Re: MAX-M8Q GPS lock problem

Zack Clobes W0ZC

Most of my testing that I did was with the cameras powered down.  

That's what is throwing me on this one - sensor seems to cause problems so I yank that, then it seems like the cameras are doing it, but I remind myself that I didn't have them turned in through most of the testing.  

I do have E/H probes on their way for the spectrum analyzer.  

I need to recharge the battery then I'll try the foil to see if it changes anything...


On Sat, Mar 23, 2019, 12:31 PM Jeff Ducklow <jeffducklow@...> wrote:
I second Micheal's advice. I once had an EMI issue with a GoPro camera not allowing a GPS lock. My solution involved the cover from an Altoids tin. Once I had enough metal between the GPS unit the GoPro I was back in business.

Jeff Ducklow

On March 23, 2019 at 11:58 AM Michael <mw@...> wrote:

Looks like you have an EMI issue, try wrapping the cameras with aluminum foil with just a small hole for the lens as small as you can get it without interfering with the view. Most likely your cameras are using a frequency that has a harmonic on the GPS frequency and with a GPS having say 165db of sensitivity, you pretty much can not get far enough away on a flight string to realize some impact, but more shielding and space will likely help. 

--Michael Willett

On Mar 23, 2019, at 11:08 AM, Zack Clobes W0ZC < zclobes@...> wrote:

I'm looking for some ideas on troubleshooting some lock problems on a new board/capsule/camera design.  The board has worked well during testing up until I started integration testing with the actual capsule with the cameras under it.  

The capsule is about 6cm thick and is mostly two layers of foam.  There are two cameras sandwiched in the middle and there is an aluminum bar holding them in place.  The GPS antenna is as far away from that as I can get.  Lid open or lid closed doesn't seem to make any difference.

During testing I noticed that this board would take a lot longer to get a lock than it's identical sister.  Initially I thought it was a bad GPS or antenna, and eventually replaced both.  Then I noticed if I unplug an external (optics) sensor, the GPS would lock up almost immediately.

So I nixed the sensor at the 11th hour and went flying.  The GPS never locked on a single time during the whole flight.  There's about 2m of separation to the next capsule.

This morning I plugged everything back in just like it flew, and it immediately got a lock.  The only thing I noticed was that after powering up the cameras, the altitude was reading about 100 meters high.  But I still had 5-9 sats.

I'm running low on ideas on what to try to isolate this problem. 




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