With the included PC application called miniAGPS, GPS Data (ephemeris data expires every 7 day) will be downloaded from a AGPS Server (free of charge) and transferred to the WondeX BT-100Y receiver wirelessly via Bluetooth.With AGPS data loaded to the WondeX BT-100Y, it knows approximately where it is located when it starts looking for the GPS satellites. It knows which sats should be in view and which sats to look for. With this AGPS, the time-to-first-fix (TTFF) is dramatically shortened from minutes to under 5 seconds!The limitation is your downloaded GPS data will expire in every 7 day. Once expired, you could simply re-download. Otherwise, your acquisition time without AGPS is around 30 secs, which is still faster than most SiRF StarIII and MTK based Bluetooth GPS receivers.