Abstract: A method and corresponding devices for monitoring the performance of a radar system (2, 4) which is equipped with a shield 2 (radome) to protect it against weather influences are described. For this purpose, a part of the radiated radar signal is modified and fed as a monitor signal to the reception system after interacting with a coating (5) which is possibly present on the radom (2). Influences of a damping or reflecting coating (5) on the radom (2) change the monitor signal. By analyzing these changes it is possible to draw conclusions about the coating of the damping or reflection of the radar signals which is caused by the coating (5).

Abstract: A method for calculating a center frequency and a bandwidth for a radar doppler filter is herein described. The center frequency and bandwidth are calculated to provide radar performance over varying terrain and aircraft altitude, pitch, and roll. The method includes receiving an antenna mounting angle, a slant range, and velocity vectors in body coordinates, calculating a range swath doppler velocity, a track and phase swath bandwidth, and a phase swath doppler velocity. The method continues by calculating a range swath center frequency based on the range swath doppler velocity, calculating a phase swath center frequency based on the phase swath doppler velocity, and calculating a level and verify swath bandwidth based upon the track and phase swath bandwidth.

Abstract: A method for main beam alignment verification includes providing data pertaining to one or more patterns associated with an antenna, measuring power levels of a signal acquired by the antenna, and comparing the measured power levels with the data to determine whether a direction of the signal is incident upon a main beam of the antenna.

Abstract: A radar mount direction alignment device to be used for aligning the transmit/receive direction of a radar device 2D mounted on a member on which a radar device is to be mounted, such as a vehicle 1. The radar mount direction alignment device has receiving sections b9, b10 for receiving a signal emitted from the radar device 2D, and transmission sections a9, a10 for transmitting a signal to the radar device 2D. The radar mount direction alignment device has the function of emitting, toward the radar device 2D, a signal which, upon receipt of a signal output from the radar device 2D, behaves as if having been received at and reflected from a position farther from the radar device 2D than a distance between the radar device 2D and the radar mount direction alignment device.

Abstract: A system and method for radar detection and calibration. By measuring the true range of a calibration target on entry to the radar's detection zone, the actual detection capability of the radar in current atmospheric conditions with the actual radar can be determined. The radar system is also adapted to determine a sensed position at a sensed time of a target in the radar's detection zone. A calibration target, preferably an unmanned air vehicle (UAV), includes a position device for determining the actual position of the calibration target. A calibration device communicates with the radar system and the calibration target and receives the sensed and actual positions of the calibration target. The calibration device calculates the error between the sensed position and the actual position and adjusts the radar system to minimize the error. The target may include a signal augmentation device to augment the radar cross-section of the target to replicate the radar cross-sections of targets of various types.

Abstract: A synthetic aperture radar (SAR) compensates for ionospheric distortions based upon measurement of the group delay, particularly when operating in the VHF/UHF band. The SAR is based upon a multi-input multi-output (MIMO) technique for estimating the effective ionospheric conditions, which is referred to as the group delay approach. The group delay approach is divided into a 1-dimensional (range) approach and a 2-dimensional (range and cross-range) approach. The group delay measures the effective or observed TEC, which is used to reduce the ionospheric distortion.

Abstract: A synthetic aperture radar (SAR) for a moveable platform includes an antenna, a radar transmitter and radar receiver cooperating with the antenna. A radar processor is connected to the radar transmitter and radar receiver to account for the Faraday rotation introduced by propagation through the ionosphere by estimating an individual ionospheric distortion for each received echo pulse based upon a measured Faraday rotation, and reducing the ionospheric distortion for each received echo pulse based upon the estimated individual ionospheric distortion associated therewith for providing a compensated echo pulse.

Abstract: One preferred embodiment of the present invention provides a system and method for suppressing motion artifacts introduced by movement of a radar detection system. Briefly described, in architecture, one embodiment of the system, among others, can be implemented as follows. The system includes a Doppler radar module configured to transmit a microwave signal directed towards an object and receive the reflected microwave signals from the object and a living subject positioned behind the object. Also, the system includes a reference module configured to transmit a reference signal towards the object and receive the reflected reference signal from the object. By comparing the two reflected signals from the Doppler radar module and the reference device, a signal processor suppresses motion artifacts generated by movement of the Doppler radar module to identify the presence of the living subject behind the object. Other systems and methods are also provided.

Abstract: If the maximum time width Lt of the intensity of received light of reflected waves from a vehicle ahead is smaller than a reference time width, it is judged that the vehicle ahead is positioned in proximity to the detection limit distance of an obstacle detection device for vehicle. Thus, there is no problem, for example, even if a cut-in vehicle is present in reality between the vehicle ahead and the vehicle of interest and nevertheless, the distance to the cut-in vehicle cannot be detected. It can be judged whether the vehicle ahead is positioned in proximity to the detection limit distance of the device by judging the magnitude relation between Lt and the reference time width. As a result, the detecting capability of the device can be judged with accuracy.

Abstract: The invention provides systems and methods for providing improved wireless data communication. Preferred embodiments of the present invention utilize multiple antenna beams in the forward link to provide increased forward link capacity and/or improved forward link signal quality. Multiple orthogonal sub-pilots are transmitted from a plurality of antenna elements for use in determining forward link channel characteristics according to a preferred embodiment. Forward link channel estimates may then be made by the preferred embodiment subscriber units and provided in a reverse link control channel to the corresponding base station. Multiple beams may also be utilized in the reverse link to provide increased reverse link capacity, such as for use in providing feedback of forward link channel estimates.

Abstract: An automobile radar which serves to provide data for cruise control or other systems in a host vehicle, comprising means for measuring radar boresight misalignment by detecting the presence of apparent variations in the spacing of stationary objects from the direction of motion of the host vehicle and utilizing such detection to compensate for any misalignment.

Abstract: To provide a radar system mounted on a vehicle that reliably detects the reception of the interference wave with high-performance and inexpensively. There is provided a radar system mounted on a vehicle for detecting a target object, including a transmitter for transmitting an electromagnetic wave, a receiver for receiving the electromagnetic wave reflected by the target object, a signal processor for measuring a distance between a vehicle of his/her own and the target object and a relative velocity on the basis of the transmitting electromagnetic wave and the receiving electromagnetic wave, and an interference detector for suspending a transmit operation of the transmitter under a control of the signal processor to detect an interference signal from another external device.

Abstract: A chirp-based method and apparatus measures phase variation through a reference frequency transport cable for a phased array antenna. A chirp is injected into the a signal transport path from a remote transmit/receive portion of the antenna, so that the chirp is conveyed over the signal path, reflected from an upstream bandpass filter at a local transmit/receive portion of the antenna, and returned to a remote transmit portion of the antenna. Energy in the returned chirp is extracted by a downstream bandpass filter and correlated in a delay lock loop with energy in an auxiliary chirp signal, that is delayed relative to the injected chirp. The delay of the auxiliary chirp is adjusted to maximize the correlation output and provide an indication of the delay through the signal path.

Abstract: A guided wave radar transmitter comprises a probe defining a transmission line including a relatively low impedance target marker above an expected sensing region of the probe. A pulse circuit is connected to the probe for generating pulses on the transmission line and receiving a reflected signal from the transmission line. The reflected signal selectively includes a target pulse representing the target marker and a level pulse representing material along the length of the probe. A controller is operatively connected to the pulse circuit. The controller normally operates at a relatively low gain to determine a level time to the level pulse to determine material level, and periodically operates at a relatively high gain to determine a target time to the target pulse. The target time is used to compensate the level time for properties of vapor above the material level.

Abstract: Signals-of-interest are identified by distinguishing such signals from signals constituting environmental or internal receiver noise. A received signal is rapidly sampled in order to set a dynamic, system threshold. Signals above the threshold constitute signals-of-interest.

Abstract: Radar apparatus and methods of use thereof for imaging and/or spectrometric analysis. The invention employs pulsed radar signals for magnifying, imaging, scale measuring, identifying and/or typecasting the composition of substances by radargrammetric imaging and/or statistical analysis of energy/frequency spectrums. The invention may be used to locate and/or distinguish a substance from other substances, to image a substance/feature and to monitor the movement of an imaged substance/feature. The systems and methods can be adapted for a variety of applications at a wide range of scales and distances, from large scale, long range applications such as geophysical imaging/analysis, to the small scale such as material typecasting applications and small scale (including microscopic) imaging/analysis, including biological and medical imaging and diagnostic applications. The invention includes novel antenna assemblies and novel data processing techniques.

Abstract: A chirp-based arrangement derives a measure of phase variation through a reference frequency transport cable of a phased array antenna architecture, such as a spaceborne synthetic aperture radar system. A direct digital synthesized chirp signal is injected in an upstream direction into the transport cable from a downstream end thereof, so that the chirp signal is transmitted in an upstream direction, reflected from an upstream bandpass filter, and returned in a downstream direction. At each of a plurality of nodes that are distributed along the transport cable, the two chirp signals are extracted and frequency domain-processed to derive said measure of transport delay through the cable between the source of the reference frequency signal and each of the nodes.

Abstract: In a position detecting system used to monitor a suspicious person and to give an alarm by using a radar which transmits/receives a microwave or a millimeterwave, the shape of a detectable area of the radar and that of the area to be monitored are not always equal to each other, and thus, an alarm may be erroneously given in response to the object outside the area to be monitored. For its solution, the area to be monitored is surrounded by a plurality of reflectors, and the coordinate values of the reflectors and the detecting object are calculated based on the signals reflected from the reflectors and the detecting object and then compared. When the coordinate value of the detecting object is inside the area to be monitored, it is determined that the detecting object is an intruding person or the like and an alarm is given.

Abstract: A radar system derives a correction for an actual boresight (311) of a radar monopulse antenna mounted on a moving platform from ? data and ? data generated with respect to an a priori known, calibrated boresight (309). The monopulse antenna (602) is coupled to a ground position measuring system (616) while acquiring data. The radar receiver acquires a ? and ? synthetic aperture map of the same radar scattering location with respect to the calibrated boresight. ? SAR data and the ? SAR data are motion compensated using the position and velocity supplied by the ground positioning system. A computer forms a ratio of the aligned ? pixels to the aligned ? pixels for each of a plurality of aligned ? pixels located near the calibrated boresight. The correction for the location of the actual boresight of the monopulse antenna is computed by an analysis of the ratio of aligned ? pixels and corresponding aligned ? pixels over the radar scattering location.

Abstract: Systems and methods for automated detection and removal of solar interference in real time from NEXRAD or other similar radar products. The radar site latitude and longitude and scan elevation time are extracted from the radar data and a position of the Sun is determined for the extracted latitude and longitude and scan time. A radial that has been contaminated with solar interference is determined and the solar interference is removed from that radial; The removal process does not impact the timeliness of critical products, and conservatively removes solar interference. In addition inaccuracies with NEXRAD clock time synchronization are accounted for to ensure accurate results.

Abstract: A signal from CW radar is received, and the received power detected by the CW radar's swinging in all directions is averaged in each direction. Then, the maximum value and the minimum value of the received power are detected for each direction, and the difference between the maximum value and the minimum value is computed. An average power value of obtained power is also computed. On a 2-dimensional plane on which the difference between the maximum value and the minimum value and the average power value are used for coordinate axes, slice processing is performed using a threshold indicated by a line graph or a curve.

Abstract: A system and method for optimizing transmission of radio frequency communication link signals in a radio frequency communications network comprises determining a statistical difference between a mean radio frequency communication link propagation loss value based on a set of measured radio frequency communication link propagation loss values, and a radio frequency communication link propagation loss model value; calculating a signal to noise ratio of a radio frequency communication link signal; computing a confidence interval based on a measured signal to noise threshold ratio of a measured radio frequency communication link signal, and a standard deviation associated with the calculated signal to noise ratio; assigning a probability value based on the confidence interval; and generating a radio frequency communication link packet completion rate performance level based on the probability value. The transmission of radio frequency communication link signals occurs in either jamming or no jamming situations.

Abstract: A radar detector (10) includes a first period detector (76, 122), a second period detector (96, 120) and a third period detector (86, 124) within a multi-period periodicity validator 38. The first period detector (76, 122) detects radar pulses exhibiting one-half of an expected pulse period (48), the second period detector (96, 120) detects radar pulses exhibiting the expected pulse period (48), and the third period detector (86, 124) detects radar pulses exhibiting twice the expected pulse period (48). A plurality of pulse-train records (40) can simultaneously track a plurality of possible pulse trains. A control element (84, 136, 138) accounts for missing pulses and corrects the expected pulse period when missing pulses have caused the expected pulse period to be inaccurate.

Abstract: An HF radar system comprises a transmitting system, a receiving system, a signal processing system and a frequency management/ionospheric sounding system. The transmitting system comprises a transmitting antenna array configured to transmit a beam in a near vertical direction and a transmitting device arranged to drive the transmitting antenna array at frequencies suitable for downward refraction by the ionosphere. The receiving system comprises a receiving antenna array configured to receive returning signals from a target area returning to the receiving antenna array via refraction at the ionosphere. The signal processing system comprises a digital data processing system. The frequency management/sounding system comprises cooperating transmitting and receiving systems sending HF signals to the ionosphere and analysing the returning signals. Alternatively, the system may have a duplexed antenna array.

Abstract: A concealed object detection system for detecting objects concealed on a person includes radar transponders that are each configured and positioned to direct a radar signal at a person and to detect a portion of the radar signal reflected by the person. A processor connected to the radar transponders processes the portions of the radar signals detected by the radar transponders to determine whether the person is carrying a concealed object. The system may produce a real-time alert, such as an audible alert, when a concealed object is detected.

Abstract: Disclosed is a radar apparatus equipped with a function for detecting an abnormality of modulation width. Distance rt2 at time t2 is calculated from the values of the distance Rt1 and the relative velocity Vt1 measured at time t1 and the elapsed time t2−t1, and the difference relative to the actual measured value Rt2 is compared with a threshold value C1. If the difference relative to the actual measured value exceeds the threshold value C1, the modulation width is judged to be abnormal.

Abstract: The present invention relates to the field of radar level gauging systems, in which a level of a surface of a product stored in a container is measured. The gauging system comprises: a radar level gauge arranged above the surface of the product which is arranged to transmit a microwave signal towards the product surface and receive a reflected microwave signal from the product surface; a calculation unit arranged to determine a measured value of the product level based upon the received signal; means for comparing the measured value of the product level with a predetermined value; and a second level gauge arranged closed to the bottom of the container and arranged to determine the product level when the measured value is below the predetermined value.

Abstract: The present invention relates to a radar unit and provides a radar angle correction method for correcting an error in a radar angle caused by the front cover of an antenna. The radar angle correction method comprises the steps of: measuring a peak power of a beam received from a reference target at each of a plurality of radar angles; plotting a theoretical quadratic curve whose beam width corresponds to a value specified for the radar and whose peak indicates an average of peak values; adopting a difference between a theoretical value indicated by the theoretical quadratic curve and a received beam power as a correction value with which the received beam is corrected; and subtracting the correction value from the received beam power.

Abstract: In an adaptive array antenna receiving apparatus, signal to interference ratio (SIR) measuring units are provided in signal processing units, respectively. The SIR measuring units measure signal to interference ratios of existing fingers to supply the measured results for an antenna weight succession processing unit. The antenna weight succession processing unit selects one of the existing fingers on the basis of the measured results. The antenna weight succession processing unit extracts antenna weights from one of the signal processing units that corresponds to the selected finger. The antenna weight succession processing unit supplies the extracted antenna weights to a newly assigned finger or one of the existing fingers that path timing is greatly changed.

Abstract: Disclosed is a radar apparatus equipped with a function for detecting an abnormality of noise floor level. An abnormality of noise floor level is detected by measuring the level in a region not lower than 60 kHz when FM modulation is stopped or modulation width is made infinitely small by instruction from a CPU to a modulating signal generator.

Abstract: A radar apparatus for a vehicle includes a casing, a correction member, and a selection indication. The casing includes a functional portion, which performs searching, and a reference surface. The correction member includes a plurality of correction surfaces. The selection indication indicates which one of the correction surfaces and the reference surface an attachment-direction adjustor is to be placed on during an attachment operation of the radar apparatus to the vehicle.

Abstract: A method, apparatus and circuit for testing a radio altimeter is disclosed. During the test-mode operation of the altimeter, a signal processor controls a transmitter to generate a radio frequency signal at a first period of time, which is transmitted through an attenuator, transmitted then through a receiver and received by the signal processor at a second period of time for processing of altimeter operational information.

Abstract: The invention concerns a method for generating calibration signals for calibrating spatially remote signal branches of antenna systems. In accordance with the invention, a base signal is generated by mean of a timer and is fed to a distributor unit for distribution of the base signal to amplifier circuits on the signal distribution lines respectively allocated to them. At the output of the amplifier circuits, a calibration signal is generated respectively via amplification of the base signal within a specifiable upper amplitude limit and a specifiable lower amplitude limit, which is fed to the respective feed-in point of the signal branch to be calibrated that is allocated to an amplifier circuit.

Abstract: A method for testing radar system performance is disclosed which utilizes radar data test points in a radar data file. The method includes interpolating GPS data from a flight test to provide a GPS data point for every radar data test point, generating body coordinate values for every point in a corresponding digital elevation map (DEM) file using the interpolated GPS data, and applying a bounding function around at least a portion of the body coordinate values generated from the DEM file at a given time. The method also includes determining which body coordinate value generated from the DEM file is closest a current GPS data point for the given time and comparing the determined body coordinate value to the radar data test points at the given time.

Abstract: A method and an apparatus for operating a radar sensor system with a number of adjacent individual sensors (3, 4, 5, 6), extensively synchronized with one another, for determining the position of a target object (15) are proposed. In one measurement cycle, the transit time of the radar signal emitted from one individual sensor and reflected by the target object to this individual sensor (3, 4, 5, 6) (direct echo (13, 14)) and to a different individual sensor (3, 4, 5, 6) (cross echo (16)) is evaluated. From the evaluation of the direct and cross echoes (13, 14, 16), at least the position of the target object (15) is determined, and a detection quality signal (Q) is ascertained, and once a predetermined amount of the detection quality signal (Q) is reached for a target object (15), a calibration is performed.

Abstract: A method, apparatus and circuit for testing a radio altimeter is disclosed. During the test-mode operation of the altimeter, a signal processor controls a transmitter to generate a radio frequency signal at a first period of time, which is transmitted through an attenuator, transmitted then through a receiver and received by the signal processor at a second period of time for processing of altimeter operational information.

Abstract: A method and an apparatus for aligning the elevation of an automotive radar unit.

Abstract: A method of aligning a sensor device attached to an automobile includes the steps of positioning a first detection object relative to the automobile and generating a plurality of beams at the sensor device. A beam crossing point common to first and second adjacent beams is selected, and the sensor alignment is verified by determining whether the beam crossing point is coincident with the first detection object.

Abstract: A method and apparatus for testing assisted position location capable devices that includes providing a position determination entity (PDE) simulator that is in communication with a base station simulator simulating one or more base stations and connecting an assisted position location capable device under test (DUT) to the base station simulator and a global positioning system (GPS) simulator. Then, initiating a test sequence wherein the DUT receives a set of predetermined GPS signals and at a desired time the DUT requests assistance data from the base station simulator and the base station simulator requests assistance data from the PDE simulator, wherein the PDE simulator provides data that is independent of the GPS simulator data to the base station and the base station transfers the PDE data to the DUT. The PDE data is a set of predetermined responses to any one of a plurality of DUT requests indexed by elapsed test time.

Abstract: An N-way RF/microwave power divider/combiner utilizes one input and N outputs, or conversely N inputs and one output to divide (or combine) RF/microwave power while simultaneously and non-invasively measuring reflected power present due to mismatched loads or other failed components. The Gysel divider/combiner technique is used with the addition of N temperature measuring devices placed directly on the N isolation loads separated from the main divider/combiner lines. Because of high isolation between the N channels of the divider/combiner, the temperature above ambient of each isolation load is strongly correlated to the amount of power reflected back to an output port. The temperature is sensed external to the RF circuit whereby a measure of reflected power can be made without the use of invasive directional-coupler techniques. This is highly advantageous since directional-coupler techniques would increase the insertion-loss, cost, and complexity of the divider/combiner.

Abstract: The occurrence of an axis displacement in a horizontal direction in a vehicle-to-vehicle distance controlling radar is detected, the amount of the axis displacement is determined, and an azimuth angle is corrected using the thus determined amount of the axis displacement. The frequency with which vehicle-to-vehicle distance control is released or re-set is measured and, if the frequency is higher than a threshold, it is determined that the axis is displaced. The amount of the axis displacement is determined from the angle of the locus of a stationary target. The azimuth angle of the target is corrected using the thus determined axis displacement angle.

Abstract: A method and apparatus are provided that determine a frequency dependent calibration vector for a set of transmit or receive chains of a radio communications system using only differential phase and amplitude between the transmit chains and the receive chains, respectively. In one embodiment, the invention includes an antenna array adapted to transmit and receive radio communications signals with a plurality of other terminals, a transmit chain to transmit a calibration signal through the antenna array to a transponder on at least two different frequency bands, and a receive chain to receive through the antenna array a transponder signal from the transponder, the transponder signal being received on at least two different frequency bands and being based on the calibration signal.

Abstract: A method and system for probing incident radar fields in a target test zone of a radar cross-section (RCS) test facility is provided. The present invention accomplishes probing by exploiting the angular radar response of a string or wire stretched horizontally or vertically through the test zone. One end of the string is fixed, while the other end is moved by a wall-mounted or floor-mounted actuator. The angle of the string is gradually changed with respect to the direction of arrival of incident waves generated by the test facility. The radar echo from the string is measured as a function of the string angle. The data is then processed to yield a profile of the incident wave intensity along the string. This probing can be routinely achieved for any desired frequency.

Abstract: A radar apparatus is provided in which an antenna axis and vehicle axis can agree with each other even when the antenna face is covered with a cover. In an assembling process of the radar apparatus composed of a chassis, an antenna incorporated in the chassis and a cover attached to the chassis to cover the antenna, a correlative positional relation between an antenna axis of the antenna incorporated into the chassis and one portion of the chassis or bracket is detected, and the thus detected data is inscribed on a seal and the seal is stuck to the chassis or the data is stored in an internal memory, and the chassis into which the antenna is incorporated is covered with the cover, so that the radar apparatus is manufactured. When this radar apparatus is attached to a vehicle, the antenna axis can be adjusted parallel to the vehicle axis by utilizing data of a correlative positional relation between the antenna and one portion of the chassis or bracket.

Abstract: A monopulse radar system aims to correct an amplitude error and a phase error developed between receiving channels and improve the accuracy of a detected angle. To achieve the above aim, part of a transmit signal is supplied to respective channels on the receiving side through a signal transmission line for calibration. At this time, the gains of a variable phase shifter and a variable gain amplifier are adjusted so that an azimuth angle of a pseudo target, based on a signal for calibration, which is calculated by signal processing means, reaches a predetermined angle. Therefore, calibration work is simplified and an angular correction can be automated. Therefore, the present monopulse radar system is capable of coping even with variations in characteristic after product shipment due to environmental variations and time variations in parts characteristic.

Abstract: A method of aligning a sensor device attached to an automobile includes the steps of positioning a first detection object relative to the automobile and generating a plurality of beams at the sensor device. A beam crossing point common to first and second adjacent beams is selected, and the sensor alignment is verified by determining whether the beam crossing point is coincident with the first detection object.

Abstract: A method for correction of the detection range of a distance sensor, which is installed with an eccentricity laterally offset with respect to the central axis of a motor vehicle. In order to correct the detection range, a correction angle is used, with which the eccentricity of the distance sensor is corrected at the time of its installation. Thus the distance sensor is not aligned parallel to the longitudinal axis of the vehicle, but to its central axis. Thus, the detection range is advantageously covered approximately symmetrically to the longitudinal axis of the vehicle. The correction angle is determined either empirically, via appropriate test measurements, or mathematically.

Abstract: A method of identifying a radar requiring alignment and of adjusting the alignment of the radar fixed to a mounting assembly. The identification method includes the steps of determining a misalignment threshold, determining the misalignment angle of the radar, and creating an alignment notice if the misalignment angle exceeds the threshold. The mounting assembly for the adjustment method includes a housing and an adjustment mechanism coupled to the housing. The method includes the steps of determining a radar misalignment angle, consulting a mapping table having adjustment mechanism manipulations associated with each of a plurality of radar misalignment angles to identify an appropriate adjustment mechanism manipulation for the misalignment angle, and performing the adjustment mechanism manipulation identified in the mapping table for the determined radar misalignment angle.

Abstract: A radar system having a tactical mode and a calibration mode includes a transmitter section for providing high-power amplification of an RF pulsed waveform from an exciter during the tactical mode and the calibration mode. A circulator system has an input port connected to an output of the transmitter section and including first, second and third switchable junctions, and a high-power attenuator. The circulator system provides a transmit tactical mode signal path and a transmit calibration mode signal path of virtually identical electrical path lengths for a transmitter output signal, the tactical path passing through the first, second and third junctions in a first direction to an antenna I/O port, the calibration path passing through the first, second and third junctions in a second direction and through the high-power attenuator to an output port.

Abstract: A radar transmitter includes a digital ramp generator circuit for generating a VCO control signal. The ramp generator includes a digital signal processor and a digital-to-analog converter. In one embodiment, the VCO output signal is up-converted to provide the transmit signal and in another embodiment, the VCO operates over the transmit frequency. Also described is a VCO comprising a DR and a phase shifter. A temperature compensation feature includes detecting the transmit frequency and comparing the DSP output generating the detected frequency to a DSP output stored in association with the detected frequency. Also described is a technique for compensating for non-linear VCO operation in which the DSP output words are adjusted to provide a waveform complementary in shape to the non-linear VCO characteristic. Susceptibility of the radar to interference is reduced by randomly varying at least one parameter of the ramp signal, such as offset interval or voltage range, in at least one ramp signal cycle.