Some iPads don't have a GPS so can't be used for tracking...

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kjs

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There has been a perplexing issue where some iPads seemed to have problems with the Featherweight Tracking app. The symptom: "The arrow is basically stuck pointing in one direction, the elevation 'bubble' is stuck near zero, and distance usually says the rocket is really far away."

We now know that it is because some iPads (ones without cellular capability) don't have an internal GPS and only use WiFi location (and so at a launch the iPad may think you are at the last location where you were connected to WiFi - usually where your home is...).

You can still use it to get accurate GPS location of the rocket and some audio readout of descent, but calculated altitudes, distance and elevation will be wrong as it will be relative to your home...

I saw it happening during a flight for the first time yesterday (where it was obviously not pointing in the direction of the rocket). What I noticed as odd was the iPad was still calling out descent altitudes and receiving good GPS packets from the tracker. And the iPad had GPS coordinates displayed (but I now realize I didn't glance at whether they were updating...). Anyway, it made no sense that we were obviously getting good packets from the rocket but the "math to tell us where it was at wasn't working..."

After it landed I decided the GPS location of the rocket had to be correct but something was wrong with the iPad - so we pulled up the location on a computer / google maps to sanity check it and then they put it in their phone to go retrieve the rocket. When they got back, they noted that the distance to the rocket that was being displayed was ~62 miles which was the distance back to their home... The flyer now plans to get a cheap iPhone off of ebay to use instead.

Googling for "apple ipad no gps capability" this morning confirms the lack of GPS in (at least some) WiFi only iPads...

I do not know if you created a local hotspot if the iPad would get an updated location...

Anyway, wanted to let people know if they are planning to track with an iPad... (I personally prefer a smaller phone device just for convenience when retrieving a rocket...)
 

AllDigital

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You are correct. WiFi only iPads do not have a GPS. When connected to “database known WiFi SSIDs” they will approximate location. iPads with the cellular option have native GPS, but you don’t need a SIM card or data plan to access the GPS. This will impact location accuracy and bearing equally. When using applications that need gps location of the “base station” you need to use an iPad cellular model or any iPhone.
 
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WillMarchant

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AFAIK, you only get GPS built into your iPad if you buy a cellular model. That adds quite a bit to the price.

There are aftermarket GPS receivers with bluetooth for use with iPads. Perhaps one could run one of those with the Featherweight app at the same time?
 
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phyzzld

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Sorry for the confusion, but I thought that the ground station had GPS in it. Couldn't the ipad get location info from it via bluetooth?
(Assuming you are carrying the ground station with you.)
 

kjs

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Sorry for the confusion, but I thought that the ground station had GPS in it. Couldn't the ipad get location info from it via bluetooth?
(Assuming you are carrying the ground station with you.)
Good question! The original Ground Station was actually a full blown tracker mounted to a 'daughter card' in the GS box so it certainly had GPS in it. The newer GS2 ground stations are a single board by themselves without a GPS on them - so they use the phone/pad GPS for location.
 

phyzzld

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Good question! The original Ground Station was actually a full blown tracker mounted to a 'daughter card' in the GS box so it certainly had GPS in it. The newer GS2 ground stations are a single board by themselves without a GPS on them - so they use the phone/pad GPS for location.
Thanks for the info. Does that mean that both versions are available or is only the GS2 version available now. I have one of the GS1 versions. Where is my GPS location coming from, my phone or the ground station? Are there any plans to stop supporting the GS1 (hopefully not)?
 

kjs

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Thanks for the info. Does that mean that both versions are available or is only the GS2 version available now. I have one of the GS1 versions. Where is my GPS location coming from, my phone or the ground station? Are there any plans to stop supporting the GS1 (hopefully not)?
With a GS1, it is currently getting the location from the GS. The GS1 should continue to be supported, but realize that the newer trackers have the power header turned the other way to make for better space usage inside small diameter rockets. That means if you got a new tracker and wanted to put it in your GS1, the power header would need to be de-soldered and turned around.
 

kjs

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Thanks Kevin.
Oh, it also means that if you needed another tracker, you might consider getting the GS2 which would free up your existing tracker that is inside your GS1...
 
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