- Analog signal
Analog signals vary over time and have an infinite number of values over a continuous range. It transmits a specific property of the signal information through a medium, such as an electrical wire.
If you plot the voltage over time, you can find that the analog signal appears as a smooth and continuous curve without any discrete changes.
- Digital signal
Digital signals represent data as a series of discrete values.
When using digital signals, physical quantities can express information in a number of ways:
Variable current and voltage
The phase or polarization of an electromagnetic field
Sound pressure
Magnetization of magnetic storage media
Digital signals can be used in all digital electronic devices, including computing devices and data transmission devices. - Analog electronics
Most electronic components, such as resistors, capacitors, inductors, diodes, transistors, etc., are basically analog components.
Analog circuit design is much more complex than digital circuit design.
Analog circuits are generally more susceptible to noise, and even minimal noise can have an impact on the voltage, leading to significant errors and effects in subsequent processing.
Analog signals are usually used to transmit continuous signals in voice, data, image, signal, video and other communication systems. Depending on how the input signal is combined with the carrier signal, analog transmission is divided into two basic types: amplitude modulation (AM) and frequency modulation (FM).
Amplitude modulation transmits signals by adjusting the amplitude of the carrier signal. Frequency modulation transmits the signal by adjusting the frequency of the carrier signal.
- Digital electronics
Digital circuits usually use binary systems. All data is represented by two states (0 and 1), and larger values are represented by binary bits. For example, 1 means 1, 0 means 0, 00 means 0, 01 means 1, 10 means 2, and so on.
Digital circuits are synchronous, which means they need a reference clock to coordinate the operations of multiple circuit modules so that all of them operate in a predictable manner. In contrast, analog electronics are asynchronous, meaning that signals are processed only when they reach the input.
Digital circuits are simpler to design than analog circuits, but they cost more. - Signal conversion of analog-to-digital conversion (ADC) and digital-to-analog conversion (DAC)
Many systems need to process both analog and digital signals. In communication systems, analog signals are often used as a transmission medium for sending and receiving information. These analog signals are converted to digital signals for filtering, processing, and storage. - ADC operation principle
The analog-to-digital conversion (ADC) process is shown in the figure. The input analog signal is first processed by a sampling-and-hold (S/H) circuit to generate an approximate digital representation of the signal. The amplitude of the signal is no longer continuous, but quantized to discrete values based on the resolution of the ADC. High-resolution ADCs provide finer quantization steps to more accurately represent the input analog signal. The final stage of the ADC encodes the digital signal into a stream of binary bits, representing the amplitude of the analog signal. In this way, the digital output can be further processed in the digital realm.
- DAC operating principle
Digital-to-analog conversion (DAC) performs the reverse operation of analog-to-digital conversion. A DAC receives a binary data stream from a digital system, converting it into a near-real analog signal. In the analog signal chain, a post-filter is also commonly used to further smooth the output waveform.
- Advantages and disadvantages of digital signals
Advantages:
The digital signal transmission noise, distortion and interference are less, the information transmission is more clear.
The reproduction cost of digital circuit is low and it is easy to achieve mass production.
Digital signal processing is flexible and can be programmed to change the way it operates.
Digital information is more secure and easy to encrypt and compress.
The digital system is highly accurate, and error detection and correction can reduce the possibility of errors.
Digital signals can be easily stored on magnetic or optical media via semiconductor chips.
Digital signals are suitable for long-distance transmission.
Cons:
Digital communication requires higher bandwidth than analog communication.
Digital signal processors (DSPS) process signals at higher speeds, resulting in increased power consumption; The analog signal processor consumes less power because of the use of low energy passive devices.
Digital systems and processing are often more complex. - Advantages and disadvantages of analog signals
Advantages:
Analog signal processing is relatively simple.
Especially suitable for audio and video transmission.
Can provide higher information density and detail.
The required bandwidth is lower than for digital signals.
It accurately reflects changes in physical phenomena such as sound, light, temperature, position or pressure.
The electrical tolerance sensitivity is low, which makes the analog communication system more stable.
Cons:
It is prone to accidental interference when transmitting over long distances.
Analog signals are prone to signal loss.
Analog signals are more susceptible to noise and distortion than digital signals.
The signal quality is usually inferior to that of digital signals.
