DDCS

Connection, setup, and operational features of a radio station with DDCS functionality

DDCS — DSC Digital Communication System DSC — Digital Selective Calling

DDCS is a system for receiving navigation data from vessels equipped with radio stations with DSC functionality. Unlike AIS, DDCS uses the DSC protocol to transmit target position, course, and speed data. DDCS targets are displayed on the chart similarly to AIS targets, in accordance with IEC 62288 requirements, and are processed using the same filtration and activation settings.

DDCS Setup

Menu path
→ → Sensors → Add sensor → DSC Radio

Sensor Connection

The sensor connection and setup are performed in accordance with the procedure.

Message Processing Setup

When configuring the sensor, ensure that received message processing is correctly configured:

• Header and message type processing is enabled

• Checksum verification is enabled

DDCS Message Identification

DDCS message headers must contain:

• CD — digital selective calling (DSC)

This allows the system to identify incoming messages as DDCS data.

After configuring and enabling the DDCS sensor, the DSC Target window will become available in the Multifunction window.

Caution

Some radio station models have a built-in GNSS receiver.

The manufacturer does not recommend using the radio station’s built-in receiver as a positioning sensor due to its unpredictable behavior and low position accuracy.

DDCS Operational Features

Getting Started with DDCS

Enable DDCS target display:

Menu path
→ DSC Layer

DDCS Operating Principle

DDCS receives signals from radio stations with digital selective calling (DSC) functionality, as well as standard navigation data with a structure similar to AIS data.

Data reception features:

• Data reception is possible only when the transmitting station is properly configured

• Data transmission interval is determined by the settings of the encountered vessel’s radio station; by default, navigation data is transmitted only when a distress signal is sent or when the PTT button is pressed on the radio station

• The absence of data reception from an encountered vessel via the DSC channel does not indicate a malfunction of your equipment or ECDIS

Tip

If DDCS targets are not displayed on the ENC, verify:

• The DDCS sensor is configured and active

• The DSC layer is enabled in the operational settings

• The encountered vessel is transmitting data via the DSC channel with correct settings

Note

DDCS Target Display Settings

The system uses the same filtration and activation settings as for AIS targets. Visibility radius, auto-activation, class filtration, and approach criteria parameters configured in the AIS → Filtration and Activation section are also applied to DDCS targets.

DDCS targets are displayed on the chart upon data reception.

DDCS target vectors are displayed on the chart based on the data from their last received message, in accordance with ECDIS settings.

Target Activation and Deactivation

DDCS target activation and deactivation are performed in automatic and manual modes.

Automatic mode:

• A DDCS target is automatically activated upon receiving the first message from the target, if the target is within the guard zone or when the target transmits a distress signal

• The target is automatically deactivated (placed in “sleeping” status or removed) when messages from the target cease within the timeout period

Manual mode:

To forcibly activate/deactivate targets: hover the cursor over the target, right-click (press and hold) to open the context menu, select Activate or Deactivate. The target will be activated.

Target Information

View detailed information about a DDCS target:

1. Select the target on the chart (left-click on the target symbol)

2. The target will be highlighted with a frame on the chart

3. The DSC Target tab will open in the Multifunction window with information about the selected target

The following data is displayed in the DSC Target window:

• Target position (coordinates)

• Course (if transmitted)

• Speed (if transmitted)

• Target identifier

• Last data update time

Important

Motion Parameter Display Limitations

DDCS target motion parameters (speed vector and course) are transmitted in the NMEA sentence $PNAVRIS. If the connected radio station does not support transmission of this sentence, DDCS target symbols will be displayed without vectors.

NSR ECDIS NES-3000 does not accumulate target data for calculating target motion parameters (TMP) based on historical data. Motion vectors are displayed only when transmitted in real time.

Warning

DDCS Message Requirements

DDCS target coordinates are transmitted in the NMEA message $--DSC. However, the same field may contain the data transmission channel and frequency instead of coordinates. The type of transmitted data depends on the radio station manufacturer’s settings.

If coordinates are not transmitted in the correct format, DDCS target display will not be possible.

For correct display and processing of DDCS targets, a complete set of NMEA sentences from the onboard radio station with DSC functionality is required:

• $--DSC — target coordinates

• $--DSE — extended target data

• $PNAVRIS — target motion parameters

Lost Targets

When Lost Target is enabled in the AIS settings, targets from which no data is received within the set timeout will be marked as lost.

System behavior on target loss:

• The lost target is removed from the chart

• A lost target warning is displayed in the notification area

• Warnings are generated only for active targets

Note

The lost target timeout is configured in the AIS → Filtration and Activation → Lost Target section. This parameter applies to both AIS targets and DDCS targets.

Targets Table

The targets table provides a summary view of all tracked targets: AIS, DDCS, and radar. The table allows viewing targets that may not be displayed on the chart due to filtration settings or visibility radius.

Methods to open the targets table:

Menu path
→

Or the button on the AIS, ARPA, or DSC Target tabs in the Multifunction window.

No.	Element	Description
1	Targets list	Table of all tracked DDCS targets
2	Update	Forced data refresh in the table
3	Automatic update	By default, data in the table is updated each time it is opened or forcibly using the button. For automatic updating, select the update interval from the drop-down list: 1s, 3s, 5s, 15s, 30s
4	Table updated *** ago — time indicator	Time elapsed since the last target data update
5	Source	Indicates the source from which target data was received
6	Full target data	Opens the table with the target form
7	Go to target position	Centers the chart on the target position. If the DSC layer is disabled, centering will be performed on the target position, but the target will not be visible
8	Sorting	In the corresponding column by ascending or descending values. By default, the table is sorted by Distance
9	Selected only	Only selected (tracked) targets will be displayed in the table
10	Send Message	DCS does not support the message sending function
11	Unread message	Press to view the unread message
12	Messages from DSC	Indicator of messages from the DDCS target; an icon is displayed when unread messages are present

DDCS Warnings

TEXT	CATEGORY	CONDITION
DDCS sensor malfunction: <sensor name>	Alarm	When data from the sensor stops being received according to the configurable timeout
<sensor name> SOS	Alarm	When an alarm signal is received from the target

Alert Handling

DDCS Alarm Types

DDCS transmits various alarms generated by other radio stations:

Automatic actions on alarm:

1. The target symbol is highlighted in red on the chart

2. In the overview window, the chart is automatically centered on the position of the target that transmitted the alarm signal

3. An alarm indicating the type and source is displayed in the notification area

An alarm is displayed in the notification area:

To view target information, select the target. The alarm type will be displayed in the DSC Target window (the alarm type is determined by the transmitting radio station).

Clearing Alarm Status

After handling the alarm or confirming that the danger has passed, the alarm status can be cleared from the DDCS target:

1. Select the target with an active alarm on the chart (left-click)

2. In the context menu or the DSC Target window, select End the Alarm

3. The alarm for the target will be cleared

4. The target symbol will change color from red to green, indicating the target’s normal status

Important

Clearing the alarm does not mean that the target has stopped transmitting the alarm signal. If the transmitting station continues to transmit the alarm, the alarm status will be set again upon the next message reception.