OS3D_POINT_SET

ID: 3104

Payload Definition

Data Type	Name	Description
u32	ping_number	assigned sequentially from power on
float	sos_mps	speed of sound (meters per second) used in angle calculations
u16	num_points	number of points reported in the points field
u16	points_type	0 = unclassified, 1 = bottom points, 2 = water column points (we are not currently doing point classification in the device, so will be 0 for now)
float	pwr_threshold	min pwr value used in point detection
u64	utc_msec	time at start of ping, UTC milliseconds (1970 epoch). Will be 0 if not available.
u32	pwr up msec	time at start of ping from power on
u8	version	0
u8	device number	must be < number of devices (so it will be 0 for a single device)
bool	pts_have_pwr	normally will be true (only for compatibility with old data files)
u8	reserved	0
u32	reserved[12]	reserved for future (12 words)
atof_t	point_data[num_points]	see below for atof_t definition

struct atof_point_t
{
	float angle; // radians;
	float tof;	 // time of flight in seconds
	float pwr;	 // power level of the beam at this point
} PACKED_STRUCT;

Interpreting Angle

Zero angle is perpendicular to the face of the RX16 receive module. With the "dot" end of the RX16 facing the forward direction, and the transducer side down, positive angles are to the starboard side.

Note that the angles given in the data were computed with the speed of sound also given in the data. To adjust the angle in post processing for a different speed of sound, use the Snell's Law relation:

sos1 * sin(angle1) = sos2 * sin(angle2)