Gps tracker for recovery

[astroadrian99]

Hey guys, i was wondering if anyone of you know of GPS tracker that can be used to find a rocket once it lands. The rocket is going to pass the CoCom limit so I need one that would be able to relock. It has to be gps since I'm launching near the ocean and there's a chance it could land somewhere in it.

 

[vance2loud]

Are you after something cell based or what sort of radio range would you require?

 

[thomas]

Well if he is really flying 1200 mph above 60000 feet the cellphone reception is probably bad. ^^

If you are only hitting one of the limits, you can choose a module which needs both conditions to be fulfilled to quit operation, you can find a comparison here:
https://ukhas.org.uk/guides:gps_modules

One possibility is probably:
https://www.multitronix.com

 

[bigredbee]

Shameless plug: The 70cm 100mw BigRedBee GPS transmitter uses a u-blox 7 GPS module good for altitudes > 100K. It transmits on the 70cm amateur radio band. It's been used on many flights exceeding that altitude including the one that won the Carmack prize in 2012. I believe it's reached 140K on high altitude balloons.

https://www.bigredbee.com/beelinegps.htm

 

[bobkrech]

https://www.multitronix.com/ has non-ham solutions like Kate, but be prepared to spend some change.....

Kate is very reliable and works over 140 kft. and provides a real time data downlink, and has IMU backup IIRC.

You should not rely on any system that requires a cell phone network for tracking as you may not have cell coverage when you need it.

A ham radio system using APRS can be used provide that the prerequisite ham repeater network is available. It works really well as you can track it via the internet as well as via your own transceiver.

 

[bigredbee]

Where did you get the info regarding Kate working > 140K ? I've never been able to get any info from u-blox regarding that -- only that it works up TO 140K.

Repeater networks are nice, but not required. Most repeater networks are on the 2 Meter band, so that won't help out on 70cm. But with a good base antenna, you don't need to rely on a repeater network.

BTW, BigRedBee offers a more affordable 900 Mhz radio as well for unlicensed use (but without the cool Kate voice

 

[ksaves2]

https://www.multitronix.com/ has non-ham solutions like Kate, but be prepared to spend some change.....

Kate is very reliable and works over 140 kft. and provides a real time data downlink, and has IMU backup IIRC.

You should not rely on any system that requires a cell phone network for tracking as you may not have cell coverage when you need it.

A ham radio system using APRS can be used provide that the prerequisite ham repeater network is available. It works really well as you can track it via the internet as well as via your own transceiver.

One comment on using APRS on the 2 meter band. First off, the national frequency on 144.390Mhz is where the "National" backbone is located and one would have to count on having digipeater/igate stations nearby in order to get the telemetered position packets placed on the APRS-IS network (https://aprs.fi/). Secondly, if one does a high rate APRS tracking on 144.390 at one position packet every 5 seconds, which is just about the highest reliable refresh rate APRS can do (I've done once every 3 seconds using a trick only valid for ground testing), the APRS NAZIs will have a spasz attack due to "the imbecile who's clogging the national backbone". Hams don't like seeing high rate stuff on the national backbone as it clogs it up for use by the masses.
Yeah, one can juggle the PATH statement (WIDE2-1) to make sure the Rf packet doesn't get re-transmitted too many times but then again, must get the packet to a station that has an internet connection to get the packet on the -IS backbone so it can be "seen" on aprs.fi. Personally, I'm the only one interested in my flights so I use 70cm (no APRS-IS network available) or something other than 144.390Mhz so I wouldn't disturb the national backbone with
high rate reporting.

Thus it would be poor form to track a rocket on 144.390 at a high refresh rate. Now there are some propagation advantages to tracking on the ham bands that are more apparent and more likely advantageous for stupid high, stupid fast and stupid far
flight profiles. (Note well, not meant to be derogatory. It's only stupid if one attempts such flights in the wrong venue.) 900Mhz might not be the best albeit I believe Multitronix is probably as optimized as it can get in the 900Mhz bands judging by some of the flights they have documented going extremely high. If one wants to APRS track locally off 144.390Mhz, I don't think anyone cares what refresh rate is used. The high altitude balloon folks use the national network to their advantage if their balloon gets out of their local tracking receiver footprint. They use refresh rates of several minutes though and from 50,000 to 100,000 feet the coverage is so great that their packets are bound
to hit an IGATE that will get their position into aprs.fi. Plus they can choose their PATH statement so their position "doesn't" get re-transmitted several times by the ground station digipeaters via Rf on 144.390Mhz.
One can see the advantage there in that they could switch to a cellphone internet service and track their balloon via aprs.fi if it's out of range of their receiver. Of course as long as they have internet service!

Greg Clark has 70cm and 2 meter APRS trackers in high and low powered models. Keep in mind with higher power, the battery and size requirement is greater. There are other concerns like Byonics that caters to the do-it-yourselfer and the Sainsonic
AP510 which is about the cheapest but has a very high learning curve. The 510 has a GPS chipset (Sirf III or IV depending what's printed) that is optimized for terrestrial use and will help one find their rocket but not good to rely on for altitude reporting.
That said I've had correspondence from those who have flown an AP510 next to a BeelineGPS tracker (the BLGPS is approved for TRA record attempts mind you) in a high altitude balloon and the altitudes corresponded very closely. Me thinks the
SIRF III or IV is not good for altitude reporting in the high dynamic state of a rocket launch/flight. A slow, sedate balloon and it's not so bad. To simply find a rocket, SIRF III or IV will work as long as the chipset continues to report at altitude.

If one wants power comparisons, John Coker's site: https://www.jcrocket.com/gps-tracking.shtml has a good reference though is doesn't take into account the newer GPS trackers. The information on power output still stands well. Be aware if one moves towards >100mW power, must be absolutely certain that the tracker doesn't interfere with the deployment electronics. The newer deployment devices like anything by EggTimer or altimeters with opto-isolators on the output circuits are resistant to
Rf. Anything like pad deployment of the charges or shutdown of the electronics leading to a ballistic flight can be had if one is not careful. Kurt

 

[bobkrech]

A ham friend of mine was involved in this balloon flight. https://makezine.com/projects/near-space-balloon-cam-with-arduino-and-aprs-radio/ The guy in the green tee shirt in the last photo. Our club webmaster, also a ham, twice borrowed my UV-5R for 2 balloon flights using APRS. It works fine, and is simply used to track the balloon and determine where it lands so it can recovered, and that's all I'm suggesting you use APRS for. If you want more frequent sampling, it's easier to stream down to your own receiver, and on a UHF frequency since the antenna sizes are smaller and the ground antenna has more gain for a given size.

I understand that APRS is not designed for high data rates. My interest is simply to know where my rocket landed, not to obtain real-time flight data. Obtaining several good fixes during the last 1000' feet under chute is usually puts you sufficiently close to the LZ so you will find your rocket.

There are several really good rocketry specific products available if you want higher real-time data rates. The BigRedBee hardware is reasonably priced and works well, and Kate, while more expensive, has some pretty high end features such at audio tracking. Both have proven ranges in excess of 20 miles which is what you need for really high altitude flights where you can see the rocket. There are several other systems that can use ham radio transmitters and also work well.

 

[ksaves2]

A ham friend of mine was involved in this balloon flight. https://makezine.com/projects/near-space-balloon-cam-with-arduino-and-aprs-radio/ The guy in the green tee shirt in the last photo. Our club webmaster, also a ham, twice borrowed my UV-5R for 2 balloon flights using APRS. It works fine, and is simply used to track the balloon and determine where it lands so it can recovered, and that's all I'm suggesting you use APRS for. If you want more frequent sampling, it's easier to stream down to your own receiver, and on a UHF frequency since the antenna sizes are smaller and the ground antenna has more gain for a given size.

I understand that APRS is not designed for high data rates. My interest is simply to know where my rocket landed, not to obtain real-time flight data. Obtaining several good fixes during the last 1000' feet under chute is usually puts you sufficiently close to the LZ so you will find your rocket.

There are several really good rocketry specific products available if you want higher real-time data rates. The BigRedBee hardware is reasonably priced and works well, and Kate, while more expensive, has some pretty high end features such at audio tracking. Both have proven ranges in excess of 20 miles which is what you need for really high altitude flights where you can see the rocket. There are several other systems that can use ham radio transmitters and also work well.

High rate updating can be potentially interesting but the vagaries of acquisition of the satellite signal, receiving and then decoding the relayed data comes into play. One would expect on descent under drogue, the reception would be great all the time but
that isn't always the case. I've missed positions on 70cm and 915Mhz bands. With APRS, I've experienced positions just after apogee and received enough packets to tell that the descent rate is consistent with drogue deployment and then there
may be nothing for 10 to 20 seconds until more position/altitudes come in further on in the descent. This could be due to the effective radiating power (15mW vs higher power) and antenna position.

One thing I find helpful is running a sim on the rocket and using a stopwatch to track the time to apogee. Man it seems like forever sometimes until packets start to come in again. I refer to the stopwatch and don't have to start worrying unless I get several seconds past the expected apogee!

Yeah, one should only expect GPS tracking is a tool to find the rocket expediently so they can launch their next one quickly. Can always download the altitude data from the deployment electronics later.

Remember, all it takes is one or two positions at low altitude to find a rocket. I found that out on a first EggFinder GPS tracker flight that went in ballistic. For some reason I didn't receive any positions in flight until the rocket
was coming in hot 50 to 100 feet off terra firma. That's all it took to find the rocket and I would have been able to get a perfectly flyable unit back if I didn't crack the nosecone with the shovel trying to get it out of the clay.
I had to replace the nosecone and put in a new tracker and all is well.

As an aside, I've always kept a tracking program on in my basement with a TNC and Handitalkie. There's a digipeater 1200' away from me so I can Rf a packet to the digi and take advantage of the 100' antenna and 90 watts power.
Some years back high altitude ballooning was actually more prevalent in my area and was easy for my Rf only station to track area high altitude balloons through the local digipeater. Not unusual for the digipeater to hear a balloon from 425 miles away. I saw on the internet a group was flying a balloon with a Kenwood D7A(g) APRS rig as the tracker in the balloon payload package. Yeah, that's a heavy payload but they flew it. I knew the D7A has messaging capability and fired off several messages to the balloon that the fliers could read after recovery. Ten days later I get an envelope in the mail with a CD of all the pictures the onboard camera took and a stamped metal tag
commemorating the flight! If I ever do an L3 project, that tag is going along for the ride as it has already been at altitude along with a business card that went to space in an UP Aerospace project.

It was also fun watching a night balloon flight that hit the jet stream and was trucking along at between 150 to 180mph! It was a university project and of course since it was at night, didn't carry a camera. They did have a flashing LED lighted triangle dangling below the balloon for what it's worth! (You know, the slow vehicle triangle sign. Like that's going to prevent a midair collision!) Kurt