Abstract: A technique and apparatus for increasing the peak output pulse power of a capacitor driven high-power diode and square-loop saturable reactor pulse compression generator or transmitter (such as a Loran-C transmitter or other high power pulse generator) with the aid of a minority carrier sweep-out circuit interposed, within the pulse compression circuit.

Abstract: Methods and apparatus are provided for radar systems using multiple pulses that are shorter than the expected range delay extent of the target to be imaged. In one implementation, a method for performing radar includes the steps of: transmitting a plurality of pulses, each pulse having a different center frequency and a time duration shorter than an expected range delay extent of a target, wherein a total bandwidth is defined by a bandwidth occupied by the plurality of pulses; receiving reflections of the plurality of pulses; and performing pulse compression on the received pulse reflections to generate a detection signal having a radar resolution approximately equivalent to the transmission and reception of a single pulse having the total bandwidth. In preferred form, the pulses comprise ultrawideband (UWB) pulses each occupying a sub-band of the overall system bandwidth.

Abstract: A stepped-frequency chirped waveform improves SAR groundmapping for the following reasons. Range resolution in SAR image is inversely proportional to the transmitted signal bandwidth in nominal SAR systems. Since there is a limit in the transmitted bandwidth that can be supported by the radar hardware, there is a limit in range resolution that can be achieved by processing SAR data in conventional manner. However, if the frequency band of the transmitted signal is skipped within a group of sub-pulses and received signal is properly combined, the composite signal has effectively increased bandwidth and hence improvement in range resolution can be achieved. The proposed new and practical approach can effectively extend the limit in range resolution beyond the level that is set by the radar hardware units when conventional method is used.

Abstract: A current source modulator (202; 302, 502) provides power to radar transmitters. The modulator comprises a power supply (210, 310, 510) providing, when enabled, a known current to a storage capacitor (145). A comparator circuit (220) provides a signal (V220) when voltage (VC) across the storage capacitor (145) falls a reference voltage, and an enable circuit (225) responds to the comparator signal (V220) and an ON command signal to enable the power supply (210, 310, 510). The modulator (202, 302, 502) further includes a network (220N) associated with the comparator circuit (220) to retain the value of the signal (provide hysteresis) when the voltage across the storage capacitor is above the reference voltage. The modulator (202, 302, 502) may include a second network (320N) associated with a second comparator circuit, operable to retain a second signal when capacitor (145) voltage VC is above a reference voltage. In this aspect, there is a rapid charge and a trickle charge that reduces any charging overshoot.

Abstract: In order to create a method for eliminating dummy objects in short-range pulse radar sensors, in which radar pulses are transmitted at a defined frequency, and the time until they are reflected by an object and received again is measured, and besides the transmitted pulse (TX pulse), a delayed second pulse (RX pulse) is generated, which avoids the known disadvantages of the prior art and with which the elimination of dummy objects in short-range pulse radar sensors can be assured, it is provided that the transmitted pulses (TX pulses) and the additionally generated second pulses (RX pulses) delayed relative to them are modulated by a binary phase-shift keying process.

Abstract: A method for processing a received, modulated pulse (i.e. waveform) that requires predictive deconvolution to resolve a scatterer from noise and other scatterers includes receiving a return signal; obtaining L+(2M?1)(N?1) samples y of the return signal, where y(l)={tilde over (x)}T(l)s+v(l); applying RMMSE estimation to each successive N samples to obtain initial impulse response estimates [{circumflex over (x)}1{?(M?1)(N?1)}, . . . , {circumflex over (x)}1{?1}, {circumflex over (x)}1{0}, . . . , {circumflex over (x)}1{L?1}, {circumflex over (x)}1{L}, . . . , {circumflex over (x)}1{L?1+(M?1)(N?1)}]; computing power estimates {circumflex over (?)}1(l)=|{circumflex over (x)}1(l)|2 for l=?(M?1)(N?1), . . . , L?1+(M?1)(N?1); computing MMSE filters according to w(l)=?(l)(C(l)+R)?1s, where ?(l)=|x(l)|2 is the power of x(l), and R=E[v(l)vH(l)] is the noise covariance matrix; applying the MMSE filters to y to obtain [{circumflex over (x)}2{?(M?2)(N?1)}, . . . , {circumflex over (x)}2{?1}, {circumflex over (x)}2{0}, .

Abstract: The invention relates to a pulse-modulated source with adjustable parameters and to its use in an IFF or secondary radar emitting assembly. The architecture of currently used IFF emitting assemblies is such that there is a limit to the possible reduction in the space requirement of such equipment, and this limit is soon reached. Furthermore, the precision in terms of frequency remains coarse and the number of IFF emitting modes is very small. A programmable source of pulse trains on an intermediate frequency is disclosed.

Abstract: A wave-form generator drives a number of microwave generating devices each operating at different frequency bands. The output of each microwave generator is connected to its own transmission channel of limited bandwidth which contains all the non-linear components necessary for transmission such as an amplifier, T/R switch, rotary joint and beam switch. These individual channels are finally combined onto a common wideband channel which contains only substantially linear components such as a single waveguide and the antenna itself. Because of the isolation between channels there is little or no opportunity for the generation of harmonics or intermodulation distortions which would otherwise occur in a transmitter capable of operating over a very wide bandwidth.

Abstract: A method for transmitting a radar signal comprises the step of transmitting a series of pulses, each of the pulses being separated in time by an interpulse period, and each of the pulses in the series being modulated in accordance with a different character of a first code

Abstract: A pulse radar device includes a rectangular signal generating section for generating a rectangular signal that is a reference signal; a transmit timing voltage setting section for setting a voltage value for determining a transmit timing; a transmit pulse generating section for generating a transmit pulse based on the rectangular signal and the voltage value; a receive section for receiving a reflection wave obtained by reflecting the electric wave transmitted by the transmit section by a plurality of objects; a receive saw-tooth wave generating section for generating a saw-tooth wave in synchronism with the transmit pulse; a receive signal sample hold section for sample-holding the receive signal based on the outputs from the saw-tooth wave and the rectangular signal; and a detecting and distance measuring section for detecting the objects and measuring a distance to the objects based on the sample/hold output.

Abstract: A radar system is operated by controlling and thereby limiting the mean power of the transmitted signal in response to the mean power of the received signal thereby limiting the power to a predetermined power range. Preferably the power control or regulation is performed by varying the pulse repetition frequency and/or the pulse duration of the transmitter pulses. This method is well suited for operating a motor vehicle range warning system.

Abstract: A pulse radar system has a high-frequency source, which supplies a continuous high-frequency signal and is connected on the one side to a transmission-side pulse modulator and on the other side to at least one mixer in at least one receive path. A pulse modulator is connected upstream of the mixer with regard to its connection to a receiving antenna. The mixer evaluates a radar pulse reflected by an object together with the signal of the high-frequency source. This system does not require a ZO switch and is insensitive to interference.

Abstract: This invention features an improved technique for search and track surveillance. In this invention, distinct and random (in both space and time) signal beams are simultaneous transmitted from an array of transmitter source elements in a manner to cover all sectors about a source location. In addition, countermeasures against a system according to the invention are difficult because the signal waveforms for each beam are distinct and random, making prediction of any signal waveform for any beam very unlikely. An array of receiver sensor elements is provided to receive signals that are scattered from remote objects and may or may not be co-located with and share the elements of the source array element. The scattered signals are received and processed to yield the direction and range of the remote objects.

Abstract: A radar device includes elements for generating a carrier signal having a carrier frequency fT, elements for generating pulses with a pulse repetition frequency fPW, elements for distributing the carrier signal to a transmission branch and a receiving branch, elements for modulate the carrier signal in the transmission path using the undelayed pulses, elements for modulating the carrier signal in the receiving branch using the delayed pulses and for generating a reference signal, elements for mixing the reference signal in the receiving branch with a received signal and elements for integrating the mixed signal. Elements are provided for binary phase shift keying (BPSK) modulation of the carrier signal and elements are provided for switching the polarity of the received signal. A method for suppressing interference in a radar device is also described.

Abstract: A method of controlling a switching element in a switching regulator power supply of a radar. The method of controlling the switching element comprises only switching the switching element during predetermined time intervals, the predetermined time intervals advantageously being sample intervals of a pulse repetition interval of the radar. Thereby by having knowledge of the time intervals the switching element is switching, being able to remove or diminish any influence the switching can have on the quality of received signals and subsequent processing of these signals.

Abstract: A method for transmitting a radar signal comprises the step of transmitting a series of pulses, each of the pulses being separated in time by an interpulse period, and each of the pulses in the series being modulated in accordance with a different character of a first code

Abstract: The invention relates to a pulse-modulated source with adjustable parameters and to its use in an IFF or secondary radar emitting assembly. The architecture of currently used IFF emitting assemblies is such that there is a limit to the possible reduction in the space requirement of such equipment, and this limit is soon reached. Furthermore, the precision in terms of frequency remains coarse and the number of IFF emitting modes is very small. A programmable source of pulse trains on an intermediate frequency is disclosed.

Abstract: An object of the present invention is to facilitate positioning of a metal member for mounting a high-frequency diode and of a dielectric strip, thereby remarkably improving control of oscillation characteristics and workability in production.

Abstract: A radar apparatus provided with a transmitter for periodic transmission of mutually disjunct groups of N radar transmitter pulses and provided with a receiver for the receipt of echo signals of the groups of radar transmitter pulses. The radar apparatus includes a video processor for processing echoes in a listening time observed between two of the mutually disjunct groups of radar transmitter pulses. By choosing a suitable staggering of the pulses in a group, the target range and velocity may be unambiguously determined.

Abstract: The invention provides a magnetron drive circuit which drives a magnetron to produce a generally rectangular-shaped narrow transmission pulse having sharply shaped rising and falling edges. The magnetron drive circuit includes a nonlinear load circuit and an active damper circuit. The nonlinear load circuit becomes on at around 80% of a peak output voltage of a pulse transformer (at which the magnetron begins to oscillate) is connected to a secondary winding of the pulse transformer in parallel with the magnetron. The active damper circuit absorbs residual energy left in the pulse transformer without any need for an absorption resistor conventionally connected between both ends of a primary winding of the pulse transformer.

Abstract: A doppler radar device having comparing means 142 for comparing the level of pulse signal to be transmitted, sampled through a burst gate, with a predetermined threshold value and search means 143 for changing a set position of the gate, wherein a timing of oscillating the pulse signal is monitored and tracked to fix “range 0” by shifting a timing for triggering transmission of the pulse signal in consideration of a deviation of the timing of oscillating the pulse signal and a jitter value.

Abstract: A radar system having an arrangement for producing a code, an arrangement for modulating a transmission signal in a transmit branch, using the code, an arrangement for delaying the code, an arrangement for modulating a signal in a receive branch, using the delayed code, and an arrangement for mixing a reference signal with a receiving signal, the modulation of one of the signals being performed by an amplitude modulation (ASK; “amplitude shift keying”) and the modulation of the other signal by a phase modulation (PSK; “phase shift keying”). Furthermore, a radar system is proposed in which blanking of phase transitions is provided. Also described are methods which may advantageously be carried out, using the radar systems described herein.

Abstract: A system and method for generating an ultra-wide band communication signal having data occurring a specific frequencies precisely excised at baseband. The data to be transmitted is transformed into a function of time where the data to be excised can be removed in the time domain. After the data has been successfully removed in the time domain, the data is then transmitted in the frequency domain in which no data is transmitted at the frequencies where the data was precisely excised.

Abstract: A pulse radar device includes a transmitting unit, a receiving unit, a first integrating unit for sampling a reception signal at predetermined time intervals from transmission and integrating results of a predetermined number of times of the sampling at each sampling timing, a differential operating unit for, each time a predetermined time period has passed, reading results of the integrating at each sampling timing and differentiating the read results of the integrating in a sampling direction, a second integrating unit for integrating absolute values of a predetermined number of outputs from the differential operating unit at each sampling timing, a peak detecting unit for detecting the peak of an output from the second integrating unit, a distance measuring and detecting unit for calculating a distance to an object and judging presence or absence of an object based on an output from the peak detecting unit and the like.

Abstract: A radar device is described having means (12) for generating a first code, means (18) for modulating a transmission signal in a transmitting branch using the first code, means (32) for delaying the first code, means (20) for modulating a signal in a receiving branch using the delayed first code, and means for mixing a reference signal with a reception signal, multiple receiving channels (111, 112, . . . 11k) being provided, the receiving channels (111, 112, . . . 11k) having means (1201, 1202, . . . 120k) for generating additional codes (C1, C2, . . . Ck), the receiving channels (111, 112, . . . 11k) having means (131, 132, . . . 13k) for demodulating using the respective additional codes (C1, C2, . . . Ck), and means (15) being provided for modulating the transmission signal using at least one of the additional codes (C1, C2, . . . Ck). A method which may be implemented advantageously using the radar device described is also described.

Abstract: A radar device includes elements (10) for generating a carrier signal having a carrier frequency fT, elements (12, 14) for generating pulses with a pulse repetition frequency fPW, elements (16) for distributing the carrier signal to a transmission branch and a receiving branch, elements (20) for modulate the carrier signal in the transmission path using the undelayed pulses, elements (22) for modulating the carrier signal in the receiving branch using the delayed pulses and for generating a reference signal, elements (24) for mixing the reference signal in the receiving branch with a received signal and elements (26) for integrating the mixed signal. Elements (28, 30) are provided for binary phase shift keying (BPSK) modulation of the carrier signal and elements (32) are provided for switching the polarity of the received signal. A method for suppressing interference in a radar device is also described.

Abstract: A doppler radar device having comparing means 142 for comparing the level of pulse signal to be transmitted, sampled through a burst gate, with a predetermined threshold value and search means 143 for changing a set position of the gate, wherein a timing of oscillating the pulse signal is monitored and tracked to fix “range 0” by shifting a timing for triggering transmission of the pulse signal in consideration of a deviation of the timing of oscillating the pulse signal and a jitter value.

Abstract: The present invention relates to a radar system having means (12) for producing a code, means (18) for modulating a transmission signal in a transmit branch, using the code, means (32) for delaying the code, means (20) for modulating a signal in a receive branch, using the delayed code, and means (26) for mixing a reference signal with a receiving signal, the modulation of one of the signals being performed by an amplitude modulation (ASK; “amplitude shift keying”) and the modulation of the other signal by a phase modulation (PSK; “phase shift keying”). Furthermore, a radar system is proposed in which blanking of phase transitions is provided. The present invention also relates to methods which may advantageously be carried out, using the radar systems according to the present invention.

Abstract: A microwave transmitter circuit including a divider series feed signal line, a collector series feed signal line, a plurality of parallel solid state amplifier coupler circuits connected between divider series feed line and the collector series feed line, and phase shifting circuitry distributed along the collector series feed line for compensating phase tracking error between the divider series feed line and the collector series feed line.

Abstract: The invention relates to a device for emitting high-frequency signals, comprising a signal generation unit (6), a signalling line (12), an emission cable (16) and an antenna configured as a circular waveguide (10), said antenna being sealed in an end section by a rear wall (15). According to the invention, the signal generation unit (6) creates the high-frequency signals, the signalling line (12) conducts the high-frequency signals along the emission cable (16) and said emission cable (16) projects into the interior of the antenna (10) and is positioned approximately parallel to the rear wall (15). The invention aims to provide a device for emitting electromagnetic waves, which is characterized by optimized emission characteristics. To achieve this, the distance (Z) between the emission cable (16) and the rear wall (15) of the antenna (10) is approximately &lgr;/6, whereby &lgr; is the wavelength of the high-frequency signals borne by the antenna (10).

Abstract: A combined defense and navigational system on a naval vessel is disclosed. The disclosed system includes a track-while-scan pulse radar which is controlled to provide either navigational information or tracking information on selected targets. Additionally, the disclosed system includes a plurality of guided missiles, each of which may be vertically launched and directed toward intercept of a selected target either by commands from the track-while-scan radar or from an active guidance system in each such missile.

Abstract: The invention provides a magnetron drive circuit which drives a magnetron to produce a generally rectangular-shaped narrow transmission pulse having sharply shaped rising and falling edges. The magnetron drive circuit includes a nonlinear load circuit and an active damper circuit. The nonlinear load circuit becomes on at around 80% of a peak output voltage of a pulse transformer (at which the magnetron begins to oscillate) is connected to a secondary winding of the pulse transformer in parallel with the magnetron. The active damper circuit absorbs residual energy left in the pulse transformer without any need for an absorption resistor conventionally connected between both ends of a primary winding of the pulse transformer.

Abstract: A radar for locating and tracking objects based on the use of a pulsed waveform, each pulse of the pulsed waveform being made up of a plurality of spectral components having different frequencies, including an antenna. The radar further includes a transmitter operatively coupled to the antenna for generating the plurality of spectral components that make up each pulse of the pulsed waveform and a receiver operatively coupled to the antenna for receiving signals at the frequencies of the plurality of spectral components.

Abstract: A technique is described for providing a pulsed radar exciter signal, in a radar exciter including a direct digital synthesizer (DDS). The DDS is reset pulse-to-pulse to provide a pulsed DDS signal having pulse-to-pulse phase discontinuities due to the resetting of the DDS. The phase of the pulsed DDS signal can be shifted pulse-to-pulse by a phase shift that is held constant over a pulse to correct the pulse-to-pulse phasing of the DDS signal. A discrete phase modulator can provide the phase shift. The phase of the pulsed DDS signal can be shifted pulse-to-pulse by an additional phase shift which is a linear phase sequence from pulse-to-pulse, or by an additional phase shift which is a quadratic phase sequence from pulse-to-pulse to produce a ranging waveform.

Abstract: A mixer used in a millimeter-wave band and a microwave band capable of achieving loss reduction, a radar module, and a communication apparatus incorporating the mixer and having high efficiency. The mixer includes two electrodes formed on one main surface of a dielectric substrate and another electrode formed on another main surface thereof such that non-electrode portions on both main surfaces are opposed to each other via the dielectric substrate. Additionally, a diode is connected bridging a slit between the two electrodes on one main surface to constitute a circuit board. The circuit board and a dielectric strip are arranged between upper and lower conductive plates.

Abstract: A multifrequency phase-coded signal structure is presented for use in a system like a radar or sonar or detecting a remote target. The signal structure comprises at least one pulse signal in the form of a mutually complementary set of M sequences, each sequence being composed of M phase-modulated bits. Each two adjacent sequences are modulated on subcarriers separated by a frequency fs such that fs=1/tb, tb being a bit duration, and a the subcarriers are transmitted simultaneously.

Abstract: Identity transform filters, such as sin(x)/x filters, are used to coherently fragment the frequency continuum of a wideband waveform, such as an ultra wideband radar signal, into a plurality of spectral segments that are capable of fitting into unoccupied spectral regions of a partially occupied electromagnetic spectrum. The wideband waveform has a bandwidth that falls within the partially occupied portion of the electromagnetic spectrum, and exceeds that of any unoccupied spectral region. The total useable bandwidth of the unoccupied regions is at least equal to that of the wideband waveform.

Abstract: In a method and device for the encoding/decoding of the power distribution at the outputs of a system, the distribution encoder comprises an element that receives a signal s(t) and a piece of distribution information i(t), and that superposes said piece of distribution information i(t) received on said signal s(t) received. The piece of information i(t) is used for the subsequent distribution of the total power Ps of said signal s(t) at said output or outputs {S&Ggr;} of a system &Ggr;. The distribution decoder comprises one or more inputs on which there is received an encoded signal c(t) or an encoded signal divided into several signal (cj(t))j&egr;[1,2N] comprising the useful signal s(t) and the piece of distribution information i(t). It also comprises one or more outputs connected to the outputs {S&Ggr;} of said system &Ggr; to which said signal s(t) is transmitted by distributing the total power received Ps according to said piece of distribution information i(t).

Abstract: This invention features an improved technique for search and track surveillance. In this invention, distinct and random (in both space and time) signal beams are simultaneous transmitted from an array of transmitter source elements in a manner to cover all sectors about a source location. In addition, countermeasures against a system according to the invention are difficult because the signal waveforms for each beam are distinct and random, making prediction of any signal waveform for any beam very unlikely. An array of receiver sensor elements is provided to receive signals that are scattered from remote objects and may or may not be co-located with and share the elements of the source array element. The scattered signals are received and processed to yield the direction and range of the remote objects.

Abstract: The duty cycle of a pulse train from a pulse radar antenna is increased by dividing the antenna aperture into sub-apertures (1-5), generating separate pulse trains from said sub-apertures (1-5), and time shifting the separate pulse trains between themselves to produce a resulting pulse train having shorter pulse spacing or wider pulses.

Abstract: The digital coherent radar generates its transmitted waveform from a low intermediate frequency (IF) and a local oscillator (LO) by digitally generated waveforms after passing through digital-to-analog (D/A) converters. The LO is increased in frequency using a product multiplier. The IF representation of the transmitted waveform is upconverted using the LO. The transmitted waveform is amplified and passed through a circulator to an antenna. The echos are received through the antenna and passed through the circulator and receiver protector. The received signal is then downconverted to a digital signal and passed on to a processor. Finally, the waveform is reset and restarted by the local oscillator generator, the digital-to-analog converters, and the analog-to-digital converter at the beginning of each pulse. It must be insured that all pulses in a pulse train are identical even though there are deterministic errors in the representation of the transmitted signals desired coherent component.

Abstract: A time domain reflectometry measuring instrument uses a microprocessor that provides added functionality and capabilities. The circuit electronics and probe are tested and calibrated at the factory. Installation and commissioning by the user is simple. The user installs the probe. The transmitter is attached to the probe. The user connects a standard shielded twisted pair to the electronics. Power is applied and the device immediately displays levels. A few simple parameters may need to be entered such as output characteristics and the process material dielectric constant.

Abstract: The invention relates to solid-state radar transmitter, comprising a number of amplifier modules (4.i). To prevent the trailing edge of a steer pulse supplied to the radar transmitter from becoming too steep when passing the amplifier modules (4.i) driven in saturation, the supply voltage on at least One amplifier state in each amplifier module (4.i) is switched off just before the end of the steer pulse.

Abstract: A radar system employing Doppler tolerant radar pulses such as linear FM or hyperbolic FM chirps includes a pulse compressor configured as a digital finite impulse response filter. In one embodiment, the radar returns are split into in-phase and quadrature phase components for manipulation in complex form within the filter.

Abstract: A pulse radar system includes a frequency-agile magnetron comprising an input for giving a feeding voltage of a magnetron tuner. A modulator connected to said magnetron forms pulses of a feeding voltage for the magnetron. A low power signal source also connected to said magnetron generates microwave frequency signals which are given to the magnetron in pauses between pulses. These signals have the frequencies differing from the frequencies of the signals generated by the magnetron and fixed during each period of magnetron pulse repetition. This radar system also includes a signal converter receiving the low power signals reflected by the magnetron. These signals are converted into the signals connected in time to the moments, when the frequencies of the low power source and the frequencies of the magnetron oscillating system coincide with each other. Further, said signals are used for triggering the modulator connected to said converter.

Abstract: A meteorological radar apparatus which calculates a shift of the pulse synchronization of a transmission pulse signal output from a transmission unit and corrects the transmission timing of the transmission pulse signal based on the shift of the pulse synchronization so that the Doppler velocity of a reference target becomes zero, thereby preventing deterioration in the measurement accuracy of the Doppler velocity caused by the shift of the pulse synchronization of the transmission pulse signal.

Abstract: The present invention relates to radars and sonars, and more particularly to a synthetic-band technique of pulse compression making it possible to reach a very high distance resolution. Synthetic band consists in transmitting a waveform pattern consisting of a string of N coherent elementary pulses, linearly frequency-modulated, following one another at a recurrence frequency F.sub.r, of rectangular frequency spectra of elementary band B and of stepped carrier frequencies such that their frequency spectra will link up exactly one ahead of another to form a global spectrum of width N.times.B. On reception, the frequency spectra of the signals received in return for the N elementary pulses of a pattern are extracted by calculation, translated and juxtaposed so as to reconstruct a global frequency spectrum of width N.times.B and then compressed. Pulse compression is thus obtained which is equivalent to that which would result from the transmission of a waveform having a single pulse of frequency band N.times.

Abstract: The invention concerns a method of synthesizing a replica used in the compression filter of pulse compression radar.The replica is calculated from the spectrum of a required impulse response.The required impulse response is preferably obtained from an analytical function, such as a sinc function or a weighted sinc function, and a template.It is preferable to use calibration signals of the instrument to calculate the replica.The invention also applies to synthetic aperture radar.

Abstract: A processing method for use in providing improved SAR imagery at high duty factors that provides for enhanced radar sensitivity. Radar signals are transmitted that embody a high duty factor ultra-high resolution SAR waveform generated using a biphase code with a predetermined high pulse compression ratio. Received radar returns comprising a SAR map are Fourier transformed and multiplied by a stored set of complex weights. The resultant Fourier transformed complex weighted SAR map is then inverse Fourier transformed to obtain compressed range bins. The inverse Fourier transformed SAR map is then processed for display.

Abstract: The present invention provides a covert radar system in which radar signals emitted are capable to search receiver thermal noise and, therefore, are substantially undetectable in the normal radar operating range.