| EM datagrams on *.kmall format Reg.no. 410224 Revision H

Extra detections

### Introduction

When the feature Extra Detections are active, the system will search for extra candidates in all beams and for all ranges. Any false detections (like side lobe echoes etc.) will be removed and the remaining candidates are organized into classes. These classes, which in essence are depth ranges with some acceptance criteria, are user definable with an initial default setup. All candidates which are accepted into a class are subsequently stored.

### Detailed description

There are seven classes (CL1–CL7) of detections. The sea floor is always defined as 100 %. The classes are enabled by default, but can be individually enabled and disabled. Disabled classes are stored, but will not be displayed.

#### Parameters to be entered in K-Controller:

- Start and stop depth (%): The estimated depth of the class. Note that the Stop value for a class is always the Start value of the next class. I.e. only the start depth for the first class can be changed by the user
- Quality factor (%) : Estimated depth error
- Reflectivity (dB) : Backscatter
- Confidence level (dB) : Signal to Noise Ratio
- Alarm treshhold : Number of extra candidates to trigger the alarm flag for the specific class.

A typical classification layer is presented in the table and picture below. These limits may be adjusted by the operator in K-Controller.

Number | Description | Percentage
--- | --- | ---
1 | Water column, upper part | CL1 < 30 %
2 | Water column, central part | 30 % ≤ CL2 < 60 %
3 | Water column, lower part | 60 % ≤ CL3 < 95 %
4 | Close to bottom | 95 % ≤ CL4 < 100 %
5 | Bottom | CL5 = 100 %
6 | Close below bottom | 100 % < CL6 < 105%
7 | Sub bottom | 105 % ≤ CL7

### How and where to extract the data

The extra detection data is included in the raw range and depth datagram #MRZ, EMdgmMRZ_def. In .all, the same data was included in the 'l'. datagram. See Datagram format philosophy and How to decode the datagrams for how to extract the extra detections data.