An Analysis of Ship Radar Technology

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Experiment No.07

A.1 Aim:

Summarize the selected papers with reference to the following points:

  1. Abstract
  2. Brief description
  3. Advantages/Disadvantages
  4. Inferences.
  5. Questions answered.
  6. List of questions to be answered.
  7. Conclusion
  8. References

A.2 Prerequisite:

1. Study materials on your topic.

2. Hard copy of all the research papers.

A.3 Outcome:

After successful completion of this experiment students will be able to

  1. Understand the fundamentals of their topic.
  2. Develop an understanding of how to read a research paper.
  3. Student should be able to prepare summary report as per the points suggested.
  4. Students should be able to answer question partially based on the understanding for their respective topics.
  5. List out the performance evaluation metrics in their respective topics.

A.4 Theory:

  1. Abstract- In this section a summary of all the sub-points of the research paper should be written. The abstract should be of 500 words.
  2. Brief Description- In this section the author’s works is to be explained in brief with the help of diagrams/figures, tables, graphs etc in your own words (No copy paste). This section should include each and every concept explained in the paper.
  3. Advantages/Disadvantages- Students should list out the advantages and the disadvantages of the concept explained by the author in the paper.
  4. Inferences- In this section the students should be able to explain the experimental setup done by the author in this paper. Students have to comments on robustness and effectiveness of the paper well.
  5. Questions answered- List the questions that are answered in the experiment no.2.
  6. List of questions to be answered- List out the questions that are not answered in the experiment no.2. List the extra questions to be answered if any.
  7. Conclusion- Explain the conclusion drawn by the author in your own words.
  8. Reference- List all the references in the format given below;

Author name,”Title”, publication name, volume, month & year.


  1. Wendi B. Heinzelman, Anantha P. Chandrakasan, and Hari Balakrishnan, "An Application-Specific Protocol Architecture for Wireless Microsensor Networks",in IEEE Transactions on Wireless Communications, Vol. 1, No. 4, OCT. 2002.

A.5 Procedure:

A.5.1 TASK 1:

  1. Summarize all the research papers based on the points stated in aim statement.
  2. Compare the algorithms/protocols etc.
  3. Draw a conclusion and try to match the abstract with conclusion.
  4. Create notes for different sections of the paper.
  5. List out the key points in the paper.
  6. Save and close the file and name it as PRA7_your Roll no.docx



B.1 Document created by the student:


Automatic radar plotting aid (ARPA) is a radar system used in ships and other overseas transportation services.

It is a system that is developed on various raster scanning processes. It carries out the function of acquiring various targets at the same time. These targets are basically obstacles such as glaciers, coral reefs or any other obstacle that’s encountered on the sea/ocean bed. Some of the targets also include opposing obstacles such as missiles. It is also used for automatic ground stabilization which is used for navigational purposes.

PAD means predicted area of danger. It is a graphical display which is used to display collision assessment information directly on the PPI. It also has the ability to perform trial maneuvers, including course changes, speed changes, and combined course changes.


The ARPA has a raster scan PPI. It has a display with an effective display diameter of 180mm, 250mm, or 340mm depending upon the gross tonnage (capacity) of the vessel. The raster-scan display makes it easier for design engineers in the way auxiliary data can be written.


The ARPA display should include all the data required to be provided by a radar (raster) display in accordance with the performance standards for navigational radar equipment. Raster scanning enables such tasks to be handled efficiently. This is done by describing various collision points and the time of attack.

This is achieved by taking the following factors under consideration:

  1. Navigational lines and maps: Isolated rocks are indicated with symbols. These allow the observer to prepare and store the pattern at a convenient time when passage planning and subsequently to recall it when required.
  2. Potential point of collision: This enables the observe the courses that are unacceptable, because they intersect a collision point.


Stabilization signal can be derived from any transmitting compass. It allows true bearings to be read off directly and quickly from the fixed bearing scale without the need to check the direction of the ships head at the same instant.

Following are the types of stabilized modes of ARPA:

  1. Sea stabilized: True-track anti-collision mode is activated in this stage. Here, data related to own vessel’s motion is fed from the speed log to gather information regarding the obstacles encountered in the sea bed.
  2. Ground stabilized: An isolated land target with good response is selected as reference.It is acquired and tracked by one of the ARPA tracking channels and then designated as a fixed target.This makes it possible for the tracker to calculate the ground track of own vessel and hence to maintain the movement of the electronic origin of the display in correlation to it.

Use of raster scans marine radar display:

Mariners are subjected to recent research which has highlighted the possibility of misleading occurring with RSD that suffer from a loss of certain input signals. This problem basically occurs in loss of video input and loss of azimuth signal. Loss of video input resulted in freezing pf pictures. This effect is not detected unless the range is not changed. This is because of the screen image generated a video processor. If the signal is lost, the display doesn’t redraw or refresh.

The loss of azimuth signal led to rotation of targets or targets being depicted on wrong bearings.

Mariners should investigate the type of RSD fitted to determine the response of the system to loss of input. RSDs are specially used to avoid such problems.

Track Change:

Whenever a potential danger has been encountered the alarm will warn the user to check the targets that are untracked. So the targets which are of lower priority, example: minor obstacles like rocks or coral reefs, would be ignored and the tracking pointer will be shifted to the targets having higher priority; example: opposing targets like missiles.


Until the unwanted data is removed, an alarm indicator would be activated whenever false information or data is fed.


Extrapolation of the present situation using the trial maneuver facility with current course and speed as inputs can provide valuable information on which of the other vessels in the vicinity may have to maneuver in order to avoid collisions between each other.

Various constraints are to be taken in to account while planning out the strategy, so that the effectiveness is properly assessed.


Suppose a target, which is being tracked but, due to some reason does not respond on one scan. The tracker will find a response and continue to track. If it fails to find a response, the tracker will continue to search for the echo in an area where the actual target is supposed to be acquired for up to five successive scans.

If the target is still not detected, an audible alarm is activated letting the observer know the position of the target by the echo.


  1. If the observing ship maintains speed while the target begins toincrease speed, the collision point will begin to move along the target track.
  2. When the target speed has increased to that of the observing ship, the secondary collision point will appear at infinity.
  3. RSDs when stabilized, acquire clear and appropriate display of the target.
  4. Collision avoidance and other important navigator applications can be achieved.
  5. It is relatively easy tovisualize the outcome of a maneuver where two ships are involved.
  6. This will help in avoiding collision of the two ships
  7. This radar facility makes steering of the vessel easy for the observer by providing directions and keeping him alert on collision situations.


  1. The data which is given to the ARPA as input data will make sure that the ARPA will provide the data as accurate as that of the input due to which the resulting display would be much more complex than the radial scan display. A lot of memory is required in this process.
  2. So input failures may lead to collision of acquire targets.
  3. Uneven tracks of targets or apparent instability of motion may be taken to indicate that tracking of that target is less precise than it might be and the displayed data should be treated with caution.
  4. If the target speed is increased drastically, then the primary and secondary collision points will start moving towards each other, arriving at the possibility that the two collision points would disappear at some point, causing the target to escape eventually.
  5. Due to loss of signal, the radar display may not display accurate readings of the acquired target.
  6. Outcome of a maneuver of two ships is difficult to be observed in dense traffic, leading to collision of the two ships.

B.3 Observations and learning:

When a request is sent, the ARPA has the capacity to display the past positions of any acquired target over a period of 7-10 minutes. This enables an observer to check whether a particular target has maneuvered in the recent past, possibly while the observer was temporarily away from the display on other bridge duties. This knowledge is useful in showing the observer what has happened. It will also help him to predict what the target is capable to do in the future.

B.4 Conclusion:

With large ships and limitedsea room, it is necessary to plan and update the whole collision avoidance strategy as quickly as possible in light of the continually changing radar scene. Hence, time maneuver techniques for any radar system must be strictly investigated before it’s deployment. Stabilization is very necessary for maintaining the radar stability, so that the radar functions accurately when it’s put to use. It can be used to avoid collisions and to boost other navigational applications.