Difference between GPS cold start and warm start

　　The GPS module generally supports two modes: cold start and hot start (Note: warm start warm-start is not discussed)

　　Generally, the cold start time is much longer than the hot start time. Taking a good enough signal as an example, the hot start time of SirFIII is within 15 seconds, and the cold start time is within 42 seconds; in the case of weak signal, it will take longer; as follows:

　　(1) The location information (latitude, longitude, altitude) before the last shutdown is known (so the next shutdown in the garage must be a cold start);

　　(2) The current time, almanac, and ephemeris are known (requires real-time clock support, E666 support)

　　(3) The last shutdown time is no more than 4 hours (if the time is too long, the ephemeris changes, that is, the previous satellites cannot be seen)