GPS tracker for under $60

dch said:

I recently purchased a Amzdeal GSM GPRS GPS Tracker from a dealer on Amazon.
This tracker sends a text with its current GPS coordinates when you call it. You can use the coordinates in a smartphone app such as Polaris Navigation which will help you walk to the coordinates. Mine also sends a text with a link that you can open in google maps showing a satellite image with the location marked. So one limitation for using this device is the availability of cell service at the launch site.

I've flown this device twice and it worked as designed. Luckily I did not need to use it to find the rocket but the coordinates returned by the device were accurate.
I bought this device on Amazon for under $30, but after much looking I can't find my records of the purchase. I can say that it did come from China. Searching on Amazon you can find it for around $22.

The GPS Tracker requires a SIM card from a GSM cell phone service provider, I used AT&T. Their goPHone sim card with $15 prepaid service cost $25. Each text costs 20 cents. The $15 prepaid service is good for thirty days, you then have 59 days after the prepaid service expires, or is used up, to buy more prepaid service without voiding your SIM/phone number. If you go past the 59 days without purchasing more time, you would have to purchase another SIM card.

The GPS package came with the Tracker, two batteries, a charger, an extra battery cover, instruction manual, mini-CD

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Yes, this has already been posted before in a thread. I bought mine in February and it worked fine with good accuracy at several launches up until July.
Now the GPS module seems to be bad, I have not been able to get a good GPS fix for a while. I used ATT sim card and just added $5 but is only good for 30 days.
The other problem is that the battery goes dead after a few months but I found another 1000mAh LiIon battery that worked. The battery pins in the device
are also flimsy and don't connect well to the battery contacts so I just soldered wires on the contacts and it works better. I am going to try out the Byonics 2 meter MT-400 next.

-John

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Tetrahedron said:

Yes, this has already been posted before in a thread. I bought mine in February and it worked fine with good accuracy at several launches up until July.
Now the GPS module seems to be bad, I have not been able to get a good GPS fix for a while. I used ATT sim card and just added $5 but is only good for 30 days.
The other problem is that the battery goes dead after a few months but I found another 1000mAh LiIon battery that worked. The battery pins in the device
are also flimsy and don't connect well to the battery contacts so I just soldered wires on the contacts and it works better. I am going to try out the Byonics 2 meter MT-400 next.

-John

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The power of the Byonics might cause deployment electronics to lock up. Put ematches on the altimeters, turn everything on and let it
sit for 30 minutes at least. If no cycling, might be OK. Kurt

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ksaves2 said:

Tetrahedron said:

The power of the Byonics might cause deployment electronics to lock up. Put ematches on the altimeters, turn everything on and let it
sit for 30 minutes at least. If no cycling, might be OK. Kurt

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Good point. I flew my beeline 2M GPS transmitter 1W (The MT-400 is 0.4 W) in the nose and it worked fine without any issues.

-John

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Tetrahedron said:

ksaves2 said:

Good point. I flew my beeline 2M GPS transmitter 1W (The MT-400 is 0.4 W) in the nose and it worked fine without any issues.

-John

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Take a look at this article: https://www.apogeerockets.com/downloads/PDFs/GPS_Recovery.pdf by Michael Konshak before using high powered trackers.
Some deployment electronics are more susceptible to Rf than others. I know a P6K and Adept 22 won't play well with high-powered Rf transmitters.
I've seen deployment on ascent and another event when 2 altimeters do nothing riding in the same bay as a dog tracker leading to a core sample of a very large project. When another project was completed of the same rocket design, putting the dog tracker 30 " away from the same brand of altimeters did nothing to alleviate the problem.
The altimeters shut down after several minutes on a ground test. Fortunately a ground test showed the problem and different electronics can be used in the future. Kurt

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MisterMan said:

Okay, thanks so much for the dimensions and various warnings and tips. It looks like it will fit in a 2.1" (54mm) airframe/nosecone or larger, and thats great.

Regarding the warnings about high powered RF transmitters jamming altimeters, you're talking about transmitters like the Byonics and the dog collar type units, right? I just want to make sure you're not saying that these cheap little cell phone based systems will cause altimeters to lose their minds.

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ksaves2 said:

Tetrahedron said:

Take a look at this article: https://www.apogeerockets.com/downloads/PDFs/GPS_Recovery.pdf by Michael Konshak before using high powered trackers.
Some deployment electronics are more susceptible to Rf than others. I know a P6K and Adept 22 won't play well with high-powered Rf transmitters.
I've seen deployment on ascent and another event when 2 altimeters do nothing riding in the same bay as a dog tracker leading to a core sample of a very large project. When another project was completed of the same rocket design, putting the dog tracker 30 " away from the same brand of altimeters did nothing to alleviate the problem.
The altimeters shut down after several minutes on a ground test. Fortunately a ground test showed the problem and different electronics can be used in the future. Kurt

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Yes, I read the article and it's a good one. However, I have flown the Beeline 70cm GPS in the avionics bay several times together with the ARTS2 and Adept22 without any mishaps.
The flight with the 2M Beeline 1W GPS in the nose was with an ARTS2 and Adept 22 as well.
I am not saying that the author is wrong, I agree that the transmitter will "create an inducing current in the avbay's internal wiring" but I am not convinced it's a real problem unless I see a static
test with an altimeter bay turned on and running on the ground with for instance a 2 meter Beeline 1W GPS transmitter running simultaneously in the avbay to see that it's triggering the altimeters.
Actually, I remember doing this exactly with e-matches hooked up and for an hour without nothing happening. But to be safe I would line the inside of the altimeter bay like the fiberglass tubes
in most of the fiberglass kits these days with aluminum tape to create a Farraday Cage when using a high power (1W+?) GPS transmitter in the nose cone.

-John

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Tetrahedron said:

ksaves2 said:

Yes, I read the article and it's a good one. However, I have flown the Beeline 70cm GPS in the avionics bay several times together with the ARTS2 and Adept22 without any mishaps.
The flight with the 2M Beeline 1W GPS in the nose was with an ARTS2 and Adept 22 as well.
I am not saying that the author is wrong, I agree that the transmitter will "create an inducing current in the avbay's internal wiring" but I am not convinced it's a real problem unless I see a static
test with an altimeter bay turned on and running on the ground with for instance a 2 meter Beeline 1W GPS transmitter running simultaneously in the avbay to see that it's triggering the altimeters.
Actually, I remember doing this exactly with e-matches hooked up and for an hour without nothing happening. But to be safe I would line the inside of the altimeter bay like the fiberglass tubes
in most of the fiberglass kits these days with aluminum tape to create a Farraday Cage when using a high power (1W+?) GPS transmitter in the nose cone.

-John

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The problem is frequency dependent and the length of the leads can be a factor. The dog trackers are on 150Mhz MURS band and the DC20,30 and 40 output 2 watts. If one does a test of the appropriate duration to see if their devices are compatible that
gives them the best chance of success. I've mentioned a 16" diameter 16 foot tall rocket that went in ballistic with two Adept 22's and a dog tracker riding in the ebay. The builder recreated the same project with two new Adept 22's and was going to run the
dog trackers 3 feet from the ebay. I implored him to test it out first and fortunately he did. Discovered the altimeters shut down and reset that would have given another ballistic flight. Switched to different deployment electronics and passed the test.
Unfortunately when the launch attempt was made, the aft end of the 6 inch diameter motor case blew out, rocket made it to the top of the tower, tipped over and burning grains dribbled out the end as it fell down and eventually incinerated most of the rocket
and the tire off the launch tower trailer. It was the fourth firing of the motor case when it failed.
I've personally had on pad ejection of the recovery laundry the result of a 150mW RDF tracker and drogue on ascent deployment with the same hardware. No, it was not a mach flight so mach delay wasn't an issue even though it was set for 5 seconds.
Sooooo..... I learned my lesson and simply espouse this caution so no one else has suffer a loss like I did. Kurt

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