小弟用過Garmin110,它是SiRF4的,聲稱可以取消以下干擾: http://www8.garmin.com/aboutGPS/
Intentional degradation of the satellite signal - Selective Availability (SA) is an intentional degradation of the signal once imposed by the U.S. Department of Defense. SA was intended to prevent military adversaries from using the highly accurate GPS signals. The government turned off SA in May 2000, which significantly improved the accuracy of civilian GPS receivers.
美國國防部2000年五月關掉這干擾,所以原則上SiRFIII和SiRF IV無甚分別。
Garmin110顯示過去果lap既平均pace/速度,所以唔係幾合用。
小弟最近改用310XT,除了外型略大外,非常滿意其表現,字體夠大,有實時速度/pace,心跳率有得set幾多來提醒,提醒時有震動及聲音,好正! 小弟都經常在高樓滿佈的跑街,接收完全無問題。