UPDATE Unlike XT1, XT2 works well for car use, but it seems to require some nimimal velocity (5km/h) for dynamic updates of the position, which can be a problem for hiking. Ongoing discussions in this thread.
Intro Back in February 2003, we broke the newsof the release of SiRF's Xtrac firmware and were amazed by its sensitivity...but later realized that it came at too high of a cost, a crippling delay as discussed in detail in this article on the first "dual-mode" GPS. The conclusion was that we needed a firmware that took reception conditions into account switched automatically and gradually between the ST (standard) and XT (Xtrac) modes...
Well, 14 months later, it appears that SiRF have performed this feat, making the use of Xtrac possible for standard use with the bonus of high sensitivity and unchanged hardware.
Index 1. Index and quick facts 2. Comparisons: ST/Xtrac v1/Xtrac v2 3. Xtrac v2 receivers at 07/09/04 4. Review - SysOn CF GPS v2 5. Conclusion
Quick facts - Hardware: ST/Xtrac v1 and Xtrac v2 receivers use the same IIe/LP chipset with the Xtrac receivers adding a more precise crystal for time synching - WAAS: Xtrac does not support SBAS (Satellite Based Augmentation System), which will rule out its use for mission critical GPS use. - Trickle mode: Xtrac does not sppport the energy saving trickle mode of ST SiRF receivers.
Links - Haicom BT401/HI303S review in the forums by grenadaman