On Mon, Jun 25, 2012 at 4:59 PM, Tilman Baumann
<address@hidden> wrote:
On 25/06/12 15:52, Marvin Wang wrote:
hi Chris,
i had tried that use ublox center in windows and it get lock within 1
minute,(first time), but when it goes on my lisa/m2.0, it is another
story. the GPS is very hard to get locked, up to 10~20 minutes to get
locked on my balcony. in the field it takes more than 2 minutes. i
dont know what causes this.
I might have observed the same pattern. I have not looked much into it, but I had massive problems recently getting a stable fix. And the only change was that I used a UBEC to power the +5V line on Lisa.
I might need to clean that up a bit. I don't expect that UBEC to be any good (no name 3A 5V thing) but since everything it ought to power actually runs on 3.3V I thought it might not matter so much.
I thought the LDO will smooth that out. But perhaps they don't...
Can't prove those issues yet. Just want to mention since our experience seems similar.
Any tips what I should try to clean the power rail?
+5V is looped through a ferrite ring a few times.
Modem runs directl on 3.3V rail of Lisa. (could also hook it up on 5V. I soldered VCC behind the voltage regulator on the XBee breakout because this serial port was only 3.3V by default. But it's switchable)
uBlox MAX-6Q runs on 5V with it's own voltage regulator for 3.3V