Salvaged Egg Finder with different GPS

I built an EggFinder GPS tracker several months ago and did a very stupidhead thing. When testing it on a window ledge, I didn't position it right and the thing hit the floor on edge and the top of the GPS receiving antenna snapped right off the base. I figured what the hay, I took a cut off wheel to the base and carefully cut it in half. Then laid an iron across the solder pads and each half fell off. I saw I cut one of the traces but didn't want to try to put a new Maestro GPS on the already populated board. Yeah I could'a desoldered a bunch of components but I still didn't know if a repair would work. It ended up in the junk drawer and I actually cannibalized the switch.

Well there was talk on another thread about using another GPS unit and that the only thing needed is a 3.3V connection and to solder wires to the RXD and TXD pads on the board. So I picked up one of these for about the same
as a Maestro receiver:

https://www.ebay.com/itm/Ublox-NEO-...297?pt=LH_DefaultDomain_0&hash=item2ec7488539

Well lo' and beholden it fired right up:



The only weird thing noted was when the * is in the display (which mean more than 10 satellites used for a fix I believe) the altitude goes weird with like 130 or 120 or 100 sort of thing. The altitude displayed on the GPS Rocket locator program stays accurately reported as does the Android program "Bluetooth GPS"



Here the display above shows a "0" with the *. Sometimes it's a triple digit like I wrote above.

ATTACH=CONFIG]247406[/ATTACH]

This display below is showing the 9 satellites and a closer to correct field elevation.

This was just a kluged together arrangement I didn't expect to work. It does though this morning it didn't. Close inspection show some kind of metal dust on it and it works fine now after I cleaned it. There were some comments that a different chipset might report the altitude a little more accurately than the SIRF unit and perhaps this might
satisfy one's itch in that regard. I still have to sort out this "weird" altitude display that I've noticed if more than 10 satellites are locked on.

As far as mounting, I could put the Neo6M board under the EF and the GPS antenna trailing in a small frame on the sled. Sure it wouldn't lend itself to a small rocket but salvaging something I thought was trashed and learned something from was a benefit to me.

Oh, I didn't need the momentary switch and the RDY and 1S LED's are non-functional. Makes sense because that info comes off the Maestro's pads. The Neo 6M has it's own LED Kurt

Experience with the Neo-6m with the EggFinder board is sort of less than satisfying. First off, the Android apps Bluetooth GPS Provider and Bluetooth GPS are brilliant utilities to monitor what is directly going through the Maestro or whatever GPS is connected to the EggFinder. I especially recommend Bluetooth GPS if one doesn't have the EggFinder LCD unit as one can take a quick look as to what is coming directly off the EF (Egg Finder) then close it and open GPS rocket locator.

Second, the altitude reporting is not consistent with the Neo-6m. At times the HDOP will disappear even with * showing greater than 9 satellites for a fix and a totally "wrong" altitude in the display. While in this state, the altitude reading on the GPS Rocket Locator program, that is taking the data from the B/T link, will be a reasonable and close to nominal value. The other utilities will show shifting HDOP values, the "accuracy" value is "2" which indicates a DGPS
fix. Now while an inaccurate altitude is displayed, the lat/long is totally withing the limits of error.

At other times, the HDOP bar will go all the way up, the altitude display is perfectly close to an expected field elevation ASL and all looks good. The weird thing is the behavior with the LCD can go kooky with an * which indicates more than 9 satellites.

REMEMBER ONE THING!! THIS IS ONLY WITH THE EXTERNAL NEO-6M ATTACHED TO THE BOARD!!! The Sirf based Maestro doesn't do this but the altitude accuracy is not as well as it could be. Will add to this note as time goes on. I did fire up the ublox configuring utility but found nothing there the I could understand to change the GPS. The Neo-6M is still O.K. for lat/long tracking.

I remember I have a GT-320FW UniTraq module lying around I can reprogram it to 9600baud and see if that gives a different result. It is a GPS that can be used for high altitude ballooning. Kurt

Ok, Sorry to be talking to myself but for the benefit of others who may end up with a dorked stock Maestro, I have some additional results.

Ublox Neo-6Q: https://www.csgshop.com/product.php?id_product=62 Unfortunately out of production. Gave the best results. The Sarantel antenna likely would
give the best performance in a rocket.

Ublox GP-635T https://www.sparkfun.com/products/11571 Teeny-tiny unit. Works O.K. but still gives some unusual altitude display at times like the Neo-6m.

Wanted to try a Uni Traq GT-320FW https://www.unitraq.com/old/pro_03_GPSmodule.html#320 but the device I have isn't recognizable by any of the programming software I have. Can't change it to 9600 baud from 4800 so it won't work with the EggFinder.

Sooooooooo, A better solution would be to simply build an EggTimer TRS which will telemeter the altitude coming from the altimeter's baro chip as opposed to the
GPS altitude.

If one does break the Maestro off of its base. Carefully slice the base partially through with a cutoff wheel right down the middle. Try to be careful not to gouge into the board with the wheel. Wick off as much solder as possible from the outer pads and the component may fall off. Might have to suck out the solder from the grounding pads. Once the base is off, one just needs to have access to the TX and RCV pads to solder the wires from the new unit and just pull the power from the 3.3V source from the end of the board. If you ding one of the "wide" traces, scrape some resist off and jump with a wire.
The altitude readings may go inconsistent on the Egg Finder LCD receiver with an aftermarket GPS module but the readings on the Android "GPS Rocket Locator" program remain within a reasonable range. The readings of the altitude with some other Android apps that allow pairing with an external GPS also show nominal readings. Lat/long remain accurate no matter what GPS is plugged into the board.
One advantage is you can safely switch the unit with an external switch and not have to "activate" it with the momentary switch on the board. In fact the switch on the board isn't needed nor is the 1S LED or the Green LED. Can see the space for the switch is bare when you click on the picture above. Kurt