Electronic information processing#
The structured design approach presented in this book puts the design of analog electronics in the perspective of information processing. To fully appreciate this approach, one must first understand some basic concepts from information processing.
Information processing systems#
Fig. 5 shows the architecture of a simple information processing system. The information processing system processes the information acquired by some source and passes the results to an observer. All takes place in an environment in which noise is present.
Fig. 5 Architecture of a data acquisition system.#
In the above description, we used some terms that need further explanation:
What is a signal?
What is data?
What is information?
What is noise?
Fig. 6 Architecture of a system that acquires information from a process, processes the information, and controls the process.#
Fig. 6 shows a more complex situation. The system depicted in this figure also controls the process. Hereto, it provides control signals to actuators that influence the progress of the process.
In the section Basic concepts, we will define important concepts from information processing.
In section Limitations of information processing we will show that the amount of information that can be processed by a physical system is limited, and introduce the fundamental physical, technological and economical limitations.
Basic concepts#
Signal
A signal is a physical quantity that contains meaningful data.\ In electronic systems, we use electrical signals: the time-varying values of electrical current or electrical voltage.
Data
Data comes from the Latin word datum, which means: something given. Here, data are properties or details of the signal that may contain information.
Information
Information is the meaning of the data. One could say: if the data provides an answer to a question, it contains information.
Interpretation
Interpretation is the process of extracting the information from the data.
Environment
The environment is the total of surroundings in which this all takes place. Each environment imposes specific limitations to environmental conditions, such as temperature, shock, vibration, humidity, sensitivity to radiation of any kind, etc.
Noise
Noise is a physical quantity whose data is meaningless. If added to a signal, it compromises the retrieval of the information from the signals. Noise can be of any kind: thermal, optical, acoustic, electromagnetic, etc.
Interference
Interference is considered noise of which specific properties are known. This knowledge can be used to compensate for the adverse effects of interference on the retrieval of information.
Signal source
The signal source provides a signal.
Observer
The observer is the device or the person that needs the information.
Excitation
Excitation is a signal with specific properties that lets a process generate responses that provide information about the process.
Transducer
A transducer is a device that transfers the signal from one physical domain to another.
Sensor
A sensor is a transducer that converts a non-electrical signal into an electrical signal.
Actuator
An actuator is a transducer that converts an electrical signal into a non-electrical signal.
Limitations of information processing#
The amount of information that can be processed by a physical system is limited. We will distinguish fundamental physical, technological and economical limitations.
Fundamental physical limitations#
According to Shannon [10] the amount of information processing errors can be arbitrarily low if the amount of information transported over a linear channel, perturbed by white noise is limited to the Channel Capacity \(C\):
where \(B\) [Hz] is the bandwidth of the channel, \(P\) [W] the signal power, and \(N\) [W] the noise power. Any physical system adds noise and suffers from power and speed limitations. Hence, the addition of noise, the limitation of the signal power, and the limitation of the rate of change of signals are regarded as fundamental physical limitations of information processing.
Technological limitations#
The technology not only determines the strength of the above fundamental physical limitations. It also introduces processing errors that result from the non-ideal implementation of the physical operating mechanism. An example is the distortion of a signal in amplifiers due to their non-linear behavior.
Economical limitations#
A shortage of the required resources, such as matter, energy, time, and space, can also lead to errors in information processing. Like technological limitations, they determine the strength of the manifestation of the fundamental physical limitations.