Abstract: One aspect of this disclosure relates to a method for processing a received, modulated radar pulse to resolve a radar target from noise or other targets. According to an embodiment of the method, a radar return signal is received and samples of the radar return signal are obtained. A minimum mean-square error (MMSE) pulse compression filter is determined for each successive sample. The MMSE filter is separated into a number of components using contiguous blocking, where each component includes a piecewise MMSE pulse compression filter segment. An estimate of radar range profile is obtained from an initialization stage or a previous stage. The piecewise MMSE pulse compression filter segments are applied to improve accuracy of the estimate. The estimate is repeated for two or three stages to adaptively suppress range sidelobes to a level of a noise floor. Other aspects and embodiments are provided herein.

Abstract: It is an object of the present invention to prevent the sensitivity of radar apparatus from falling. A spread spectrum radar apparatus which detects an object, includes a carrier wave oscillator which generates a carrier wave, transmission unit which transmits a spread signal which is the carrier wave spread using a first PN code, an intermediate demodulated signal generating unit which receives a reflected wave which is the spread signal reflected from the object, and despreads the reflected wave using a delayed second PN code that has a cyclically reversed logical value of the first PN code, to generate an intermediate demodulated signal, a low-pass filter through which a specific frequency component of the intermediate demodulated signal passes, and a sampling unit which samples an output signal from the low-pass filter, and the sampling unit samples the output signal in synchronization with the cycle of the reversal.

Abstract: It is possible to generate D/A conversion voltage in which an error generated by numeric irregularities of a D/A conversion element such as resistor constituting a D/A converter 11 is corrected. A waveform generation method characterized in that input data into a D/A converter 11 are provided to the D/A converter in order at a timing at which a voltage of a desired waveform which has D/A conversion data indicating a conversion amount of the input data obtained by varying the input data by a minimum conversion unit or a unit obtained by multiplying the minimum conversion unit by an integer, and which varies with time series, becomes substantially equal to a D/A-converted voltage, whereby the D/A-converted voltage is generated in accordance with the desired waveform.

Abstract: A method and apparatus is operative for multiple target detection in a radar system which employs a radar waveform of two or more frequency diverse subpulses. The apparatus adds coherent processing of the subpulse echo signals to determine the presence of multiple scattering centers within the radar resolution cell. The subpulses are coherently combined and one can then estimate the number of scattering centers by forming a sample covariance matrix between the subpulse frequency channels and then performing an Eigenvalue decomposition. The resulting Eigenvalues represent the signal strengths of the scattering centers when the associated Eigenvectors correspond to the optimal subpulse weights associated with that signal. A single strong Eigenvalue indicates a single target while two or more strong Eigenvalues or those Eigenvalues larger than the noise related Eigenvalues or a threshold, indicates the presence of multiple targets.

Abstract: Method and apparatus for a frequency diverse array. Radio frequency signals are generated by a plurality of independent waveform generators and simultaneously applied to a transmit/receive module. A progressive frequency shift is applied to all radio frequency signals across all spatial channels. Amplitude weighting signals are applied for sidelobe control. Phase control is included for channel compensation and to provide nominal beam steering. The progressive frequency offsets generate a new term which cause the antenna beam to focus in different directions as a function of range.

Abstract: Systems and methods for avoidance of partial pulse interference in radar. The systems and methods include a radar processor for generating control signals that direct the generation and transmission of two consecutive radar pulses using a waveform and pulse train generator and transmitter. The systems and methods also include receiving reflected echoes corresponding to the transmitted pulses using a receiver and processing the echoes using an analog to digital converter, filter, and digital signal processor to separate echoes from each pulse, process them, and combine the results to avoid partial pulse interference while maintaining pulse energy and an acceptable signal to noise ratio.

Abstract: Embodiments of the invention are concerned with improvements to Doppler radar systems, and are suitable for use with frequency scanning radar systems. In one arrangement the improvements are embodied in a frequency scanning radar controller for use in controlling a frequency generator; the frequency generator is arranged to generate a plurality of sets of signals, each set of signals having a different characteristic frequency and comprising a plurality of signals transmitted at a selected rate, and the radar controller is arranged to select the rate in dependence on the characteristic frequency. The invention can be embodied in a pulsed radar, for which each set of signals comprises a set of pulsed signals and each pulsed signal is repeated at a selected repetition rate. The radar controller is then arranged to modify the repetition rate in dependence on the characteristic frequency of the pulsed signal.

Abstract: The invention relates to a measuring device comprising a transmitter (6) for transmitting (38, 60) a measuring signal (16) that lies within a frequency range, a sensor (8) for receiving (40, 62) an evaluation signal (20) that has been induced by the measuring signal (16) and a control unit (10) for evaluating (42, 66) the evaluation signal (20) to produce a measured result. According to the invention, the function of the control unit (10) is to check the frequency range before the transmission (38, 60) of the measuring signal (16) for the presence of a signal (28) that is independent of the measuring signal (16).

Abstract: A system and method are described for generating waveforms for use in radar and sonar systems. The system includes waveform generation circuitry a waveform generator and an up-conversion module. The waveform generator generates concatenated pulse waveforms at an IF band. In a given pulse repetition interval (PRI), the concatenated pulse waveforms comprise a first and second pulse types associated with first and second IF frequencies respectively. The up-conversion module up-converts the concatenated pulse waveforms to an RF band to form first and second sets of pulses. In the given PRI, each pulse is up-converted to a different RF frequency, pulses of different lengths are associated with a similar carrier frequency, and at least one pulse from each of the sets of pulses implements frequency diversity.

Abstract: Method and apparatus for a frequency diverse array. Radio frequency signals are generated and applied to a power divider network. A progressive frequency shift is applied to all radio frequency signals across all spatial channels. Amplitude weighting signals are applied for sidelobe control. Phase control is included for channel compensation and to provide nominal beam steering. The progressive frequency offsets generate a new term which cause the antenna beam to focus in different directions as a function of range. Alternative embodiments generate different waveforms to be applied to each radiating element, permitting the transmission of multiple signals at the same time.

Abstract: A transmission signal generating unit has a window function calculator that generates a window function that makes all frequencies without a center frequency of an input signal and its adjacent frequencies zero and makes the signal to noise ratio of the center frequency maximum; and a transmission signal generator that generates a transmission signal whose amplitude is modulated in a shape of an envelope curve based on the window function generated by the window function calculator.

Abstract: A system and corresponding method for the concurrent operation of multiple radar systems on a common frequency and in the same geographical area includes a waveform generator that specifies certain operating parameters for the transmitted radar pulses. In a first instance, the carrier frequency can include an offset for each radar system. In a second instance, complementary codes can be used for the radar pulses such that each radar system operates with a unique code for substantially reducing the cross-talk between the radar systems. In another instance, both carrier frequency offset and complementary coded waveforms can be used to increase the number of radar systems that operate concurrently. Carrier frequency offset can also be used to combat range-wrap by using different carrier frequencies for adjacent radar pulses.

Abstract: A radar device includes a code generator, a transmission section, a reception section, a delay section, a despreading process section, a correlation value detection section, a target detection section, an estimation section, an acquisition section, and a correction section. The estimation section estimates a reception intensity of a reflection wave from a target located at a first distance on a basis of a detected correlation value. The acquisition section acquires a cross-correlation value between the first distance and a second distance, on a basis of the estimated reception intensity of the reflection wave from the target located at the first distance, a delayed despreading code used to detect a correlation value for the first distance and a delayed despreading code used to detect a correlation value for the second distance. The correction section corrects the correlation value for the second distance on a basis of the cross-correlation value.

Abstract: A general purpose system and method for transmitting and coherently detecting UWB waveforms is predicated on the formation of conjugate pair of UWB waveforms. The in-phase and conjugate quadrature waveforms are orthogonal to each other and have the same power spectrum so that when squared and added they sum to the modulation envelope of the waveforms. By defining the waveform pair in this manner, a relatively simple and inexpensive transceiver can be used to transmit and receive the waveforms and yet preserve maximum range resolution and recover all possible energy in the returned waveforms. The transceiver transmits the in-phase UWB waveform and the conjugate quadrature UWB waveform with either a known time delay or orthogonal polarization relation. The time delay may be varied to suppress aliased return signals.

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: 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 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 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: 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 radar system has improved range resolution from linear frequency modulated (LFM) first sub-pulse and second sub-pulse, both having linear frequency modulation about different center frequencies. The first transmitted sub-pulse and the second transmitted sub-pulse have chirp slope &ggr;. Sample shifting and phase adjusting is performed for the first radar returns with respect to second radar returns to form a line of frequency modulated chirp slope &ggr; with respect to time, the line connecting the center frequencies of the center frequencies. The first sub-pulse and second-sub pulse can have equal time duration, where the first and second center frequency are equidistant from a reference frequency. The returns are reflected by a target located at a location near a reference point s.

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 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: 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 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 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 random pulse type radar apparatus sends out as an output signal a spectrum spread radio wave including a pseudo random signal-less period and receives echoes in this signal-less period to thereby significantly reduce transmission peak power.

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: An apparatus and method for generating an electromagnetic environment in which the free field, plane wave response of electronic systems of an electrically large (greater than several wavelengths in its longest dimension) object, or objects, under test can be measured in the electromagnetic radiating near field of the transmitter array apparatus. The apparatus comprises: (1) one or more transmitting station(s), each station home to an array of radiating elements; (2) a software operating system and computer that controls the electronic circuits of the apparatus and executes an optimizing algorithm based on a Genetic Algorithm to control the radiation of each transmitting station; and (3) mechanical and electrical circuits that enable the apparatus to conduct self calibration and adjustment as required. In operation, the apparatus is placed and distributed about an object under test.

Abstract: Presented in this invention is a technique for producing a null in the frequency spectrum of an FM signal pulse, the null matching an interference that has been superposed on the signal pulse. By matching the null to the interference, the energy in the frequency spectrum is shifted in such a way that when the interference is rejected by a band elimination filter, none of the useful energy would be discarded along with the rejected interference. Consequently, a signal resulting from the technique has a much higher amplitude than previously filtered signals. This leads to the signal being more readily recognized by detection systems, such as a radar detector.

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: In a method for operating a radar system, the object is to determine by simple means and at low cost the distance and/or the radial velocity of at least one target object with high resolution. For this purpose, in each measuring phase of the measurement process in the "pulse FMCW radar system", switchover between a transmission mode and a receiving mode is effected a multiple number of times and at short intervals of time. In the transmission mode, all receiving units of the radar system are switched off, while a pulse-shaped (frequency-modulated) transmission signal with time-successive transmission pulses having a specific pulse-on time and a specific carrier frequency is emitted from at least one transmitter unit of the radar system.

Abstract: A source for a linear homodyne transceiver that generates repeated linear chirps. A YIG oscillator with a main coil and an FM coil receives a basic linear current ramp at the main coil to generate a chirp. The FM coil is coupled to receive a PLL error signal. The PLL receives a sample of the output signal from the YIG oscillator at one input and a linear chirp reference signal at the other input generated by a DDS chirp generator. Any variation between the linear chirp frequency at any instant and the actual frequency output by the YIG is corrected by an error signal to the FM coil to correct for nonlinearities of the YIG caused by variations in the chirp rate, the rate of change of frequency per second per chirp, temperature variations and microphonics.

Abstract: A power distribution system (12) is provided in radar apparatus to distribute power from a 270 VDC source (60) through an intermediate power converter (70) and very high frequency (VHF) regulator/modulator units (80). Bus conductors (71,74) interconnect the source, the intermediate power converter, and the VHF units. Capacitors (71, 76) are connected to the bus conductors on the input and output sides of the intermediate power converter. Each VHF unit supplies modulating pulses to RF amplifiers (82) of an AESA array of the radar apparatus.

Abstract: The encoding/transmission of information in an OFDM system is enhanced by using complementary codes and different patterns of amplitude modulation representing respective data words. The complementary codes, more particularly, are converted into phase vectors and modulated by the selected pattern. The result is then used to modulate respective carrier signals. The modulated result is then transmitted to a receiver which decodes the received signals to recover the encoded information.

Abstract: An apparatus and method of linear frequency modulation waveform bandwidth multiplication including a digital linear frequency modulation waveform synthesizer for generating a synthesized waveform having an upchirp component of linearly varying frequency during a first half signal duration of the synthesized waveform followed by a downchirp component having linearly varying frequency during a second half of the signal duration of the synthesized waveform. The synthesized waveform is upconverted and subsequently bandpass filtered to provide a filtered waveform to a mixer for mixing with local oscillation signals. The upchirp and downchirp components of the filtered waveform are respectively mixed by first and second local oscillation signals having respective first and second oscillation frequencies in the mixer.

Abstract: A modular radar system using both FM/CW and pulse waveforms for automotive collision avoidance applications.

Abstract: A semiconductor diode is connected across the cathode-to-anode path of a magnetron and through a storage capacitor and collector resistor to a supply voltage for enabling charging of the capacitor. A control pulse causes a switching transistor to conduct to discharge the capacitor through its collector-to-emitter path, an emitter resistor, and the magnetron, for causing the latter to oscillate. A feedback signal representative of the difference between the magnetron output frequency and a reference frequency is applied to a linear amplifier transistor which conducts through the emitter resistor for controlling the current flow through the switching transistor and the operating frequency of the magnetron.

Abstract: A monolithic digital chirp synthesizer (DCS) chip using GaAs/AlGaAs HI.sup.2 L technology. The 6500 HBT gate DCS chip is capable of producing linear frequency modulated (chirp) waveforms or single frequency waveforms. The major components of the DCS are two pipelined accumulators, a sine ROM, a cosine ROM and two digital to analog converters.

Abstract: Synthetic aperture radar imaging for nonlinear trajectories utilizing range relative doppler processing, invariant mapping of information from arbitrary shaped cells onto an X--Y coordinate system, and round trip signal delay which allows accurate synthesis of a reference signal for each range cell. A synthetic signal synthesizer produces the reference signal for synchronous demodulation in the radar.

Abstract: Low time-bandwidth product linear frequency modulated chirp pulses are repetitively generated as contiguous subpulses to form a pulse of extended duration with each subpulse respectively mixed with one of a plurality of stepped intermediated frequencies so that the bandwidth of the contiguous subpulses is increased to the frequency bandwidth of all of the stepped intermediate frequencies such that the contiguous signal formed has a linearly varying frequency over the increased bandwidth and increased pulse duration, providing a large time-bandwidth product linear frequency modulated chirp waveform particularly useful in radar systems.

Abstract: A method is described for improving the target-detection performance of a linear pulse compression radar system by reducing the amplitude of the temporal sidelobes contained in the autocorrelation function output of a matched filter receiver. The method involves generating a transmitter signal pulse using a waveform which linearly varies the frequency of a baseband signal between first and second frequencies which are selected so as to optimize the percentage cycle-to-cycle frequency variation in the transmitter signal pulse. In one example, the minimum frequency of the carrier waveform is set close to 0 MHz. Optimization of the percentage cycle-to-cycle frequency variation causes a reduction in the width of the compressed pulse, which the designer may choose to forego, in favor of reducing the amplitude of the temporal sidelobes of the compressed pulse signal output.

Abstract: A pulse-compression, MTI, doppler-radar system for determining target velty information from a single, frequency-coded uncompressed target-return pulse includes a coded modulator, two pulse compressors, and a phase-comparison processor. The coded modulator generates for transmission an uncompressed pulse with the first and second halves of the pulse coded with the even and odd harmonic sidebands of a pulse repetition frequency, respectively. The first and second halves of the pulse returning from the target are pulse compressed simultaneously by the two pulse compressors. The phase comparison processor then determines the phase difference between the compressed pulses to obtain the target velocity information.

Abstract: A radar transmitter in which a pseudo-random sequence of pulses are transmitted, each at a different frequency. Prior to the return of the first pulse, a receiver is retuned to the first transmit frequency, then the transmitter is retuned to the second transmit frequency and so on. The return pulses are integrated coherently across the sets at a each frequency to achieve the highest signal level. The pulses are integrated noncoherently within a set over all the frequencies transmitted to improve the signal-to-noise ratio.The technique of the present invention requires accurate knowledge of the range to the target. In a specific multi-line embodiment, the range calculation is provided by the centerline carrier frequency operating at a medium pulse repetition (prf) frequency. The retuning is then performed with the sidebands operating at a low prf.

Abstract: A radar system (20) has a chaotic code source (22) with a chaotic code output (23), which generates a chaotic code according to a chaotic difference equation. The radar system (20) further includes a transmitter (24) with a carrier signal source (28) of a carrier signal (29), and an encoder (30) having as a first input the carrier signal (29) of the carrier signal source (28) and as a second input the chaotic code output (23) of the chaotic code source (22), and as an output a transmitted radar signal (36) having the chaotic code output (23) encoded onto the carrier signal (29). A radar system receiver (26) includes a correlator (46) having as a first input the chaotic code output (23) of the chaotic code source (22) and as a second input a received radar signal (44), and as an output an indication of the correlation of the first and second inputs. The correlation is used to determine the distance, speed, or other characteristic of an object that reflected the radar signal.

Abstract: Scaled multiple function non-linear FM waveforms are generated for use in digitally implemented low frequency radar. The non-linear FM waveforms are generated by combining a plurality of functions, each having varying characteristics, to form a single waveform which has the desirable characteristics of weighted linear FM waveforms without the undesirable attributes due to weighting. Accordingly, the use of the non-linear FM waveform results in an increase in detection range of eight percent over existing linear FM waveforms with no degradation in range resolution.

Abstract: A digital chirp generator for generating linear frequency modulated signals, comprises a plurality of frequency/phase accumulators pipelined together. Each frequency/phase accumulator includes a frequency accumulator driving phase accumulator. In the pipelined configuration the frequency accumulator and the phase accumulator of each frequency/phase accumulator are interconnected with the corresponding frequency accumulator and phase accumulator adjacent of the frequency/phase accumulator.

Abstract: A wideband radar apparatus is provided having improved interference suppression characteristics. The known time versus bandwidth characteristic of the transmitted pulse is utilized to effect intermediate frequency bandwidth reduction in received swath echo signals. During the interpulse period, basebanded swath echo signals are then subjected to a series of adaptive interference suppressing updates. The adaptive weight vector produced during each of these updates is then applied to the same data used to generate the weights. Preferably, adaptive weight generation is performed in a systolic array according to a QR decomposition algorithm.