Analysis, Digitization And Implementation Of FPGA Circuit About Chaotic Sequences

With rising of Internet of Things and the development of the global mobile communications, the traditional spread spectrum sequences in amounts will fail to meet demand, and they still exist many drawbacks. There has to be a fairly large number, good performance of spread spectrum sequences. Chaotic sequences generated by discrete dynamic chaotic system, which are sensitive to the initial value, have pseudo random, small auto-correlation and small cross-correlation etc. characteristics. Therefore, chaotic sequences used in communication system have aroused the concern of scholars. Most discrete chaotic sequences are generated by maps.After quantized and encoded, we can get digital chaotic sequences.Because the accuracy of computer is limited, chaotic sequences which we get by using computer simulation have small period. To overcome this difficulty at present there are mainly two ways:adding random disturbances and multi-bit quantization to reduce the loss of accuracy.Standard Tent map in addition to exist outside small cycle, they are unstable. Aimed at the two problems, this paper presents the Tent map with a kind of small disturbance.This improved Tent map does not exist already said above shortcomings.And we study performances of the digital Tent chaotic sequences under different amplitudes of random disturbances in the MATLAB software, and give the range of the amplitudes. Only the performance of amplitude within the scope,just suits to do spread spectrum sequences. Experimental results show that the improved Tent map's transmission properties are superior to other maps'.For existing digital spread spectrum communication systems, chaotic real sequences spread spectrum is not compatible, so we need to quantify the real value sequences to binary sequences. Binary quantization is common. To explore chaotic sequences in digital communication applications, we propose an integer quantization based on Logistic map and Chebyshev map.First, we get digital sequences of Logistic map using 32-bit integer quantization method, and then the hardware realization principle of Logistic map is given in detail, next we get digital chaotic sequences based on Logistic map with the FPGA hardware circuit; using the same method, the 2,4 and 8-order Chebyshev digital chaotic sequences are got. Finally, compared with the numerical data of the sequences, the results show that their performances are better than binary quantization sequences obtained.