Perhaps its just that now the GPS is onboard, its closer to the other electronics on my jDrones hexa - but I'm suffering with an inability to get a 3D fix on the GPS.
My previous setup had the radio RX (JR RG831B DMSS receiver) and its telemetry unit (RA01T) on the lower carrier plate, the APM1 on the top plate, and the GPS receiver on the top of the dome on a standard jDrones hexacopter. This worked fine, GPS always got lock and seemed pretty stable.
Moving to the APM2, I've still got the radio RX on the lower plate, and now the APM2 above it. However, if the RX is powered, then the GPS won't lock - it occasionally acquires 1 or 2 satellites but never makes it further.
I've tried to isolate it somewhat - powered the 2 devices separately (APM2 from USB, RX from a lipo+BEC) and removed all the interlinks - still see the same problem. I've covered the top plate with foil, then place the APM2 onto foam on the foil - and it was better until I hooked up the PWM connections. I've removed the RA01T telemetry TX and that makes no difference.
If I place the APM2 alongside the RX, its fine. ie. if I remove the top plate and place it alongside the bottom plate on my work bench - then indoors I see 5 or 6 satellites and get a 3D fix.
Is this just a 'noisy' DMSS receiver? Is anyone else seeing this? Is there a recommended layout of the electronics that I've missed?
I've had a variety of receivers in the stack above my APM2 board and it does not seem to have affected getting GPS lock, although it varies hugely in the time it takes to lock.
If there is adjacent interference it can affect a receiver. Placing a possible interfering transmission away a few inches can help much.
The rule is inverse distance square from seeing light or RF. Unless focused.
Yup, all understood. I have got the RX in a position that allows the APM2 board to eventually see 8/9 satellites with a reasonable HDOP (100 ish), but cold start is very slow - 20-30minutes or so.
For a unit that claims '35 seconds typical', this suggests a problem still. I'll carry on trying things to see if I can improve it (and figuring out a way to power the GPS during LIPO changes....)
I don't like the position of the GPS. You want it to be on a high point of a plane, with many planes this will
be difficult. Also any attached cables sprout like a forest around it, providing a screen for a chunk of the sky.
I'll be using my old GPS on a ribbon cable. It did not get too great reception with the stock cable it came with, but when I got an extended cable and placed it right on the top of the airframe, it was great. I can't do that with this board :(
Justin, I don't think that will be a problem:
In the other hand the daughter board will come in four flavors: GPS+MAG+SD, GPS+SD, MAG+SD and SD. For example if you want to attach only the magnetometer (Compass) externally you just buy the option GPS+SD.
My problem is being quick on the trigger and having one of the first boards with the onboard GPS (which is fine for a hexacopter).
Its definitely an RFI problem that I'm seeing. Cold boot time with RX powered is 20-30minutes. Unpower the RX and coldboot is about 30seconds - at which point powering up the RX causes HDOP to drop for a while before recovering - but its the fastest approach for me at the moment.
It is for me because I was an early adopter as well.
But no worries. I just think it would be better to have not designed one with the GPS on the daughterboard and then bundle it with the existing remote MTK. Up to them though.
You can attach a battery to it, although perhaps not now it is fixed? that might fix the cold boot. The other option would be to shield it if you can which also helps it collect the sky better.
Did anyone with this issue ever find a way to resolve it? I haven't isolated the problem to my receiver yet, but once I get a chance I'll try to. I do get a lock when powered by USB indoors in a room with windows in about 5min. Outdoors, and powered by lipo, I'm the same as you guys: 1 sat, then 2 sats, then 1 sat, then 2 sats, then 0 sats. Every once in a while, I'll get to 3, but only for a moment. Occasionally, I have gotten a lock outside during a flight, but it is very rare. Would LOVE to get this issue fixed.
Anyone got a fix?
Wasn't my receiver.. The culprit turned out to be my ReadyMadeRC camera or the harness/wiring going to it. Once I unplug this device, the number of satellites goes up and I got 6 satellites right next to my house.
I have the same issue, even with no RX onboard, only 6 ESCs (Hobbywing Skywalker 20A) each min. 2" away from the APM2. As soon as I connect my ESCs I have no Lock. I am trying and searching for weeks. Some day it is working quite good, but only for one day.