GPS测试 QXDM测到的卫星的CN0与看到的CN0不一致
GPS测试 QXDM测到的卫星的CN0与看到的CN0不一致
测试GPS功能时，发现通过QXDM工具看到的modem侧的每个卫星的CN0都比手机软件上看到的要低3-3.5db，抓取实时log发现HAL层log打印出来的CN0值就与modem侧不一致。
高通给的解释是： This is by design, which has been introduced from the end of 2018. That is to day, the signal strength value (CNo) keeps the same the one in Antenna part, not baseband part. By contrast, qxdm report CNo from baseband part. The difference is the total loss from Antenna to baseband, i.e. approx. 3db ~ 3.5 db. Also, reporting antenna part signal strength could keep consistent with other vendor and Google definition
就是说天线和modem侧的CN0会有损耗，大概3.5db左右，HAL层的CN0值是从天线获取的，所以和QXDM看到的有差异。 当然也有一些手机平台比较旧，没有合入这个算法，所以看到的CN0是一致的。
android log：关键字搜索 LocSvc_LocApiBase
06-10 02:24:33.441 770 1726 V LocSvc_LocApiBase: 000: GPS 04 0.000000 0.000000 0.000000 1575420032.000000 0x1A 0x 1
06-10 02:24:33.441 770 1726 V LocSvc_LocApiBase: 001: GPS 07 0.000000 73.000000 272.000000 1575420032.000000 0x1B 0x 1
06-10 02:24:33.441 770 1726 V LocSvc_LocApiBase: 002: GPS 08 0.000000 49.000000 36.000000 1575420032.000000 0x1A 0x 1
06-10 02:24:33.441 770 1726 V LocSvc_LocApiBase: 003: GPS 09 0.000000 14.000000 215.000000 1575420032.000000 0x1A 0x 1
06-10 02:24:33.441 770 1726 V LocSvc_LocApiBase: 004: GPS 11 0.000000 73.000000 98.000000 1575420032.000000 0x1A 0x 1
06-10 02:24:33.444 770 1726 V LocSvc_LocApiBase: 005: GPS 13 0.000000 2.000000 323.000000 1575420032.000000 0x1A 0x 1
06-10 02:24:33.444 770 1726 V LocSvc_LocApiBase: 006: GPS 16 0.000000 7.000000 91.000000 1575420032.000000 0x1A 0x 1
06-10 02:24:33.444 770 1726 V LocSvc_LocApiBase: 007: GPS 17 0.000000 6.000000 234.000000 1575420032.000000 0x1A 0x 1
06-10 02:24:33.444 770 1726 V LocSvc_LocApiBase: 008: GPS 22 0.000000 0.000000 0.000000 1575420032.000000 0x1A 0x 1
06-10 02:24:33.444 770 1726 V LocSvc_LocApiBase: 009: GPS 27 0.000000 17.000000 47.000000 1575420032.000000 0x1A 0x 1
06-10 02:24:33.444 770 1726 V LocSvc_LocApiBase: 010: GPS 28 0.000000 18.000000 292.000000 1575420032.000000 0x1A 0x 1
06-10 02:24:33.445 770 1726 V LocSvc_LocApiBase: 011: GPS 30 0.000000 43.000000 309.000000 1575420032.000000 0x1B 0x 1
06-10 02:24:33.445 770 1726 V LocSvc_LocApiBase: 012: GLONASS 74 0.000000 33.000000 116.000000 1598062464.000000 0x1A 0x10
06-10 02:24:33.445 770 1726 V LocSvc_LocApiBase: 013: GLONASS 76 0.000000 26.000000 326.000000 1601437440.000000 0x1A 0x10
06-10 02:24:33.445 770 1726 V LocSvc_LocApiBase: 014: GLONASS 75 0.000000 68.000000 21.000000 1602000000.000000 0x1A 0x10
06-10 02:24:33.445 770 1726 V LocSvc_LocApiBase: 015: GLONASS 84 0.000000 14.000000 28.000000 1603124992.000000 0x1A 0x10
06-10 02:24:33.445 770 1726 V LocSvc_LocApiBase: 016: GLONASS 85 0.000000 73.000000 33.000000 1604249984.000000 0x1A 0x10
06-10 02:24:33.445 770 1726 V LocSvc_LocApiBase: 017: BEIDOU 201 0.000000 35.000000 126.000000 1561097984.000000 0x18 0x10000
06-10 02:24:33.445 770 1726 V LocSvc_LocApiBase: 018: BEIDOU 202 0.000000 40.000000 217.000000 1561097984.000000 0x18 0x10000
06-10 02:24:33.445 770 1726 V LocSvc_LocApiBase: 019: BEIDOU 203 0.000000 49.000000 175.000000 1561097984.000000 0x18 0x1000006-10 02:24:33.445 770 1726 V LocSvc_LocApiBase: 020: BEIDOU 204 0.000000 23.000000 112.000000 1561097984.000000 0x18 0x10000 06-10 02:24:33.445 770 1726 V LocSvc_LocApiBase: 021: BEIDOU 205 0.000000 22.000000 243.000000 1561097984.000000 0x18 0x10000