2. The Move to High-Sensitivity : SiRFstarIII : This all changed in mid-2005 when Garmin announced they would be using the high sensitivity SiRFstarIII chipset in their upcoming n?vi car system and a bit later in the 60/76 Cx handhelds. The SiRFstarIII chipset was launched by SiRF in early 2005 to take over from the SiRFstarII chipset that was already more powerful than the old Garmin chipset, respective tracking ratings being -159dBm, -148dBm and -143dBm (the lower the better). Acquisition sensitivity remained at about -143dBm as this is the level of signal required to download the live ephemeris data from the satellites needed to calculate a position, but with its massive correlation the power, the SiRFstarIII was able to scan the sky for satellites and TTFF (time to first fix) was much faster, provided that minimum level of signal was available.
This move was applauded by most users as it made acquisition times in the morning much more consistent, never more than a minute in good conditions, a bit more while driving and the GPS systems kept tracking virtually everywhere, including indoors, not that it was really useful...The flip-side was that very weak satellite signals were now being used, resulting in a much less stable position, one of the reasons to stick to low-sensitivity systems for marine GPS systems.
