Lastweek, I was trying to deliver to a industrial estate in Hounslow, close to the airport.
My satnav was fine until I got close to the town centre. I then spent an hour doing circles around Hounslow with a 30 ton box struggling to find the place. After finally finding it by chance, I left, happily going along the A30 out of heathrow when my satnav then directed me through Bedfont. Strange! Croydon was my reload!! My satnav has never let me down (pnn 300 pronav) so was this a one off, or has delboy been messing with sat dishes again.
Anyone had the same problem??.
I find that the truck navs have trouble with the timed weight limits in London, so they try and avoid them at all times not just at the times they’re active…
You spent an hour driving round, can’t blame the nav for that 
I’ve always had this theory that driving on roads where there is a pylon running alongside might have an effect on the satnav.
There’s a layby on the LHS coming off the clockwise M25 going towards bedfont where you get to park nearly right under the pylons. I took a 45 there once, and got the spanish inquisition when I got back to the office, demanding how I’d managed to completely fall off the Isotrack map for nearly an hour! 
Makes me wonder if Pylons overhead is like wrapping a wet towel around your head in “Total Recall”■■
Thats interesting Winseer,…I think i’ll use my A2Z next time if things get dodgy around there. There is obviously a conflict of frequencies that satnavs don’t like and isotrack also has problems. Maybe a techno head can explain.
skoowif:
Thats interesting Winseer,…I think i’ll use my A2Z next time if things get dodgy around there. There is obviously a conflict of frequencies that satnavs don’t like and isotrack also has problems. Maybe a techno head can explain.
Maybe interference from ground radar at Heathrow? My early TomTom used to go a bit loopy around the horseshoe at Heathrow but I always blamed the massive amount of mobile radio and cellphone activity around there.
There is a theory that High voltage overhead lines do disrupt the signals to GPS, but latest research says its not possible unless your directly underneath a big pylon, like a building.
So it’s not the cables causing it but the actually pylon blocking your line of sight between the satellites and your reciever.
Bit like you get if you are travelling around a city with lots of tall buildings, the signals get bounced around a lot off of all the buildings and hence it is hard to position you properly and correctly. And then the GPS marker moves about on the map loads of times and gets confused trying to recalculate your route and current point accordingly, causing it to have a brain meltdown like you experienced.
If you really want to hide from GPS signals (not sure about ISOtrack and what signals that uses), park directly under the canopy of trees in an avenue, prefeably wet ones! They shield you from all the signals, always makes my job more impossible than it needs to be! 
However if you are up in Scotland at the moment, the military are delibrately jamming GPS in a large NATO miltary exercise, however as you was not there, it can’t be them…or can it 
HTH
C
In the picture above, I was parked to the right of that foreground car, stuck at the tail end of a line of nobbies and stobbies as one usually finds hogging the pull-ins. There’s another place where I’ve managed to achieve the same effect, but not every time, so I wonder if cloud/atmosphere also has a mitigating effect on it as well?
Here’s the other site of which I speak…
Here we have a pylon cable running parallel with the place you park up. Since the direction to the left in this picture is “north”, then perhaps only satellites hovering above the UK latitude will effectively have that power cable in line-of-sight?
Any radio hams on here? 
