The Research And Implementation Of Modulation Pattern Recognition Algorithm Based On FPGA

In order to solve the problem of slow recognition speed and excessive resource consumption,In this paper,on the basis of the theoretical research of modulation pattern recognition algorithm,we optimize and improve the parameters of common time-frequency domain,and propose three new recognition parameters,and test the feasibility of the optimization algorithm on the Quartus ? 9.0.In this paper,The hardware circuit of system uses the modular design,which is composed of two top-level functional modules,namely Modulation function Module and Pattern Recognition function Module.The Modulation function Module includes 4kinds of digital pulse modulation modes,namely 2FSK,4FSK,2PSK,4PSK,which functions are realized by the key control method.Modulation Recognition function Module is realized by the optimized 3 parameters(P?l ?S),and specific operations are as follows: FSK and PSK signal Recognition Module calculates the P value in the light of the characteristics of the input signal,and then compares it with the parameter decision threshold t1 so as to determine the input measured signal is FSK modulation or PSK modulation.2FSK and 4FSK signal Recognition Module calculates the l value of the input signal,and compares it with the parameter decision threshold t2 so as to determine the input measured signal is 2FSK modulation or 4FSK modulation.2PSK and 4PSK signal Recognition Module calculates the S value of the input signal,and compares it with the parameter decision threshold t3 so as to determine the input measured signal is 2PSK modulation or 4PSK modulation.The frequency is replaced by the unit time zero crossing number,and under the condition of high sampling frequency,the differential operation can be replaced by letting the signal left shift one sampling interval and then subtracting with it's original signal.The parameter decision threshold of each module is determined by a lot of experiments.In particular,in the design of2 PSK and 4PSK signal Recognition Module,according to the phase absolute value characteristic of 2PSK and 4PSK signal,In this paper,the phase average value is directly set to 90 degrees,and also we have set a 90 degrees phase reference standard,which greatly simplifies the operation of the system.The test results show that,When the sampling rate is 100 MHz,the symbol rate is2 MHz,the maximum carrier frequency is 12.5MHz,the parameter decision threshold t1=2,t2=5,t3=1,the overall system identification effect is the best and the speed is fastest,which the system can identify the 2FSK signal and 4FSK signal around 7.36 us,and identify the 2PSK signal and 4PSK signal around 10.88 us.At the same time,the resource consumption of the system is the least,which is less than 1% of the total resources.Therefore,the test results have proved the feasibility of the improved algorithm,and also we have achieved the purpose of the design.