Question about comand navi in W203

[sobeus]

Hello!

I have an W203 Facelift. I have instaled an Comand navi in it. Now to the question. When you go to the menu where you can se your longitude and latitude and height and number of satelites. The height and satelites come and goes all the time. 2 sec it shows like 8 sat and height 0 then its - - and then 2-3 secounds later its maybe 10sat and 50m. Is this normal. The longitude and latitude is always there.

 

[Diesel Benz]

Do you meant the height is shown "- -" for short periods of time? GPS is not very accurate at all for height measurements, the car shows altitude at 50 m increments. So if you are close to see level, the display can easily change between 0 and 50 metres.

I've never looked at the altitude display at low number of satellites, it could be that Comand drops the altitude indication before the longitude/latitude indication. Theoretically one more satellite is needed for altitude measurement than "simple" location on ground (approximately). In practise the geometry may be poor at low number of satellites and the system may drop the figure.

Are you sure the number of satellites never goes to zero? I was just wondering if you have some intermittent contact issues for the GPS antenna. The latitude/longitude info could be present without any satellites, the car anyway keeps track of the location with other means (but I have not checked if it shows longitude/latitude in this case, I don't see why not).

Where do you have the GPS antenna installed?

It sounds quite possible that nothing is wrong with your car.

 

[sobeus]

The thing is that i mean that when looking at the menu where you can display number of satelites etc. It says 9satelites the secound after its just - its like it loses satelites and the find them again the secound after. It goes 9sat then 2 sec later its - then maybe 7 sat and 2 sec later -. I just want to check if its normal? Maybe its looking for sat all the time so its some kind of mode? Or my antenna loses sat and then the secound after finds them? The thing is the comand works just fine it shows me the way and where i am exactly.

 

[Diesel Benz]

The thing is that i mean that when looking at the menu where you can display number of satelites etc. It says 9satelites the secound after its just - its like it loses satelites and the find them again the secound after. It goes 9sat then 2 sec later its - then maybe 7 sat and 2 sec later -. I just want to check if its normal? Maybe its looking for sat all the time so its some kind of mode? Or my antenna loses sat and then the secound after finds them? The thing is the comand works just fine it shows me the way and where i am exactly.

If it is the number of satellites showing "randomly" 7 or above and "-" shortly at other times, it does not sound right. Does it also happen when the car is stationary?

Perhaps you could try playing with the GPS cable, connector and the GPS antenna itself. Perhaps a poor contact somewhere.

 

[pos.k]

Hi, I have the same with mine, nothing for a while when switching on from cold, but soon finds 5 or 6, sometimes up to 10, but always looking for current number visible (?)
Presumably the -- flashing on start up is whilst it is downloading the starting parameters - same as a tom tom does before it realises where it is.

Strange thing is that it always seems to know EXACTLY where it is - the 'dead reckoning' seems just too good to not have any satellite info. I know this is ongoing in another thread, but a comfort to know that not just me.

What type of antenna are you using, as I have installed a cheap antenna off ebay for now, but I am considering an upgrade soon to an MB original, as I figured it might be something to do with being too mean to buy the proper part, but if that behaviour is normal, then I'll use the money to buy a new hedgetrimmer instead (plus a team of gardeners....)

 

[Diesel Benz]

Hi, I have the same with mine, nothing for a while when switching on from cold, but soon finds 5 or 6, sometimes up to 10, but always looking for current number visible (?)
Presumably the -- flashing on start up is whilst it is downloading the starting parameters - same as a tom tom does before it realises where it is.

Strange thing is that it always seems to know EXACTLY where it is - the 'dead reckoning' seems just too good to not have any satellite info. I know this is ongoing in another thread, but a comfort to know that not just me.

What type of antenna are you using, as I have installed a cheap antenna off ebay for now, but I am considering an upgrade soon to an MB original, as I figured it might be something to do with being too mean to buy the proper part, but if that behaviour is normal, then I'll use the money to buy a new hedgetrimmer instead (plus a team of gardeners....)

Cold or warm start is different from what I understood sobeus had. It does always take a while for GPS to get a fix, the time to fix depends on how accurate info it has from the previous use (time, previous location, satellite orbit info/almanac).

I understood sobeus getting satellite fix, the device finding 7 to 9 satellites and then suddenly loosing connection to all.

The car does keep pretty accurately its location without any satellite info, based on gyros and speed signals. The error gets larger over time and distance but works fine for tunnels or other underground roads/parking lots but may sometimes be necessary in big cities with skyscrapers.

 

[pos.k]

Thanks Diesel Benz

Trying to establish if genuine antenna gives quicker id of satellites from start up and just keeps the count steady?

When my cheap antenna finds the satellites after a few minutes it does then flash the number on and off most of the time, and the count goes up and down (as you would expect) Is this normal, or is it a 'feature' of ebay antennas with the power levels fluctuating and continually resetting?

 

[Diesel Benz]

There could be a difference for the start up although it normally comes more from the time to read all the necessary data from the satellite(s). You know the almanac & ephemeris data is transmitted at a speed of 50 bits per second. It could still be a bit faster with a good antenna if the GPS receiver would not need to abandon reading one satellite when the signal gets poor.

As long as the GPS receiver is not able to read all 12 visible satellites, the number would fluctuate a bit. The signal from the weakest comes and goes but the minimum number of satellites that are constantly monitored would be higher with a good antenna (placed in a good position).

You said the number of satellites flashes on and off most of the time, do you mean between different numbers or really zero or dash, meaning no satellites? At reasonable conditions (at least a reasonable percentage of open sky visible) the number of satellites should not go to zero even temporarily. In motion things get a bit difficult, not sure if it could happen in UK cities, I wouldn't expect that.

 

[pos.k]

OK - it goes like this..

switch on and it shows -- for sats and alt.

few minutes later it finds say, 5 sats & 400ft

as you drive along - display shows 5 for 2 secs, then -- for 2 secs, then 6 for 2 secs, then --for 2 secs, then 8 for 2 secs, then -- for 2 secs......
always seems to know where it's going though...

 

[Alfie]

OK - it goes like this..

switch on and it shows -- for sats and alt.

few minutes later it finds say, 5 sats & 400ft

as you drive along - display shows 5 for 2 secs, then -- for 2 secs, then 6 for 2 secs, then --for 2 secs, then 8 for 2 secs, then -- for 2 secs......
always seems to know where it's going though...

You have a faulty antenna.

This is very characteristic of a non OEM antenna. What is happening is that it is intermittantly causing an open circuit hence the '--' display coming and going. This will be generating errors on the comand unit and making it work harder to find satellites. I've seen this many many times.

Genuine antenna's dont have this problem

 

[pos.k]

Thanks Alfie, will be in touch for a new antenna soon - will have to shelve the garden maintenance division for now

 

[speedybiker]

Thanks Diesel Benz

Trying to establish if genuine antenna gives quicker id of satellites from start up and just keeps the count steady?

When my cheap antenna finds the satellites after a few minutes it does then flash the number on and off most of the time, and the count goes up and down (as you would expect) Is this normal, or is it a 'feature' of ebay antennas with the power levels fluctuating and continually resetting?

Yes the genuine one does give quicker ID and will also keep the count steady. I know this for a fact because I live in the country surrounded by a valley and the cheap one was giving me problems.
Genuine is of a far better build quality and gets a better signal.
These are the part Numbers you need:

A203 820 09 75 GPS Antenna

B6 782 3533 Adapter cable

Alex.

 

[speedybiker]

Sorry I must have been typing at the same time as Alfie.

Hi Alfie how are you doing, long time no speak.

Alex.

 

[sobeus]

Hi, I have the same with mine, nothing for a while when switching on from cold, but soon finds 5 or 6, sometimes up to 10, but always looking for current number visible (?)
Presumably the -- flashing on start up is whilst it is downloading the starting parameters - same as a tom tom does before it realises where it is.

Strange thing is that it always seems to know EXACTLY where it is - the 'dead reckoning' seems just too good to not have any satellite info. I know this is ongoing in another thread, but a comfort to know that not just me.

What type of antenna are you using, as I have installed a cheap antenna off ebay for now, but I am considering an upgrade soon to an MB original, as I figured it might be something to do with being too mean to buy the proper part, but if that behaviour is normal, then I'll use the money to buy a new hedgetrimmer instead (plus a team of gardeners....)

My antenna is also a 15pound ebay antenna. But as you write my gps always know where i am. And it havent failed me yet when going frome a to b. But star diagnos says open circut on antenna. So they must be really bad qaulity these ebay antennas.

My gps finds satelites within 10 secounds after starting up.

 

[sobeus]

Yes the genuine one does give quicker ID and will also keep the count steady. I know this for a fact because I live in the country surrounded by a valley and the cheap one was giving me problems.
Genuine is of a far better build quality and gets a better signal.
These are the part Numbers you need:

A203 820 09 75 GPS Antenna

B6 782 3533 Adapter cable

Alex.

And they are in cost?
I have 30-40% discount here in sweden on most Mercedes parts

 

[speedybiker]

And they are in cost?
I have 30-40% discount here in sweden on most Mercedes parts

They cost around £48 if memory serves me right.

Alex.

 

[Diesel Benz]

And they are in cost?
I have 30-40% discount here in sweden on most Mercedes parts

Are you sure your local MB does not add 60% to the German price level? Can you give some parts price examples for comparison. Discount itself does not matter anything, the actual price you pay does.

 

[whitenemesis]

From the dealers

A203 820 09 75 GPS Antenna £56.06

B6 782 3533 Adapter cable is £43.20

 

[sobeus]

Are you sure your local MB does not add 60% to the German price level? Can you give some parts price examples for comparison. Discount itself does not matter anything, the actual price you pay does.

I live in Sweden so coparing prices to Uk is not god. Because swedish krona is so poor against the pound.

But an example i baught an new glove compartment box for a week ago. It was 128 pounds here in sweden. I baught it for 78. Thats a really relly good price. Also i baught a new mercedes star for the front (some idiots had stoled it. It was 24 a got it for 15.

 

[sobeus]

Are you sure your local MB does not add 60% to the German price level? Can you give some parts price examples for comparison. Discount itself does not matter anything, the actual price you pay does.

Ofcourse they ad 50-60% on everything they sell. Every business does that. Thet cant sell parts frome mercedes Germany for just 10% more tahn they buy it for. Your MB dealer in UK does the same.