Development of efficient radar pulse compression technique for. Pulse compression is a signal processing technique commonly used by radar, sonar and echography to increase the range resolution as well as the signal to noise ratio. Two analog pulse compression techniques are discussed in this chapter. Pulse compression techniques for laser generated ultrasound. The major aspects that are considered for a pulse co mpression technique are signal to. Optimum side lobe magnitude estimation of different pulse. Higherorder dispersion beyond gvd leads to even further distortion of the pulse and causes asymmetry in the.
Lfm pulse compression technique is conducted by adding frequency modulation to a long pulse at transmission. In pulse compression analysis, the crosscorrelation between the mean removed captured temporal thermal distribution of each pixel ht with chosen nondefective reference pixel st for a given frequency modulated thermal excitation is computed as 10. In this paper, details of these techniques are given which achieves high range. Introductionpulse compression pc is an important module in many of the modern radar systems. But at the output of pulse compression filter, sidelobes are present and these unwanted outputs may mask a weaker target. Pdf a study on barker code of radar pulse compression. This is achieved by modulating the transmitted pulse and then correlating the received signal with the transmitted pulse.
The main techniques investigated are pulse compression using chirp pulses, mismatched filtering and pulse compression. The use of pulse compression techniques to improve the sensitivity of meteorological radars has become increasingly common in recent years. In our previous studies,31,32 the superresolution fmchirp correlation method based on multiple signal classi. Pulse compression, the compromise transmit a long pulse that has a bandwidth corresponding to a short pulse must modulate or code the transmitted pulse to have sufficient bandwidth, b can be processed to provide the desired range resolution. Pdf a new pulse compression technique for polyphase. In pulse compression technique a pulse having long time duration and low peak power is modulated either in linear fm or phase coded signals before transmission and at the receiver side, received signal is passed through a matched filter to accumulate convert the energy in a short duration pulse. This paper examines the linear frequency modulation lfm pulse compression technique on a generic signal model.
The pulse compression technique plays a very important role for designing a radar system. The use of pulse compression technique in nondestructive. Pulse compression techniques that are capable of producing a large signaltonoise snr enhancement, have been used successfully in many different fields. Pulse compression techniques for laser generated ultrasound r.
A note on the application of pulse compression techniques to. Pulse compression following the see and not be seen guideline for radar, the energy in a pulse can be spread over a longer time at a lower power, if the pulse is modulated in some way. Pdf improvement of radar performance using lfm pulse. A long pulse is deliberately produced by stretching a short, lowenergy pulse in a single mode optical fiber. Abstract pulse compression technique is a method of acheaving benefits of short puloses while keeping the peak power within practical limits.
Pulse compression method for radar signal processing. For that reason, the research on pulse compression techniques is briskly studying. These practical difficulties in making good filters \\ould have normally affected the wider use of matched filters but for the introduction in the recent years of. Real time pulse compression was carried out over dsp kit tms320c67. Pulse compression allows us to achieve the average transmitted power of a relatively long pulse, while obtain ing the range resolution corresponding to a short pulse. Bandwidth and resolution enhancement through pulse. Us7081846b1 ecm techniques to counter pulse compression. The other popular pulse compression techniques include costas codes, binaryphase codes, polyphase codes and nonlinear. Pulse compression technique is a method of achieving the benefits of short pulses while keeping the peak power within practical limits. These techniques improve the range resolution and range using the same output power. Effectiveness of pulse compression signal processing. Introduction to radar waveforms and their properties. In pulse compression technique, a short pulse is converted to long duration pulse of low peak power, which is then modulated either in frequency or phase before transmission.
Experimental evaluation of longrange acoustic sensing using. An active phased array doppler sodar with distributed low peak power transmit modules requires pulse compression to provide high sensitivity and fine range resolution. Pulse compression is a signal processing technique to increase the signal and noise ratio, detection range and range resolution. The aim of this paper is to provide an introduction to principle behind the pulse compression radar. Aug 11, 2014 pulse compression technique is a signal processing technique used in radar systems to avail the benefits of large range detection capability of long duration pulse and high range resolution capability of short duration pulse.
Pulse compression allows achieving the performance of a shorter pulse using a longer pulse and hence gain of a large spectral bandwidth. Range resolution is an ability of the receiver to detect nearby targets. This method is also known as intrapulse modulation modulation on pulse. Radar pulse compression using linear frequency modulation. Range resolution is important performance parameter to distinguish a target accurately. Since a short pulse requires a high peak power which is unattainable for many constraints such as voltage breakdown, dimension of waveguide etc, the radar system uses a longer pulse and pulse compression technique. In these techniques a long duration pulse is used which is either phase or frequency modulated before transmission and the received signal. Pulse compression is an important signal processing technique used in radar system to reduce the peak power of a radar pulse by increasing the length of pulse, without sacrificing the range. Priyanka and others published pulse compression techniques for target detection find, read and cite all the. Todays pulse radar systems frequently use pulse compression techniques. Pulse compression for weather radars geoscience and remote. Radar pulse compression techniques request pdf researchgate.
A pulse compression radar is a practical implementation of a matchedfilter system. Distribution statement radar maxinu n likelihood processor radar altimetry unclassified unlimited. Radar systems use pulse compression techniques to enhance the long range detection capability. The pulse compression technique is a technique that introduces a frequencyswept signal into an object and the signal reflected from the target is decoded to compress the signal, therefore the signal to noise ratio snr is increased and the resolution is enhanced. Superresolution techniques involve the use of highresolution optimal estimation methods these methods are based on an eigenstructure technique that makes use of the covariance matrix of the received signal ref 2,p 18 intiapulse pulse compression. Pulse compression for weather radars geoscience and. Generation of few cycle femtosecond pulses via supercontinuum. Oelze, member, ieee abstracta novel pulse compression technique is developed that improves the axial resolution of an ultrasonic imaging system and provides a boost in the echo signaltonoise ratio esnr. The matched filter output consists of unwanted but unavoidable side lobes however the reduction of this side lobe strength is the active.
Implementation of pulse compression for space applications. In this chapter, we will analyze analog and digital pulse compression techniques. Linear frequency modulation pulse compression technique on. Pulse compression is an important signal processing technique used in radar system to reduce the peak power of a radar pulse by increasing the length of pulse, without sacrificing the range resolution associated with a shorter pulse. Development of radar pulse compression techniques using. Polyphase compression codes are derived from step approximation of linear frequency. In these techniques a long duration pulse is used which is either phase or frequency modulated before transmission and the received signal is passed through a. Application of pulse compression techniques to monostatic.
New techniques for timereversalbased ultrawideband. Investigation in pulse compression techniques for radar. Application of pulse compression techniques to monostatic doppler sodar 1 a. In that paper, the generation and reception of coded pulse signals. Figure 1 shows the construction of such a compressor. Pulse compression is an important signal processing techniq.
The technique of pulse compression consists of transmitting a pulse which sweeps through a range of frequencies with a carefully designed relationship of frequency to time. In this paper, the pulse compression technique is described to resolve two small targets that are located at long range with very small separation between them. Based on the results obtained, we conclude that it is a very efficient technique of pulse compression. With the help of pulse compression, a relatively long transmission pulse with comparatively low peak power can achieve a better, longer range than the basic radar equation would suggest. Linear frequency modulation pulse compression technique. Pulse compression techniques are used in radar systems to avail the benefits of large range detection capability of long duration pulse and high range resolution capability of short duration pulse with low power consumption. Although the dispersion of the prism material causes different wavelength components to travel along different.
Section 2 discusses several journal papers on radar pulse compression techniques. For example, the signal time compression technique is equally useful where there is a need to reduce the time taken to perform signal analyses. Pulse compression is an important signal processing technique used in radar system to reduce the peak power of a radar pulse by increasing the length of pulse. A prism compressor is an optical device used to shorten the duration of a positively chirped ultrashort laser pulse by giving different wavelength components a different time delay. Development of efficient radar pulse compression technique. The implementation of the recommended technique is. Pulse compression techniques have been well established for applications in military and aviation systems where the backscattering medium consists of hard targets. In pulse compression technique, the transmitted signal is frequency or phase modulated and the received signal is processed using a specific filter called matched filter. Pulse compression radar waveforms offer several advantages over uncompressed waveforms. Two weather radar systems operationally using pulse compression have been recently. This was performed using wide bandwidth emats and pulse compression signal processing techniques, using chirp excitation.
Improving weather radar observations using pulsecompression. The obtained range from the compressed pulse accedes to the actual range of the target sound source. Bandwidth and resolution enhancement through pulse compression. The main techniques investigated are pulse compression using chirp pulses, mismatched filtering and pulse compression using other. Pdf pulse compression veggalam virisahitya academia. Pulse compression pc is an important module in many of the modern radar systems. This study discusses the lfm pulse compression technique simulation on. Pulse compression is a method for improving the range resolution of pulse radar. It is used to overcome major problem of a radar system that requires a long pulse to achieve large radiated energy but simultaneously a short pulse for range resolution 1. Doppler sodar transmits a short pulse of duration typically a few tens of milliseconds of intense sound. Hutchins2, gui yun tian3, junzhen zhu3, qiuji yi3, marco ricci4 1department of.
Pulse compression allows a radar system to transmit a pulse of relatively long duration and low peak power to attain the range resolution. The pulse compression ratio is also equal to the product of the time duration and the spectral bandwidth timebandwidth product of the transmitted signal. Pulse compression is used to achieve large radiated energy but simultaneously a short pulse for range resolution. The phase changes can be used to increase the signal bandwidth of a long pulse for purpose of pulse compression. But the output snr can be reduced by 1 to 2 db due to windowing, this leads to reduce the false alarm rates in object detection applications. The matched filter performs the same effect as the analog pulse compression technique just described.
Medical ultrasound imaging using pulse compression. Figure6 compressed pulse figure7 ambiguity diagram of compressed pulse v. Mom, monte carlo simulations, pulse compression techniques, range gating and rcs calculation. The pulse compression ratio is the ratio of the width of the expanded pulse to that of the compressed pulse. In the pulse compression technique imaging system, a pulse compressor having a correlator at the ultrasound receiver achieves the effects of the short pulse transmission technique. High resolution low power radar pulse compression techniques. Investigation of a pulse compression technique for medical. In the paper, this issue is examined through modelsimulation studies. Windowing is used in lfm pulse compression to reduce the side lobes. Keeler and passarelli 5 have traced the evolution of pulse compression techniques in the weather radar community. The first technique is known as correlation processing which is dominantly used for.
Pulse compression an overview sciencedirect topics. Jul 11, 2015 the pulse compression technique considerably extends the range of the radar, sonar etc. Pulse compression is one of the key steps in the signal processing of a radar system. Pulse compression techniques are used in radar systems to avail the bene. The medium used for acoustic chirp propagation is air. Accordingly, it is capable of effectively increasing the snr by transmitting the coded long pulse having a lower voltage than the peak voltage in the short pulse. Pdf pulse compression techniques for target detection. A numerical simulation of the technique has confirmed the performance. Pulse shaping and compression by secondharmonic generation. A pulse compression signal modulation involves switching or keying the amplitude, frequency, phase of the. The most common and popular among them is the linear frequency modulation lfm which was invented by r. Army vehicle technology directorate, arl, amsrlvts, nondestructive evaluation sciences branch, nasa langley research center, hampton, va 23681 e. Increasing the spectral bandwidth of the output pulse leads to the generation of a compressed pulse shorter in duration than the input one. Investigation in pulse compression techniques for radar systems.
Pulse compression is a method which combines the high energy of a longer pulse width with t he high resolution of a narrow pulse width. Comparison of the performance of different radar pulse. Conclusion nowadays pulse compression has become an inevitable part of radar system. The received reflected pulse is crosscorrelated with the digital version of the transmitted pulse and the resulting waveform is a narrow pulse of large magnitude. Modulation also spreads the signal in the frequncy domain, increasing the information bandwidth of each pulse. The destination of modern radar systems, to overcome the limitations of existing analog radar systems, i s to improve the range resolution of the distance with low transmission power. The system uses a timereversalbased pulse compression scheme with onebit processing obtr to achieve high compression gain. Psl and isl comparison of various pulse compression schemes pc techniques psldb isldb snr loss db new technique blackman 8 121. The need of pulse compression is explained in section 3. Barker coded waveform poly phase coded waveforms are waveforms that use only two phase shifts of 0 and s.
The purpose of this paper is to compare the performance of the matched, mismatched and adaptive pulse compression methods by considering different types of optimal codes and also for different snr values. The new technique, called the resolution enhancement compression rec technique, was val. Introduction the pulse compression technique is a technique that introduces a frequencyswept signal into an object and the signal reflected from the target is decoded to compress the. Radar, pulse compression pc, peak sidelobe level psl, range resolution, sidelobes. This is a method of combining the high resolution capability of a short pulse with the high. To overcome this problem pulse compression techniques are used in the radar systems. The exemplary frequency modulation method can become fundamental to the development electronic countermeasures ecm techniques to counter the pulse compression pc class of radars. Several methods of pulse compression have been used in the past. Pulse compression allows us to use a reduced transmitter power and still achieve the desired range resolution. This gives a greatly improved signal to noise ratio snr for noncontact experiments, increasing the speed of data acquisition. This is a method of combining the high resolution capability of a short pulse with the high energy of a long pulse. Pulse compression can also detect small target signals out of clutter. A new pulse compression technique for polyphase codes in.
This is achieved by modulating the transmitted pulse and then matching the received. Performance evaluation of barker codes using new pulse. Comparison of radar pulse compression techniques ieee. Recall the matched filter in chapter 9 on complex modulation and demodulation. Pulse compression introduction to radar systems 2004.
This is because pulse compression can still detect echo signals that have already disappeared in the noise before pulse compression. In an earlier paper coli and storey, 19641 tech niques for the application of pulse compression to ionospheric sounding were discussed. Pulse compression is a signal processing technique commonly used by radar, sonar and echography to increase the range resolution as well as the signal to. Psl of proposed pulse compression technique table 1. Us6350240b1 ultrasound imaging method and apparatus based. A matched filter is a linear network that maximizes the output peaksignal to noise ratio of a radar receiver. In pulse compression technique within transmit power limitations. This study discusses the lfm pulse compression technique simulation on matlab and gnu.
Medical ultrasound imaging using pulse compression technique based on split and merge strategy masayuki tanabe 1, takuya yamamura. Real time implementation of digital lfm pulse compression. In this paper the pulse compression technique will be described and compared. Madaras nondestructive evaluation sciences branch, nasa langley research center, hampton, va 23681. These radars using pulse compression techniques were recently installed in spain and mexico, as brie. Radar pulse compression technique for linear frequency. Pulse compression with gaussian weighted chirp modulated. All digital radars can also perform pulse compression, but using a different method. For medical applications, frequencydependent attenuation in soft tissue can limit the usefulness of this method. Matched filtering algorithm for pulse compression radar. Optimization of the pulsecompression technique applied to. Using this technique with a prism chirpedmirror gires tournois interferometer compressor, 4.
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