Hi Strat00s,

The concept is that some type of EMF radiation from the electronics 
somehow causes a disturbance in the in the wires that feeds back to the GPS.
At least that is the theory and some folks appear to actually get better
results with shielding the wires.

I use Matek GPS units which seem to get sat fix decently fast anyway and I
didn't notice any appreciable difference with shielding or without. Cheaper
GPS units may be more effected. Don't know. 

In actual testing, it seems that sometimes shielding helps and sometimes
it doesn't; reason unknown. It is a cheap thing to try. If it improves the
sat fix time, Great. If not, you are not out a lot of money.

(26-Dec-2022, 03:49 PM)iFly4rotors Wrote: Hi Strat00s,

The concept is that some type of EMF radiation from the electronics 
somehow causes a disturbance in the in the wires that feeds back to the GPS.
At least that is the theory and some folks appear to actually get better
results with shielding the wires.

I use Matek GPS units which seem to get sat fix decently fast anyway and I
didn't notice any appreciable difference with shielding or without. Cheaper
GPS units may be more effected. Don't know. 

In actual testing, it seems that sometimes shielding helps and sometimes
it doesn't; reason unknown. It is a cheap thing to try. If it improves the
sat fix time, Great. If not, you are not out a lot of money.

Yes. But the GPS is a self-contained module. It does not require anything else to work except power. Those wires are purely for communication between FC and the GPS module. And considering that the communication is using mostly 5V logic, you would need some serious interference to get no data from the GPS to FC. And there is a pretty simple check for that. Open GPS tab (e.g. in inav) and see if you are getting any new messages. If so, no amount of shielding on the communication wires between FC and GPS is going to help, as you are already getting all the data.
Unless the interference is going all the way inside the GPS module (which itself is shielded) and causing some trouble there. But then again, the GPS signal is digital so there should be minimal interference anyway.

I do agree that there is no logical explanation for the communication in the wires to be disturbed and that leading to less satelites. Due to the digital nature that is just not possible. Its either receiving the data or not.
What i think is happening and all my experimental and repeatable experience is telling me is that the wires when not shielded act like an antenna and pass electrical signals over the wire into the gps unit bypassing the shielding of the unit and causing some internal interferrance. Could be these stray (noise) signals drop the internal signal to noise level such that it affects the effectivenes of the gps unit receiving antenna or something similar to that.
One experiment i did (and noticed accidentaly) is the orientation of nearby wires makes a huge difference.
When i changed the orientation of the crossfire antenna wire from almost 90 degrees crossing the gps wires to parralel i saw a huge drop in sattelites almost immediately. Reversing that gave me back the sats.
Moving the crossfire further away of cause made it even better but the oriention with the wires was the biggest discovery. Same for the power (lipo) wires in relation to the gps wires.
And this effect is waaaaay worse when not shielded compared to shielded.

So i have zero doubts about its effectiveness on the 3 quads i have it deployed (all with the top of the line mateks ). And its little efford so no brainer.
In the process i take special care of the wire routing/cable management to prevent any nearby parralel wires with the gps wires.

Hi Fpvapnea,

That is the best and most reasonable explanation that I have seen so far.

I will reiterate that I mount the GPS high and to the rear which provides quite 
a bit of "air" or "buffer" space between the GPS and the rest of the quad including
the electronics. I also work to keep some shielding between the GPS and the VTX.

EDIT:  Where my GPS is located necessitates the use of long wires.
          I don't know if the length of the wires has anything to do with
          it but it is something that differentiates locations such as mine
          from those where the GPS is located right down at the frame
          level. Also, it is common practice for builders to make all wires
          as short as physically possible and solder them directly. 

           Hmmm. 
          That is another thing, I always use connectors on my GPS units.
          Again, I don't know what effect this might or might not have except
          that it may {maybe ??} change the resonence of what ever signals
          or waves being emitted by the wiring harness. 

          Also, my GPS wires are generally long enough that they are folded
          back over each other a time or two. Again, I don't know what, if any,
          effect this has, however, it is likely different that other builders. 
          Yeah, I certainly don't know the physics of it; Just another thought. 

I do believe that putting space between the GPS and the electronics on the quad
does have a positive effect. I find it interesting that this method has been used 
for some time on the larger quads, however, folks like to put the GPS right on top
of these smaller quads. Hanging it off the back at the rear helps, but putting it
up higher seems to work better...at least for me. 

If I ever build another quad that needs a GPS, I will likely do some shielding,
however, I will still mount the GPS high and to the rear; location is paramount.
 

(27-Dec-2022, 12:57 AM)fpvapnea Wrote: I do agree that there is no logical explanation for the communication in the wires to be disturbed and that leading to less satelites. Due to the digital nature that is just not possible. Its either receiving the data or not.
What i think is happening and all my experimental and repeatable experience is telling me is that the wires when not shielded act like an antenna and pass electrical signals over the wire into the gps unit bypassing the shielding of the unit and causing some internal interferrance. Could be these stray (noise) signals drop the internal signal to noise level such that it affects the effectivenes of the gps unit receiving antenna or something similar to that.
One experiment i did (and noticed accidentaly) is the orientation of nearby wires makes a huge difference.
When i changed the orientation of the crossfire antenna wire from almost 90 degrees crossing the gps wires to parralel i saw a huge drop in sattelites almost immediately. Reversing that gave me back the sats.
Moving the crossfire further  away of cause made it even better but the oriention with the wires was the biggest discovery. Same for the power (lipo) wires in relation to the gps wires.
And this effect is waaaaay worse when not shielded compared to shielded.

So i have zero doubts about its effectiveness on the 3 quads i have it deployed (all with the top of the line mateks ). And its little efford so no brainer.
In the process i take special care of the wire routing/cable management to prevent any nearby parralel wires with the gps wires.

In such a case a GPS with better filtering or its relocation would be much more effective.

I don't want to go against your experience, but I still can't but say that this is either a placebo or some heavy un/luck when it comes to getting sats.  Just like me yesterday. Wanted to go flying and didn't get anything. Come back home and gets 6 sats no problem. Later that day I try again to get some sats and nothing. Today in the morning I moved the GPS to the front of my drone and immediately got 8 sats. The cables were always shielded except once I moved the GPS to the front.

placebos are not repeatable. And i am not sure a matek M10 requires replacement with a gps with better filtering.....
But regardless , use what works for you, i use what works consistently for me (20+ sats in the field in 30-60 secs and 14+ in center of amsterdam )

I used to have trouble getting sats almost every time I went flying. Especially in new locations. Either I didn't get enough and had to wait for the last few to get a lock or it was really slow to even get the first few. Did the shielding and after that I haven't had a single session with those problems. Not one.

I must just be impatient... I am getting more than 8 sats in less than a minute
and more in the next 30 seconds or so. For me, I thought that was pretty slow,
but it seems like my perception was off a bit and that is actually pretty good overall.

Since I want max Fly Time, I want to get that bird in the air as quickly as possible
after I connect the primary battery... matter of seconds if possible.

(30-Dec-2022, 04:54 PM)iFly4rotors Wrote: I must just be impatient... I am getting more than 8 sats in less than a minute
and more in the next 30 seconds or so. For me, I thought that was pretty slow,
but it seems like my perception was off a bit and that is actually pretty good overall.

Since I want max Fly Time, I want to get that bird in the air as quickly as possible
after I connect the primary battery... matter of seconds if possible.

VTX eats most of the battery while not flying. So if you can enable pit mode or lower the output while waiting for sats, you will lose minimum battery (I would guess that you will lose seconds even at max output).

Hi StratOOs,

I have actually put the VTX power leads on BT2 connectors so that I can
completely power down the VTX while satellites are being fixed. Yeah, it
does work. 

I like the BT2 connectors because they are easier for me to use in the field.
For me, the JST PH-2 connectors are hard to work with, especially in the
field. 

@Ifly: Hi, I suffer power consumption OCD too For my latest analog build I’ve connected the matek gps to the usb supplied 4.5v source, and since I like to keep thinks minimal in the field, I just use my phone usb as the external battery bank to power up the gps and fc while waiting for sats. I carry the phone anyway but also use the SpeedyBee app for easy config adjustments in the field. Once sat fix is obtained, it’s literally as long as it takes to connect the battery and disconnect the usb.

I don’t get the gps wire shielding thing either, doesn’t make sense to me for all the reasons mentioned. I have experienced a gps performance hit with 1.2ghz vtx’s because the frequency is so close to the gps L1 and L2 frequencies and there is always bleed over; resulted in halving of sats as soon as it turned on, but it was still useable with 10-11 satellites, down from 20+. Not sure what it could be with 5.8/2.4, but perhaps some rf witchcraft and sorcery is going on.

Hi roteron,

Here is the thing, most of the FC boards that I have do not have the +4.5 USB rail
available on a pad. That is, all of the pads are +5 volts and only power with the
main battery.

On the positive side, I thought that waiting 60-90 seconds was a long time, but
it seems that is quicker than I thought and better than many others.

I have tinkered with a variety of methodologies including the USB one (which was
not effective by the way), however, most seem to be more hassle than they are
worth; at least to me. 

When I was contemplating long range flights, I did not know that such flights
violated the FAA regulations. Now I do and don't fly long range. Since I am now
basically keeping my flights within Visual Line Of Sight, I don't really need a GPS.

I have lost a couple of quads to the trees where the GPS was essentially useless
since I couldn't retrieve the quad anyway. Yeah, I knew where it was, just could
not get to it. There is a long story here. Thing is, I don't need a GPS anymore.