Losing satellites all at once, then back again

[Rick F.]

Last night when driving home on I-95, I had my TT on without a destination entered. I just had it on to monitor my driving speed (alarm set if I go over 75 ). All of a sudden I noticed it went from 7 or 8 satellites to none. But TomTom still showed me moving on the interstate. This happened off and on about 5 or 6 times in the next 20 minutes. I turned the unit off for a few minutes, then back on. It acquired satellites in about 20 secs. But then again it lost satellites off and on. I'm not talking about going down from 7 or 8 satellites to 3 or 4, I'm saying going to 0 satellites... nada... zip!

Here's what's really strange... while there were no satellites shown ? screen in gray scale ? I took the exit ramp off I-95. TomTom shows me getting off on the ramp! Something is really weird going on here!

Then at the stop light on the exit ramp, I had TT navigate to my home. After that it never lost satellites again the rest of the way home. The only thing I can think of is on I-95 I was going due south. When I got off the interstate, I was heading due west. Could all of the satellites be blocked by something in my car while heading south? Very strange.

 

[canderson]

OK - this thought, such as it is, is based upon the very specific description that you have provided.

ALL USERS - be aware that some truck drivers who prefer that their employers NOT have a constant log of their location have been buying satellite signal jammers (made in China, of course) and installing them in their rigs. The objective is to kill the on-board track loggers that the employers use on their vehicles. Some of these jamming units are actually strong enough to disrupt GPS signals for a substantial distance. Frequent use of these units by truckers on the Jersey Turnpike has actually fouled up the ability of Newark airport to certify their LAAS system.

GPS/Cellphone Jammers Also Snarl Aviation Navigation Systems P3air

Since the problem seemed to travel with you until you got off the highway, it's possible you were the victim of one of these nasty little gadgets.

 

[Rick F.]

Thanks for your reply Canderson.

Interesting that you linked to that article. I was an FAA Systems Specialist for over 30 years. I remember when Langhorn Bond was Admn and remember him stating the concern about jamming GPS signals. That was over 10 years ago.

I honestly don't remember if there were any trucks around me when I was driving south on I-95. Could have been though. A good test would have been if I had my TT 3rd with me to see if it was affected the same way. I might just put that in my glove box just in case it happens again.

One question remains... when I got off the interstate with NO satellites being received, why did TomTom show me actually getting off on the ramp? I didn't have time to tap the satellite icon to see if there were satellites there, but weak or grayed out. Maybe that was the case. Interesting.

 

[canderson]

I honestly don't remember if there were any trucks around me when I was driving south on I-95.

As an aside - while trucks are by far the most frequent users of these gadgets, anyone who drives for a living might employ one to keep a GPS tracker from working.

 

[Data_Dan]

I had a similar situation with my TomTom 2505. The map display kept changing from grayscale to colour about every 10 sec. and the display showed "acquiring satellite signal" I switched to the satellite status screen and it alternated from a dark background to a light background.
This occurred over a period of an hour's driving.
I rebooted the unit by pressing the power switch for about 20 sec and it worked normally after that!

 

[canderson]

That's what I have to do with my 740 on those rare occasions where it seems unable to find any satellites after a crash/reboot. I sometimes forget to clear the last route when shutting down and wind up paying for it. Sure would be nice if they'd ever get around to fixing that.

 

[mikealder]

Are they carrying out any testing for that "Light Squared" mobile phone service in that area per chance?? - Mike

 

[lbevil]

GPS Interference

I had a similar experience with my 540XXL on a recent trip. As I was driving on US Hwy 19 in West Virginia, I noticed a triangle with an exclamation popped up on my screen, along with a pause sign. Then the screen went blank. I looked around to see what might be in the area and noticed a Police car monitoring traffic - pointing in my general direction. I am assuming he had his radar on. I assumed that maybe I had been interfered with because of his radar signal. It took me several seconds before I could restore the screen. When it finally restored, my route home was still intact. I had not seen this action before on my TomTom nor my Garmin GPS.

 

[Uncle Dave]

My GPS lost its' way on I-25 in Denver CO for about 5 miles.

Started a search as to why. Came up with Light Squared. Also on this trip I was driving through an area Clear Creek, CO and area mentioned in my reading about Light Squared.

While living in Mass. I was on the local Fire Department, and worked in Broadcasting.

I do not like what I am seeing.

My present next door neighbour works as an Aircraft Controller for the FAA. How do I report this?

 

[canderson]

My GPS lost its' way on I-25 in Denver CO for about 5 miles.

Started a search as to why. Came up with Light Squared. Also on this trip I was driving through an area Clear Creek, CO and area mentioned in my reading about Light Squared.

I missed any reference to testing in our area, if there was one. But be advised that LS has NOT been authorized to deploy a single terrestrial based system using the band adjacent to L1, so whatever you may have been seeing, that isn't it (yet). The working group's final (6/15) report shows that the LS plan was a train wreck, just as one would have expected from the earliest testing. It appears that LS is going to have to trade some bandwidth with someone else. FWIW, Sprint is royally screwed on this deal. The day the working group's report was due out (it was released late) Sprint signed a bazillion dollar deal with LS for bandwidth for their 4G build-out. Someone back at Sprint was obviously asleep during all of the LS vs. GPS testing discussions.

How do I report this?

Without being able to single out a specific cause, it's not really reportable as such. If you were on I-70, don't discount the original post about jammers installed on trucks.