# Computer Officer/Bank IT Officer Exam Preparation Materials

- Data must be transformed into electromagnetic signals prior to transmission across a network.
- Data and signals can be either analog or digital.
- A signal is periodic if it consists of a continuously repeating pattern.
- Each sine wave can be characterized by its amplitude, frequency, and phase.
- Frequency and period are inverses of each other.
- A time-domain graph plots amplitude as a function of time.
- A frequency-domain graph plots each sine wave’s peak amplitude against its frequency.
- By using Fourier analysis, any composite signal can be represented as a combination of simple sine waves.
- The spectrum of a signal consists of the sine waves that make up the signal.
- The bandwidth of a signal is the range of frequencies the signal occupies. Bandwidth is determined by finding the difference between the highest and lowest frequency components.
- Bit rate (number of bits per second) and bit interval (duration of 1 bit) are terms used to describe digital signals.
- A digital signal is a composite signal with an infinite bandwidth.
- Bit rate and bandwidth are proportional to each other.
- The Nyquist formula determines the theoretical data rate for a noiseless channel.
- The Shannon capacity determines the theoretical maximum data rate for a noisy channel.
- Attenuation, distortion, and noise can impair a signal.
- Attenuation is the loss of a signal’s energy due to the resistance of the medium.
- The decibel measures the relative strength of two signals or a signal at two different points.
- Distortion is the alteration of a signal due to the differing propagation speeds of each of the frequencies that make up a signal.
- Noise is the external energy that corrupts a signal.
- We can evaluate transmission media by throughput, propagation speed, and propagation time.
- The wavelength of a frequency is defined as the propagation speed divided by the frequency.