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

[jimlux]

On 10/21/19 10:06 PM, Dana Whitlow 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?


Clpuds and even light rain won't change the received SNR very much at L 
band.

I'm going to guess that there's something that is cloud correlated - 
open and closing ventilation shutters? Soil or ground cover moisture 
changes, which changes the strength of a multipath signal. Some sort of 
thermal expansion effects changing the spacing of siding panels when the 
sun shines on them vs no.


> 
> Meanwhile I think I have finally persuaded him to install
> the antenna outside on the roof.
> 
> Dana    (K8YUM)
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