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FMARTINEZJ
08-14-2009, 11:00 AM
In the Forerunner 305 diagnostics screen there is very interesting information. I don´t understand 2 things.

The first is the reference to "Bravo versión: 204". Anybody knows the meaning of that in a SiRFstar III chip?

The second is the parameter "XO Drift". Anybody knows what means?

SEILOGRAMP
08-14-2009, 11:20 AM
According to http://www.bing.com:
BRAVO -Operating system version
Don't know about xo drift

FMARTINEZJ
08-18-2009, 10:32 AM
Bravo version

About the bravo software version, my question is "What is the meaning in the Forerunner (Forerunners Chipset is SiRFstar III)?

XO Drift

I think XO Drift is a "Xip Onboard" that solves the drift between the satellites clock and the clock of the user. While satellites clocks
have a very good accuracy and stability (incorporate an atomic clock, which are very precise and very stable), this is not the case for the receivers since their price would be exorbitant.

Could any Garmin people explain is that is right?

T_SMIT
08-18-2009, 12:30 PM
I have no idea what a "Xip Onboard" would be, but in this context, XO stands for Crystal Oscillator. The XO drift parameter might show what the frequency error is between the oscillator's frequency and the nominal value.

In a GPS receiver, the clock offset is estimated (and corrected) by obtaining ranges to at least four satellites. This lets you solve for four unknowns: latitude, longitude, altitude, and time. Having exactly four satellites gives you a single solution. Having more than four satellites gives you multiple solutions that you can then use to determine your probable error footprint.

FMARTINEZJ
08-20-2009, 08:32 AM
I have no idea what a "Xip Onboard" would be, but in this context, XO stands for Crystal Oscillator. The XO drift parameter might show what the frequency error is between the oscillator's frequency and the nominal value.

In a GPS receiver, the clock offset is estimated (and corrected) by obtaining ranges to at least four satellites. This lets you solve for four unknowns: latitude, longitude, altitude, and time. Having exactly four satellites gives you a single solution. Having more than four satellites gives you multiple solutions that you can then use to determine your probable error footprint.

Thanks a lot. I think you´re right about Crystal Oscillator.