Differential Frequency Hopping Signal Detection Based on HHT

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Differential frequency hopping communication system as a new concept of communication systems has become an important development direction of the current shortwave confidential communications. In this paper, on the DFH communication mechanism based on the establishment of a function, the function design m sequences designed based on HHT transform DFH signal detection design, experimental results show that this scheme can effectively achieve DFH Signal generation and detection of a communication system. KEYWORD: DFH; G function; HHT transform; detection International Conference on Social Science, Education Management and Sports Education (SSEMSE 2015) © 2015. The authors Published by Atlantis Press 710 unknown Research hopping signal detection method differential signal parameters under the conditions. 2 BASIC PRINCIPLE OF DFH The concept stems from a DFH enhanced 1995 Sandes company developed Spread Spectrum (Correlated Hopping Enhanced Spread Spectrum, called CHESS) system, CHESS radio with DFH (Differential Frequency Hopping, referred DFH) as the core technology to achieve high-speed frequency hopping, hopping speed up to 5000 hops / sec transfer rate up to 19.2kbit / s, and anti-jamming, strong anti-fading capability. DFH has two key technologies, namely signal detection technology design technology and the receiving end of a differential frequency hopping pattern. DFH system uses a new technology system, its design is based on the hopping pattern called a mathematical relationship of G function, at the sending end, the frequency value of the current time n f is by the frequency value 1 n f  and the current time data symbols n X decision. An implicit difference equation is expressed as [8]: ) , ( 1 n n n X f G f   (1) G(∙)indicates a function transform relations, referred to function. Its frequency, data transformation relationship can be expressed in the form of a diagram of transformation function in Figure 1. Fig.1 The G function transform Differential frequency hopping communication system, the receiver uses a variety of new technology to receive broadband, digital signal processing. At the receiving end, by the broadband receiving digitized, characterized by the FFT analysis of all signals within the bandwidth of the frequency hopping, 1 n f  and n f is determined. Restore the data transmitting side by the inverse transform function, namely: ) , ( 1 1 n n n f f G X    (2) Wherein G -1 denotes inverse transform function of G, which requires the function G must have reversible. Its inverse transform relationship can be expressed in the form of a diagram 2. Fig.2 The inverse G function transform 3 G FUNCTION ALGORITHM PRINCIPLE In the differential frequency hopping, G function is a specific frequency transfer function, can be seen as a directed graph, directed graph node represents a frequency point of each frequency set, each node separates 2 f  branches, BPH representative of the number of bits per hop transmission, also called the fan-out coefficients. Are marked on each bifurcation current information symbols to the set of frequencies containing frequencies of 64, for example, when each hop transmission 1bit, each node has two bifurcated (0,1). BPH transmission bit stream bits per symbols constituting a transmission symbol stream according to a given differential frequency hopping sequence with a frequency corresponding to the generated map. 3.1 1 bit G function design G function design approach are many, including those based on the theory of congruence G function design, based on the state of the shift register design function G, G function m-sequence-based design and so on. In this selection of designs based on G function m sequences. Algorithm is described as follows: Step1 First reads the data n X to be transmitted, the data is encoded, the encoded data n d is calculated.