The 2 Dogs Posted June 13, 2002 Share Posted June 13, 2002 I am always surprised at the claim by people, both in the know and not, that weather conditions, especially cloud cover, have absolutely no bearing or effect on GPS signals. I have quite a bit of experience in the setting up and usage of satellite TV signals and have found that these are very much affected by cloud cover, storms, and passing aircraft at various times. Anyone who has ever watched satellite TV transmissions would be aware of the "Rain Fade" effect that depletes signals significantly during heavy cloud cover and storms. (lovely sparkles all over your video screen) This phenomenon often renders TV signals from sats as almost unusable. Given that this happens even when using a finely positioned parabolic dish and a significantly higher output from the TV birds, it is kind of hard to accept that the weaker GPS signal is not affected. My theory is that they ARE affected but the result is less obvious given the multi channel pickup of a GPSr. It could also be a Analogue Vs Digital thing. Any thoughts or experiences. Hounddog Quote Link to comment
+benjamin921 Posted June 13, 2002 Share Posted June 13, 2002 Yup, rain fade for my Dish is sometimes bad but never had any problems with the III+, except in heavy tree cover sometimes. I'm sure that I have been off course more in bad/heavy cloud cover before but always get where I am going. Quote Link to comment
+GOT GPS? Posted June 13, 2002 Share Posted June 13, 2002 Try it outside during a thunderstorm, and see if it works. Especially in a location that normally gets a good signal. has anybody used a GPS in a thunderstorm?? My home page about GPS units and information Quote Link to comment
+a182pilot Posted June 13, 2002 Share Posted June 13, 2002 Although not the wisest thing to do, I have been caught in a very severe afternoon thunderstorm while caching (they are very common in Tennessee in the summer). I was getting an average accuracy of 15 ft. prior to the storm and during the periods of heavy rainfall it would vary to 30 to 50 ft. When lightning flashed the sat. reception would go crazy but settled down quickly. I seem to have bigger problems with reception in dense fog than during storms. BTW I use a Garmin Map76S. He who angers you, controls you. Quote Link to comment
+MrGigabyte Posted June 13, 2002 Share Posted June 13, 2002 There is a "rain window" about 1.5Ghz and that is one of the reasons GPS is there. There is almost no attenuation even in the heaviest downpour. (Just a db or two). On the other hand, just a few millimeters of standing water will absorb/reflect 1.5Ghz waves. Quote Link to comment
+majicman Posted June 13, 2002 Share Posted June 13, 2002 Yeah, but what about the Red Meat effect? (Oops - wrong thread!) Always trade UP in both quantity and quality and Geocaches will be both self-sustaining and self-improving! --majicman Quote Link to comment
Kerry. Posted June 13, 2002 Share Posted June 13, 2002 Well to satisfy some peoples curiousty it's fairly simple to show just how immune GPS generally is to weather. With the number of permanent recording stations around the world all one needs is a specific date/time/location of the meanest weather one can offer and process/analysis the data. GPS (or the GPS signals) is actually used in the weather prediction process but the thing is it's a "system" not simply a single signal. Cheers, Kerry. I never get lost everybody keeps telling me where to go Quote Link to comment
Kerry. Posted June 13, 2002 Share Posted June 13, 2002 Well to satisfy some peoples curiousty it's fairly simple to show just how immune GPS generally is to weather. With the number of permanent recording stations around the world all one needs is a specific date/time/location of the meanest weather one can offer and process/analysis the data. GPS (or the GPS signals) is actually used in the weather prediction process but the thing is it's a "system" not simply a single signal. Cheers, Kerry. I never get lost everybody keeps telling me where to go Quote Link to comment
+georgeandmary Posted June 13, 2002 Share Posted June 13, 2002 quote:Originally posted by MrGigabyte: There is a "rain window" about 1.5Ghz and that is one of the reasons GPS is there. There is almost no attenuation even in the heaviest downpour. (Just a db or two). On the other hand, just a few millimeters of standing water will absorb/reflect 1.5Ghz waves. http://www.geocoins.ca Is this why I seem to have so much trouble finding caches near shores of lakes and streams? george Remember: Half the people you meet are below average. Quote Link to comment
Couch_Potato Posted June 13, 2002 Share Posted June 13, 2002 quote:Originally posted by majicman: Yeah, but what about the Red Meat effect? Red meat will also absorb/block GPS signals I'm not lost! I just don't know where I am. Quote Link to comment
Couch_Potato Posted June 13, 2002 Share Posted June 13, 2002 quote:Originally posted by majicman: Yeah, but what about the Red Meat effect? Red meat will also absorb/block GPS signals I'm not lost! I just don't know where I am. Quote Link to comment
+Pepper Posted June 13, 2002 Share Posted June 13, 2002 I was out doing some caching this morning by the SF Bay and my GPS did GREAT, but my phone on the other hand was rendered useless. I know not much about this sort of thing only what I experience! Team SuperGenius Pepper Horizontals where it's at! Quote Link to comment
+apersson850 Posted June 13, 2002 Share Posted June 13, 2002 Comparing the GPS signals to TV signals isn't correct. The data rate in TV signals is much higher than it is in the GPS signals. The data transmitted (we aren't talking about the pseudo random code now) is only 50 baud. Besides, when it comes to phasing in with the pseudo random code, the GPS tries that over and over again, and if it manages fairly often, the positioning will work. When looking at a TV screen, you'll notice all the frames that aren't reproduced correctly. More water on the leaves on the trees will absorb more of your signal, though. Anders Quote Link to comment
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.