Introduction

The Target Intercept facility described in this chapter, is an addition to the Target Functions and ARPA/ATA Functions described in Chapters 7 and 8 of the BridgeMaster E User Guide 65800010A.

The Target Intercept facility allows the operator to plan and execute intercept manoeuvres between one vessel and another. Interceptions can be from own ship to any tracked target, from a tracked target to own ship, or from one tracked target to another. The course to achieve the intercept is calculated and displayed on the screen. Intercept vectors are displayed in the video circle to indicate where the intercept will take place.

Target Intercept is available in all modes where tracking facilities are available. Access to the facility is via the INTCEPT soft key which replaces the TRIAL key, see Trial Manoeuvres below.

Trial Manoeuvres

In the standard commercial radar, the Trial Manoeuvre facility is accessed via a dedicated soft key (TRIAL) located in the bottom right corner of the display.

In the Special Naval Features radar, the TRIAL soft key becomes the target intercept (INTCEPT) key, and Trial Manoeuvre becomes an option within the ARPA menu.

Access to the TRIAL MANOEUVRE Facility.

1.	Position the screen cursor over the ARPA soft key located in the bottom right corner of the display.

2.	Left click to reveal the ARPA menu.

3.	Within the ARPA menu, position the screen cursor over the TRIAL MANOEUVRE line.

2.	Left click to access.

From this point the Trial Manoeuvre facility is the same as described in Chapter 7 of the BridgeMaster E User Guide 65800010A.

Target Intercept

1.	Position the screen cursor over the INTCEPT soft key located in the bottom right corner of the display.

2.	Left click to reveal the TARGET INTERCEPT menu. See example left.

Notes - A right click on the INTCEPT key will temporarily suppress the display of intercept vectors. The vectors are re-displayed by a second right click on the INTCEPT key, or on entering the Intercept menu.

A left click on the EXIT TGT INTERCEPT key will close the menu.

Selecting the Intercept Mode

1.	Position the screen cursor over the MODE line in the TARGET INTERCEPT menu.

2.	Left click to cycle through the options available (PLANNING, RUNNING). The option displayed is the option selected.

Alternatively, a right click will reveal a list of the options available. Left click on the option required. See example left.

Note - OFF can only be selected from the drop down list.

The usual course of action is to select PLANNING first, set up the parameters of the intercept required and then, when satisfied with the plan, select RUNNING.

Selecting the Interceptor

The FROM line in the INTERCEPT menu relates to the Interceptor and will show OWN SHIP, TARGET nn or a series of dashes. If the radar is a static site, the OWN SHIP text is replaced by RADAR HEAD.

1.	Position the screen cursor over the FROM line in the INTERCEPT menu.

2.	Left click to access.

The cursor is forced into the video circle and the operator is prompted to select the interceptor. This can be own ship or any tracked target.

3.	Within the video circle, position the cursor over the required target origin or video circle origin (for Own Ship).

4.	Left click to select.

The menu will reflect the selection made.

Selecting the Interceptee

The TO line in the INTERCEPT menu relates to the Interceptee and will show OWN SHIP, TARGET nn or a series of dashes.

1.	Position the screen cursor over the TO line in the INTERCEPT menu.

2.	Left click to access.

The cursor is forced into the video circle and the operator is prompted to select the interceptee. This can be own ship or any tracked target.

3.	Within the video circle, position the cursor over the required target origin or video circle origin (for Own Ship).

4.	Left click to select.

The menu will reflect the selection made.

Intercept Graphics

When the interceptor and interceptee have been selected, the intercept vectors are calculated and displayed in the video circle, see example below.

Within the INTERCEPT menu the following parameters are calculated automatically and are NOT selectable. The information is updated dynamically to follow changes in the velocity of the interceptee.

For the Interceptor

COG FOR INT	Course Over Ground for intercept. This will be
CSE when the speed mode is water locked.

TTG	The Time To Go to intercept.

DTG	Distance To Go to intercept.

For the Interceptee

SOG	Speed Over Ground. This will be STW when the
speed mode is water locked.

T BRG	True Bearing from the interceptor.

If the time to intercept (TTG) is greater than 199 minutes, or the range to intercept (DTG) is greater than 80 n.m, it is assumed that the intercept is not possible and the course and range data is dashed out in the menu. The intercept vectors are also suppressed until conditions fall within the above limits.

Planning the Intercept

Once the interceptor and interceptee have been successfully selected, the operator can plan the intercept by varying the speed of the interceptor (the only adjustable parameter available to the operator). This allows the operator to plan the intercept point and/or the time of the intercept. This could be of assistance in meeting the tide when returning to a port or harbour.

1.	Position the screen cursor over the SOG (or STW) FOR INT line in the INTERCEPT menu.

2.	Left click to access.

3.	Move the screen cursor left or right to change the speed (between 1 and 150 KT), and observe the intercept graphics.

4.	Left click to accept the new speed.

Alternatively, a right click on the SOG (or STW) FOR INT line will reveal a dropdown numeric keypad from where the speed can be entered, see Chapter 15 in User Guide.

When the intercept plan is as required, reselect the MODE line in the INTERCEPT menu and set for RUNNING.

Defaults and other Operating Conditions

By default, intercepts are from OWN SHIP to a target. It is not possible to select a target which is not established.

The initial default for interceptor speed is 25 KT, but subsequently the last entered planning speed is used.

A suitable prompt is raised if it is not possible to switch from OFF to either PLANNING or RUNNING modes due to the system being in unstabilised presentation, range scale or compass error state, or being in STANDBY.

If any target involved in the intercept is cancelled, either automatically or manually, the intercept is switched OFF and a prompt raised.