Does heavy cloud cover affect GPS reception?

Here, in our first best of the boards post, I'm quoting from alt.satellite.gps. The question that was asked  was, does heavy cloud cover affect GPS reception?

Dave Patton, Canadian Coordinator of the Degree Confluence Project had posted the best answer as of this morning...

The GPS signals will not be affected by clouds, rain, fog, snow, etc., because of the combination of their passing through water vapour, and the signal wavelength meaning they "pass through" rain etc.

On the other hand, water will block/attenuate GPS signals. For example, you can't receive GPS signals underwater, although having a GPS receiver antenna very close to the water surface may allow some reception.

Most cloth that would be covering a GPS receiver's antenna will pass GPS signals(e.g. backpack, jacket, etc.), but cloth with a metallic component will block/attenuate the signals.

Cloth that covers a GPS receiver's antenna and gets wet (e.g. from rain) can also block/attenuate the GPS signals. In fact, you don't even need the cloth - water on the case that covers the GPS receiver antenna can block/attenuate the GPS signals. That water could be drops, and/or a film of water. I've seen that happen myself, when using my etrex Venture in the rain - the signals were weak/blocked, but a quick drying-off of the GPS case over the antenna brought the reception back, which then degraded again as water accumulated on the case. Similarly, GPS signal reception is degraded in wet forest canopy conditions compared to when the forest canopy is dry.

Comments

[Kim]

good and useful article. May I ask a question, I am in Mexico and bought a GPS tracker. It is good working at good weather, but it can't work or work bad at bad weather with many thick clouds, and there is frequently storm weather here. I contact the supplier, they told me it is normal situation because the device will be affected by the bad weather especially under many thick clouds. And as your article indicate The GPS signals will not be affected by clouds, rain, fog, snow, etc., therefore, could you please help me to analyze the problem and show your opinion , thank you very much in advance. Best regards
Kim

[Rich Owings]

Does it have a transmitter (cellular?) that could be affected by the weather? Is it in a vehicle?

[Kim]

hi Rich,thanks for your reply. Sometimes in the car, sometimes not,so I think it is no the problem no matter I use it in the car or not. And for the transmitter, do you mean the transmitter in the device for receiving the GPS signal? I think there will be the transmitter in the device, and if the transmitter is affected by the weather, is it the same mean that the device also affected by the weather like heavy clouds and rain, and so on?

[Rich Owings]

Okay, I'm not sure if you have a navigation device or a tracking device. What brand and model is it?

[Kim]

Thanks for your reply. It is tracking device. I bought it from China, and it is no special brand and model number, but I can show you the link: http://www.xexun.com/ I bought the model TK102.

[Rich Owings]

Kim,

The device reports back (transmits) via cellular signal. I'm not sure how much these are affected by weather, but it could be an issue.

On the (GPS) reception side, while clouds and fog will not affect it, condensation / moisture collecting on your car can. Metal blocks signals as well, so locating the device in a window will help.

When carrying it outside the car, be aware that your body will block signals too. A mesh pocket of a daypack is often a good location, but in ideal conditions, a purse may work fine. The further from your body the better.

All these blocking materials (metal, your body) become much worse if the container carrying the device (purse, car, etc.) has a thin film of moisture on it.

The specs say the device has a SiRFstar III chipset, which generally has excellent performance under tough conditions.

Hope this helps.

[Kim]

hi rich, thanks so much for your kind detail response. Actually the celluar signal working good no matter clouds or not, it can feed back SMS anytime ,but the latitude and longitude data is wrong or no. And please be noted it can work normally if the weather is good without cloud or light cloud. That's I suspect it may affected by the weather. And in the testing time, I already pay attention the possibility blocking factor. After read your articl, I am confused now.

[Rich Owings]

Sorry Kim. I've about exhausted the possibilities that I know of. I suppose the device could have some very poor quality chipset firmware. You might want to discuss the issue with the manufacturer or retailer.