Eggtimer mini performance

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kclo4

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I have a Eggtimer TRS and an Eggfinder Mini flying in different rockets now, and I think I am seeing worse tracking and radio connection performance out of the Eggfinder Mini. Is this normal?

Eggtimer TRS currently has the wire whip antenna and the Finder Mini has the stock screw on antenna.
Using an Eggfinder LCD receiver with the SMA connector and the long plastic shelled antenna Cris sells.
Both units working off a 2S lipo for board power.


Example, when my Eggfinder LCD receiver is connected to the TRS it usually shows about 14 satellites in view and the Eggfiner Mini shows about 7 satellites in view. The mini also takes a few times longer to get fix and can't for example, be under the hatch of my car at the launch field.

Ground performance seems to be better with the TRS as well. LCD doesn't show the "countdown since last communication" from as far out on the TRS compared to the Mini. The last landing I had with the mini the rocket was only about 1000 feet away in gently rolling sand and brush and I was loosing connection. I have not yet done a 1 to 1 test by placing in the same locations yet.

Near as I can tell the mini was soldered well, with extra care to get solder on all the ground plane pins for the GPS module. Not sure what else I could have done that would effect performance.

Is there anything I should look for on the board, or are these performance differences normal?
 
I would be performing the 1:1 test side by side, inside and outside the rocket. Also, look at any differences in the mounting of the two in the respective rockets. Are there any potentially interfering objects in the the Mini installation. Are the body or nosecone painted with metallic paint (see the thread discussing this).

Also, if you have access to a spectrum analyser, check the output level of each tx module, as you might also have 900MHz link issues, not just GPS signal issues.
 
I recently ran a Mini and a TRS in my Drago 4XL to 12,200', got packets from both of them throughout the flight except for a few seconds during boost. As far as I have been able to tell from flight testing, there's no difference in performance. Now that being said, theoretically a TX or TRS should be a little bit better because the ground plane for the transmitter antenna and the GPS module is larger, but I haven't seen this empirically. It definitely DOES take a little longer to acquire satellites (and so does the LCD-GPS Module because the board is small), but I haven't seen that translate into reduced GPS performance.

As far as the RF range, I haven't seen any significant difference between the TX and the Mini. Remember that ground range is highly variable, it depends on a lot of things including which way the antenna pointed when it landed... if it points right at you or directly away from you then you'll get the least range. 1000' range on the ground is fine considering that your last received packet should be very close to your actual landing point; you'll get the final location when you get close.
 
Any update on this? Specifically why the number of satellites is lower for Mini, as well as not being able to get lock from a location where you could with the TRS (under the hatch of the car)?

Just curious if you found a resolution, or if further testing revealed anything.

Thanks!
 
I haven't tested any further, but in clear air there shouldn't be much difference once it locks. Again, it does take longer to lock, primarily because the ground plane for the Mini's GPS antenna is much smaller than the one on either the TRS or the TX. I recognized that when I was designing it, which is why I went with the screw-on stubby antenna instead of a wire antenna; the extra gain makes up for the smaller ground plane.
 
I haven't tested any further, but in clear air there shouldn't be much difference once it locks. Again, it does take longer to lock, primarily because the ground plane for the Mini's GPS antenna is much smaller than the one on either the TRS or the TX. I recognized that when I was designing it, which is why I went with the screw-on stubby antenna instead of a wire antenna; the extra gain makes up for the smaller ground plane.

Thanks for the reply. I'm very covered up at the moment as my primary hobby is pyrotechnics, but around the end of July I'll likely be looking at an eggfinder of some sort.
 
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