The Eggfinder - A Low-Cost GPS/RF Tracking System

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Just an FYI. I asked a general question to the MapSphere developers over 6 months ago. I received a nice answer but the respondent added that the software was no longer going to be developed. My impression of it was it was supposed to be a Faceb--k type of travel software more interested in showing one's travels to one's friends directly, with real time online capability. It doesn't seem to have "taken off" so they lost interest in it.

I only mention this as the problems with using it in new OS's aren't likely to go away as I guess it could be considered orphan software. Kurt
 
I have just finished building my Eggfinder TX and LCD RX kit..........
Both devices went together quite easily,,,
powered up just as they should
and told me exactly where my garage is......lol
If anyone is on the fence about this I'd highly recommend it...
The bang for the buck is just fantastic...
I am super excited to try it out on a first flight....
If there was anything I'd say to someone interested in doing this build,,,
it would be --- go very light on the solder....
I'll get a few pic's up tomorrow.....

Thank you again Cris......
You really have made a fantastic product.....

Teddy
 
+1 to what Teddy said. Tried mine out for the first time at Airfest 20 and even though I could see where my rocket landed, I followed the arrow on my Garmin GPS and walked right to my rocket. Great product.
 
Same results here, recovered three rockets at Airfest, under less than ideal conditions. First was my L-3 cert rocket, a DS Extreme, which was in a field of millet 1.5 miles from the launch area. I walked right into the red shock cord you can see in this picture:

IMG_3804.jpg


Second was Jughead, my 5" Jart, which has been recovered six times using the Eggfinder and an Android using the Rocket locator app.
Finally, I recovered my 54mm MD blackhawk, which has the Eggfinder stuffed into the N/C with the antenna sticking through a bulkhead at the bottom. It flew to 5900 ft. in windy conditions, and when I plugged in the GPS co-ordinates from my LCD RX to Motion-X, it took me to a field of weeds, where I got no signal with either my LCD or bluetooth RX, despite the "high gain" magnetic based antenna I had attached to the LCD RX. I thought I had lost it, but as I was driving back, both systems regained signal 1/2 mile from where the original co-ordinates sent me. The wind had carried my rocket 3/4 mile from the position originally saved by the LCD GPS. Keep that in mind when you are flying in windy conditions.
 
That pic of the red line in the crop field......
Now that's a testimonial.......

Teddy
 
Yup,

No more ham requirement if one doesn't want to go there. Although I will say one can learn about tracking by going through the licensing process.
The LCD version is the one to get. Kurt
 
I test my eggfinder in the nose of my nike smoke , in a ebay with 2 treads rods and it work fine at 600+ meters and also at 700+ meters more than i need in our field Saturday.

eggtimer.jpg
 
What about using the all-thread AS the antenna?
.
I believe it would take some experimentation plus one would be limited to the length of the all-thread
in order for it to be resonant. Plus there is the issue if one uses two all-threads parallel to each other with one
acting as a "driven" element. I believe it's best to keep free space free of long pieces of metal from around the antenna for optimal range.

I run a wire antenna in a main chute bay that is close to the inside wall. It's a 16mW BeelineGPS and there is
a centrally located eyebolt. I've had no problem with flights to 7000' and landings 1 mile away. If it "looks like"
an antenna and parallels ones "real" antenna, the radiation efficiency can drop significantly. This also reportedly includes batteries mounted directly on the opposite side of the transmitter antenna. Kurt
 
If I recall your design Gerard, the all-threads don't lie directly parallel to the antenna. Your antenna lies ahead of the threaded rods. Which is desirable.
The configuration that is to be avoided was the all-thread lying next to the antenna as could happen if someone tried to mount it in the ebay with the deployment electronics. (As dicey as that setup might be unless the antenna was on a bulkhead mount outside.) Kurt

No it's another Nike Smoke, the antenna was parallel with the treaded rods. I'm not looking for world record, as long as I have 1500 feet I'm ok. The treaded rod are not grounded so they will not absorb the signal.
 
I see three issues with that. First is the length, it needs to be 80mm +/- 1 mm for optimal performance. That's a pretty short AV bay. Secondly, the threads on an allthread are going to play havoc with the signal, causing "hot" spots and most likely detuning it. If you had a smooth rod with threads on the end, one side with a threaded connector running to a coax and the other side threaded with a rounded nut on the end it might work. Finally, you still need some kind of ground plane for the antenna. Maybe a metal plate around the rod at the coax end would work, but to be effective it would need to be at least 160mm in diameter, although if it was 80mm it would do OK. You also have to contend with the other stuff in the AV bay, essentially running parallel to the antenna and interfering with the signal.

If you look at the Eggfinder TX PC board, you'll see that there's a full ground plane on one side, and the other side has a ground plane on the other side next to the antenna. This isn't optimal because it's not as large as it should be for a 1/4 wave antenna (80mm), and it's not perpendicular to the antenna element, but it works OK. Most other small transmitters have some kind of similar antenna/ground setup, it ends up being a compromise between optimal performance and practicality. If you add a 1/4 wave rubber duckie, you don't need to worry about the ground plane; the ground counterpoise is built into the antenna.


What about using the all-thread AS the antenna?
 
No it's another Nike Smoke, the antenna was parallel with the treaded rods. I'm not looking for world record, as long as I have 1500 feet I'm ok. The treaded rod are not grounded so they will not absorb the signal.

Well, if you only need 1500' then the allthreads probably won't pose a problem. 5000' might be a different story.
 
(Snip) Finally, you still need some kind of ground plane for the antenna. Maybe a metal plate around the rod at the coax end would work, but to be effective it would need to be at least 160mm in diameter, although if it was 80mm it would do OK. You also have to contend with the other stuff in the AV bay, essentially running parallel to the antenna and interfering with the signal.

If you look at the Eggfinder TX PC board, you'll see that there's a full ground plane on one side, and the other side has a ground plane on the other side next to the antenna. This isn't optimal because it's not as large as it should be for a 1/4 wave antenna (80mm), and it's not perpendicular to the antenna element, but it works OK. Most other small transmitters have some kind of similar antenna/ground setup, it ends up being a compromise between optimal performance and practicality. If you add a 1/4 wave rubber duckie, you don't need to worry about the ground plane; the ground counterpoise is built into the antenna.

If one were really trying to squeeze every bit out, besides a panel antenna up on a 10' pole, a tiger tail with a terminal connector might optimize the ground plane:

https://www.hamuniverse.com/htantennamod.html

Now how effective this would be for 900Mhz I don't know but would be worth a try if one expected a rocket to recover more than a couple of miles away from the receiver site.

Some might pooh-pooh a tracker in a 1500' flyer but if drifting into tall grass or crops a prospect, could saves one's launch day from spending hours looking for
an errant rocket. Kurt
 
I can tell you first-hand that you CAN lose a rocket from 1500', even if you're flying on flat level ground... that's why I made the Eggfinder in the first place. Beats the crap out of wandering around the desert lakebed in 110F weather for an hour...
 
Any chance a 2m or 70cm kit version could be made available for more range? Would require a HAM, but still being a kit would be a great option.
 
The Eggfinder doesn't have any provision to send out a call sign "occasionally" per the FCC Part 97 rules, so that would not be an option at this time. It could be done, but it would require some hardware and firmware changes, plus the call sign would have to be programmed into it somehow.

Any chance a 2m or 70cm kit version could be made available for more range? Would require a HAM, but still being a kit would be a great option.
 
Any chance a 2m or 70cm kit version could be made available for more range? Would require a HAM, but still being a kit would be a great option.

I believe a fellow made it to 13,000 feet and was able to track in a very nice fashion. A patch antenna on the receive end would help further.
The EF isn't an APRS tracker. The Hope module uses FSK modulation and how the NMEA strings are decoded I don't know. I was trying to
see if I could decode the strings via one of those cheap SDR dongles but so far can't figure it out. I can get a nice spectrum of the incoming
signal though. Using a laptop and an SDR dongle is not practical as knock the thing and will lock the program up. More info here with a representative program: https://sdrsharp.com/

More power isn't necessarily better as it can interfere with the deployment electronics.

One interesting fact with the EF is it will send a packet once a second. It is recommended with APRS trackers to have them transmit once every 5 seconds. Now with the Beeline GPS tracker this is irrelevant as it will save to memory the positions more frequently if the flyer desires it. Once every 5 seconds is fine to find a rocket. This allows the BLGPS to be used for Tripoli altitude record attempts plus it uses a GPS
chipset more amenable for flight. The EF is a SirfStar IV chipset that works perfectly fine to locate a rocket.
It is the most economical means to locate a rocket, the range is adequate and I don't see any advantage to making a "Ham" version. In fact
a "Ham" version would have a much more narrow market. One can have a perfectly viable GPS tracker for much less than an APRS setup
and less than the RDF trackers like Rocket Hunter or Walston.

There is only one advantage to APRS tracking I can think of besides the fact that only APRS trackers with onboard memory can be used for record attempts. One can interface a Kenwood D72A, VX-8GR or FT1DR directly into a handheld mapping Garmin GPS. Just push a button and a datum line will appear on the Garmin GPS and track one to the rocket. All sorts of information can be displayed. GPS Rocket Locator will give a datum line but not as much information. Is it worth the $800.00 to get all the stuff together to do that? For most folks, no. I know because APRS was the only game in town 7 years ago, I invested in it and am going to continue to use it. I'm also going to use my EggFinders liberally. It doesn't hurt as much to crash a $70.00 tracker as opposed to a $215.00 one.

One other interesting fact is that the stock Egg Finder receiver can be plugged into a USB port on a laptop and the incoming NMEA datastrings can be monitored and recorded (to varying degrees) on a map using UI-View, Xastir or YAAC. Kurt
 
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Can beleive it, today i give a real test to my Eggfinder and Rocket Locator on my cell phone , but a small problem, I leave the receiver with Bluetooth on my table.....

head_zpsf1340018.jpg
 
Ya, I had Rocket Locator/Bluetooth barf on me once during a flight, and my backup laptop with the dongle and MapSphere ran out of batteries right before the launch. THAT is why I made the LCD receiver... it's nearly foolproof.
 
Ya, I had Rocket Locator/Bluetooth barf on me once during a flight, and my backup laptop with the dongle and MapSphere ran out of batteries right before the launch. THAT is why I made the LCD receiver... it's nearly foolproof.

Similar situation here. I had a laptop in a vehicle to record a flight with a tracking program and had a new "aftermarket" plugin
power source that turned out to be garbage (ie. didn't work). Laptop's batteries ran out, lost the track but my
backup handheld took me to the rocket without trouble. Then it turned out the BeelineGPS ran out of space because the G-Switch was activated on the pad! I swore I set it down softly.:facepalm: Soooooo, lost my second chance at a .kml file too. Oh well, as long as one gets it back intact is the deal. Kurt
 
So, I am wondering if I cooked something or if I just don't understand the power on sequence. I just assembled my eggfinder TX. I am powering it with a 2S Lipo. When plugged in the red power light comes on and the two LED on the radio blink once. When I press the button, nothing happens. If I hold the button, nothing happens. Isn't the green ready LED supposed to come on? I checked the LED, the LED is wired properly and still works when I power it directly with a battery. I have gone over all of my solder welds and due to my constantly tripple checking have caused some new bridges that were not there before. However, those bridges have been dealt with and I still am getting the same thing. Any ideas what to check next as I am running out of ideas. I did e-mail Chris so I hope he has some good suggestions as well. However, I thought I would throw it out to this group as well. Any guidance would be appreciated. And yes, I am about to the conclusion that I toasted a component.
 
When soldering fine items on a circuit board
the less solder the better...
It only takes a tiny amount of solder..
When your done soldering a single pad there should be a shiny thick film of solder,, not a blob...

Teddy
 
Yeah, I know.. small amount of solder on surface mount. I didn't have bridge issues until after I completed the build and then starting going back over connections without enough clearance for my thick fingers to control the iron.
 
Update - I think I have it working now! After a few e-mails back and forth and taking some zoomed in pictures with a document camera at work, I found a gap on one of the pad connections and a tiny, tiny, tiny bridge almost under the GPS unit. After many wick/cool cycles it appears to be working properly!
 
Ok so I got a mac last week and am now starting to use it for my eggfinder and eggtimers. What i can't seem do is get to the serial ports to change the settings and get everything connected. Can someone please help me out on how to configure the port settings on Mac OS X. I can't find anything about it on the web. Any help appreciated.:):)
 
Ok so I got a mac last week and am now starting to use it for my eggfinder and eggtimers. What i can't seem do is get to the serial ports to change the settings and get everything connected. Can someone please help me out on how to configure the port settings on Mac OS X. I can't find anything about it on the web. Any help appreciated.:):)

Ummmm,

The EggFinder I believe you only need to connect up if one is flashing the firmware to the LCD receiver unit. For the EggTimer, you need a terminal control program of which I don't have the slightest idea with the Mac. I'm sure they're out there. You have to make sure you get
the USB cable correctly connected to the E.T. and follow Cris instructions. I have to look at them a lot to refresh my memory when I want
to change anything since it is very programmable. Kurt
 
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