# CSV export

Since the Surveyor is a multi-beam echo sounder, each time we emit a sonar pulse, we receive multiple signals and combine them to get multiple beams. Each ping consists of multiple “detections” and each detection is a row in the CSV.

Some data is per-detection, and some is per-ping.

The following columns are presented in CSV export:

| column                 | notes                                                                                                                       |
| ---------------------- | --------------------------------------------------------------------------------------------------------------------------- |
| latitude               | detection's geodetic latitude in decimal degrees north of equator (or negative south)                                       |
| longitude              | detection's geodetic longitude in decimal degrees east of prime meridian (or negative west)                                 |
| altitude (m)           | height of detected point above sensor. Will be negative.                                                                    |
| northing (local m)     | detection's Cartesian position in meters north. Relative to an arbitrary origin.                                            |
| easting (local m)      | detection's Cartesian position in meters east. Relative to an arbitrary origin.                                             |
| ping number            | sequence number of the ping which produced this data. Each ping has multiple detections, and thus multiple rows in the CSV. |
| elapsed (s)            | time the ping was sent, in seconds since the session started                                                                |
| datetime               | time the ping was sent, in UTC                                                                                              |
| altitude (m above MSL) | Altitude of the point relative to Mean Sea Level                                                                            |
| northing (UTM m)       | detection's georeferenced Cartesian position                                                                                |
| easting (UTM m)        | detection's georeferenced Cartesion position                                                                                |
| coordinate projection  | Which UTM zone the georeferenced coordinates are in                                                                         |

Positions are represented as Local Cartesian Coordinates (x,y,z). x=north, y=east, z=down.