[time-nuts] Do ordinary clouds adversely affect GPS reception?

[Dana Whitlow]

As far as I know, my friend's GPS dropout problems have been associated with
simple clouds with no rain (at least no rain reaching the surface).

Dana


On Wed, Oct 23, 2019 at 2:00 PM Tim Shoppa <tshoppa at gmail.com> wrote:

> I don't think clouds is the direct cause, but of course clouds in the sky
> can be correlated with wet foliage.
>
> Especially if the GPS Field Of View has a lot of angle taken up by tree
> canopy, wet foliage can substantially degrade not just GPS reception but
> other VHF and UHF signals.
>
> I notice this the most in the fall when the leaves are large and mature and
> are start losing their waxy coat, but have not yet fallen.
>
> Even after all the leaves have fallen, wet branches have attenuation
> ability as well.
>
> Some research papers have connected windy conditions with UHF attenuation
> especially deep fading as well (
> https://ieeexplore.ieee.org/document/1337081
> ).
>
> Tim N3QE
>
> On Tue, Oct 22, 2019 at 2:01 AM Dana Whitlow <k8yumdoober at gmail.com>
> wrote:
>
> > A friend of mine living in SE lower Michigan recently bought
> > a Geppetto GPS clock, and swears that it tends to lose
> > satellite lock on cloudy days but does OK on sunny days.
> >
> > He is admittedly using a very poorly-sited antenna,
> > placed in a window because his house has aluminum
> > siding.  He reports that his Garmin handheld GPS
> > has much less trouble acquiring and maintaining lock
> > on cloudy days than does the Geppetto, but still tends
> > to show higher levels of probable position error on
> > cloudy days.  I don't yet know if he takes the Garmin
> > outside for these comparisons.
> >
> > Is this a real phenomenon, or is my friend just imagining
> > things?
> >
> > Meanwhile I think I have finally persuaded him to install
> > the antenna outside on the roof.
> >
> > Dana    (K8YUM)
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