Study Of Weak Signal Measuring In Chaotic Dynamics

A potentially feasible method is the use of a chaotic system's high sensitivity under condition to detect weak signals, which is quite different from all present methods. Fixing parameter of components in a nonlinear circuit, chaotic orbits change with the measured signal. A distance has been defined. By measuring the distance of orbits, very weak signal can be detected because of the sensitive dependence on initial conditions. In theory, the measuring precision is infinite.But a chaotic system is also extremely sensitive to noise, an orbit in a circuit will exponentially drift apart the one of the map with identical initial condition. Is it impossible to measure very weak signals in a chaotic system? The key problem is whether we can reduce noise or depart the useful information from the interferential orbits or not. If we can, very weak signal can be measured based on the sensitive dependence on initial conditions.A new method of noise reduction is proposed in this paper. By coupling of many chaotic circuits, orbits can be closed each other, distance can be shorted, and noise in measuring can be reduced. Circuit experiments consisting of two measuring units and computer analysis prove the method is effective, and circuit experiments consisting of N measuring units show noise reduction will be better as N increases.Otherwise, an active integral chaotic measuring circuit is suggested based on the analysis of the present nonlinear circuits in this paper, which gets rid of nonlinear distortion of map function in constant-voltage mode and defect of constant-current source operating on-off state. Using a general operational amplifier, high precision can also be obtained. A nth-order chaotic measuring system can be composed of its interconnection.