External NEO-7N Mod

Seabee · Aug 21, 2015

Ian
Thanks for the prompt reply.
Have you tried also connecting and using the mag compass in the external Neo 7N? Would like to get the mag compass out of the leg where it does not like rebar in concrete. Which Neo 7N are you using? There seem to be many available. Do you think the Neo M8N with a LNA is too sensitive to interference even with the SAW filter?
Thanks.

Ian [P13] · Aug 21, 2015

Seabee said:
Ian
Thanks for the prompt reply.
Have you tried also connecting and using the mag compass in the external Neo 7N? Would like to get the mag compass out of the leg where it does not like rebar in concrete. Which Neo 7N are you using? There seem to be many available. Do you think the Neo M8N with a LNA is too sensitive to interference even with the SAW filter?
Thanks.

I was thinking to do the same myself, use the compass in the GPS puck instead of the leg, I asked Philip Rowse who's a tech lead for the Pixhawk 2 and he advised me against going so, I didn't quiz him to why as his advice is always good so I left it at that.

That also goes for the M8N, back last year on the APM/Pixhawk group before I even had a clue who Philip was (and the Solo was unheard of) he was advising people not to pair the M8N with a Pixhawk and he's been consistent with that advice since. The long and short of it, is that 3DR tested the M8N with the Solo against the NEO-7N, although the satellite lock and H/PDOP reads much better on the M8N in practice the precision of the lock was found to be little better, apparently the testing was done in the US, EU and Australia before 3DR made a decision. I'm told if there was ever to a recommendation for an 8 series ublox to be used, it would be the LEA-M8T.

I've not really posed the question, would the M8N be fine used with the Solo on a mast, the reality is I'm not seeing less than 9 satellites in practice now, so there would be no benefit changing and only risk. As long as you've a low H/PDOP and more than 6 satellites you're always generally fine.

There are some GPS improvements in the firmware released today. So I'd always advise anyone having GPS problems, a) get the new firmware b) contact 3DR support c) if you'd rather fix the issue yourself, do the mod to put the shielding 4mm away from the copper, but use a material that won't absorb water (so don't use cardboard), also don't put the material touching the antenna feedline.

Seabee · Aug 21, 2015

Ian

Thanks for the good info.

Frank Foster · Feb 5, 2017

Wow! an old thread, but I'm going to try this. I don't like the stock GPS antenna being under all the plastic. Seems to me that being on top, even if not on a mast, would be better. I have a few GPS units, claimed to be Ublox M8N, but upon inspection, I found the stickers have been removed, so I dunno?

Pedals2Paddles · Feb 5, 2017

So, what do you think the dome over that external GPS is made of? What do you think every GPS module for basically every single application of a gps is made of? Your concern is a bit illogical.

Frank Foster · Feb 5, 2017

Sooo, does anyone know the wiring of the stock GPS? There are 6 wires on the connector. Only 5 pads on the stock GPS unit ??? What is the sixth wire ???

GND
TX (As is marked on stock GPS, to left of connector. Only 5, what is the 6th ??)
RX
+5v
3v3 ???

And to ad to my confusion, the wire colors on the stock harness from top to bottom, as they would be when plugged in to the GPS, and main board.

black = GND
blue = TX ???
orange = RX ???
yellow = +5v ??? seems to me it should be red
brown = 3v3 ??? whatever that is
red = who knows, red is usually power ???

All I see needed to connect a different GPS, is GND, TX, RX, +5v That's only 4 wires. Why 6 on the stock GPS ???
I do not want to see magic smoke

The Ublox M8N I want to plug in, has 4 wires for GPS,
Black = GND
Red = power 5v ??
Green = TX
Yellow = RX

fpvsteve · Feb 5, 2017

Frank Foster said:
Sooo, does anyone know the wiring of the stock GPS? There are 6 wires on the connector. Only 5 pads on the stock GPS unit ??? What is the sixth wire ???

GND
TX (As is marked on stock GPS, to left of connector. Only 5, what is the 6th ??)
RX
+5v
3v3 ???

And to ad to my confusion, the wire colors on the stock harness from top to bottom, as they would be when plugged in to the GPS, and main board.

black = GND
blue = TX ???
orange = RX ???
yellow = +5v ??? seems to me it should be red
brown = 3v3 ??? whatever that is
red = who knows, red is usually power ???

All I see needed to connect a different GPS, is GND, TX, RX, +5v That's only 4 wires. Why 6 on the stock GPS ???
I do not want to see magic smoke

The Ublox M8N I want to plug in, has 4 wires for GPS,
Black = GND
Red = power 5v ??
Green = TX
Yellow = RX

Here is all you need to know if you want to mess with your GPS:
Get the Maximum out of Your 3DR Solo GPS - Hackster.io

Sid nguyen · Feb 5, 2017

i flew 6 batteries yesterday. i noticed that with every battery, the gps was getting faster locks. my first flight usually takes 3-5 minutes before it tells me fly. by the 4th battery, by the time the solo fully booted and connected to wifi, controller said fly. thought that was kind of cool.

pyrate · Feb 5, 2017

there is a small battery on the gps unit, that retains the lock between batteries
it should improve after initial lock on any flying day

Frank Foster · Feb 5, 2017

Well, I gave up on my experiment, for now. Got power to the external GPS, using the red and black wires. Tried the brown and yellow wires for TX and RX. TX from gps to RX on solo, got a beeping ?? Tried TX to TX and RX to RX, got nuttin. Plugged my Mro back in, and had to do the unplug the transmitter battery thing, to get it working again. Test flew w/14 sats. More to come.