Novatel-GPS要点积累

1、GPS数据格式：BESTPOSA and BESTPOSB from an OEM6 family receiver.ASCII:#BESTPOSA,COM1,0,78.0,FINESTEERING,1427,325298.000,00000000,6145,2748;SOL_COMPUTED,SINGLE,51.11678928753,-114.03886216575,1064.3470,-16.2708,WGS84,2.3434,1.3043,4.7300,"",0.000,0.000,7,7,0,0,0,06,0,03*9c9a92bbBINARY:0xaa, 0x4

2、4, 0x12, 0x1c 0x2a, 0x00, 0x02, 0x20, 0x48, 0x00, 0x00, 0x00, 0x90, 0xb4, 0x93,头3Byte 头长数据ID 数据长度0x05, 0xb0, 0xab, 0xb9, 0x12, 0x00, 0x00, 0x00, 0x00, 0x45, 0x61, 0xbc, 0x0a, 0x00,0x00, 0x00, 0x00, 0x10, 0x00, 0x00, 0x00, 0x1b, 0x04, 0x50, 0xb3, 0xf2, 0x8e, 0x49,0x40, 0x16, 0xfa, 0x6b, 0xbe, 0x7c, 0

3、x82, 0x5c, 0xc0, 0x00, 0x60, 0x76, 0x9f, 0x44, 0x9f,0x90, 0x40, 0xa6, 0x2a, 0x82, 0xc1, 0x3d, 0x00, 0x00, 0x00, 0x12, 0x5a, 0xcb, 0x3f, 0xcd,0x9e, 0x98, 0x3f, 0xdb, 0x66, 0x40, 0x40, 0x00, 0x30, 0x30, 0x30, 0x00, 0x00, 0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x0b, 0x0b, 0x00, 0x00, 0x00, 0x06, 0x00, 0x03

4、,0x42, 0xdc,0x4c, 0x48BESTPOS: 0xaa, 0x44, 0x12, 0x1c 0x2a, 0x00HEADING: 0xaa, 0x44, 0x12, 0x1c 0xcb, 0x03/#BESTPOSA, ;SOL_COMPUTED,NARROW_INT,31.84537570594,117.19885425530,66.7478,-4.7000, WGS84, 0.0163,0.0145,0.0272,"AAAA",0.400,0.000, 11,11,11,11, 0, 01, 00, 33*0048582e/Header- | 状态 定位

5、类型 纬度(度) 经度(度) 海拔(m) 椭平误差 数据ID 纬-经-高度偏差 基站ID 差分-定位时间 跟踪、定位的卫星数 留 扩展状态 留 使用的信号 /#HEADINGA,;SOL_COMPUTED,NARROW_INT,1.275547862,129.770889282,-0.592071533,0.0,0.788234651,1.056749940,"AAAA",11,11,11,10, 0, 01, 0, 33*7c36f63d/Header- -| 状态 定位类型 基线长? 航向(度) 倾角(度) 留 航向误差 倾角误差 基站ID4种定位卫星数 留 扩展状态

6、留 使用的信号 数据精度：BESTPOS、RTKPOS、GPRMC数据中的精度一样，来自同一算法解算结果BESTPOS数据帧中信息最全：包括差分期、定位误差等。北斗张工：差分期5秒以内，定位精度在1-2cm，5-10秒以内，精度在3-4cm。参考：differential age, which is useful in predicting anomalous behavior brought about by outages in differential corrections. A differential age of 0 indicates that no differential

7、correction was used.With the system operating in an RTK mode, BESTPOS reflects the latest low-latency solution for up to 60 seconds after reception of the last base station observation. After this 60 second period, the position reverts to the best solution available and the degradation in accuracy i

8、s reflected in the standard deviation fields.With the system operating in an RTK mode, this log reflects if the solution is a good RTK low latency solution (from extrapolated base station measurements) or invalid. A valid RTK low latency solution is computed for up to 60 seconds after reception of t

9、he last base station observation. The degradation in accuracy, due to differential age, is reflected in the standard deviation fields, and is summarized in the Standards and Reference page available on our website at See also the PSRDIFFTIMEOUT command on page 188.a. The RTK system in the receiver p

10、rovides two kinds of position solutions. The Matched RTK position is computed with buffered observations, so there is no error due to the extrapolation of base station measurements. This provides the highest accuracy solution possible at the expense of some latency which is affected primarily by the

11、 speed of the differential data link. The MATCHEDPOS log contains the matched RTK solution and can be generated for each processed set of base station observations.The Low-Latency RTK position is computed from the latest local observations and extrapolated base station observations. This supplies a

12、valid RTK position with the lowest latency possible at the expense of some accuracy. The degradation in accuracy is reflected in the standard deviation and is summarized in our An Introduction to GNSS book, available through our website at through Support | Knowledge and Learning > Learn About GN

13、SS > GNSS Book.The amount of time that the base station observations are extrapolated is in the "differential age" field of the position log. The Low-Latency RTK system extrapolates for 60 seconds. The RTKPOS log contains the Low-Latency RTK position when valid, and an "invalid&quo

14、t; status when a Low-Latency RTK solution could not be computed. The BESTPOS log contains either the low-latency RTK,OmniSTAR HP, XP or pseudorange-based position, whichever has the smallest standard deviation.b. The RTK velocity is computed from successive Low-Latency RTK position solutions. The RT

15、KVEL log contains the RTK velocity, when valid and outputs an invalid status if a Low-Latency RTK velocity solution cannot be computed. The BESTVEL log contains the Low-Latency RTK velocity when the BESTPOS log contains the Low-Latency RTK position.In a BESTVEL, PSRVEL or RTKVEL log, the actual spee

16、d and direction of the receiver antennaover ground is provided. The receiver does not determine the direction a vessel, craft or vehicle ispointed (heading) but rather the direction of motion of the GNSS antenna relative to ground.速度：速度的精度一般在0.03m/s左右，物体速度越慢，其速度精度越低，物体停止时，输出的速度0-0.5m/s为随机数。Velocity

17、(speed and direction) calculations are computed from either Doppler or carrier phase measurements rather than from pseudorange measurements. Typical speed accuracies are around 0.03m/s (0.07 mph, 0.06 knots).Direction accuracy is derived as a function of the vehicle speed. A simple approach would be

18、 to assume a worst case 0.03 m/s cross-track velocity that would yield a direction error function something like:d (speed) = tan-1(0.03/speed)For example, if you are flying in an airplane at a speed of 120 knots or 62 m/s, the approximate directional error will be:tan-1 (0.03/62) = 0.03 degreesConsi

19、der another example applicable to hiking at an average walking speed of 3 knots or 1.5 m/s. Using the same error function yields a direction error of about 1.15 degrees.You can see from both examples that a faster vehicle speed allows for a more accurate heading indication. As the vehicle slows down, the velocity information becomes less and less accurate. If the vehicle is stopped, a GNSS receiver still outputs some kind of movement at speeds between 0 and 0.5 m/s in random and changing directions. This represents the ra