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askrob

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Hi all. I would like to get a GPS tracker for my rocket (PML Tethys). Eventually, I would like to do dual deployment, but not in this rocket. Any suggestions on a GPS tracker, or refer me to a post with that recommendation? I tried to contact Eggtimer Rocketry, but the email bounced.
 

MOF410

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I have a 2g gps tracker that was recommended by the rocket store...hes been using for years. Uses a sim card to send coordinates. Seems to work great so far.



There is another post about this, will update if I can find.
 

The-Rocket-Store.Com

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^^^^ This - If you are looking for small, simple, and you just want to find your rocket after it lands, it does the trick. I was experimenting with 4G unit that is twice the size, 3 times the weight-------and it works no better
 

askrob

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Interesting. I'm a bit concerned about cell (mobile) coverage. I'll be launching in Argonia, KS. My in-laws live in Anthony, KS (a few miles down the road), and I've had spotty coverage with T-mobile. Though that was better coverage than when I had Verizon about 5 years ago.
 

cerving

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Hi all. I would like to get a GPS tracker for my rocket (PML Tethys). Eventually, I would like to do dual deployment, but not in this rocket. Any suggestions on a GPS tracker, or refer me to a post with that recommendation? I tried to contact Eggtimer Rocketry, but the email bounced.
Hmm... PM me and I'll get back to you, I don't know why the email would have bounced.
 

ksaves2

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Like others have said. The cell phone network trackers have the lowest learning curve and as long as you have service onsite, should work ok for finding your rocket.
 

heada

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2G cell service has a stated limited life. Most cell carriers have said they'll stop supporting 2G in the near future (2021 or so). Nothing written in stone but I'd rather not risk an investment for a limited lifespan. Eggtimer's GPS is good stuff. Featherweight seems to have a decent one too.
 

The-Rocket-Store.Com

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2G cell service has a stated limited life. Most cell carriers have said they'll stop supporting 2G in the near future (2021 or so). Nothing written in stone but I'd rather not risk an investment for a limited lifespan. Eggtimer's GPS is good stuff. Featherweight seems to have a decent one too.
It's under $20, and 2G has been "disappearing" for a decade now.
 

heada

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It's under $20, and 2G has been "disappearing" for a decade now.
AT&T discontinued 2G in 2017
Verizon has a date of Dec 31 2020 to have all 2G turned off (3G at the same time)
T-Mobile has a date of Dec 31 2020 to have all 2G turned off (but may delay until sometime in 2021)
Sprint has a date of Dec 31 2021 to have all 2G turned off

As 2G towers die, they're not being fixed or replaced as the costs to maintain them isn't justified. Eventually the carriers will just turn them all off like AT&T already did.
 

QFactor

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It looks like the Tethys has a nice long nose cone for installing an Eggfinder or Missile Works T3.
 

ChicagoDave

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if you have an iPhone the Featherweight GPS tracker is top notch and has worked extremely well for me. The only down sides are 1) iPhone only and 2) no map integration with the app (that I know of).

Here's a video of my Featherweight in action at Mini Midwest Power a few months back: Featherweight GPS Tracker
 

HHaase

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Does the Featherweight use its own GPS receiver for the iphone side of the equation, or is it dependent on the phone gps? I've found that the GPS receivers in phones are just not very good at all.
 

Bat-mite

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I use the BigRedBee 900MHz set (BRB900). Put the Rx in the rocket, turn on the Tx, receive real time coordinates. No learning curve until you want to download data and view in Google Earth (which is fun). No HAM required, no soldering required. The only catch is that you need something to navigate you to the coordinates. I use an old Magellan 315 hiker's GPS, about $20 on eBay.

1597174722585.png
 

ChicagoDave

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And watching the video reminds me I need to give you an easy "copy coordinates to clipboard" (or other way to share with a mapping application...!
Ha ha yeah, I guess I'm lucky that I can remember the GPS coordinates and type them in before I forget :cool: But having an easy way to get them to a map app would be great.
 
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John Kemker

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AT&T discontinued 2G in 2017
Verizon has a date of Dec 31 2020 to have all 2G turned off (3G at the same time)
T-Mobile has a date of Dec 31 2020 to have all 2G turned off (but may delay until sometime in 2021)
Sprint has a date of Dec 31 2021 to have all 2G turned off

As 2G towers die, they're not being fixed or replaced as the costs to maintain them isn't justified. Eventually the carriers will just turn them all off like AT&T already did.
Sprint's turn-off date matches T-Mobile's, as they're part of T-Mobile, now.
 

cerving

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The Eggfinder LCD receiver with the GPS add-on is a single-device ground solution... you don't need a phone to navigate or view the data. Plus, it remembers the received data, so if you drop it and it shuts off when the driver of the Jeep you're riding in gets a little too yahoo, you can turn it back on and it will pick up where it left off.
 

Cory

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Big Red Bee 900 mhz GPS is nice.
Missile Works RTX is nice.
Altus Metrum is nice.
All are effective - all are expensive.
 

kjs

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Does the Featherweight use its own GPS receiver for the iphone side of the equation, or is it dependent on the phone gps? I've found that the GPS receivers in phones are just not very good at all.
Currently the ground station (GS) for the Featherweight system is actually a full blown tracker just mounted to a 'mother board' so it fits in the enclosure and supports battery charging and external on/off switch. In that mode, the phone is using the GPS unit on the tracker inside the GS. For reasons I can't go into yet, I'm going to also work on using just the phone GPS to track to a location as an option. Having said that, I find the phone to be the same +/- 30 feet that most GPS like to spec... Perhaps I should record the delta for a while and test that...
 

HHaase

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Currently the ground station (GS) for the Featherweight system is actually a full blown tracker just mounted to a 'mother board' so it fits in the enclosure and supports battery charging and external on/off switch. In that mode, the phone is using the GPS unit on the tracker inside the GS. For reasons I can't go into yet, I'm going to also work on using just the phone GPS to track to a location as an option. Having said that, I find the phone to be the same +/- 30 feet that most GPS like to spec... Perhaps I should record the delta for a while and test that...
I'd suggest checking more long term to see how stable the phone is. Typically the phone stuff also has a much slower refresh rate. I tried doing some telemetry during autocross with my phone GPS and found it nearly useless. It was refreshing too slowly, and accuracy was intermittent. At times I'd get a 5m accuracy, other times I'd be lucky if the phone saw me being within a quarter mile of my location. This was with a few generations of iphones. I eventually gave up and got an external GPS receiver, which worked great until they stopped updating the associated app for newer generations of IOS. Now this is with actual GPS data, the cellular locating data tends to be more stable as long as you're in good coverage, though not as accurate.

-Hans
 

kjs

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Typically the phone stuff also has a much slower refresh rate. I tried doing some telemetry during autocross with my phone GPS and found it nearly useless. It was refreshing too slowly, and accuracy was intermittent. At times I'd get a 5m accuracy, other times I'd be lucky if the phone saw me being within a quarter mile of my location.
That is interesting.... I can say that when enabling the location tracking in a phone, there are different options for precision that can be used from 'finest' to much more coarse (because the finer resolution consumes the battery more). In one case I saw something about 3km accuracy and thought that was a little worthless. Anymore in these days though people plug their phones into their cars and use them for (successful) navigation so I would think they are much better now...
 

cerving

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GPS's give you a better fix the longer that you leave them on, the ones in cars and phones tend to stay powered on all the time (although they may be running in the background). The ones in rockets are generally not powered on until shortly before flight. That's one reason we got rid of the power switch on our transmitters... if you power it on first thing while you're prepping then you maximize the amount of time that the GPS has to find satellites and get a good quality fix. Turning it on right before you launch is not a good practice, unless you power it on ahead of time and put it into a "sleep" mode (which is what the original Eggfinder TX had, but we found out that it was not very workable in practice).
 

manixFan

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I'd suggest checking more long term to see how stable the phone is. Typically the phone stuff also has a much slower refresh rate. I tried doing some telemetry during autocross with my phone GPS and found it nearly useless. It was refreshing too slowly, and accuracy was intermittent. At times I'd get a 5m accuracy, other times I'd be lucky if the phone saw me being within a quarter mile of my location. This was with a few generations of iphones. I eventually gave up and got an external GPS receiver, which worked great until they stopped updating the associated app for newer generations of IOS. Now this is with actual GPS data, the cellular locating data tends to be more stable as long as you're in good coverage, though not as accurate.

-Hans
The refresh rate of phones is the same as any other consumer grade GPS system - once per second. Tens of millions use their phones for real-time mapping and navigation every day without issue. If phone GPS was as bad is you indicate, how could it possibly be used for real-time highway navigation at speeds of 60 -80 mph? This study showed that the average error rate of an iPhone 6 was 7-13m on GPS only:


Your experience seems to be limited by some other factor than your phone. Perhaps it was the app itself or the autocross environment - that fact that an external antenna solved the problem seems to indicate that may have been the issue.. But the idea that modern smartphones don't have sufficient GPS capabilities does not match with real world experience.


Tony
 
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HHaase

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I just know that I regularly have issues when I try to use my phones for navigation. When I was trying to locate my rocket last week, the app I was using would occasionally tell me I had 5m accuracy, but most of the time was bouncing between 250m and 5,000m. I ended up being about 100m away from the rocket when somebody else found it..... despite my phone telling me I was at the coordinates that my eggfinder gave me. My phone seems to work particularly bad in Minneapolis for some reason. It's always amusing when I travel for work and I arrive at my convention/training class/seminar while my phone is still telling me to take a left turn out of the hotel parking lot. I still carry a dumpy old Garmin GPS because it's simply more reliable for me than the three generations of iphone I've had.
 

DankMemes

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Depends on what you're looking for, if you're looking for somethings that's drop in and go for a tracker these are some good options, albeit pricey these are in the $400 range with all the accessories

Altus Metrum TeleGPS (Requires HAM License)

Apogee Simple Tracker
 

askrob

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I can solder, but not good at it. I might try the eggtimer or missleworks. Thanks all for the advice. Gives me some things to think about. I may end up getting my L1 first and then seeing what people are using at the launch. Much to decide.
 

DankMemes

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Here’s some videos detailing the assembly of the eggfinder tx and receiver.

Will give you an idea of what that’s like and if you’d be interested. It’s doable just need some patience and a steady hand for the smaller surface mount components


 

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