sensor_msgs/NavSatFix Message

1 sensor_msgs/NavSatStatus Message

http://docs.ros.org/en/api/sensor_msgs/html/msg/NavSatStatus.html

# Navigation Satellite fix status for any Global Navigation Satellite System

# Whether to output an augmented fix is determined by both the fix
# type and the last time differential corrections were received.  A
# fix is valid when status >= STATUS_FIX.
# 是否输出增强的定位 取决于 定位类型 和最后一次收到差分校正的时间。 
# 当状态 >= STATUS_FIX 时，此定位才有效。

int8 STATUS_NO_FIX =  -1        # unable to fix position 不能定位
int8 STATUS_FIX =      0        # unaugmented fix        未增强的定位
int8 STATUS_SBAS_FIX = 1        # with satellite-based augmentation　
int8 STATUS_GBAS_FIX = 2        # with ground-based augmentation   

int8 status

# Bits defining which Global Navigation Satellite System signals were
# used by the receiver.
# 定义接收机使用了哪种全球导航卫星系统信号

uint16 SERVICE_GPS =     1      # GPS导航系统
uint16 SERVICE_GLONASS = 2      # GLONASS导航系统
uint16 SERVICE_COMPASS = 4      # includes BeiDou.　? 北斗对应的数字是多少？
uint16 SERVICE_GALILEO = 8      # 伽利略导航系统

uint16 service

 Compact Message Definition

int8 STATUS_NO_FIX=-1
int8 STATUS_FIX=0
int8 STATUS_SBAS_FIX=1
int8 STATUS_GBAS_FIX=2
uint16 SERVICE_GPS=1
uint16 SERVICE_GLONASS=2
uint16 SERVICE_COMPASS=4
uint16 SERVICE_GALILEO=8
int8 status
uint16 service

2 sensor_msgs/NavSatFix Message

http://docs.ros.org/en/api/sensor_msgs/html/msg/NavSatFix.html

# Navigation Satellite fix for any Global Navigation Satellite System
#
# Specified using the WGS 84 reference ellipsoid
# 使用 WGS 84 坐标系

# header.stamp specifies the ROS time for this measurement (the
#        corresponding satellite time may be reported using the
#        sensor_msgs/TimeReference message).
# header.stamp指定此测量的ROS时间（可以使用sensor_msgs/TimeReference消息报告相应的卫星时间）
#
# header.frame_id is the frame of reference reported by the satellite
#        receiver, usually the location of the antenna.  This is a
#        Euclidean frame relative to the vehicle, not a reference
#        ellipsoid.
# header.frame_id 是卫星接收器报告的坐标系，通常是GPS天线的位置。
# 这是相对于车辆(中心)的欧几里得坐标变换，而不是参考椭球坐标系。

Header header

# satellite fix status information    卫星定位状态信息
NavSatStatus status

# Latitude [degrees]. Positive is north of equator; negative is south.
# 纬度[度]。 正数位于赤道以北； 负面是南方。
float64 latitude

# Longitude [degrees]. Positive is east of prime meridian; negative is west.
# 经度[度]。 正数位于本初子午线以东； 负面是西方。
float64 longitude

# Altitude [m]. Positive is above the WGS 84 ellipsoid
# (quiet NaN if no altitude is available).
# 海拔[m]。 正值高于WGS 84椭球（如果没有可用的海拔高度，则为NaN）。
float64 altitude

# Position covariance [m^2] defined relative to a tangential plane
# through the reported position. The components are East, North, and
# Up (ENU), in row-major order.
# 位置协方差[m ^ 2]: 相对于切线平面的位置协方差。 组件是East，North和Up（ENU），按行优先顺序排列。
#
# Beware: this coordinate system exhibits singularities at the poles.
# 注意：此坐标系在极点处表现出奇异性。

float64[9] position_covariance

# If the covariance of the fix is known, fill it in completely. If the
# GPS receiver provides the variance of each measurement, put them
# along the diagonal. If only Dilution of Precision is available,
# estimate an approximate covariance from that.
# 3 - 如果已知修正的协方差，请完全填写。
# 2 - 如果GPS接收器提供了每次测量的方差，请将其沿对角线放置。
# 1 - 如果只有“精度稀释”可用，请据此估计近似协方差。

uint8 COVARIANCE_TYPE_UNKNOWN = 0
uint8 COVARIANCE_TYPE_APPROXIMATED = 1
uint8 COVARIANCE_TYPE_DIAGONAL_KNOWN = 2
uint8 COVARIANCE_TYPE_KNOWN = 3

uint8 position_covariance_type

Compact Message Definition

uint8 COVARIANCE_TYPE_UNKNOWN=0
uint8 COVARIANCE_TYPE_APPROXIMATED=1
uint8 COVARIANCE_TYPE_DIAGONAL_KNOWN=2
uint8 COVARIANCE_TYPE_KNOWN=3
std_msgs/Header header
sensor_msgs/NavSatStatus status
float64 latitude
float64 longitude
float64 altitude
float64[9] position_covariance
uint8 position_covariance_type