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Eggfinder GPS missing satellites

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n27sb

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For the last several months my tracker only shows that my Eggfinder TX is locked onto 3 or 4 satellites. In the past I would usually get 5 or 6. Also the LED on the TX that normally blinks when 5 or more satellites are locked does not light.
Are we missing some satellites or is this maybe a software issue?
this happens on both older units as well as a very recent kit.
35BFACEF-2F95-417B-B306-EEB81C7DC357.jpeg
 
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DAllen

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5 or 6 is not a lot for any GPS unit. Where are you placing the unit? GPS signals rely heavily on direct line of site from the satellites so objects such as trees, buildings, large metal objects, etc can affect the signal quality and accuracy dramatically. This is a good summary of what affects GPS quality. Also, I am not familiar with Eggtimer GPS settings but if available I would set the unit to receive as many GPS satellite systems as possible such as GLONASS, BeiDou and Galileo.

I am by no means a GPS expert but I use a survey grade GPS rover unit at work that gets 1/8" horizontal accuracy when I have good signal with the satellites and ground station. Typical GPS units such as smart phones or Garmin eTrex type units are going to do at best 10'-16' accuracy - I don't care what your phone says it has for accuracy anything less than 10'-16' is unrealistically optimistic. But then, for our hobby that's plenty accurate enough to get us our rockets back and use our smartphones to navigate the roadways.
 

n27sb

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5 or 6 is not a lot for any GPS unit. Where are you placing the unit? GPS signals rely heavily on direct line of site from the satellites so objects such as trees, buildings, large metal objects, etc can affect the signal quality and accuracy dramatically. This is a good summary of what affects GPS quality. Also, I am not familiar with Eggtimer GPS settings but if available I would set the unit to receive as many GPS satellite systems as possible such as GLONASS, BeiDou and Galileo.

I am by no means a GPS expert but I use a survey grade GPS rover unit at work that gets 1/8" horizontal accuracy when I have good signal with the satellites and ground station. Typical GPS units such as smart phones or Garmin eTrex type units are going to do at best 10'-16' accuracy - I don't care what your phone says it has for accuracy anything less than 10'-16' is unrealistically optimistic. But then, for our hobby that's plenty accurate enough to get us our rockets back and use our smartphones to navigate the roadways.
I am placing the units in the same spots I have used for several years. At a recent launch I could not get a fix at all. Waiting for an answer from Cris at EF. I can only guess that something has changed. As far as I know the settings for GPS systems is not available to the user on EF.
 

UhClem

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You need to know what is in view to be able to tell if those numbers reflect a problem or just a bad configuration of the satellites. If the NMEA data stream is available you should examine it for more details as it includes data on the satellites in use and in view.
 

n27sb

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Found this site that lets you look at satellites that are in view.
 

swfa

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I personally built a USB cabled eggfinder receiver so I could plug it into my laptop and have it running as a backup to my LCD receiver. I use this with VisualGPSview to get a good overview of the current GPS satellite fix. It shows you the number of satellites in view and the number of satellites being used, and various other things. My eggfinders regularly have 12 satellites in view, but they don't all go into use until the eggfinder has been running for a while.
 

Rocketclar

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Hi. I've built several of these including the older B6 and B7 models. I, too, had a similar problem and I contacted Cris. Here is what he told me, "The most common reason for not picking up satellites well is that the ground pads on the bottom of the module didn't get soldered to the board. That feeds the GPS antenna ground, so if there's not a good ground then the GPS antenna doesn't work well. With the early boards, that was a relatively easy thing to have happen... the holes were small, and it was pretty easy to get solder into them but have it not reach the pads. The newer boards either have larger holes or slots, the slots make it almost impossible not to get a good bond with the PC board. I recommend that you heat up the ground pads, and maybe add a little more solder"
I did this and it worked for several of mine!
 

ksaves2

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Remember to avoid metallic paint as that can attenuate incoming and outgoing signals. I had some bad experiences and my ebays are all painted with "plain" paint. It can be especially bad in the 400Mhz Beeline GPS or tracker band. Where there is an antenna I make sure there is no metallic paint on the outside.
Everything aft of the tracker antenna can be metallic but if the antenna is inside a bay there should be no metallic paint around it. Kinda easy with a nosecone mounted arrangement. Rocket can be metallic but the nosecone painted with a non-metallic contrasting paint. I don't know how 900 Mhz behaves but am not going to try it as I find it easier to just not use metallic paint where an internal antenna is located.
Kurt
 

cerving

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How is your transmitter mounted? What kind of field are you flying at, are there any trees surrounding it that might block low-azimuth satellites? And yes, those ground pads on the bottom of the transmitter make a big difference... that's why we went to slots instead of the holes, most people couldn't get the holes soldered properly.
 

n27sb

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The units are not mounted to anything and not enclosed. Testing in my back yard where in the past had good reception. Don't think it is the ground pads. 3 out of three all test the same.
Maybe the sat geometry is poor today.
 

n27sb

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So I tested a unit that had not been used in awhile. Right away popped up with 7 satellites. Re tested one of the earlier units and still just 3 satellites.
 

n27sb

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Update,
I took the three units with poor signal and reheated the ground slots. They were all C1 versions with the elongated slots.
All 3 improved. I never had any trouble with the old version but it looks like the C1 requires more heat and persistence.
In the future I may try to Tin the GPS pads prior to assembly or at least scuff the pads with Scotchbrite.

Thanks for all the input.
 

cerving

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If you have a 1/32" tip you can actually tin the pads through the slots, that's what we recommend in the assembly instructions. Doing so will help you get a better ground... it's harder to solder to those gold-plated pads than to tinned pads.
 

Brad_G

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So you have to un-solder and remove the RX board to reheat the slots?
 

n27sb

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Update,
I dug up two Tx units that I had set aside awhile ago. A Mini and a standard.
Both get poor signal. The Mini is an older version that does not have the slots on the back.
The Standard Tx is newer with the slots.

I have reheated the slots on the Tx standard but no improvement. The mini can not be done without removing the transmitter board.

Cris are there any points that can be measured with a meter to determine if all ground pads have continuity?
this would be helpful in the future for Mini units before you mount the transmitter board.
 
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Brad_G

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I also added the GPS to the Eggfinder LCD receiver.
Is there a way to find out how many satellites it is seeing, or if you can ohm it out, to see if the ground plane has continuity?
 

cerving

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The current LCD firmware doesn't have a way to tell you how good your LCD-GPS fix is, only if it got a fix or not (it won't go to the coordinate screen until it does). That's a feature that we will be adding to a future software build.
 

n27sb

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I decided to try one more time on the TX standard. I used older wick to remove all of the solder from the slots. It looked like one of the pads did not have a tinned look.
Update,
I dug up two Tx units that I had set aside awhile ago. A Mini and a standard.
Both get poor signal. The Mini is an older version that does not have the slots on the back.
The Standard Tx is newer with the slots.

I have reheated the slots on the Tx standard but no improvement. The mini can not be done without removing the transmitter board.

Cris are there any points that can be measured with a meter to determine if all ground pads have continuity?
this would be helpful in the future for Mini units before you mount the transmitter board.
Do you know if this is possible
 

cerving

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It was a lot harder to get those pads soldered on the earlier TX/Mini's, which is why we went to the slots. You can put a lot more solder in, and you can actually tin the pads in the slots if you do it carefully. Pre-tinning the GPS ground pads before mounting has been suggested... that would work if done correctly, the problem is that I think it would actually end up making it harder to mount because it probably wouldn't sit flat. You'd have to be really careful about how much solder you put on the pads, and hitting it with desoldering wick afterwards so just a tinning layer was left would probably be a good idea.
 

Mike Haberer

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I decided to try one more time on the TX standard. I used older wick to remove all of the solder from the slots. It looked like one of the pads did not have a tinned look.
Cris are there any points that can be measured with a meter to determine if all ground pads have continuity?
this would be helpful in the future for Mini units before you mount the transmitter board.
Do you know if this is possible
I have the same question. I'm on my 2nd try of a mini and am getting nothing out of the GPS board. Having a guide for testing connections would be extremely helpful. There is no way to easily diagnose what isn't working at this point.
 

Mike Haberer

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It was a lot harder to get those pads soldered on the earlier TX/Mini's, which is why we went to the slots. You can put a lot more solder in, and you can actually tin the pads in the slots if you do it carefully. Pre-tinning the GPS ground pads before mounting has been suggested... that would work if done correctly, the problem is that I think it would actually end up making it harder to mount because it probably wouldn't sit flat. You'd have to be really careful about how much solder you put on the pads, and hitting it with desoldering wick afterwards so just a tinning layer was left would probably be a good idea.
This is likely the problem I have. I tinned them after the unit was soldered on (per the instructions). Based on this I'm sure the pads had too much solder on them before I filled the slots. Is the unit even salvageable at this point?
 

Voyager1

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A method I’ve used successfully when soldering these boards is to clean them with a very light rubbing with a fine abrasive scouring pad (NOT steel wool!) to remove any oxidation from the tinned Copper pads. Alternatively, a paper towel with cleaning paste. This results in a nice clean fresh pad to solder to. The boards are then washed thoroughly, rinsed and dried off with IPA.

Additionally, I apply a small amount of flux to the joints prior to soldering. The flux aids in distributing the heat from the iron tip and also boils off any residual grease on the pads.

It is a good idea to use a slightly larger tip when soldering ground connections due to the higher thermal load of ground pads. Obviously, the larger tip still needs to fit in the ground slots on the PCB.
 
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OverTheTop

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Cris are there any points that can be measured with a meter to determine if all ground pads have continuity?
this would be helpful in the future for Mini units before you mount the transmitter board.
Cris can chime in and correct me but measuring connections to a ground plane is notoriously difficult and needs specialised equipment normally. Measuring low resistance is tricky. You only need one connection and the resistance is down in the mud for a multimeter. That one connection could even be one of the regular pads and not the ground plane.
 

Voyager1

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To make matters worse, if all the ground leads on an RF device, such as the GPS module, aren’t properly soldered to the ground pads on the PCB, then RF currents can circulate causing interference to its normal operation. This is similar to ground loops that can exist in many electronic systems with poor grounding.

As mentioned by OTT, measuring continuity to the ground plane can be difficult and misleading, particularly if there is inconsistent contact with the ground. You might measure continuity with a meter, but it’s not telling you the whole story. It won’t tell you that all ground leads on the device are actually connected directly to the ground plane.

However, with a little care and forward planning, these boards go together very well and work well.
 
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Brad_G

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I got the RX board off. Waited 5 min. between pads to let things cool off. Re-heated the 7 holes, waiting 10 min. between holes to let things cool off. Re-soldered the RX board back on, again waiting 5 min. between pads. Powered it up and the red LED on the RX board started blinking right away. I'm encouraged, until the receiver stops at "waiting for fix". If I ever build another one of these, I will tin the ground plane pads before I do anything else.
 

n27sb

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I got the RX board off. Waited 5 min. between pads to let things cool off. Re-heated the 7 holes, waiting 10 min. between holes to let things cool off. Re-soldered the RX board back on, again waiting 5 min. between pads. Powered it up and the red LED on the RX board started blinking right away. I'm encouraged, until the receiver stops at "waiting for fix". If I ever build another one of these, I will tin the ground plane pads before I do anything else.
I agree, I have built 15 or 20 of these over the last 5 years and never had a problem until now.
I think I will tin the pads and then remove as much solder as possible with wick. Maybe some of these newer boards are a little more resistant to taking solder.
 

cerving

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This is likely the problem I have. I tinned them after the unit was soldered on (per the instructions). Based on this I'm sure the pads had too much solder on them before I filled the slots. Is the unit even salvageable at this point?
Get out a solder sucker or desoldering wick, and remove solder from the pads/holes. You may find that the pads didn't get tinned... you can fix it at that point. The slots have been out for over three years, I have not seen any endemic issues with them, and they're much easier than the old holes.
 

Mike Haberer

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A method I’ve used successfully when soldering these boards is to clean them with a very light rubbing with a fine abrasive pad to remove any oxidation from the tinned Copper pads. Alternatively, a paper towel with cleaning paste. This results in a nice clean fresh pad to solder to. The boards are then washed thoroughly, rinsed and dried off with IPA.

Additionally, I apply a small amount of flux to the joints prior to soldering. The flux aids in distributing the heat from the iron tip and also boils off any residual grease on the pads.

It is a good idea to use a slightly larger tip when soldering ground connections due to the higher thermal load of ground pads. Obviously, the larger tip still needs to fit in the ground slots on the PCB.
That's helpful. Those of us new to this soldering business need this type of advice. Is there a preferred cleaning paster that should be used?

Yeah, but the instructions say that extra flux shouldn't be needed and might result in an adverse result. For those of us that aren't soldering experts we don't know when to break away from the instructions and do something different. Curious, why is there residual grease on the PCB if it has been cleaned per the first paragraph?

This I already do...
 

Wayco

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I agree, I have built 15 or 20 of these over the last 5 years and never had a problem until now.
I think I will tin the pads and then remove as much solder as possible with wick. Maybe some of these newer boards are a little more resistant to taking solder.
I'm in the same boat, built quite a few of these, but yesterday's build isn't acting properly. No amber light, so I went back over the troubleshooting guide, checked all my joints, re-soldered a couple that I thought might be faulty, but still no amber light. I'm getting co-ordinates on my RX, but only 3 or 4 satellites. Changed out the LED, thinking it might be bad, no change.
I'm really not a technician, my electronics training is from the Marines forty years ago, but I have over a dozen functioning EF TX's and this is my first dud.
 
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