Does cloud affect GPS hold?

Blacksails

Member
My WKM powered AD8, which usually holds perfectly was wondering quite a bit in GPS when I flew today. The sky is quite overcast, but i'm still getting full GPS lock. Would the cloud be causing this sudden toilet bowl/wandering?

Cheers
 

hjls3

Member
Clouds should have zero effect on GPS signal. Not sure if that is good news to you or bad news...either way - have a good day!
 

Blacksails

Member
Ah, that'll be bad news then. Don't understand what could have caused this behaviour to suddenly appear. Possibly time of day and flying in close proximity to my house? I don't know.

Also, when yawning left if I release the stick the octo carries on turning for a short while, it does not do this when yawing to the right....but it has always done this. Yaw gain is fairly high
 

thehatguy

Member
From the Garmin website:

Sources of GPS signal errors
Factors that can degrade the GPS signal and thus affect accuracy include the following:

Ionosphere and troposphere delays - The satellite signal slows as it passes through the atmosphere. The GPS system uses a built-in model that calculates an average amount of delay to partially correct for this type of error.

Signal multipath - This occurs when the GPS signal is reflected off objects such as tall buildings or large rock surfaces before it reaches the receiver. This increases the travel time of the signal, thereby causing errors.
Receiver clock errors - A receiver's built-in clock is not as accurate as the atomic clocks onboard the GPS satellites. Therefore, it may have very slight timing errors.

Orbital errors -
Also known as ephemeris errors, these are inaccuracies of the satellite's reported location.
Number of satellites visible - The more satellites a GPS receiver can "see," the better the accuracy. Buildings, terrain, electronic interference, or sometimes even dense foliage can block signal reception, causing position errors or possibly no position reading at all.

GPS units typically will not work indoors, underwater or underground.

Satellite geometry/shading - This refers to the relative position of the satellites at any given time. Ideal satellite geometry exists when the satellites are located at wide angles relative to each other. Poor geometry results when the satellites are located in a line or in a tight grouping.
Intentional degradation of the satellite signal - Selective Availability (SA) is an intentional degradation of the signal once imposed by the U.S. Department of Defense. SA was intended to prevent military adversaries from using the highly accurate GPS signals. The government turned off SA in May 2000, which significantly improved the accuracy of civilian GPS receivers.


John
 
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Dewster

Member
Some days I'll power up and get a good signal on the ground when near buildings. Other days I'll have to launch my craft to get a good signal (steady flashing purple light). Now I will caution those that are borderline good signal. If the signal is not good your craft may become unstable and oscillate on it's own (yaw mostly). This may occur while landing near buildings and loss of a good GPS signal could occur.
 



MaNDoWn

Registered MR Crasher
I see that many people seem to think that the clouds have no effect on the GPS?
I'm not so sure about this as today I was outside setting up my compass after we had some rain.
We had some dark clouds overhead but the compass seemed to set-up fine.
I think I will set the compass up again on a clear day just to make sure.
While I still had the batteries hooked up I figured I would take a look at the LED light colors.
In altitude mode it flashed the yellow LED as it should.
When I put it in GPS mode I got two red flashes and then I didn't get any lights? Nothing!
Put it back in altitude mode and the yellow LED flashed again.
Back in GPS mode and it didn't have any lights. Not even the red lights it had the first time?

Anyone have any thoughts on this? I'll retest things when the weather clears up.
 
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MaNDoWn

Registered MR Crasher
I would have to agree with you amorealex.

I just seen the posting by hjls3 that said:
Clouds should have zero effect on GPS signal. Not sure if that is good news to you or bad news...either way - have a good day!
I would have to disagree?

From what I have seen... the clouds have a huge affect on the GPS as I couldn't get ANY signal.
This is just my thoughts so take it with a grain of salt.
I know I will not be flying GPS mode with cloud cover overhead!
 

Dewster

Member
Some days I would good GPS signal and others not, but normally all it took was for me to get the craft in the air monitor the signal status (which improved greatly) and then switch to GPS.
 

thehatguy

Member
From Garmin, a very credible source:

The Global Positioning System (GPS) is a satellite-based navigation system made up of a network of 24 satellites placed into orbit by the U.S. Department of Defense. GPS was originally intended for military applications, but in the 1980s, the government made the system available for civilian use. GPS works in any weather conditions, anywhere in the world, 24 hours a day.

There you have it. Clouds don't affect GPS signals.

John
 

MaNDoWn

Registered MR Crasher
After a little research... CLOUDS DO NOT AFFECT THE GPS.:) I did find out the answer to the issue I was having.
It seems USER ERROR will affect the GPS!:livid: When I was playing around with my radio I changed my settings on my 1,2,3, switch.
 

Eoin

Member
Have to chime in and say that in my experience cloud cover does not have any noticeable effect.
I can get full lock on the dullest of cloud covered days. The only time I have experienced gps problems turned out to correspond with Sun activity.
 

In this era of Global warming ETC regarding cloud cover the heavy rain filled clouds do have an effect on GPS signals, alot of rain clouds these days cover a lot more sky than ever before, they also seem to hold a lot more water, with no real breaks in large rain clouds you can struggle to get any GPS signal.
 

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