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Quantitative radar studies are an important component of studying the movements ofbirds. Whether a bird, at a certain distance from the radar, is detected or not dependson its size. The volume monitored by the radar is therefore different for birds of differentsizes. Consequently, an accurate quantification of bird movements recorded bysmall-scale radar requires an accurate determination of the monitored volume for theobjects in question, although this has tended to be ignored. Here, we demonstrate the importance of sensitivity settings for echo detection onthe estimated movement intensities of birds of different sizes. The amount of energyreflected from a bird and detected by the radar receiver (echo power) depends not only on the bird’s size and on the distance from the radar antenna, but also on the beamshape and the bird’s position within this beam. We propose a method to estimate thesize of a bird based on the wingbeat frequency, retrieved from the echo-signal, independentof the absolute echo power. The estimated bird-size allows calculation of sizespecificmonitored volumes, allowing accurate quantification of movement intensities.We further investigate the importance of applying size-specific monitored volumes toquantify avian movements instead of using echo counts. We also highlight the importance of accounting for size-specific monitored volumeof small scale radar systems, and the necessity of reporting technical information onradar parameters. Applying this framework will increase the quality and validity ofquantitative radar monitoring.

This paper presents a single antenna radar sensor with Ku-band radar transceiver IC realized in 0.13 μm CMOS processes. In the radar receiver, a sensitivity time control using a DC offset cancellation feedback loop is employed for constant SNR irrelevant on the distance. To reduce the direct coupled Tx signal to Rx in single antenna radar, stub tuned hybrid coupler is adopted instead of circulator. The measured distance is 8.2 m with horn antenna and metal plate target.

This paper presents a single antenna radar sensor with Ku-band radar transceiver IC realized in 0.13 μm CMOS processes. In the radar receiver, a sensitivity time control using a DC offset cancellation feedback loop is employed for constant SNR irrelevant on the distance. To reduce the direct coupled Tx signal to Rx in single antenna radar, stub tuned hybrid coupler is adopted instead of circulator. The measured distance is 8.2 m with horn antenna and metal plate target.

Sea clutter is interference background in radar target processing. It is difficult to detect long-range weak target in sea clutter. Sea clutter signal changes complex, with high intensity. For close signal, radar receiver will overload and reach saturation point. We are interested in the most dynamic range for displaying target echo and fast changing component of clutter. By analyzing spatial and temporal correlation of sea clutter, slow changing component can be minus from sea clutter. The innovation of this paper is to propose a linear prediction error method for sea clutter to increase dynamic range of radar receiver. It prevents overloading and reaching saturation point at close range.

Paper presents a Ku-band FMCW radar transceiver IC realized in 0.13 pm CMOS processes. In the radar receiver, a sensitivity time control using a DC offset cancellation feedback loop is employed, which preserves the receiver's SNR not depending on the distance. The radar receiver achieves the full chain gain of 82 dB, P1dB of −2.0 dBm at the minimum gain, and noise figure of 7.9 dB with 106 dB dynamic range. The measured result of the radar transmitter reveals 9 dBm output power. The radar transceiver consumes 115 mA from a 1.2-V power supply. With the aid of an external PLL, the Ku-band FMCW radar module is implemented and verified radar function by measuring the distance of various objects.

The effect of ship navigation radar signal processing has a great impact on the overall performance of the radar system. In this paper, the signal processing algorithm is studied. Firstly, the principle of radar azimuth and distance monitoring is introduced, then the pulse accumulation algorithm and median filtering algorithm are analyzed, and finally a sea clutter suppression algorithm based on sensitivity time control (STC) and a rain and snow clutter suppression algorithm based on constant false alarm rate are designed to improve the target monitoring performance of radar. In the test of the algorithm, the radar signal processing algorithm designed in this study has good precision as monitoring error of the target's azimuth and distance is controlled within 1%; and it also has a better suppression effect of sea clutter and rain and snow clutter, which can suppress the clutter well, improve the target clarity, and ensure the safe navigation of the ship. The experiment proves the effectiveness of the proposed algorithm and provides some theoretical basis for the better processing of radar signals, which is beneficial to improve the environment perception ability of ships in harsh environments and promote the further development of the navigation industry.

In this paper we are explosively the fundamental theory of radar system modules STC (sensitivity time control) or sea clutter and FTC (fast time constant) or rain clutter. The STC and FTC are commonly used to some clutter. The radar signal is widely used for weather forecast, air port traffic control, military and fire control. The system implements radar processing procedures in real time mode in FPGA (field programmable gate array). The FPGA device providing good performance of cheap platform for research and development. The compact structure of STC and FTC can Implementations of Xilinx FPGA using the generated VHDL code.

In this work, a complementary metal-oxide semiconductor (CMOS) based transceiver with a sensitivity time control antenna is successfully implemented for advanced traffic signal processing. The collected signals from the CMOS radar system are processed with optimization algorithms for vehicle-type classification and speed determination. The high recognition rate optimization algorithms are mainly based upon the information of short setup time and different environmental installation of each sensor. In the course of optimization, a video recognition module is further adopted as a supervisor of support vector machine and support vector regression. Compared with conventional circuit-based detector systems, the developed CMOS radar integrates submicron semiconductor devices and thus not only possesses low stand-by power but also is ready for production. In the meantime, the developed algorithm of this study simultaneously optimizes the vehicle-type classification and speed determination in a computationally cost-effective manner, which benefits real-time intelligent transportation systems.

In order to solve the problem that the echo dynamic range is far greater than the range of the linear amplifier, this paper presents a short-range dynamic laser echo ranging approach. This method could generate wave by the FPGA and high speed DAC circuit, and then the STC (sensitivity time control) circuit could weaken the influence of the large echo dynamic range. Theoretical calculation and experimental results show that this scheme can be used for short-range laser radar echo processing, which not only can extend the distance of the dynamic range, but also can improve accuracy ranging. This method would be widely used in short-range laser radar systems.

We have developed the scanning laser sensor for underwater 3-D imaging which has the wide scanning angle of 120o (Horizontal) x 30o (Vertical) with the compact size of 25 cm diameter and 60 cm long. Our system has a dome lens and a coaxial optics to realize both the wide scanning angle and the compactness. The system also has the feature in the sensitivity time control (STC) circuit, in which the receiving gain is increased according to the time of flight. The STC circuit contributes to detect a small signal by suppressing the unwanted signals backscattered by marine snows. We demonstrated the system performance in the pool, and confirmed the 3-D imaging with the distance of 20 m. Furthermore, the system was mounted on the autonomous underwater vehicle (AUV), and demonstrated the seafloor mapping at the depth of 100 m in the ocean.

We developed an underwater three-dimensional (3-D) imaging sensor using a 532-nm laser. The sensor system combines a dome lens with coaxial optics to realize a wide-scanning angle of 120 deg (horizontal)×30 deg (vertical) while having a compact size of 25-cm diameter and 60-cm length. A detector sensitivity time control circuit and a time-to-digital converter are used to detect a small signal and suppress the unwanted backscattered signals due to marine snow. 3-D imaging of the seafloor with 20-m width and 60-m length was demonstrated in the sea around Ishigaki Island, Japan.

The subsurface radar suffers from two typical problems, i.e., strong clutter from surface and severe wave attenuation in the underground. This paper presents a unique countermeasure to these problems using a polarimetric FM-CW radar and an equivalent sensitivity time control (STC) technique. The authors apply the polarimetric filtering principle to suppress surface clutter either in the Co-pol channel or in the X-pol channel of synthetic aperture radar, yielding to polarimetric enhanced target image. This technique works when the surface clutter and target have different polarization properties. Moreover, they use an equivalent STC technique specially suited for FM-CW radar for a deep object sounding to compensate wave attenuation within the ground. These techniques contribute to a significant improvement of the radar performance and the detection image contrast, although the detection of the target is in general a much more complicated topic. The field experiments were carried out to show the usefulness of the method. Some detection results are presented.

In modern surveillance radar, pulse compression is applied to achieve long range coverage while maintaining both low transmit peak power and desired range resolution. When there is a requirement to increase the radarpsilas range without a corresponding increase in the transmitted peak power it is required that a longer uncompressed pulse be used. As a consequence the blind range, associated with blanking the receiver whilst transmitting the pulse, will increase and short range coverage will be lost. In this paper we initially present a system of concatenated waveforms that provide simultaneous radar coverage for both near and far ranges. The solution incorporates a combination of longer sub-pulses for far range and shorter sub-pulses for near range. Although the concatenated waveforms have a number of attractive attributes, they present a challenging problem in that different sub-pulses will reflect back from different ranges and be received at the same time. Therefore since each sub-pulse is not separable at the RF front end a more complex sensitivity time control (STC) is required. In the second part of this paper we analyze this phenomenon and propose a STC scheme to address the issue.

This work mainly focuses on the digitisation of Sensitivity Time Control for Radar receivers using Field Programmable Gate Arrays (FPGAs). Sensitivity Time Control (STC) is one of the gain control methods for RADAR signal processing. Gain control is used to adjust the sensitivity of the receiver thereby regulating the intensity of the returns. STC helps in increasing the dynamic range of the receiver and thus prevents the receiver saturation. STC is achieved by applying an attenuation that varies with the range thus making the receiver signal strength range independent. The attenuation to be applied to the echo signal is constant up to a certain range and then varies exponentially depending upon the clutter environment. The digital implementation technique using FPGAs gives a high degree of flexibility in selecting the STC laws in real time depending upon the environment. This design calculates the attenuation value up to an accuracy of 0.001dB.

A modern coherent Antarctic radar depth sounder for probing the ice sheets of Antarctica and Greenland has been designed and developed by the University of Kansas. It was successfully tested during the austral summers of 1987 and 1988 at Downstream Β and Upstream B, Antarctica. Ground-based measurements were made with the radar in a mobile hut hauled by a Sno-cat in 1987 and in a Spryte vehicle in 1988.The coherent Antarctic radar depth sounder (CARDS) is an unfocussed synthetic-aperture chirp radar where the along-track resolution is improved by extensive coherent integration. Surface acoustic wave (SAW) devices are used to implement pulse expansion and compression. A common stable oscillator for the transmitter and the receiver establishes coherency. The system signal-to-noise ratio is enhanced by pulse compression and coherent integration. Antennas for the ground-based measurements are configured with an array of eight dipole elements, four active and four passive, the latter acting as reflectors. The aircraft antennas also consist of four active elements hung underneath the two wings. The wings serve as reflectors. A PC facilitates system control and data recording on a high-density recorder. Α-scope plots of selected records allow frequent field checks on system performance. More descriptive display facilities have been incorporated in the latest version of the system.The radar transmits 60 ns, 20 W peak power at 150 MHz. The number of coherent integrations is selectable up to 64 k. The system is capable of 5 m range resolution and 5 km range in ice. A programmable sensitivity time control (STC) increases the receiver dynamic range. System parameters such as pulse-repetition frequency, number of integrations, and display modes can be chosen during field operations by user-friendly software.This paper describes the design and field operations of the system. Some results of the 1987 operations at Downstream Β are presented.

A new short-pulse digital profiling radar system that operates at lower frequencies than most ice radars used in polar regions to date has been designed and built by the U.S. Geological Survey. The transmitter is an avalanche transistor pulser which drives a resistively loaded dipole transmitting antenna. A similar, but separate antenna is connected to the receiver. The receiver has adjustable sensitivity time control (STC) of as much as 60 dB to compensate for attenuation and geometric spreading factors. A fiber-optic cable is used to transmit both control signals and data. The data-acquisition and display system incorporates very high-speed digitizing and signal averaging, real-time profile display, and data storage on standard computer nine-track magnetic tape.The system was successfully used on Ice Stream B in West Antarctica at centre frequencies of 1, 2, 4, 8, and 12.5 MHz. Bottom-return signal-to-noise ratios of more than 40 dB were obtained at 2 MHz through 800 m of ice. Convoluted internal surfaces not related to present bottom topography were resolved within the ice streams and anomalous strong reflections or “bright spots” were identified near the base of the ice. At present, there is no satisfactory glaciological explanation for either of these observations.

Three channel microwave receivers are widely used in almost all tracking radars utilizing monopulse technique for precision angle tracking. In this paper, the design and realization of a high dynamic range monopulse microwave receiver front- end for a highly application specific airborne tracking radar system has been presented. This design is unique in terms of achieving the desired dynamic range avoiding implementation of sensitivity time control (STC) and automatic gain control (AGC), realized within the space and weight constraints of the system. Phase and amplitude matching between the channels, isolation from transmitter leakage were the other important factors considered. Basic configuration has been presented along with the results of simulation which has been carried out using electronic design automation (EDA) software. Measured results have also been compared with the simulation and presented.

A range of new limiter and receiver protector devices is described, comprising planar device structures in drop-in and packaged surface-mount constructions. Low-loss, low leakage limiters are presented, spanning L (1.1 GHz), S (3 GHz) X (9 GHz) and Ku (16 GHz) frequency bands. Device designs are also shown which feature switching, sensitivity time control (STC) attenuation and noise sources as additional functionality integrated within the planar limiter module.

The new generation of radar has to be equipped with a high performance exciters and receivers to cope with the threat in an Electronic Warfare scenario. The threat in a complex environment with interfering signals requires a reliable signal generation with proper frequency agility and efficient gain controls in receiver units. This is quite cumbersome to achieve in analog domain. Due to digital technology advancements, it is possible to have efficient and high performance Analog-to-Digital converters (ADC),processors, high-density memories and efficient algorithms to realize highly reliable, flexible and upgradeable exciters and receivers. In this design, exciter unit comprises of various digital modules for waveform generation, clocks and synchronization signal generation for different sub-systems of the radar and digital code generation for the frequency to be synthesized. These codes are used to control the Local Oscillators (LOs) output utilized for the up-conversion. In the Receiver unit main focus is on the digital implementation of gain control like sensitivity-time-control (STC), Generation of various controls required by Synthetic noise generator and Automatic Gain Control (AGC) and Digital amplitude Phase Demodulation (DAPD) of down-converted sampled intermediate frequency (IF) signals. This work projects the digital design methodology behind the various modules identified for the Radar Signal Generation and Receiver units. The main highlight of the paper is that the entire design models described are implemented using digital methods using FPGAs. The Xilinx System Generator (XSG) design tool is used to accomplish this, which generates directly the code for a Xilinx FPGA on a target board.

Modern solid-state limiter receiver protection devices are described, addressing the broad range of operating frequencies and system power levels encountered in modern radar systems. In particular, the replacement of legacy transmit/receive (TR) cells with solid-state receiver protectors (SSRPs) enables receiver protection performance without the added lifecycle costs of radio-active gas fillings and high-voltage power supply infrastructure. Where high power levels persist, due to operational or asynchronous conditions, then gas tube (pre-TR tube or gas switch) solutions can be used, neither of which require a radioactive or high-voltage corona primer within the tube. Multifunction devices allow the integration of the receiver protector with further system functions, such as noise sources, sensitivity time control (STC) attenuation and filtering, optimising electrical performance, physical size and mass of the device.

This paper develops a method to calculate the effects of sensitivity time control (STC) on interference, experienced by one radar, caused by another radar. The probability density function (PDF) of STC attenuation is determined by, and is related to the overall probability distribution that determines the probability of interference. This method is consistent with, and complementary to the method of calculating the effects of antenna-to-antenna coupling between the radars. >

The airborne synthetic-aperture radar (SAR) system developed for the Canada centre for remote sensing is discussed. The SAR consists of two radars at C- and X-bands. Each radar incorporates dual-channel receivers and dual-polarized antennas, a high quality, seven-look, real-time processor; a sensitivity time control for range-dependent gain control; a motion time control for range-dependent gain control; a motion compensation system for antenna steering in azimuth and elevation; and baseband I- and Q-signal phase rotation. The system features a high-power transmitter with a low-power backup and can map to either side of the aircraft, at high or low resolution, at incidence angles which in high resolution span 0 degrees to 80 degrees . The radar operating parameters, data products, key specifications and the motion-compensation scheme used are given. Properties of the real-time imagery are discussed and examples of C-band SAR data in the three operating modes are presented. >

The need for increased dynamic range at the input to the radar digital signal processor has increased steadily over the last decade or so. This has been the result of lower expected radar cross sections, the need for better clutter suppression, and the desire to operate without sensitivity time control (STC) in some radar applications. The analog-to-digital converter (ADC) is the most significant bottleneck in achieving this needed dynamic range (DR). An approach for improving the effective DR utilizing multiple ADC is described. The ADC are arranged in parallel channels with different gains and the approach is referred to as a "stacked A-to-D converter", or "stacked ADC". Detailed results are presented for an experimental brassboard system assembled to demonstrate and evaluate the concept.

The need for increased dynamic range at the input to the radar digital signal processor has increased steadily over the last decade or so. This has been the result of lower expected radar cross sections, the need for better clutter suppression, and the desire to operate without sensitivity time control (STC) in some radar applications. The analog-to-digital converter (ADC) is the most significant bottleneck in achieving this needed dynamic range performance. In this report, an approach for improving effective dynamic range using multiple ADCs is described. The ADCs are arranged in parallel channels with different gains and the approach is referred to as a "Stacked Analog-to-Digital Convener," or "Stacked ADC," in this report. Detailed results are presented for an experimental system assembled to demonstrate and evaluate the concept.

Two high-dynamic-range receiver subsystems for use in airborne radar fire control and tracking applications are described. The X-band dual-channel monopulse tracking receiver operates at 9.36+or-0.290 GHz with a 6-dB noise figure and a linear instantaneous dynamic range of 42 dB. A total of 80 dB of RF and IF gain control is programmable with less than +or-15 degrees phase and +or-1 dB amplitude tracking errors. The Doppler radar receiver operates at 9.3+or-0.15 GHz and has a 4.6-dB noise figure with >or=80 dB of instantaneous dynamic range. An 18-dB sensitivity time control (STC) circuit and a 60-dB dump attenuator allow close-in target reception. >

A completely transistorized automatic sensitivity time control (ASTC) circuit was designed and developed to operate in conjunction with a side-looking airborne radar surveillance set. The ASTC technique is a closed loop system which automatically controls the radar receiver gain vs range function in accordance with the average signal return. The addition of ASTC substantially improved the imagery of a side-looking airborne radar recorded during low altitude flights.

The return signals from a pulsed air /underwater laser radar system can have dynamic ranges that exceedthe capabilities of normal photomultiplier tubes, creating spurious signals. By actively controlling thegrid voltage of a photomultiplier tube, the usable dynamic range of a receiver can be extended. Careful active control of the grid voltage on an ITT 6 stage 4084 photomultiplier has resulted in gain changes inexcess of 50 dB in a time frame of several hundred nanoseconds. This programmed STC (sensitivity timecontrol) has allowed the recording of enhanced signal returns covering larger dynamic ranges than previouslypossible, without spurious signals resulting from multiplier overload.IntroductionThe Naval Air Development Center operates an SH -3 helicopter equipped with an air /underwater laser radar system. Applications include communication, target recognition, and oceanographic data collection.The use of a short pulse, high power, frequency doubled Nd:YAG laser yields high initial air backscatter

This paper presents a description of the Airborne Bathymetric System (ABS) laser sounder system hardware. The system was designed for installation and operation aboard a P-3 aircraft. In normal operation, the aircraft flies at a 500 meter altitude and a speed of 180kts (100m/s). With these operation parameters and a 270m survey swath width, the system surveys at about 100km2 per hour. For an average daily flight of four hours, 400km2 of coastal ocean can be mapped. The laser sounder system collects 400 Light Detection And Ranging (LIDAR) measurements a second for up to 4 continuous hours. It has a horizontal resolution of approximately 10m and a vertical resolution of about 0.54m, at a 15° scan angle. The LIDAR system sports a KD>3 (K=diffuse attenuation coefficient, D=depth penetration) performance. The ABS laser sounder has taken advantage of new parallel processing computer architectures, improved waveform digitizers, and optical disks. In this system, digital real time processing has replaced past analog processing. This is due to the realization that it is easier to build and implement an adaptive digital algorithm than it is to build an adaptive hardware analog processor. The system hardware consists of a transceiver, Sensitivity Time Control (STC) circuit for the gateable Photo-Multiplier Tube (PMT), dual computer system (data collection system and real time read after write processing system) using six single board computers, 400 mega-sample per second waveform digitizer, High Density Digital Recorder (HDDR), Global Positioning System (GPS) receiver/pre-processor, aircraft Inertial Navigation System (INS) interface/pre-processor, millisecond resolution clock, two information displays and an optical disk.

The need for improved Sensitivity Time Control circuits in Air Traffic Control radar equipment becomes more imperative as Emergency Mission System search and precision radars become more sensitive and all-weather tracking and controlling to within a mile of the radar site becomes standard procedure. This report traces the development of a sophisticated logarithmic STC circuit from previously derived concepts through incorporation in, and evaluation of, the latest EMS search radar. The development of Digital Video Data processing equipment led to design and experimental work on a digital STC concept. The preliminary investigation of this concept indicates that a significant advance in this direction is possible in clutter attenuating devices. Reference is also made to the current EMS system including test results plus recommendations for improvements in anti-clutter devices for present and future search and precision radars.

This paper presents a method to predict site-specific radar coverage. The method is based on solving the monostatic scattering problem by using the physical optics (PO) or Kirchhoff method, in combination with the use of geographical information systems, to model the specific terrain. The possibility to calculate the radar coverage, the time of arrival of the reflected pulses and the power delay profile allows the effect of clutter and multi-reflections to be analyzed in detail. Radar parameters, such as its location, antenna types, pulse duration and pulse repetition frequency can be optimized. Also, this information is of great interest in the design and improvement of sensitivity time control (STC) and constant false-alarm rate (CFAR) systems.

We have proposed a technique for measuring the ultrasonic attenuation constant of tissues in vivo, using a linear-scanned B-mode tomogram which is widely employed in abdominal diagnosis. In this technique, the attenuation constant of a tissue can be estimated by measuring its attenuation related to a reference scattering phantom with known attenuation constant. The merits of this technique are independent of the sensitivity time control (STC) and almost free of the beam focussing. This paper outlines the technique.