Satellite Reception......

[Dutchman]

BMW NavII is six months old and has worked faultlessly both on the GS and in my car, with an external aerial.......

Last couple of days I've been getting repeated' lost satelllite' messages in areas where I've always previously had good reception...ie open country, no high buildings or mountains.......

Is there an inherent or developing fault I'm not aware of...or should I simply time the warranty claim to coincide with the launch of the NavIII.........?

Cheers

Dutch

 

[Schtum]

I've been getting the same thing on the SPIII. Twice today...once in Kirkcaldy and once when I got home.

This article indicates how easy it can be to disrupt GPS reception......

http://www.gpsworld.com/gpsworld/article/articleDetail.jsp?id=43404&&pageID=1

 

[Dutchman]

Good article......y'dont think those crazy Yanks are messing with 'our' satellites, do you.......?

Thanks

Dutch

 

[Schtum]

Good article......y'dont think those crazy Yanks are messing with 'our' satellites, do you.......?

I know that it's very easy for them to selectively disable satellite reception in specific areas. Try to get a satellite fix anywhere near the White House, for example..... Also, whenever I go up and down the M6 I note that there is one area where I lose reception.

 

[PanEuropean]

I've encountered this problem (crappy satellite reception) occasionally in the past, and I suspect it has more to do with the operators of the satellite system tweaking things around (possibly quite benignly) than it does with the GPSR developing problems.

I usually wait a few days to see if the problem goes away before getting worked up about it. Who knows, maybe the satellite that hovers over your house was due for a lube, oil and filter, and the Americans took it in for a spring tune-up.

Michael

 

[Mike Werner]

Bush at times of special military actions tunes down their gps system for civilians. It's the reason we Europeans are launching our own gps system, giving that power to Blair/Chirac...

 

[Bezzler]

Bush at times of special military actions tunes down their gps system for civilians. It's the reason we Europeans are launching our own gps system, giving that power to Blair/Chirac...

Scary or what !!!!!!!

 

[PanEuropean]

[the Americans] at times of special military actions tunes down their gps system for civilians...

Yes, this is true, but the technology in the latest constellation of satellites allows them to do this for a very specific geographic area - for example, an area with a radius of 10 miles or so - rather than having to do it on a global basis. That's the main reason why the Americans dropped the 'selective availability' (global degradation) of the civilian satellite signals back in 2000 - they didn't need to do that any more.

My experience has been that 99 times out of 100, if satellite reception is poor, it's due to something quite innocent - for example, poor satellite geometry, perhaps due to one satellite being out of service. Whenever there is a widespread or intentional degradation of the civilian signal in the Western world, all the electronics enthusiasts pick up on it right away and it is normally quite widely reported within the satellite / electronics interest forums.

In other words - don't get paranoid about it, it is more probable that on the day you had crappy reception, one satellite happened to have the flu, or maybe you left one of your gloves stuffed under the windscreen and it was blocking the antenna.

Michael
(A Canadian, and no apologist for the Americans)

 

[Wolfman]

Poor reception

I've been having poor recepection, and as usual it happens as you come to a point of change.

Over a trip down the M6, M42, M40, A40 and back, lost reception 26 times, from a few seconds to 5 minutes.

Loosing confidence in the 2610 , never had the problem with the SP3 I had.

Comments, Garmin have changed the unit for me , but still seem to be having problems.

Wolfman

 

[PanEuropean]

Wolfman, have you tried using an external antenna with your 2610? That's the quickest and easiest way to determine if there is a problem with the internal antenna in your GPSR. Just plug in the external antenna (this automatically disconnects the internal one), and see how the thing works.

Be aware that some third party (non-Garmin) mounting brackets for the 25xx, 26xx, 27xx GPSRs are designed such that they cover up the internal antenna in the GPSR. The internal antenna is about the size of a large postage stamp, and it is mounted exactly in the center top of the GPSR - in other words, centered from side to side, and centered from top to bottom.

Also, be aware that if your GPSR is tilted considerably off vertical (to allow you to see the screen more easily), this will degrade reception. All GPS antennas function best when they are flat (parallel with the ground) - once you get them tilted past about 15° off vertical or horizontal, things go downhill pretty quickly from there. If you find that you want to have your GPSR more than 15° off vertical to allow you to view the screen easily, then it's best to get a little external antenna and mount it somewhere else - flat, of course. There are lots of discussions here on the forum about how and where to put it.

Finally - do you have WAAS/EGNOS turned on? If so, turn it off. That will reduce the number of times you see a 'lost satellite reception' message, by freeing up two additional channels to track other 'conventional' satellites.

Michael

 

[Micky]

My BMW Nav II tends to lose satellite reception far easier than Sue's old 3Plus! I don't think it's a question of the satellites being tweaked, cos the Nav II doesn't do it in open territory, but slight tree cover, or close buildings may sometimes, but not always, cause it to lose signal! The old 3+ parked alongside, is still receiving a good signal!

Close to some Ministry of Defence establishments, and air bases we have both lost the signal in open territory. I guess they were 'jammed'

Also happened in Russia, riding past an air base, we both lost the signal at the same time, and only when well clear did both units receive a signal again. Return journey the same thing happened

 

[PanEuropean]

Hi Micky:

Without a doubt, the old 'post style' antenna on the SP III or the BMW Nav I was better than the current internal antenna, if for no other reason than the fact that you could adjust it to keep it pointed straight up.

I work in the aviation industry, and sometimes notice loss of GPS reception when I am near certain civil aviation support buildings. I don't think this is nefarious, I suspect it is a result of some other RF radiation (aircraft radar systems, test equipment, secondary surveillance radar, etc.) functioning in close proximity to my GPSR. I have never encountered any loss of GPS satellite constellation reception when I am inside an aircraft at an airport, for example, on a taxiway or runway.

Again - make sure you have WAAS/EGNOS turned off, and if your GPSR is mounted significantly off vertical, consider using an external antenna with it.

Michael

 

[Kritou]

Hi Micky:

... I have never encountered any loss of GPS satellite constellation reception when I am inside an aircraft at an airport, for example, on a taxiway or runway.
..Michael

Even allowing for the construction of a 'Bus (!) you are sitting underneath a pretty good ground plane with, by definition, a good sky view and hopefully horizontal antenna!. If there were any local degradation of signal it would surely be an issue for RNP, Vnav performance etc. OTH signal loss when riding a Pan down 25L should be the least of your worries!

 

[John Armstrong]

and hopefully horizontal antenna!

Err what happens on take-off, landing and when you're turning.

Or, have the laws of aerodynamics changed?

 

[araspitfire]

In my experience (15 years, several GPS's at work, and 3 of my own), the antenna orientation makes just enough of a difference to see it on the strength bars... but is not all that critical for the purpose (of navigation), unless you are in a situation of near loss of signal anyways... (like under wet foilage)...

More critical in my experience is that with some GPS's an internal antenna is awfully close to the tiny radiation sources inside the GPS itself... the Etrex Vista (original) suffered from poor sensitivity because of that... Still... I carried it nearly vertical (patch antenna wants to be horizontal) on my pack strap all the time and unless I was under wet foilage it still worked fine..

Now I have a 60C and it's "internal" helix antenna is sticking out, and is a kind that likes to be vertical, and I mount it on my bike nearly horizontal... it still works fine... It does work better on my pack strap though... less loss of signal in wet foilage...

Anyways.... like the bike.... just use it. Dont rely on it's recorded maximum speed, because a brief loss of signal in a turn will result in a high speed jump to the proper position when it locks back on.. And be prepared for loss of signal in cities and wet forests to cause it to be searching for satalites just when you want to know if this is the lane you need to turn up... simple really..

Al...

 

[PanEuropean]

Err what happens on take-off, landing and when you're turning...

Takeoff and landing are non-events for GPS reception, because the aircraft is (hopefully) wings level at all times during the process. An aircraft generally does not turn for longer than 60 seconds at a time, and normally not at an angle of bank greater than about 30 to 40 degrees. You do lose view of some of the satellite constellation when turning, but normally you still have sufficient satellites in view during a turn to maintain at least 2D navigation. Once you roll out level at the end of the turn, the GPSR picks the rest of the satellites up very, very quickly.

Michael

 

[Kritou]

Err what happens on take-off, landing and when you're turning.

Or, have the laws of aerodynamics changed?

in the context of possible local interference Michael was saying "...when I am inside an aircraft at an airport, for example, on a taxiway or runway"