Problems to answer(IT 122-Comp Org)

Problems
1. Define the term "sample" as it applies to digital systems.
>The overwhelming majority of todays computers do not use analog levels of electricity or the positions of mechanical devices. Instead, they represent an analog value by converting it to a number with a fixed resolution. This measurement referred to as digital value. So, when the computer records an analog signal such as the sound waves from music, it does it by taking a sequence of snapshots. Because the computer can only measure the signal at intervals. Each measurement is called sample.

2. Define the term "sampling rate" as it applies to digital systems.
>And the rate at which these samples are taken is called sampling rate.

3. What are the two primary problems that sampling could cause?
> There are two primary problems arise from the sampling process:
(1) Information can be lost between the measurements. If the sampling rate is too slow, then some details of the signal may be missed.
(2) Information can be lost due to the rounding of the measurements. If the computer does not record with enough accuracy, an error may be introduced between the actual measurement and the recorded value.

4. Name the tree parts of the system over an analog signal into a digital system and describe their purpose.
>sensor, signal conditioning, analog to digital converter
The interface between the external condition and the electronics of the system is the sensor. This device converts the environmental conditions into a signal readable by analog electronics. Often, this signal is weak and is easily distorted by noise. Therefore, the output of the sensor is usually amplified and cleaned up before being converted to digital values by Analog-to-Digital Converter (ADC). Continuous operation of this system results in a sequence of digital measurements or samples that are stored in the computer where it can be viewed much like the table of numbers in spreadsheet.

5. Name four benefits of a digital system over an analog system.
> (1) if an analog signal is transmitted over long distances, noise attaches itself to the signal. To keep the signal strong enough to reach its destination, it must be amplified. All of the noise that attached itself to the signal is amplified along with the original signal resulting in distortion. Noise cannot attach itself to a digital signal. Once an analog signal has been converted to a sequence of numbers, the signal’s characteristics remain the same as long as the numbers don’t change. Therefore, digital systems such as the contemporary long-distance phone system do not suffer from degradation over long distances.
(2) Once a signal turned into a sequence of numbers, mathematical algorithms can be used to operate on the data. Disciplines such as Digital Signal Processing (DSP) and the study of wavelets allow for much more accurate processing of signals than analog systems were able to achieve.
(3) A sequence of digital numbers can also be stored more compactly than an analog signal.
(4) Supplementary data can be stored along with the samples for information such as digital watermarking for security codes for error checking or error correction.

6. Name three drawbacks of a digital system over an analog system.
> (1) if the samples are taken too slowly, details of the analog input are missed.
(2) If the resolution of the sample is not fine enough, the signal may not be precisely represented with the digital values.
(3) Additional hardware is required to convert the signal from analog to digital.

7. True or False: Since non-periodic pulse trains do not have a predictable format, there are no defining measurements of the signal.
> False, there are defining measurements of the signal. Though they do not look meaningful, but once the reader is given the tools to interpret the signal, the data they contain becomes clear.

8. If a computer runs at 12.8GHz, what is the period of its clock signal?
> period = _______1_______ 12.8000000000
=


9. If the period of a periodic pulse train is 125 nanoseconds, what is the signal’s frequency?


10. If the period of a periodic pulse train is 50 microseconds, what should the pulse width, Tw be to achieve a duty cycle of 15%?

11. True or False: A signal’s frequency can be calculated from its duty cycle alone.
> False.