On Mon, Jul 14, 2008 at 10:45 AM, Kalle Kärkkäinen <<a href="mailto:kalle.karkkainen@intstream.fi">kalle.karkkainen@intstream.fi</a>> wrote: <div class="gmail_quote"><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
In my past life I developed a fleet management device that had GPS and<br>
GSM in it, able to send the fix data to server in intervals. we even<br>
implemented some location alerts (around the vicinity of, or near<br>
customer..).<br>
<br>
Based on that experience, we used on of falcoms devices for it, it most<br>
probably did not have much of a cache for gps data (black box, tough to<br>
tell), but it needed a strong antenna for gps. For a GSM antenna you<br>
could use a hairpin, anything that had 10-15 cm of length was totally<br>
enough for good quality gsm connection. GPS required much more, in our<br>
case we supplied all the devices with external antennas.<br>
<br>
My knowledge is based solely on this work experience, I'm no radio-geek<br>
so I cant really tell much about antennas and signal catching. What kind<br>
of GPS-antenna is there in FR? Embedded for sure, but could that be the<br>
problem?<br>
<br>
I guess your TomTom comes with an external windshield antenna?<br>
<br>
--<br>
<font color="#888888">Kalle.</font></blockquote><div><br>No, it has no external antenna, only a window-mount with antenna connector but without one connected.<br>
That GSM works better is sure, because mobile GSM devices can receive at -110 dBm (usually ~ -70 to -90) while GPS chips receive at up to -160 dBm (usually between -130 and -150 at the antenna).<br>I think the antenna in the freerunner is not that bad, it even has a preamp. Ublox can receive at -158 dBm (according to the datasheet), what is pretty good (and definitely not worse than every good navigation device), and should get at least -130 dB (good enough for a cold boot fix) _after_ the antenna (preamplified) I guess. It even has it's own additional amp on chip. So the problem is imho only bad build quality (QA) at least in some of the devices (might be a defect connector by 3rd party, don't know).<br>
Short version: antenna good (I bet it's better than the antennas in most other smartphones with GPS), chip very good -> bug.<br><br>And btw. - SIRF Star III are damn good chips and used in many navigation devices and bluetooth gps devices, but the antaris is almost at the same level.<br>
<br>It surely is no software issue, theoretically it could be a firmware issue of the u-blox, but I don't think it is.<br></div></div>