mRo upgrade: 17 satellites below threshold for Solo flight?

[Zzz]

I upgraded my Solo to the mRo GPS last night and flew it this morning. It took about 2 minutes to register any satellites, which seems ok for a first boot of a GPS receiver in a new part of the world. Then it started acquiring them rapidly. Before I knew it, 17 satellites.

BUT... the solo controller still was reporting "searching for GPS." At one point I had 22 satellites locked in during a flight, which is so awesome. But then, I descended behind some tall trees and it dropped down to 17 satellites and the value turned red and started reporting "searching for GPS."

What gives? That's better than any GPS satellite lock I've ever had on this thing, but with the rev B GPS, it would call it good at 8 satellites and not complain. Is there a quality to the satellites? As I understand, this thing now receive Glonass too. Is that a factor? Does the software somehow evaluate usability of the satellites to arrive at the red or white sat count?

 

[fpvsteve]

I upgraded my Solo to the mRo GPS last night and flew it this morning. It took about 2 minutes to register any satellites, which seems ok for a first boot of a GPS receiver in a new part of the world. Then it started acquiring them rapidly. Before I knew it, 17 satellites.

BUT... the solo controller still was reporting "searching for GPS." At one point I had 22 satellites locked in during a flight, which is so awesome. But then, I descended behind some tall trees and it dropped down to 17 satellites and the value turned red and started reporting "searching for GPS."

What gives? That's better than any GPS satellite lock I've ever had on this thing, but with the rev B GPS, it would call it good at 8 satellites and not complain. Is there a quality to the satellites? As I understand, this thing now receive Glonass too. Is that a factor? Does the software somehow evaluate usability of the satellites to arrive at the red or white sat count?

Likely an issue of poor shielding. Best is to replace the original copper shield with the 3DR V2 GPS shield or the fabric mRo is selling on their web page.

 

[Zzz]

Likely an issue of poor shielding. Best is to replace the original copper shield with the 3DR V2 GPS shield or the fabric mRo is selling on their web page.

Perhaps. The copper shield that covered the rev B board seemed adequate and in good shape. Maybe I'll try the stuff mRo sells.

 

[EZL]

Perhaps. The copper shield that covered the rev B board seemed adequate and in good shape. Maybe I'll try the stuff mRo sells.

I went ahead and purchased this shield off of Ebay plus a mRo GPS:
3DR GPS shield New | eBay
I also placed the copper factory shield over this shield and I've had as many as 12 sats inside and outside 24 so
the new mRo GPS does make a big difference in how fast it aquires them and how quick.

 

[Zzz]

I went ahead and purchased this shield off of Ebay plus a mRo GPS:
3DR GPS shield New | eBay
I also placed the copper factory shield over this shield and I've had as many as 12 sats inside and outside 24 so
the new mRo GPS does make a big difference in how fast it aquires them and how quick.

Thanks.

Ok, so satellite count is one thing. But can anyone shed light on the fact that 17 satellites was still showing as a red satellite icon and showing the message "searching for GPS" ?

 

[JBAlaska]

I'm still on the Rev B board, isolation board and just tossed the copper shield in my spare parts, and so far I have not had any issues at all. I've just seen to many posts here and elseware on upgrade parts "taking the piss" as our brit buddies say. So until I have a issue I'm staying on the "if it's not broke, don't mess with it" side of the fence

 

[swaggy]

it isn't the number of satellites that the solo searches for. Solo looks for the HDOP value-once it reaches a certain level (around 1.5), it'll arm.

 

[XevetS]

it isn't the number of satellites that the solo searches for. Solo looks for the HDOP value-once it reaches a certain level (around 1.5), it'll arm.

Precisely look into this OP,
Also be prepared to lose GPS while you are flying your Solo at the worst possible moment remember it's not if but when you lose GPS signal......search for setting one of the controller buttons for "Manual control".

 

[BigTulsa]

HDOP can be affected by the K Index (solar interference). You can have 22 sats locked and solar can blow the HDOP out.

 

[Zzz]

it isn't the number of satellites that the solo searches for. Solo looks for the HDOP value-once it reaches a certain level (around 1.5), it'll arm.

Thanks, that's what I suspected, just wondered if anyone had any anecdotal insight. The higher number of locked satellites that are distant relative to each other, the higher the horizontal precision.

Was the Rev B board more discriminating in this regard? So with that mRO, I may have 22 satellites received but only 8 of those are worth factoring into the actual calculation?

 

[Pedals2Paddles]

It's neither sat count or HDOP. You can have more than 6 sats and an HDOP under the threshold too, and still get that message. If it still has position drift, the ArduCopter EKF will still reject it and you still get that message. This applies to any GPS you have connected.

 

[Zzz]

It's neither sat count or HDOP. You can have more than 6 sats and an HDOP under the threshold too, and still get that message. If it still has position drift, the ArduCopter EKF will still reject it and you still get that message. This applies to any GPS you have connected.

I used Solex for the first time yesterday since installing the mRo, and saw the "EKF Variance" message others have mentioned. Now I understand.

Is it still a shielding issue?

 

[Deleted member 12314]

Even though the MRO is a fairly good upgrade, it's still not the best option because it remains near the area of the gimbal and gopro which explains all the shielding required to help the GPS, the HERE is much better option on the mast by a long shot and higher reliability as well as quality of signal, HDOP.....my MRO is more reliable than my Rev. B was and gathers more satellites faster but once in a while its GPS signal is lost just not as frequent as Rev. B did.....

 

[BigTulsa]

Hmm. Through about 40 flights now with the MRO I've never experienced any GPS glitch. Maybe I'm just lucky....

 

[just_bruce]

The EKF takes into account all the sensors. Compass, GPS, Accelerometers, and Baro. If any of these is out of calibration enough it can cause EKF variance. If in a GPS mode this *can* cause SOLO to refuse to arm.

So, possibly perform a new level calibration and/or a compass calibration. You may have disturbed some things while knocking about installing the GPS.

 

[Deleted member 12314]

Hmm. Through about 40 flights now with the MRO I've never experienced any GPS glitch. Maybe I'm just lucky....

Your just lucky, others im sure will confirm the same, you need to be up on a mast away from the GOPRO for the most reliable setup.....its been proven 100 times over the EMI shield can only do so much at such a close proximity to the GOPRO which emits a terrible amount of EMI. No matter what MRO with V2 shield is a 49 dollar improvement over Rev. B and well worth the 49 dollars....

 

[jimloss]

Your just lucky, others im sure will confirm the same, you need to be up on a mast away from the GOPRO for the most reliable setup.....its been proven 100 times over the EMI shield can only do so much at such a close proximity to the GOPRO which emits a terrible amount of EMI. No matter what MRO with V2 shield is a 49 dollar improvement over Rev. B and well worth the 49 dollars....

I disagree that @BigTulsa is "just lucky". I have the purple mRo in my Solos and have well over 100 flights between the 2. One Solo has the v2 shield, the other has the original copper shield. The 2 perform equally. While I occasionally have the EKF Variance message on startup, I've had no problems with the mRo - not even a single loss of GPS since using the mRo. I fly under and near trees without any problems.

The HERE GPS/compass may be better. A mast mounted mRo may be better. The fact is that the purple mRo performs perfectly while located inside the Solo and "luck" has nothing to do with the experience of @BigTulsa.

 

[BigTulsa]

I'm not the one that's complaining. I 've had my MRO now for over 18 months and it performs very well. I was just making the statement that using the stock shield with the MRO could be the culprit and I"m still using the stock shield with no ill effects.

What could be the issue that I've expounded upon in a previous post in this thread is the Global Kp index (K index for short). If it gets up to 5 or more (and it does occasionally) I get GPS errors. I'm used to that because well before I had the Solo I have a DIY hex with a Pixhawk on it with a mast mounted GPS. It does it too during high K index events. I know there are apps specifically tailored for UAV flyers in mind that can track the K index for you. I know mission planner has it as a user item you can display in the HUD.

Planetary K-index | NOAA / NWS Space Weather Prediction Center