功耗知识
Cellular Rx signal strength (RSRP):
very poor (less than -128dBm): 2m 52s 227ms (8.7%)
poor (-128dBm to -118dBm): 1m 15s 705ms (3.8%)
moderate (-118dBm to -108dBm): 2s 367ms (0.1%)
good (-108dBm to -98dBm): 1m 21s 473ms (4.1%)
great (greater than -98dBm): 16m 3s 822ms (48.5%)