Research And Application On Wideband Digital Reconnaissance Receiver

Electronic warfare is more complex than ever before, EWRR(Electronic War Reconnaissance Receiver) is the import part of the electronic detection system for radar signal. In many radar countermeasure applications, it requires characters of EWRR that wideband, catch low probability of intercept radar signal, processing multiple signals. Traditional analog receiver has many disadvantages, so it was only used in some simply application. With the rapid development of digital techniques, EWRDR(Electronic War Reconnaissance Digital Receiver) is take a very important roles in modern electronic war. EWRDR has advanced architecture than Traditional analog receiver, it use analog-digital-converter to convert analog to digital signal, and the outstanding advantage is that it can amalgamate the high performance of soft-radio. With the using of digital signal processing techniques, EWRDR can analysis character of signal and measure property of signal in detail with high efficiency, and it even can recognize signal, also can monitor the environment of electronic in a large frequency band. So studying EWRDR with high performance and its application is very important to adapt modem complex electromagnetism environment.Based on the previous works, this paper primarily researches the high efficiency application of EWRDR associating actual projections, investigates the key technologies and implementations of EWRDR. The main works can be summarized as follows:1. The architecture of channelized receiver based on poly-phase filters is analysis. The poly-phase filter can improve the performance of traditional FIR filter, it can reduce the calculate work and simply the architecture of receiver. So, with the advantage of poly-phase filter, the system resource of receiver is less than trandition receiver . In the receiver based on poly-phase filters, the number of receiver channel is equal the decimation of poly-phase filter. The number of channel or decimation of poly-phase filter will cause the conflict of resolution between time and frequency domain. So, the selection of channel number is need to think about with careful.2. The architecture of channelized EWRDR receiver based on full parallel STFT(Short Time Fourier Transform) is provided. With the advantage of STFT, this architecture realized uniformity channel, every channel has same parameters except carrier frequency. The sample rate of ADC is up to Gsps now, even several Gsps, but the operation speed of FFT block is large lower than GHz. So, it is necessary to find some solution to match the speed of ADC and FFT block. With the help of multiple FFT blocks operation paralleled, the speed of data operation can be slow down, and each FFT block also work with lower operation clock. Full parallel processing mode with pipeline operation is provided in this paper, and its timing characters is also discussed.3. A novel and high efficiency architecture of channelized EWRDR is provided, poly-phase is employed to optimize normal channelized receivers based on the STFT. In this architecture, advantages of poly-phase filter and STFT are combined together. First step of this method is decimate time-domain data with poly-phase processing, then apply Fast Fourier transform (FFT) using decimated data, final weight for transform result. Using theory of poly-phase, the STFT can be expanded to another form. With the help of multiple parallel FFT block and decimation operation, the throughput of FFT operation can be reduced largely. The performance of receiver by new method is as same as the receiver by STFT, but the spending of receiver is more lower. The experiments with actual receiver based on new architecture shows the method is correct and its efficiency is higher.4. The processing algorithms of phase-differential and wavelet based on minimum square is presented to classify difference modulated signal. Features of some typical radar signals based on phase-differential and wavelet are discussed. And then, the method of classification of signal mixed with multiple different modulated components is presented. Under the condition of multiple dimension observed data, using ICA(Independent Component Analysis) based on minimization of mutual information, it can achieve the blind signal separate of multiple independent signal. With the help of ICA, the method of classification of signal mixed with multiple different modulated components can be convert to classify several single signal modulation. And then, the signal modulation can be recognized by signal features. The processing algorithms of phase-differential and wavelet based on minimum square is presented to classify difference modulated signal. The signal features analysis by phase-differential and Morlet wavelet is also discussed. Thus, without the beforehand information of signals, the algorithm adopting ICA and phase-differential or wavelet implements the automatic classification of mixed signal by difference modulation.5. The adaptive chirplet atomic decomposition is used to analyze the separation of multiple Chirps. After separation of signals, the TDOA(Time Difference of arrival) of each Chirp can be estimation based on maximum likelihood correlation algorithm. The basic way of atomic decomposition is that signal can be described by some components with same features as signal. Chirp shows assembly feature of time-frequency if it decomposed by chirplet atoms. Under condition of maximum likelihood, some Chirps mixed signal can be decomposed by adaptive chirplet atom, each Chirp component can be approached by one chirplet atom. In passive location system, compute the correlation of each pair atoms between main-receiver signal and sub-receiver signal in mixed Chirps, the TDOA of each Chirp can be estimated.6. To locate noise-frequency modulation jammer with TDOA in passive system, a new method of delta-modulation coding jointed cross-correlation is presented in this paper. Signal can be described by delta-modulation code, and coding sequence of sub-receiver is send to main-receiver. Using coding sequence and maximum likelihood correlation algorithm, TDOA can be estimated. The advantage of delta-modulation code is that it can reduce communication data traffic between main-receiver and sub-receiver. After coding, the sequence of noise-frequency modulation signal hold similar statistics feature of raw data. The TDOA estimated by coding sequence is same as that of the method of cross-correlation using signal sample data. Finally, the method of decimate coding sequence and interpolate correlation are analysis, and the effect of TDOA in this method is discussed.