[ntp:questions] semi OT - GPS receiver for BMW automobile on EBay

Richard B. Gilbert rgilbert88 at comcast.net
Fri Mar 2 21:56:23 UTC 2012

On 3/2/2012 9:55 AM, Ron Frazier (NTP) wrote:
> Hi all,
>  From my previous threads you know I've been considering upgrading my
> GPS receiver for NTPD. I found this GPS receiver module for BMW
> automobiles. I wouldn't know what to do with it if I bought it, but I
> thought it was interesting. There are a few of these on EBay, hopefully
> not stolen. I think one of the ads mentioned the name Trimble.
> http://www.ebay.com/itm/BMW-GPS-RECEIVER-NAVIGATION-MODULE-E38-740-750-E39-528-530-540-M5-E46-323-328-X5-/200699337078?pt=Car_Audio_Video&vxp=mtr&hash=item2eba9cd976
> Price for this one, $ 63 plus shipping.
> Sincerely,
> Ron

Don't buy it!

There are two kinds, at least, of GPS receivers.  The type you need
is a GPS TIMING RECEIVER.  It's optimized to deliver accurate time.

The other kind is a navigation receiver.  It is optimized for position.

Both kinds know both the time and the the position, it's the 
presentation that counts.  A timing receiver will have Pulse Per Second 
(PPS) output with one edge of the pulse being within something like +/- 
fifty nano-seconds of the time written out in full.

The navigation receiver outputs your current latitude, longitude, and 
elevation. Connect it to a computer with with the proper software and
the computer will display a map with "You are here!" and an arrow symbol.

With the proper software you may be able ask your computer "Where is the 
nearest hospital?" or "Where is the nearest Chinese restaurant?"

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