[ntp:questions] GPS reception problem in UK

Uwe Klein uwe_klein_habertwedt at t-online.de
Mon Apr 19 07:04:38 UTC 2010


unruh wrote:
> On 2010-04-18, David Lord <snews at lordynet.org> wrote:
> 
>>Hi
>>
>>I just noticed that the GPS used as reference for my xtal oscillator
>>clock source has from midnight last night been losing reach. Previous
>>24 hr to that logging at 6 minute intervals had all 240 entries
>>at 377 but now they are mostly at 0 or start increasing for a short 
>>period, last up to 76, then drop back to 0. Any chance this is due
>>to atmospheric volcanic ash?
> 
> 
> I sort of doubt it, unless the ash is conductive. 

The ash will change dielectric properties. real and imaginary ( as in lossy )

<from http://www.sepa.org.uk/about_us/news/2010/volcanic_ash_cloud.aspx>

Typical chemical composition of volcanic ash

Volcanoes emit a variety of gases including H2O, CO2, SO2, HCl, NH3, H2S, HF. These gases interact 
rapidly with the ash particles of a volcanic plume and especially atmospheric water to form acidic 
aerosols.

Volcanic ash may therefore contain potentially harmful substances in the form of water-soluble 
materials, mostly acids and salts, which cling to the particles of glass and crystals. The most 
common are sulphate, chloride, sodium, calcium, potassium, magnesium and fluoride. Other elements 
reported but in lower concentrations include metals such as zinc, cadmium and lead.

Finer ash is able to carry more soluble ions than coarser ash because of its larger surface area; 
fine ash and smaller-sized ash travel greater distances from an erupting volcano, typically extend 
over very wide areas than larger ash particles and may stay airborne for lengthy periods.
</>

uwe




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