Digital revise

Question 1

What are the advantages and disadvantages of the CMOS?

Answer 1

Advantages: simpler manufacture, smaller, uses less power
Disadvantages: high noise

Question 2

What are the advantages and disadvantages of CCD?

Answer 2

Advantages: low noise, high S/N
Disadvantages: high power

Question 3

Three stages of the image coder and what their function is

Answer 3

1. Image transformation - converts input image into a format better suited for encoding by transforming pixels into coefficients
2. Quantiser - compression by approximating transformation coefficients
3. Symbol encoding - compresses image by exploiting the fact that some grey levels occur more frequently than others

Question 4

Four steps in the forensic process and what they mean

Answer 4

1. Acquisition - correct consents, legal documents, and procedures in place
2. Identification - physical identification of digital equipment, bagged and tagged
3. Evaluation - how was the data produced? Who? When?
4. Presentation - interpretation of recovered data

Question 5

What is principle 1 and what does it entail?

Answer 5

Data preservation - no action should change data held on a computer

Question 6

What is principle 2 and what does it entail?

Answer 6

Competence - when necessary to access original data, person must be competent to do so and able to explain the relevance and implications of their actions

Question 7

What is principle 3 and what does it entail?

Answer 7

Audit trial - record of all the processes applied should be created and preserved. Third party should be able to examine and achieve the same result

Question 8

What is principle 4 and what does it entail?

Answer 8

Responsibility - case officer has overall responsibility for ensuring the law and these principles are adhered to