... frequency synchronization, and other fields.2. Technical specification2.1 GPS module Receive frequency: 1575.42MHz Acquisition time: <2 minute 1PPS output ... 1:1-(+) , 2-(-), 3 Ground1PPS output(optional)2.5 Indicator light (see picture 1) Then power up, POWER green LED is ... 1PPS signal is effective, 1PPS green LED indicator is light Then BCODE signal is effective, BCODE green LED indicator is ...