timtjohnson
New Member
Like others I was disappointed recently to find that whenever I have an SD card inserted in my retrofit NTG 2.5 unit, the satellite count in the compass screen drops to zero. Whilst the compass feature isn’t really a problem, I suspect this does explain why from time-to-time I am shown as ‘off road’ or running along a parallel road to my real location. From other forum postings I understood this to be a known bug in recent firmware updates.
I have two cars, both with NTG 2.5 (thank you to Alfie and Richard at ComandOnline for coding both – would highly recommend). Interestingly though, one car had the issue whilst the other works perfectly. I decided to investigate and here are my findings….
Both cars have:
· Comand NTG 2.5 with 09/29 firmware
· Version 7.0 (Europe 2011/2012) map update – btw - anyone want to buy my update DVD’s? - see my eBay item 160831759802
· Sandisk 32GB SDHC cards – [latest firmware enables the use SDHC cards]
· Mercedes GPS Antennas (MB Part No. B6 7 82 3580)
Whilst the Compass view is useful for diagnostics, the GPS Information shown in Engineering Mode (hold down Hang-up + * + 6 for 8 seconds) provides much more detail (see attached photos) - I have relied on this for my testing (referred to as GPS Info View).
With the SD card inserted, I had zero satellites showing in compass view and the GPS Info View showed nine blue satellites. If I ejected the SD card then the blue satellites turned yellow. I have assumed that each blue dot in the 3D column indicates a separate satellite signal being received, whereas a yellow dot indicates that the signal being received is reliable and its ‘locked-on’ [better explanation welcome?]. The only other real difference between the two SD card states (in or out) is that the C/N column (carrier noise) either shows zeros or low numbers when the SD card is inserted.
Clearly, the SD-Card is affecting the quality of GPS signals being received, as opposed to there being no signal at all. This would explain why I could drive around for days without an apparent signal in the compass screen and yet still be in exactly the right place on the map – (need to test what happens to the map if the GPS antenna is physically disconnected. I appreciate there is a speed signal and gyroscope but it can't be meter accurate for hundreds of miles can it – anyone?)
I then relocated my antenna from under the dashboard to outside my car and on-top of the roof…and hey presto! I had full signal regardless of the SD card status. After much playing around I found that the unit was very sensitive to the GPS antenna’s location (millimetre changes) and the way in which the excess cable was stored. I still have the antenna above the cluster (under dash) but slightly to the left and the excess cable is coiled very neatly and pinched together with the supplied cardboard ring (to about 5 inches in length) – this process is fiddly and very much trial and error but worth persisting with.
To verify my theory, I took the antenna out of my other car (the working one) and was able to replicate the issue I had.
In summary, I have provisionally concluded that the SD card creates some sort of inherence that degrades the GPS signal. This results in the GPS antenna (and cable) being extremely sensitive to location and storage. If your car has this problem, try this fix out and post your findings. If your car doesn’t exhibit these symptoms, it could be luck that the GPS antenna is already in the optimum position!
I would very much welcome other people’s thoughts, or results of testing.
I have two cars, both with NTG 2.5 (thank you to Alfie and Richard at ComandOnline for coding both – would highly recommend). Interestingly though, one car had the issue whilst the other works perfectly. I decided to investigate and here are my findings….
Both cars have:
· Comand NTG 2.5 with 09/29 firmware
· Version 7.0 (Europe 2011/2012) map update – btw - anyone want to buy my update DVD’s? - see my eBay item 160831759802
· Sandisk 32GB SDHC cards – [latest firmware enables the use SDHC cards]
· Mercedes GPS Antennas (MB Part No. B6 7 82 3580)
Whilst the Compass view is useful for diagnostics, the GPS Information shown in Engineering Mode (hold down Hang-up + * + 6 for 8 seconds) provides much more detail (see attached photos) - I have relied on this for my testing (referred to as GPS Info View).
With the SD card inserted, I had zero satellites showing in compass view and the GPS Info View showed nine blue satellites. If I ejected the SD card then the blue satellites turned yellow. I have assumed that each blue dot in the 3D column indicates a separate satellite signal being received, whereas a yellow dot indicates that the signal being received is reliable and its ‘locked-on’ [better explanation welcome?]. The only other real difference between the two SD card states (in or out) is that the C/N column (carrier noise) either shows zeros or low numbers when the SD card is inserted.
Clearly, the SD-Card is affecting the quality of GPS signals being received, as opposed to there being no signal at all. This would explain why I could drive around for days without an apparent signal in the compass screen and yet still be in exactly the right place on the map – (need to test what happens to the map if the GPS antenna is physically disconnected. I appreciate there is a speed signal and gyroscope but it can't be meter accurate for hundreds of miles can it – anyone?)
I then relocated my antenna from under the dashboard to outside my car and on-top of the roof…and hey presto! I had full signal regardless of the SD card status. After much playing around I found that the unit was very sensitive to the GPS antenna’s location (millimetre changes) and the way in which the excess cable was stored. I still have the antenna above the cluster (under dash) but slightly to the left and the excess cable is coiled very neatly and pinched together with the supplied cardboard ring (to about 5 inches in length) – this process is fiddly and very much trial and error but worth persisting with.
To verify my theory, I took the antenna out of my other car (the working one) and was able to replicate the issue I had.
In summary, I have provisionally concluded that the SD card creates some sort of inherence that degrades the GPS signal. This results in the GPS antenna (and cable) being extremely sensitive to location and storage. If your car has this problem, try this fix out and post your findings. If your car doesn’t exhibit these symptoms, it could be luck that the GPS antenna is already in the optimum position!
I would very much welcome other people’s thoughts, or results of testing.
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