# I. Introduction he Real time threat environment in the battle field is different and dangerous. In the battle field to test an ESM system there are large number of Radars which monitor or surveillance the signals emitted by the enemies. These Radars identify or trace the signals and transmit to the large group of monitors and equipment. These equipment monitors the data and the Radar parameters such as pulse width, pulse repetition interval, direction of arrival, time of arrival, frequency, type of pulse repetition of time, angle of arrival, distance of the object, pulse repetition of the frequency. These Radars parameters are identified by the ESM the system and convert into the form of pulse descriptor word format which is of 128 bits. To take the measures in order to protect from the enemy attacks the counter measures are taken with the help of Electronic Counter Measure (ECM) system. These system uses the data captured and create the counter pulses to attack the enemy Radar signal to protect the country. In order to protect from counter signals, the data is captured and transmitted to the advanced system called Electronic Counter Counter Measure (ECCM) System. # II. Modeling of Threat The field is created using Dielectric Resonator Oscillator (DRO) to generate various frequencies ranging from 1 GHz to 40 GHz. To generate higher frequencies, Voltage Control Oscillator (VCO) is used. These frequencies are given to mixer as an input. The mixer can be used as a switch to select the desired frequency by programming the FPGA control signal line. The inter pulse modulation generator is enabled using enable line to generate desired pulse. The desired frequency and pulse modulated signal is given to the programmable attenuator. The Antenna radiated pattern generated signal is also given to programmable attenuator. The output of programmable attenuator is desired signal, which is used to test the Electronic Support Measure (ESM) systems. # a) Generating Different types of Pulses Radar system uses a Radio frequency electromagnetic signal reflected from a target to determine information about that target. In any Radar system, the signal transmitted and received will exhibit many of the characteristics Radars pulse signal parameters are pulse width, pulse repetition interval, Frequency, Direction of arrival ( DOA), Time of arrival (TOA).The carrier is an RF signal, typically of microwave frequencies, which is usually modulated to allow the system to capture the required data. In simple ranging radars, the carrier will be pulse modulated and in continuous wave systems, such as Doppler Radar, modulation may not be required. Most systems use pulse modulation, with or without other supplementary modulating signals. Note that with pulse modulation, the carrier is simply switched on and off in sync with the pulses the modulating waveform does not actually exist in the transmitted signal and the envelope of the pulse waveform is extracted from the demodulated carrier in the receiver. Although obvious when described, this point is often missed when pulse transmissions are first studied, leading to misunderstandings about the nature of the signal .The pulse width ( ) of the transmitted signal is to ensure that the Radar emits sufficient energy to allow that the reflected pulse is detectable by its receiver. The amount of energy that can be delivered to a distant target is the product of two things; the output power of the transmitter, and the duration of the transmission. It also determines the range discrimination that is the capacity of the radar to distinguish between two targets fairly close together. At any range, with similar azimuth and elevation angles and as viewed by a Radar with an un modulated pulse, the range discrimination is approximately equal in distance to half of the pulse duration. The pulse width of a signal is shown in Fig 2 .1 it also determines the dead zone at close ranges. While the Radar transmitter is active, the receiver input is blanked to avoid the amplifiers being swamped or damaged. All this means that the designer cannot simply increase the pulse width to get greater range without having an impact on other performance factors. As with everything else in a Radar system, compromises have to be made to a Radar systems design to provide the optimal performance for its role. # III. Implementation The main objective of this paper is to create Radar like parameters to test an ESM system. For this we need a circuitry that generate such pulses and also a The size of window is N-1. For example in this case it is 7. Therefore, a maximum of N-1 Frames may be sent before an acknowledgment. When the Receiver sends an ACK, it includes the number of next Frame it expects to receive. For example, in order to acknowledge the group of Frames ending in Frame 4, the Receiver sends an ACK containing the number 5. When sender sees an ACK with number 5, it comes to know that all the Frames up to number 4 have been Received. # c) Sliding Window on Sender Side At the beginning of a Transmission, the sender's window contains N-1 Frames as shown in receiver sends an ACK, the source's window expands right boundary moves out words to allow in a number of new Frames equal to the number of Frames acknowledged by that ACK. For example, if the window size is 7, if Frames 0 through 3 have been sent and no acknowledgment has been received, then the sender's window contains three frames -4, 5 ,6. Now, if an ACK numbered 3 is received by source, it means three frames (0, 1, 2) have been received by receiver and are undamaged. # d) Sliding Window on Receiver Side At the beginning of transmission, the receiver's window contains n-1 spaces for frame but not the frames as shown in Fig 3 .12. As the new frames come in, the size of window shrinks. Therefore the receiver window represents not the number of frames received but the number of frames that may still be received without an acknowledgment ACK must be sent. Given a window of size w if three frames are received without an ACK being returned, the number of spaces in a window is w-3. As soon as acknowledgment is window expands to include the number of frames equal to the number of frames acknowledged. For example, let the size of receiver's window is 7 as shown in diagram. It means window contains spaces for 7 frames. With the arrival of the first frame, the receiving window shrinks, moving the boundary from space 0 to 1. Now, window has shrunk by one, so the receiver may accept six more frame before it is required to send an ACK. If frames 0 through 3 have arrived but have DOC been acknowledged, the window will contain three frame spaces. As receiver sends an ACK, the window of the receiver expands to include as many new placeholders as newly acknowledged Frames. The window expands to include a number of new frame spaces equal to the number of the most recently acknowledged frame minus the number of previously acknowledged frame. For example If window size is 7 and if prior ACK was for frame 2 & the current ACK is for Frame 5 the window expands by three 5-3=2 Therefore, the sliding window of sender shrinks from left when frames of data are sending. The sliding window of the sender expands to right when acknowledgments are received. The sliding window of the receiver shrinks from left when Frames of data are Received. The sliding window of the receiver expands to the right when acknowledgement is sent. In the ASCII sliding window protocol there are total 32 Frames. Again each frame is further divided into 7 frames. These seven frames are intended to preform seven different tasks namely Start of frame, Frame the next three Frames in its buffer. At this point the sender's window will contain six frames 4, 5, 6, 7, 0, 1 ends in that frame, then End of frame comes into play. If the command still exists even after completion of the frame, then the command is passed on to the next frame through the Break of frame accordingly. # IV. Analysis and Output Pulse generators are also sent into the switch which act as input they are namely Stagger, Jitter, constant and Dwell & switch. Only one kind of pulse generators can be sent at a time. Each different pulse generators have different pulse width (PW) and pulse repetitive index (PRI). Pulse width is width of pulse, generally measured in micro seconds (us) and pulse repetitive index (PRI) is the time duration between two consecutive pulses, generally measured in microseconds (mus). Each pulse generator has its own pulse width and PRI. These values can be manually given by the user in the GUI interface of lab view Software. Now these pulse generators and CW radar signals from the DRO are inter pulse modulated inside switch. Enable pin determines the Ton and Toff of a pulse. Modulation occurs when enable pin is set to high. Now arises the Hardware connections. The FPGA used in this is Cyclone 3. NIOS is the software used to program the pins of FPGA. Quartus is a software which is used as a Hardware programming language. It acts as medium between FPGA and Computer. These two devices are connected using JTAG USB cable. Quartus contains lots of tools in it, here we use Eclipse as tool for programming the FPGA. NIOS acts as processor of the system. The Verilog code is dumped inside the FPGA as discussed earlier and executed. Once the code is executed the output is given to an attenuator .A programmable attenuator is used for attenuating the signal amplitude. The received signal is of very high frequency and it is difficult to identify the maximum amplitude of the signal. So to differentiate the signals a programmable attenuator is used. It is used in such a way that the first pulse is attenuated to its maximum and the next consecutive pulse is attenuated a little less, this continues until the pulse which has highest frequency. Once it reaches the pulse with a maximum frequency, it is very easy to identify the pulse which has the maximum frequency, as it has the minimum attenuation. A detector is used to convert the signal from frequency domain to time domain. Consider we have three segments Continuous Radar (CW) signals are generated by the DRO's as the input in the Range of Ghz. These high frequency signals are observed in the spectrum analyser. A certain Band of frequencies can be selected by either using a binary selector given to a control line or directly give the frequency in lab view software and GUI mode. As DRO's generate high frequency signals, they can be only sending through semi rigid cables with minimal loss of signal. The frequency received can be observed in the spectrum analyser. These received signals will be send to a switch which acts as input. Each DRO is powered with a 5V dc supply voltage. Total PLLs 0 # V. Conclusion & Future Scope Modern EW threat Emulation systems are combining advanced materials, SOPC'S, solid-state modules, digital signal processors, and complex A-D converters to give a better look to military and civilian users who need the best possible capability in small, compact, and efficient packages. Recent EW threat emulation systems often have imaging capability, can yield digitized signals quickly and easily for use with graphical overlays, can be networked together so the total system is greater than the sum of its parts, and can serve several different functions such as wide area search, target tracking, fire control, and weather monitoring where previous generations of Radar technology required separate systems to do the same jobs. Most important, however, is the relative ease and speed with which modern analog Radar signals can be converted to digital information. Not only does this open wide variety of signal processing options, but it also enables Radar information to be made available in Real time or near Real time on Internet type networks for inclusion in the digital battle field and Global Information Grid visions of the future. The Emulation system developed in this paper is used to test the ESM Receiver with most of the mathematically defined signals. Two thousand levels of variation can be implemented in the case of Stagger and constant which is definitely an advancement which is possible using SOPC as implemented. ![Therefore, pulse width constrains the maximum detection range of a target.](image-2.png "F") ![b) Pulse Repetition Interval Pulse Repetition Interval is commonly known as PRI. It is the time difference between start time of pulse1 to start time of pulse2 . The difference gives the Pulse Repetition Interval (PRI) as shown in Fig 2.1. The pulse changes in PRI are less than plus or minus one present or measured jitter is believed to be incidental. Most nominally constant signals have less then plus or minus one µsecond of Jitter. Desired measures are Mean PRI, Peak-to-peak incidental jitter Drift, Basic Clock Interval Range and type of Count downs. ? (fraction visible)/ ? PRI = PD/(PRI) 2 -B e = 0 PRI = ?PD/Be optimum duty factor](image-3.png "") 121![Fig. 2.1: Pulse Repetition Interval (PRI)](image-4.png "FPGA 1 Fig. 2 . 1 :") ![Fig 3.5 . As the Frames are sent by source, the left boundary of the window moves inward, shrinking the size of window. This means if window size is w, if four Frames are sent by source after the last acknowledgment, then the number of Frames left in window is (w-4). When the Year 2016 F © 2016 Global Journals Inc. (US)](image-5.png "") 33![Fig. 3.3: Block Diagram of Inter Pulse Modulation](image-6.png "Fig. 3 . 3 :") 34![Fig. 3.4: Sliding Window](image-7.png "Fig. 3 . 4 :") ![number, Data length, Command ID, Data width, Check sum, End of frame or Break of frame. If the command](image-8.png "F") 35![Fig. 3.5: Sliding Window on Sender Side](image-9.png "Fig. 3 . 5 :") 36![Fig. 3.6: Sliding Window on Receiver Side](image-10.png "Fig. 3 . 6 :") ![Implementation of High Speed Radar Signal Processing Global Journal of Researches in Engineering ( ) Volume XVI Issue VII Version I 40 Year 2016 2016 Global Journals Inc. (US)](image-11.png "FPGAF©") 4142![Fig. 4.1: EW Threat Emulation Kit](image-12.png "Fig. 4 . 1 :FFig. 4 . 2 :") 45![Fig.4.5: Dwell & Switch PRI](image-13.png "Fig. 4 . 5 :") FPGA Implementation of High Speed Radar Signal Processing © 2016 Global Journals Inc. (US) © 2016 Global Journals Inc. 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