Overcast & No Signal

[jason.hall]

I've read in a couple places that cloud cover doesn't affect GPS reception. However, I just got my first GPS unit (a Garmin 60c), popped the batteries in, powered up, used the menu to pick my city on the map, and ....... nothing. I'm out in the open, overcast but no rain. Nothing within the 45 degree from the top of the sky, and only a couple trees in the distance & a couple houses below that. I don't get *any* bars at the bottom of the acquisition screen, and after a couple minutes I get the message popup of poor satellite reception. As per the manual I moved to a different location with the same results (front yard to back yard).

 

I guess these receivers really are impacted by cloud cover after all?

[+PDOP's]

Jason

 

How long did you try? It can take a new GPS a while to download the required information from the satellites when it's turned on for the first time.

[ghOzt]

It has been my experience that clouds do affect the signal to some degree, but never to the degree that you experienced! That's a mystery. Are you using it with GPS turned off? It might also be a defective unit.

[Kerry.]

Impacted by cloud cover, definately not.

 

Being your first GPS probably reading the manual first will help a little as immediately straight out of the box they simply don't work until initialized.

 

Leave it stationary with a clear view of the sky and let it sit for 10-15 minutes and if that don't work then look for another reason apart from cloud cover.

 

Cheers, Kerry.

[ghOzt]

Impacted by cloud cover, definately not.

Clouds never have any effect?

[+Team Shibby]

I have never had a problem wth reception due to weather. I often get my best reception when it is cloudy or raining. This may not be what you want to hear, but you just may have a defective unit. You should be getting some type of signal, but definately not NOTHING...

 

Kar

[jason.hall]

Just to give an update, everything's working fine. I picked Continue Acquiring and sure enough a minute or so later it started getting the locks - in the end it had nine.

 

I definitely read the manual cover to cover previously (I downloaded it from Garmin's site - that held me til it came in the mail), and it just said it'll take a while the first time. What threw me for a loop was the message saying Poor Satellite Reception! Well, whatever, it works fine now

 

Thanks for the tips,

Jason

[Kerry.]

Impacted by cloud cover, definately not.

Clouds never have any effect?

As far as anybody has been able ascertain, attenuation due to thick fog, torrential rain, clouds etc is insignificant at GPS frequencies and one reason why specific freq's are used. Extreme concentrations of sand, dust etc might account for something around 2cm/km in signal delay through that part of the actual sand storm.

 

There's certainly nothing to suggest clouds will block a GPS signal, there's simply nothing to substantiate any such claim and be assured many many people have an interest in this type of issue for critical applications. There are affects on systems used for critical precise applications but nothing that a recreational GPS receiver would ever be able to detect.

 

Cheers, Kerry.

Edited February 12, 2004 by Kerry.

[+Lazyboy & Mitey Mite]

I have had my signals blocked by the golden arches more than once.

[+Kewaneh & Shark]

You may want to read through the manual to see if the unit was initialized properly. All GPSrs need to be initialized the first time they are used. It may also be necessary to initialize the GPSr if the batteries have been removed for long periods of time (for Magellans, it about a half hour) or if the units have been moved a great distance (about 500 miles) while they were turned off. A re-initialization may fix your problem.

 

The newer GPSrs are much less succeptable to cloud cover than GPS units of a decade ago. We have technology to thank for that. Newer hardware and stronger signals from the satellites are only for the better. Cloud cover used to make for terrible GPS signal reception. I've been able to achieve and maintain satellite lock in with cloud cover and in thick fog. The only time you may have trouble is during stormy weather when the clouds are full of rain or snow, or during and electrical storm.

[ghOzt]

Extreme concentrations of sand, dust etc might account for something around 2cm/km in signal delay through that part of the actual sand storm.

Okay, thanks for the info. (Knowing is half the battle, right?) I knew that water droplets condense around dust particles (cloud condensation nuclei), and under most circumstances, these particles aren't numerous enough to affect satelite communication. I thought they sometimes were, though. But as you said:

...many many people have an interest in this type of issue for critical applications.

...and I'm sure many conclusive research projects have been done to disprove the myth.

Edited February 12, 2004 by ghOzt

[+tsiya]

Well, there goes my excuse for today!! It was too wet to crawl around moving leaves, so I didn't do a lot of detail searching, but My Etrex did act sort of unsure a couple of times today, and I got more weak signal messages than usual.

BTW, check out Walmart, an 8 pack of 2300Ma batteries for $17.87. That is a lot of running time.

[+flask]

there has been a lot of lively discussion about cloud cover and reception over at the VT geocacher group. it seems that a couple of the guys who have impeccable scientifice credentials say NO, absolutely not, while several people still hang on to aneccdotal evidence that yes, cloud matter.

 

so take your pick. i'm of the opinion that clouds do not matter, but my thumb blocking the antenna might.

[+tsiya]

Are there any other things that may influence getting a bearing? I was getting an indication that I should wade out North 75 feet into mud a gator wouldn't cross. From a spit of land about 150 feet North I was getting directed into the mud from the other direction. This site is in the physical shadow of a BellSouth tower, could this affect signals? This is a big error. Anyone that dropped a cache in that mud is likely still there.

[+geckoee]

Are there any other things that may influence getting a bearing?  <snip>

If your GPSr does not have a magnetic compass (or you have it turned off) when walking slower than about 1mph the bearing indicator may point the wrong way. Dial up the bearing on a pocket compass, match the north indicators, and follow that for the distance indicated on the gpsr.

[+EraSeek]

popped the batteries in, powered up, used the menu to pick my city on the map, and ....... nothing.

This happens to me on occasion when I change batteries in my Garmin Map76. Usually, I think, when I change from one type of battery to another type. You can either wait quite awhile to acquire or use a quicker method....however I forget what it is I do. Darn! I'll let you know if I remeber. It is either, shut off and turn back on, or select one of the other options given by the gps. I'll think about it. But I am certain it is this type of aquisition problem having to do with powering up. NOT CLOUDS!

[Kerry.]

ghOzt, if you like "light" reading then try THIS just take into account the application and equipment compared to what's used for caching.

 

Cheers, Kerry.

[+EraSeek]

ghOzt, if you like "light" reading then try THIS just take into account the application and equipment compared to what's used for caching.

 

Cheers, Kerry.

15 millimeters, 20 millimeters? I don't think we have to worry about it. Clouds are not a problem. Even heavy rains and sandstorms, we wouldn't notice at our level.

[phern47]

This morning, I put the old Garmin 45 in it's holder on the dash but this time, it was too cold for me to stick my arm out the window with the unit in my hand so that it would "acquire" the satellites before starting out. It was very cloudy, it was snowing very hard, it was foggy and the wind was blowing the very loose snow all over the place. Visibility was next to nil. I got to the end of my driveway and waited for a lull in traffic and "lo and behold", the unit was all fired up. With 8 strong satellite signals (max number for the 45). I was considering using an external antenna or even making an extension cord and use the existing removal antenna as an external antenna but I guess I won't have to.

When I told the kid salesman at the local hunting and fishing store that sells GPSs, that someone had loaned me a Garmin 45 he just laughed and said that it was junk and could suddenly quit working because of some internal thing that limits the life of a GPS. I guess I should go back and laugh at him for trying to sell me a pc cable and a power cable for 75 dollars each but cost me only 10 bucks total to make at home. I was surprised at the accuracy of the Garmin 45. I kept travelling over the same streets and roads and when all the tracks were laid out on "GPS Trackmaker", all the traces were tight together at the highest magnification (20meter).

I guess when my buddy will want his GPS back, I will have to buy my own. My buddy paid 35 dollars U.S. plus shipping for it but since he doesn't read english, he doesn't know how to operate it.

Are there any other GPS like the Garmin 45 but with 12 channel parallel cababilities, removable, directable, external antenna, large screen, rear connector for pc cable or power etc? I hear about other GPSs that you must hold parallel to the ground in order to get satellite reception. I have the impression that the manufacturers have used some short cuts and cheaper materials in order to save money.

[+Team HomestarRunner]

I have never noticed any problem while using my 60C in heavy cloud cover. I even get decent reception in wooded areas. As compared to my Etrex Yellow that is.

[ghOzt]

ghOzt, if you like "light" reading then try THIS just take into account the application and equipment compared to what's used for caching.

Thanks! That article was published just before I started my subscription to the Journal of Geophysical Research.

 

Man, those scientific journals are real page turners. I curse every professor that makes me write response papers to them!!

[+tsiya]

The situation I mentioned was at the Fort Mose cache in St. Augustine, where You have a wooden pier extending Eastward over the marsh, with the remains of old earthen causeways parallel to it at about 150 feet on each side, like 3 long extended fingers. Any indication at 90 degrees N or S from any dry spot puts You in the water and/or mud. I did not know about the speed factor, but I did get a reading telling Me to look in the marsh to the South of the pier. The solution is obvious, take My Grandson next time, tie a rope to Him, and throw Him into the marsh. There is one more possibility based on the clue, but that would put the distance reading off even further, by another 75 feet. Oh, well, back We go again.

[+Spoo]

Here in the north, I have put my GPSr in a center console, had an overcast and snowing sky, and had 4-6 inches of snow on the rrof of the Jeep. I still get a signal and lock. Weather and clouds should not effect the signal.

 

Sun streaming, however, will !!! This is usually in the late afternoon as the sun is setting. It is a Radio Frequency phenomona that allows CBers and HAM radio operators the cahnce to talk far further than they should be able to.

 

Were you tryin to get your GPS to work for the first time ever in the late afternoon?

[+EraSeek]

Just to put the question to rest,I was in Bellingham Washington the other day. This is near the Candian border. It was very overcast and raining. I got 11 sats up, and WAAS agumentation, with EPE of 6.8 - 7.2'. I turned WAAS off, and still had 11 sats without WAAS and 7.4' EPE for the next 10 minutes. Just a darn good day I guess for sats.

[+tsiya]

I think the cache really is out in the mud, will go at low tide next time, with My Grandson, and His GPS. Together they form a light, fast, and highly manuverable search engine. My secret weapon!

There is an interesting survey marker at this site, anyone know what it is?

N 29 55.721 W 081 19.472 It is a treated wood cylinder encased in a massive concrete base and has an aluminium disc stamped SMT LB6627. Does not show on maps I can find.

[+ZingerHead]

Sun streaming, however, will !!! This is usually in the late afternoon as the sun is setting. It is a Radio Frequency phenomona that allows CBers and HAM radio operators the cahnce to talk far further than they should be able to.

 

um, yes and no. True, the "grayline" around sunset does offer some opportunity for shortwave skip and greater-than-normal propagation distance, but at the frequencies used by GPS (1 GHz and up) that sort of propagation is less frequent. Plus the GPS signals are beaming at you from outside the atmosphere, so if they "skipped" who knows where they'd wind up .