# any ideal for this?or Topic??

Discussion in 'Homework Help' started by yang_0925, Mar 27, 2013.

1. ### yang_0925 Thread Starter New Member

Dec 9, 2011
9
0
A signal is defined as any physical quantity that varies with time, space or any other independent variable or variables. Mathematically, a signal can be describe as a function of one or more independent variables.

Examples of signals
1) Current from a current sensor.
2) The variation in pressure in the cylinder of an IC engine during operation.
3) The variation in the number of shoes sold in a certain shop during the month.
4) The variation in temperature at noon on successive days at a holiday resort.

A system may be defined as a physical device that performs an operation on a signal. It can also be regarded as a process that transforms one signal into another. The input to a system and the output from a system is signals. A group of physical components assembled to perform a specific function also defined as system. It may be an electrical, mechanical, hydraulic, pneumatic, and thermal or a combination of any of these systems.

In general a system may be represented as:-

Figure 1: System block diagram

All existing systems change with time and when the rates of change are significant, the systems are referred to as dynamic systems.

A car riding on a road can be considered to be a dynamic system (especially on a crooked or a bumpy road). The input variables could be the throttle position, position of the steering wheel or the road conditions like the slope and roughness. The choice of the output variables is arbitrary and is determined by the objective of the analysis. The position, velocity or acceleration of the car or the average fuel rate or the engine temperature can be selected as the outputs.

Another example of a system is an amplifier which modifies the amplitude of the input
signal by a gain factor at every time instant. This system is shown below.

Figure 2: Block diagram of amplifier system

In general the relationship between the input signal to the system X(t) and the output
signal from the system, Y(t) is given by:-
Y(t) = aX(t), where a is a constant.

System may be depending on one another and maybe not. In our surrounding, a system can be anything starting from a small and simple system to a big and complicated system.

Your task is to select and name one simple system surrounds us. From the chosen system, determine the system properties and related equation/function on the system. Discuss and elaborate the system properties and also signal operation inside the system.

2. ### WBahn Moderator

Mar 31, 2012
23,567
7,212
It sounds like it is YOUR task, not ours. So perhaps you might show a bit of effort toward answering YOUR homework problem. Then we can discuss.