Discuss on multiple watermarking.

Multiple watermarking refers to the process of embedding more than one watermark into a digital signal. This can be done for a variety of reasons, such as to increase the robustness of the watermark, to provide multiple layers of security, or to embed different types of information.

Here are the steps to discuss multiple watermarking:

1. Definition: Start by defining what multiple watermarking is. It is a technique used in digital signal processing where more than one watermark is embedded into a signal.

2. Purpose: Discuss the reasons why multiple watermarking is used. This could include increasing the robustness of the watermark, providing multiple layers of security, or embedding different types of information.

3. Process: Explain how multiple watermarking is done. This could involve explaining the different methods of watermarking, such as spatial domain methods and frequency domain methods, and how they can be used together to embed multiple watermarks.

4. Advantages: Discuss the advantages of multiple watermarking. This could include increased security, the ability to embed more information, and increased robustness against attacks.

5. Disadvantages: Discuss the potential disadvantages of multiple watermarking. This could include increased complexity, the potential for interference between watermarks, and the need for more processing power and storage space.

6. Applications: Finally, discuss some of the applications of multiple watermarking. This could include use in digital rights management, broadcast monitoring, and media asset management.

Remember to provide examples and evidence to support your points where possible.