Eggtimer GPS question

[RalPh8]

I just finished building the “whole enchilada” Eggtimer starter pack. And I have to say I’m very impressed! What seemed intimidating in the beginning quickly became a rapid way to perfect my soldering skills and increase my confidence in building electronics! Thank you! I love the fact it gives GPS coordinates, a compass heading, distance, elevation, and last known coordinates. I went around the neighborhood playing with it and it is dead accurate. The only thing I noticed was that it seems the distance is only about 0.4-.5 a mile. Is that correct? I figured with it being gps and using satellites that the range would be at least 3 or more miles. Do other users have this same experience? Would it help if I used a different battery rather than alkaline 9v? It is also an overcast day.

 

[tfish]

when it's laying on the ground...the radio waves back to you get blocked by things..trees, houses, cars and curvature of the earth. Raise the Tx 10 feet off the ground and things get better..raise it 100 and it gets much better. raise it 1000 and ...raise it a mile and ....

Tony

 

[gtg738w]

Clear line of sight is very important for range. Even near by objects can interact with the signal too: https://en.m.wikipedia.org/wiki/Fresnel_zone

 

[cerving]

A few tenths of a mile on the ground is normal. Assuming you have the wire antenna and the external antenna for the LCD receiver, you can expect at least 30,000' of range. Probably more... that's as far as I have personally tracked a rocket to, others have gone as far as 50K.

 

[RalPh8]

A few tenths of a mile on the ground is normal. Assuming you have the wire antenna and the external antenna for the LCD receiver, you can expect at least 30,000' of range. Probably more... that's as far as I have personally tracked a rocket to, others have gone as far as 50K.

Excellent. Thank you so much for the feedback. Your kit is awesome. I can't wait to fly it!

 

[dvdsnyd]

A few tenths of a mile on the ground is normal. Assuming you have the wire antenna and the external antenna for the LCD receiver, you can expect at least 30,000' of range. Probably more... that's as far as I have personally tracked a rocket to, others have gone as far as 50K.

I don't mean to hijack the thread... but Cris, please tell me you have stickers of your avatar

 

[Tarantula]

I was thinking the exact same thing. "Great! Now I have to by more Eggtimers to get some of those stickers!".

 

[cerving]

I don't mean to hijack the thread... but Cris, please tell me you have stickers of your avatar

Soon...

 

[ksaves2]

Yup,

When I test a GPS tracker, 2 meter, 70cm or 33cm (the 900Mhz EggTimer band) I set the E.T. tracker upright in a cardboard box with a screw-in 900Mhz antenna up on the chimney of my one story house. Range is quite acceptable.
Remember when one is tracking rockets, it's the last known position that is the real kicker here.
If the rocket is 25, 50, 75 or 100 feet up in the air when that last known position comes in, it's probably going to be touching down very closely to that position. If one gets to that last known position, if they don't see the rocket, they will likely be within range to get a new position to lead them to it.
I will also like to add that if one can add a noisemaker on the rocket harness please do so if there is the room. I was tracking an Eggfinder one time in a harvested cornfield and though I was getting good position fixes in on my receiver and it appeared I was "on top" of the rocket, I couldn't see the danged thing!
This is sooooo stoopid. Losing a GPS tracked rocket when good positions are coming in!
Well, I was using a mapping program to track my rocket and Dr. Stupidhead here eventually realized he had to increase the zoom level on the map!. I did that, now saw I was a little bit away from the rocket and walked right up to it.
There are APRS mapping, tracking programs out there that can be hacked to work with the NMEA trackers. Of course for better or worse, there's the Android program GPS Rocket Locator. I kinda like it as I was able to download photomaps of launch sites but sometimes it can be a "witch" to get the Bluetooth to connect properly. When it works, it works great and nothing like seeing that ones rocket landed past a stream or away from wires or buildings as can be seen on a photomap.
Kurt

 

[amiliv]

Would it help if I used a different battery rather than alkaline 9v?

It won't help with range, but if you want to switch to rechargeable batteries, 300mAh 2-cell LiPo battery for the transmitter (should last about 2-ish hours in the transmitter), and 1000mAh 2-cell LiPo battery for the receiver (should cover you for entire day of flying) worked well for me. 2-cell LiPo battery has nominal voltage of 7.4V (closer to 8.4V when fully charged), which is plenty for either the transmitter or receiver. A 300mAh battery is slightly smaller than 9V alkaline (1000 mAh is, of course, much larger).

I used either Fly Venom 300mAh 30C 7.4V or Turnigy Nano-Tech 300mAh 35-70C 7.4V for the rocket end, and Turnigy Nano-Tech 1000mAh 20C 7.4V in the receiver. It'd seem the Turnigy 1000mAh has been discontinued and replaced with Turnigy 950mAh 25-50C 7.4V. All of these batteries have standard 2-wire JST connector for providing power and charging, and additional 3-wire connector for balance charging support.

Both of the above 300mAh batteries also work great for dual-deployment altimeters; I used them with both Perfectflite Stratologger CF and Eggfinder TRS. I've slight personal preference for Turnigy, the only reason being I've more of those and it's convenient if batteries are same size.

If you want to switch to LiPo batteries and haven't used them before, you'd need a good LiPo charger with preferably balance charging and storage functions. If LiPo is going to be stored for long time, it needs to be charged (or discharged) to a "storage voltage" before tossing it into a drawer to prolong its lifetime; LiPo's don't like to be stored either near empty or fully charged. E.g. something like SKYRC B6AC V2.

 

[cerving]

Do NOT use an alkaline 9V with an Eggfinder, they don't have the capacity or surge capability required. Use a 2S LiPo... 300 mAH or larger is preferred, although I've used as small as 180 mAH on very small projects with model rocket motors that weren't going to be sitting on the pad for very long.

 

[Charles_McG]

Second for the ride-along noisemaker. I now have a direction mic in my range kit that I carry on long recoveries. I’ve picked up the altimeter beeps from 200’ - but it was most used for the last 20’ that time I was in marsh reeds over my head. Eggfinder minis got me -almost- all the way there.

 

[Tarantula]

... The only thing I noticed was that it seems the distance is only about 0.4-.5 a mile. Is that correct? I figured with it being gps and using satellites that the range would be at least 3 or more miles. Do other users have this same experience? Would it help if I used a different battery rather than alkaline 9v? It is also an overcast day.

I'm just reading between the lines here, but the Eggfinder TX does not communicate back to the Eggfinder receiver using GPS Satellites. There is a GPS antenna (square block) on the TX and one in the RX. That's how they "locate" their positions.

The two communicate with analog RF signals over the 33cm radio band (900Mhz). This signal is transmitted and received using the black antennas that stick out of the TX and RX units.

Several factors can effect the range of RF signals.

http://www.arrl.org/files/file/Regulatory/Band Chart/Band Chart - 11X17 Color.pdf
http://www.arrl.org/files/file/Technology/tis/info/pdf/8501031.pdf
https://en.wikipedia.org/wiki/33-centimeter_band

 

[RalPh8]

I'm just reading between the lines here, but the Eggfinder TX does not communicate back to the Eggfinder receiver using GPS Satellites. There is a GPS antenna (square block) on the TX and one in the RX. That's how they "locate" their positions.

The two communicate with analog RF signals over the 33cm radio band (900Mhz). This signal is transmitted and received using the black antennas that stick out of the TX and RX units.

Several factors can effect the range of RF signals.

http://www.arrl.org/files/file/Regulatory/Band Chart/Band Chart - 11X17 Color.pdf
http://www.arrl.org/files/file/Technology/tis/info/pdf/8501031.pdf
https://en.wikipedia.org/wiki/33-centimeter_band

Gotcha. Thanks

 

[RalPh8]

Do NOT use an alkaline 9V with an Eggfinder, they don't have the capacity or surge capability required. Use a 2S LiPo... 300 mAH or larger is preferred, although I've used as small as 180 mAH on very small projects with model rocket motors that weren't going to be sitting on the pad for very long.

I thought I remembered reading in your instructions that y’all did test flights on 9v alkalines? I have some of the lipos so I’ll make a switch today.

 

[Greg Furtman]

Second for the ride-along noisemaker. I now have a direction mic in my range kit that I carry on long recoveries. I’ve picked up the altimeter beeps from 200’ - but it was most used for the last 20’ that time I was in marsh reeds over my head. Eggfinder minis got me -almost- all the way there.

@Charles_McG Was this at Bong? Last time I flew there I spent a good amount of time sloshing through a swamp looking for my team's rocket. I can understand why people launch there in the winter when everything is frozen.

 

[Charles_McG]

@Charles_McG Was this at Bong? Last time I flew there I spent a good amount of time sloshing through a swamp looking for my team's rocket. I can understand why people launch there in the winter when everything is frozen.

Yes. Yes it was. There pictures posted here on the forum, but I can’t find them at the moment.

 

[Tobor]

Bong can be a cruel mistress when she likes to hide rockets...

 

[teepot]

Yuck. There is a problem we don't have in the desert.

 

[amiliv]

I don't mean to hijack the thread... but Cris, please tell me you have stickers of your avatar

I got one when my order arrived a week ago




The bad news is, something's wrong with RF on the receiver end... not sure if something I messed up when soldering it, but hopefully fixable :-(

 

[Arpak]

I got one when my order arrived a week ago

View attachment 456465


The bad news is, something's wrong with RF on the receiver end... not sure if something I messed up when soldering it, but hopefully fixable :-(

No way! Mine last week didn't have one, must've just missed it

 

[rkaplan]

Looking for some help on my TRS, I am trying to test the connection with Visual GPS as per Chris's instructions.
I am stuck on the initial GPS test using the Visual GPS application as that I don't see any data.

• Prolific PL2303 driver has been installed and confirmed
• On the Visual GPS there are more than one application so is there a specific one to use that will display $GP data screen? I have tried the ones from VisualGPS.net but neither show any data or connections. When connecting through the COM port it does see the Prolific interface but does ask for a BAUD rate? Was not sure what rate to use.

Also on the USB- Serial cable confirming that the BLACK wire goes to GROUND 3-pin header? Thinking the GREEN wire might be ground. Also only connecting 2 wires?
I have checked all the solder connections on the GPS pads and all looks good. I am even getting the LED blinking once per second, when I test outside. So not sure if I even have a problem.
Thanks

 

[cerving]

They recently changed the Visual GPS application, so it's a lot different than the one in the manual. You want the Command Monitor window to see the text, the Signal Quality window to see the satellites, the Navigation window to get the latitude/longitude, and the Azimuth and Elevation window. That should tell you if it's working or not.

Regarding the cable, BLACK is ground, WHITE is receive, and GREEN is transmit. You only need the BLACK and WHITE wires for this test, connect them per the instructions in the manual.

You must be an electrician... green is ground for house wiring, but black is almost always ground for low-voltage signals. In a past life I was a hardware/lighting/paint manager for Montgomery Ward, one of the things that we had to do was to hang lighting fixtures on the canopy. I had a guy working for me who was color blind, he mixed up the green and black wires all the time... until I got zapped while trying to take down a fixture and found out about it. I forbade him from hanging lights after that, and we had to check every single fixture to make sure they were wired correctly.

 

[rkaplan]

Thanks I used the Legacy version of Visual GPS and was able to get all the data as you described in the several different windows. Follow up question is that it only worked 1 time on the initial try. Is there way to retest this or does the TRS only send the data once. Disconnecting the battery didn't resend the data either so is there an order of the connection steps that I am missing? Just trying to fully understand how this works.

 

[rkaplan]

guess I didn't wait long enough, it probably only samples for updated GPS signal after a time interval?

 

[cerving]

The TRS doesn't send out any GPS data until it's armed. You can arm it remotely with the LCD recevier (after pairing with it), or you can wait for it to auto-arm after about 45 seconds for the pairing delay + 45 second for the cable delay, assuming that all selected channels have continuity. That's assuming that your TRS is fully completed... the earlier test in the instructions prior to installing the processor should generate an output stream from the GPS immediately on power-up.

 

[rkaplan]

got it. On to the next step. Thanks

 

[rkaplan]

Since by electronics bay is an all threads implementation I was thinking of extending the antenna into the bottom Drogue section attached to the bulkhead of the ebay. As this will now be near the ejection pod should I be concerned about the heat and blast from the ejection destroying the antenna? Any concerns about the shock cord clipping the antenna?

 

[Voyager1]

Since by electronics bay is an all threads implementation I was thinking of extending the antenna into the bottom Drogue section attached to the bulkhead of the ebay. As this will now be near the ejection pod should I be concerned about the heat and blast from the ejection destroying the antenna? Any concerns about the shock cord clipping the antenna?

I’d be concerned about the deployment harness damaging the antenna, particularly if you’re using the SMA-connected monopole and PCB connector. If using the wire antenna it shouldn’t be too much of an issue, but don’t expect it to stay straight.

Alternatively, you could swap your metal all threads for nylon ones.