1. Signal Classification
1.1. Based on signal form
1.1.1. Analog
1.1.1.1. An Electromagnetic wave that is continuously varying and can be propagated through various medium.
1.1.1.2. Analog signal can transmit an analog or a digital data
1.1.2. Digital
1.1.2.1. A pulse stream that can be transmitted through a certain medium.
1.1.2.2. Digital signal can transmit an analog or a digital data.
1.2. Based on signal period
1.2.1. Periodic
1.2.1.1. Analog or digital signal that has the same repetition of the pattern over a certain period.
1.2.2. Aperiodic
1.2.2.1. Analog or digital signal that has different pattern over certain period.
1.3. Based on signal composition
1.3.1. Simple signal
1.3.2. Composite signal
2. Time Domain Concept
2.1. Peak Amplitude (A)
2.1.1. maximum strength of signal
2.1.2. Usually indicated by Volt
2.2. Frequency (f)
2.2.1. Rate of change of signal
2.2.2. Indicated by cycles per second or Hertz
2.3. Period (T)
2.3.1. The required time of one signal cycle
2.3.2. T=1/f
2.4. Phase (Ø)
2.4.1. The relative position of the signal in time
2.5. Wave length (Lambda)
2.5.1. Distance/length of the one signal cycle
2.5.2. Lambda = vT
3. Frequency Domain Concept
3.1. Frequency Spectrum
3.1.1. The range of frequency contained in a signal
3.2. Absolute bandwidth
3.2.1. The width of the signal spectrum
3.3. Effective bandwidth
3.3.1. The narrow frequency band in which the signal energy is concentrated
4. Data Rate vs. Bandwidth
4.1. Data rate
4.1.1. Stated with bits per second (bps)
4.1.2. It means the amount of data that can be transmitted
4.2. Bandwidth
4.2.1. Stated with wave per second or Hertz
4.2.2. Limited by the transmitter and medium
5. Data Transmission through Digital Channel
5.1. Pulse Amplitude Modulation (PAM)
5.1.1. Analog signal as an input
5.1.2. Sampling
5.1.3. Generate a pulse signal based on the amplitude of the sampling
5.1.3.1. Sampling: take a sample of the signal amplitude in a constant interval
5.1.3.2. • Pulse amplitude represent the analog data
5.2. Pulse Code Modulation (PCM)
5.2.1. Pulse Quantization
5.2.1.1. Quantization: a method to determine a standard value within a certain sampling range
5.2.2. Code assignment to a quantized sample
5.2.2.1. Binary Digit
5.2.2.2. Transform a binary digit to digital signal by using signal encoding technique
6. Type of Information
6.1. Data
6.2. Voice
6.3. Video
7. Data and Signal Combination
7.1. Digital data, digital signal
7.2. Analog data, digital signal
7.3. Digital data, analog signal
7.4. Digital data, analog signal
8. Signal Transmission
8.1. Analog Transmission
8.1.1. In the output, the signal should be reproduced precisely as the input signal.
8.1.2. In the long distance transmission, the repeater is used to maintain that the output signal still as same as possible with the input signal
8.1.3. If we use so many repeaters, the noise will be accumulated and becomes higher
8.2. Digital Transmission
8.2.1. The output signal is not necessary to have the same pattern as the input, as long as the “0” or “1” signal can still be distinguished.
8.2.2. In long-distance transmission, a digital repeater (regenerator) is used to regenerate the pulses without any noise amplification
8.2.3. Therefore, there is almost no limitation in the installation of the regenerator
9. Data Transmission
9.1. Serial Transmission
9.1.1. A bit stream is transmitted one-by-one
9.1.2. Data transmission is slower than the parallel transmission
9.1.3. Efficient for long-distance transmission
9.2. Parallel Transmission
9.2.1. Some amount of bits (e.g. 8 bits) is transmitted simultaneously
9.2.2. Data transmission is faster than the serial transmission
9.2.3. Only efficient for the short-range transmission