How good is the OEM Gps receiver?

[M3newbie]

Hi Guys.

I am currently doing an Oem widescreen / Dvd retrofit Nav install into my M3. I have seen that a lot of people are using the cheap gps receivers from Ebay. Are these any good, or is the more expensive oem receiver a better option?

What makes a good receiver? There are all sorts of s/n info etc on the baseplate, but I don't know what it all means. I just want to get the best receiver possible.

Does anyone make an even better one than both these options thats worth paying extra for?

When I bought a Garmin, all the talk was about 'Sirf3' gps which locked onto a signal almost instantly.

Thanks for any help in advance.

Btw, Great forum

[ccfj1]

Welcome to the forum mate,

I don't think that there will be a lot of difference, its just an antenna, the GPS receiver as such is build into the MK3 and Mk4 Sat Nav drives so any antenna will do.

Others may know better, but I'd say, give it a go, if its no good you can always get a pukka one.

If you can get the MK4 dvd drive, as its a much better unit than the older ones. If you have (or get) a mk4 have a look at this page for a upgraded map disc.

http://www.xoutpost.com/navigation-sy...db-update.html

[davidr]

I bought a £20 one off ebay (Lithuania guy) and it works fine - no problems at all.

Make suryou get one with the correct BMW Mk4 connector and a long-enough lead. Retrofit locations are usually different to factor shark fin - mine was under dash (X3) and needed 5 metre cable length.

[M3newbie]

Cheers Guys.

I have fitted an el cheapo gps antennae now and it seems ok, but it could be better. I don't always get the gps logo on the top right. The settings page says that I have the almanac and it can see 6 sats.

Does anyone know what all the readings should be. From memory on the gps readings page there is a s/n column and another column thats slips my memory. P/s maybe ? Whats a good value?

Then there is another page with something like hbop vbop etc. Is a high reading good or bad?

[KiwiJochen]

Originally Posted by M3newbie

Hi Guys.

I am currently doing an Oem widescreen / Dvd retrofit Nav install into my M3. I have seen that a lot of people are using the cheap gps receivers from Ebay. Are these any good, or is the more expensive oem receiver a better option?

They don't use different RECEIVERS.

They use different ANTENNAS

Huge difference. The receiver is built in to the Mk3 or Mk4 nav unit, and is special.

The antenna, which mounts on the rear window parcel tray of the saloon, can be a generic GPS antenna. As long as the cable is long enough and terminates in an SMB connector, to plug into the Mk3 or Mk4 nav, you should be fine.

[davidr]

Originally Posted by M3newbie

Cheers Guys.

I have fitted an el cheapo gps antennae now and it seems ok, but it could be better. I don't always get the gps logo on the top right. The settings page says that I have the almanac and it can see 6 sats.

Does anyone know what all the readings should be. From memory on the gps readings page there is a s/n column and another column thats slips my memory. P/s maybe ? Whats a good value?

Then there is another page with something like hbop vbop etc. Is a high reading good or bad?

No idea what the readings should be but the attached is for East Berkshire last summer. Values are typical of what I see. I'm running v29.1 on a recent 2006 Mk4. Never seen a problem with nav positioning or sat locking.

[KiwiJochen]

hihher the S/N the better. I have typical 12 to 15 on my car (latitude 37 south) but have seen as high as 20.

I saw a car once which struggled to get over 3 or 4, always had intermittent GPS reception

[M3newbie]

Good info there guys.

I suppose the only way to tell if one is better than the other is to plug in each type, and read off the s/n ratio. Is that correct?

BTW, what does the PRN refer to?

[Terry Kennedy]

Originally Posted by M3newbie

BTW, what does the PRN refer to?

Pseudo-random number. It indicates which satellite it is. The *DOP numbers are "dilution of precision" and lower is better.

[KiwiJochen]

Originally Posted by M3newbie

I suppose the only way to tell if one is better than the other is to plug in each type, and read off the s/n ratio. Is that correct?

Correct - the higher the S/N, the stronger the signal.

Make sure you swap antenna leads quickly (within 5min), and always observe the same satellite number (check the PRN).
The GPS satellites are orbiting the earth and their position is always changing as they fly overhead.

So you cannot use one antenna one day, then compare with another antenna another day, because the satellites have changed location, and it is possible that local obstructions (trees, buildings, etc) weaken the signal.