Abstract: An image processor includes an optical processor and a microwave processor. The optical processor is configured to extract optical image information from optical image data provided by a sensor, the optical image data representing an optical image of an object. The microwave image processor is configured to produce microwave image data representing a microwave image of the object in response to the extracted optical image information and microwave measurements provided by a microwave imager based on illuminating the object with microwave radiation.

Abstract: A variable range millimeter wave method and system is disclosed. In a particular embodiment, the system includes a primary mirror having an aperture to reflect millimeter wave energy to a secondary mirror, where the secondary mirror is disposed in front of the primary mirror and adapted to redirect the millimeter wave energy to a millimeter wave sensor/detector of a millimeter wave camera. The millimeter wave camera is configured to process the millimeter wave energy to visually detect concealed objects hidden on a target and an operating frequency of the millimeter wave camera is between 225 GHz and 275 GHz. In addition, the system includes a laser rangefinder, GPS and altimeter to determine a location of the target and to optimize a focus of the millimeter wave camera. A video monitor displays millimeter wave imagery and video images spatially and temporally relative to the millimeter wave imagery to aid targeting.

Abstract: A system, method, and/or apparatus for remote measurement of terrestrial biomass contained in vegetative elements, such as large tree boles or trunks present in an area of interest, are provided. The method includes providing an airborne VHF radar system in combination with a LiDAR system, overflying the area of interest while directing energy toward the area of interest, using the VHF radar system to collect backscatter data from the trees as a function of incidence angle and frequency, and determining a magnitude of the biomass from the backscatter data and data from the laser radar system for each radar resolution cell. A biomass map is generated showing the magnitude of the biomass of the vegetative elements as a function of location on the map by using each resolution cell as a unique location thereon. In certain preferred embodiments, a single frequency is used with a linear array antenna.

Abstract: A radio frequency (RF) phased array transmitter system comprises a phased array for generating an RF signal. The phased array comprises conductive patches formed in an array, separation gaps, and active sources. Each of the separation gaps is formed between two adjacent ones of the conductive patches, and each of the active sources is formed across its associated one of the separation gaps. The system further comprises an optical source for generating an optical signal and an RF source for generating an RF signal. In addition, the system comprises an optical modulator coupled to the optical source and the RF source. The optical modulator receives an optical signal and an RF signal, and produces an RF modulated optical signal based on the received optical signal and the received RF signal.

Abstract: The system and method for standoff detection of human carried explosives (HCE) automatically detects HCE (112) up to a range of (200) meters and within seconds alerts an operator to HCE (112) threats. The system (100) has radar only, or both radar and video sensors, a multi-sensor processor (102), an operator console (120), handheld displays (122), and a wideband wireless communications link. The processor (102) receives radar and video feeds and automatically tracks and detects all humans (110) in the field of view. Track data continuously cues the narrow beam radar (118) to a subject of interest (110), (112) the radar (106), (108) repeatedly interrogating cued objects (110), (112), producing a multi-polarity radar range profile for each interrogation event. Range profiles and associated features are automatically fused over time until sufficient evidence is accrued to support a threat/non-threat declaration hypothesis.

Abstract: Vehicular arrangement for obtaining information about objects exterior to the vehicle includes at least one combined imaging and distance measuring system arranged along an edge or a side of the vehicle, each combined system including an infrared illuminator for directing infrared illumination outward from the vehicle, an imager sensitive to infrared illumination and visible light, the imager being arranged to form images of an environment around the vehicle and thereby enable identification of objects in the images, a radar or laser radar system arranged to simultaneously determine a distance between the vehicle and objects identified in images obtained by the imager with the identification of the objects in the images. A reactive system is arranged on the vehicle to consider both the identification of the objects and their distance from the vehicle and react accordingly.

Abstract: A system, method, and/or apparatus for remote measurement of terrestrial biomass contained in vegetative elements, such as large tree boles or trunks present in an area of interest, are provided. The method includes providing an airborne VHF radar system in combination with a LiDAR system, overflying the area of interest while directing energy toward the area of interest, using the VHF radar system to collect backscatter data from the trees as a function of incidence angle and frequency, and determining a magnitude of the biomass from the backscatter data and data from the laser radar system for each radar resolution cell. A biomass map is generated showing the magnitude of the biomass of the vegetative elements as a function of location on the map by using each resolution cell as a unique location thereon. In certain preferred embodiments, a single frequency is used with a linear array antenna.

Abstract: A method and apparatus determines the shape of an orbiting or airborne object. A radar determines the general location and a telescope is directed toward the object to form an image of background stars, which will be occluded by the object. The image is compared with a memorized star map, to identify the region of the image in the map. Stars visible in the map which are not visible in the image are listed. The invisible stars are paired with next adjacent visible stars to form star pairs. The midpoints are identified of lines extending between star pairs. Segment lines are drawn between a midpoint and the next closest midpoint. The segment lines define an outline of the object.

Abstract: A system for detecting weapons is provided. The system includes a radar system transmitting electromagnetic radiation, analyzing reflected signals to detect a weapon, and generating reflected signal data. An energy field parameter system receives the reflected signal data and sets a plurality of energy field parameters. An energy field system transmits energy at a location associated with the detected weapon.

Abstract: An apparatus for remote detection or neutralization of an explosively formed penetrator device. A LIDAR or LADAR unit may be used in conjunction with a RADAR unit to both detect the presence of an EFP and neutralize the EFP having an associated passive infrared sensor. The LIDAR unit's wavelength is selected to approximate the signature from the intended EFP target which then causes the safe remote detonation of the EFP. The detected EFP signature may be compared with known signatures and presented to a user via a display terminal. The display terminal may also present associated terrain or GPS data.

Abstract: A receiver, such as a miniaturized microwave-photonic coherent receiver (MMPR) is disclosed. The receiver includes an antenna to output an electrical RF signal received on a section of the antenna, a laser to produce an optical signal, a photonic modulator to receive the optical signal and the electrical RF signal and produce an EO-RF signal and to receive the optical signal and an electrical LO signal and produce an EO-LO signal, a signal combiner to provide a combined EO-RF and EO-LO signal and a photodiode to receive the combined signal and produce an IF signal. A method of detecting an object using the MMPR includes receiving an electrical RF signal corresponding to the object, outputting the electrical RF signal to a photonic modulator, modulating the electrical RF signal onto an optical carrier, demodulating the electrical RF signal to produce an IF signal and processing the IF signal.

Abstract: A detection system (1) having an optical sensor (3), a radar device (2) and a signal processor (4) communicatively connected with the optical sensor and the radar device. The signal processor comprises: a first detector (41, 410-413) for detecting a first object on the basis of a first signal coming from the optical sensor and determining at least one first property of the first object; a second detector (42, 420-421) for detecting a second object on the basis of a second signal coming from the radar device and determining at least one second property of that second object, and a signaling unit (43) for producing a signal if the at least one first property and the at least one second property satisfy a predetermined condition.

Abstract: A system for controlling a remote vehicle comprises: a LIDAR sensor, a stereo vision camera, and a UWB radar sensor; a sensory processor configured to process data from one or more of the LIDAR sensor, the stereo vision camera, and the UWB radar sensor; and a remote vehicle primary processor configured to receive data from the sensory processor and utilize the data to perform an obstacle avoidance behavior.

Abstract: In one embodiment, a radar is provided that is configured to construct an image of a target within or adjacent to a substrate according to scan points associated with a surface of the substrate while the radar is scanned in a first direction.

Abstract: A system assists a driver occupying a seat within a vehicle traveling on a road. The system includes sensing apparatus that senses a plurality of different types of conditions regarding the vehicle. Information apparatus provides information regarding the different types of conditions to the driver by respective different types of haptic inputs.

Abstract: A device and a method for triggering at least one deceleration device and/or one output-determining actuator element of a vehicle propulsion system, in particular for automatic longitudinal vehicle regulation, a first surroundings sensing device being provided, which delivers longitudinal value-optimized measured values, a second surroundings sensing device being provided, which delivers object lateral dimension-optimized measuring values, and an analyzer device being provided, which receives the output signals of the first and second surroundings sensing devices and the measured values of the first and second surroundings sensing devices being used for object identification. The device and the method are furthermore suitable for initiating or performing vehicle deceleration for collision avoidance or for alleviating the severity of a collision.

Abstract: The present invention describes a system and method of OAM diverse signal processing using classical beams for applications in which OAM signal character is controlled such as optical tagging and applications in which OAM signal character is not controlled such as clutter mitigation and interference cancellation for target detection, identification etc. This is accomplished by transmitting a source beam having a prescribed state with one or more non-zero OAM components, reflecting the beam off a ‘tagged’ or ‘untagged’ target and receiving the return beam in the direct return path to measure the one or more OAM components to identify the target. OAM processing provides additional degrees of processing freedom to greatly enhance the processing capabilities to detect and identify both ‘tagged’ and ‘untagged’ targets.

Abstract: A method of detecting a target in a scene comprises the steps of generating a comparison of the value of data elements in first and second data sets, the data elements corresponding to returns from the same part of the scene and setting a detection threshold value for the comparison so as to detect targets entering said that part of scene The method provides improved target detection in the presence of clutter.

Abstract: A method for detecting and documenting red-light violations and/or speeding violations in which a radar beam is directed across all lanes of a roadway of interest and in which the speed and the position of a vehicle which passes through the radar beam are determined from the radar signals so as to be able to predict the probability of a red-light violation from the speed and the determined distance of the measured vehicle from a stop line and to trigger the recording of images of the violating vehicle at predetermined distances from the stop line.

Abstract: A system and method for fusing depth and radar data to estimate at least a position of a threat object relative to a host object is disclosed. At least one contour is fitted to a plurality of contour points corresponding to the plurality of depth values corresponding to a threat object. A depth closest point is identified on the at least one contour relative to the host object. A radar target is selected based on information associated with the depth closest point on the at least one contour. The at least one contour is fused with radar data associated with the selected radar target based on the depth closest point to produce a fused contour. Advantageously, the position of the threat object relative to the host object is estimated based on the fused contour. More generally, a method is provided for aligns two possibly disparate sets of 3D points.

Abstract: A logging radar system and method for measuring propped fractures and down-hole formation conditions in a subterranean formation including: a radar source; an optical source; an optical modulator for modulating an optical signal from the optical source according to a signal from the radar source; a photodiode for converting the modulated optical signal output from the optical modulator to the source radar signal; a transmitter and receiver unit; and a mixer. The transmitter and receiver unit receives the source radar signal from the photodiode, transmits the source radar signal into the formation and receives a reflected radar signal. The mixer mixes the reflected radar signal with the source radar signal to provide an output. This technology can be used to describe all fractures connected to the wellbore and differentiate between the dimensions of the two vertical wings of a propped fracture.

Abstract: According to some embodiments of the invention a laser directed infrared countermeasures system (hereinafter: “LDIRCM system”) is mountable on a platform. According to some embodiments of the invention, a LDIRCM system may include a plurality of sector units. Each sector unit may include at least one laser unit and a laser guidance module. The laser unit may be adapted to generate a laser beam or laser energy that is intended for jamming a guidance system of a threat. The laser unit may be coupled to the laser guidance module. The laser guidance module may be adapted to steer at least a laser beam generated by the laser unit towards a threat.

Abstract: The multi-target tracking and discrimination system (MOST) fuses with and augments existing BMDS sensor systems. Integrated devices include early warning radars, X-band radars, Lidar, DSP, and MOST which coordinates all the data received from all sources through a command center and deploys the GBI for successful interception of an object detected anywhere in space, for example, warheads. The MOST system integrates the optics for rapid detection and with the optical sensor array delivers high-speed, high accuracy positional information to radar systems and also identifies decoys. MOST incorporates space situational awareness, aero-optics, adaptive optics, and Lidar technologies. The components include telescopes or other optical systems, focal plane arrays including high-speed wavefront sensors or other focal plane detector arrays, wavefront sensor technology developed to mitigate aero-optic effects, distributed network of optical sensors, high-accuracy positional metrics, data fusion, and tracking mounts.

Abstract: Vehicle-based lidar systems and methods are disclosed using multiple lasers to provide more compact and cost-effective lidar functionality. Each laser in an array of lasers can be sequentially activated so that a corresponding optical element mounted with respect to the array of lasers produces respective interrogation beams in substantially different directions. Light from these beams is reflected by objects in a vehicle's environment, and detected so as to provide information about the objects to vehicle operators and/or passengers.

Abstract: A time-reversal imaging radar system for acquiring an image of a remote target includes an antenna array having a plurality of spaced-apart antennas, and a transceiver coupled to the antenna array for alternately transmitting a radar signal via the antenna array toward the target and for receiving target-reflected radar signals. The transceiver includes means for multiple-pass time-reversing the transmitted and received radar signals whereby coherent beam focusing is realized at both the target and at the receiver to thereby enhance the resolution of the acquired target image.

Abstract: An apparatus for detecting radiation includes an entry window configured to receive radiation from a target, the entry window having an outer surface and an inner surface, such that the outer surface is not parallel to the inner surface. The apparatus further includes a radiation transmission assembly configured to receive at least a portion of the radiation received by the entry window. The apparatus further includes a radiation sensor configured to receive at least a portion of the radiation from the radiation transmission assembly.

Abstract: The disclosed system, device and method for an anti-missile system generally includes a ground-based sensor array generating tracking data of a guided missile tracking a target. A control node in communication with the ground-based sensor array generates targeting data from the tracking data. A phased array directed-energy unit in communication with the control node radiates the guided missile with microwave radiation based on the targeting data received from the control node, where the microwave radiation disrupts an electronic component of the guided missile such that the guided missile discontinues tracking the target.

Abstract: A method and system, which may be implemented in some embodiments as a video game, for identifying harmful airborne biota, particularly flying insects, and either killing or disabling the harmful airborne biota is disclosed. Lasers, radar, and other types of radiation may be used to illuminate objects in a detection region, with radiation returns detected and applied to a pattern classifier to determine whether the detected airborne biota are harmful, benign or beneficial. Tracking and classification information may be provided to a remotely located game participant who may be permitted to control measures taken to eliminate the harmful airborne biota, these measures including firing pulses of beamed energy or radiation of a sufficient intensity to at least incapacitate them, or mechanical measures such as flying a remotely-controlled miniature unmanned aircraft to engage and kill the pests.

Abstract: An obstacle detection system determines a probability distribution of existence of an obstacle object corresponding to a distance in an irradiation direction of a transmission wave based on detected strength data per scanning-angle supplied from a radar device. A peak-value of the strength data becomes a maximum probability of existence of the obstacle. The probability distribution has a range gradually decreasing before and after the peak-value. Even if the position indicated by the maximum probability of existence of the obstacle object is different from an actual distance to the obstacle object, it hardly occurs that the probability of existence at an actual position of the obstacle object becomes zero. This eliminates occurrence of separation/association errors. Primary and secondary existence probability relationships made based on the probability distribution are combined. Using the combined one further decreases the error detection.

Abstract: A receiver, such as a miniaturized microwave-photonic coherent receiver (MMPR) is disclosed. The receiver includes an antenna to output an electrical RF signal received on a section of the antenna, a laser to produce an optical signal, a photonic modulator to receive the optical signal and the electrical RF signal and produce an EO-RF signal and to receive the optical signal and an electrical LO signal and produce an EO-LO signal, a signal combiner to provide a combined EO-RF and EO-LO signal and a photodiode to receive the combined signal and produce an IF signal. A method of detecting an object using the MMPR includes receiving an electrical RF signal corresponding to the object, outputting the electrical RF signal to a photonic modulator, modulating the electrical RF signal onto an optical carrier, demodulating the electrical RF signal to produce an IF signal and processing the IF signal.

Abstract: The present invention provides a MKV interceptor including multiple kill vehicles with autonomous management capability and kinematic reach to prosecute a large threat extent. Each KV can self-manage its own KV deployment and target engagement for a determined target volume assigned by a designated master KV. At least one KV is master capable of managing the post-separation of all of the KVs without requiring updates to the mission plan post-separation. The autonomous capability and increased kinematic reach provides for a more efficient use of boosters and more effective engagement of the threat.

Abstract: By sharing tasks between the CV and the KVs, the MKV interceptor provides a cost-effective missile defense system capable of intercepting and killing multiple targets. The placement of the acquisition and discrimination sensor and control sensor on the CV to provide target acquisition and discrimination and mid-course guidance for all the KVs avoids the weight and complexity issues associated with trying to “miniaturize” unitary interceptors. The placement of a short-band imaging sensor on each KV overcomes the latency, resolution and bandwidth problems associated with command guidance systems and allows each KV to precisely select a desirable aimpoint and maintain track on that aimpoint to impact.

Abstract: A target acquisition system. The novel system includes a housing, a first mechanism for obtaining position coordinates of the housing, a second mechanism for measuring a pointing angle from the housing toward a target, and a third mechanism for calculating coordinates of the target using the pointing angle and housing coordinates. The system may also include a fourth mechanism for determining a distance between the housing and the target, and a control circuit for receiving a user signal and in response thereto acquiring the housing coordinates, pointing angle, and distance data. The target coordinates may be calculated from the housing coordinates, pointing angle, and distance data, or from two or more sets of position coordinates and corresponding pointing angle data. The system may also include a transmitter for automatically transmitting the target coordinates to a remote weapons system or network.

Abstract: A logging radar system and method for measuring propped fractures and down-hole formation conditions in a subterranean formation including: a radar source; an optical source; an optical modulator for modulating an optical signal from the optical source according to a signal from the radar source; a photodiode for converting the modulated optical signal output from the optical modulator to the source radar signal; a transmitter and receiver unit; and a mixer. The transmitter and receiver unit receives the source radar signal from the photodiode, transmits the source radar signal into the formation and receives a reflected radar signal. The mixer mixes the reflected radar signal with the source radar signal to provide an output. This technology can be used to describe all fractures connected to the wellbore and differentiate between the dimensions of the two vertical wings of a propped fracture.

Abstract: An example radar system for a vehicle comprises a radar antenna, operable to produce a radar beam, and a lens assembly including at least one active lens, the radar beam passing through the lens assembly. The radar beam has a field of view that is adjustable using the active lens. In some examples, the active lens comprises a metamaterial, the metamaterial having an adjustable property such as an adjustable negative index, the field of view being adjustable using the adjustable property of the metamaterial.

Abstract: The present invention provides a radio signal radiation system that alleviates the necessity of a highly specified pass band reception filter and a high performance/reliability amplifier. The radio signal radiation system includes an optical modulator; a light source for inputting an optical carrier wave into the optical modulator; a power source for applying a modulating signal having a frequency Fm on the optical modulator to superimpose a sideband wave onto the carrier wave, the modulating signal having an amplitude of N-times the drive voltage of the optical modulator; a light receiver to receive and convert the outgoing light into an electrical signal; and a radiating means for radiating a radio signal based on the electrical signal, wherein the sideband wave is superimposed at a position shifted by n×fm.

Abstract: A power transmission and imaging system for an airship comprises a transmission antenna array configured to transmit an energy beam to a patch rectenna carried by the airship. Coupled to the patch rectenna is a power distribution and control network that supplies rectified power delivered by the energy beam into the proper format for delivery to a power storage system and a motor control system. The power storage system comprises one or more batteries to store the transmitted energy, while the motor control system powers various propellers, blowers, and valves maintained by the airship in order to descend the airship to the ground. The rectenna may also function as an imaging system in real-time. The image processing system uses the patch rectenna to transmit and receive signals, and in turn store and process the return signals (images).

Abstract: A laser radar device that operates on an elapsed time basis and has a pulsating laser for emitting successive light pulses into a monitored region. A light receiver receives light impulses reflected by an object in the monitored region and generates electrical signals responsive to the received light impulses. The signals are forwarded to an evaluation unit adapted to generate a distance signal indicative of a distance between the object and the laser radar device on the basis of the speed of light and an elapsed time between the emission of the light pulses and the receipt of the reflected light pulses. A light diverter located between the laser and the monitored region continuously varies the directionality of the light impulses directed into the monitored region and includes a beam splitter that divides the energy of the emitted light pulses into a main beam and a sensing beam.

Abstract: A method of tracking a target. The method includes the steps of acquiring a first spectral image of a scene that includes the target, designating a spectral reference window, in the first spectral image, that includes a respective plurality of pixel vectors, acquiring a second spectral image, of the scene, that includes a respective plurality of pixel vectors, and hypercorrelating the spectral reference window with the second spectral image, thereby obtaining a hypercorrelation function, a maximum of the hypercorrelation function then corresponding to a location of the target in the scene.

Abstract: An optical detection system for detecting launch of an offensive projectile. The detection system includes an image detector array, an optical arrangement for focusing on to the image detector array, and a processing system associated with the image detector array. The processing system is configured to derive a series of frames from the image detector, to process the series of frames to identify a flash event and to generate and output that indicates a direction of the flash event.

Abstract: A platform such as a car has a processor receiving information representing the location of the platform and a location of a target. An emitter assembly controlled by the processor produces a visual display outside of and beyond the platform that an occupant of the platform can see. The display is transmitted along the target bearing.

Abstract: Calibration of an acceleration detector is initiated by a user depressable button such as a button indicating a vehicle is at rest and/or by the detector reading an OBDII vehicle communication protocol to determine the condition of the vehicle. Calibration permits more accurate measurements in a vehicle performance test.

Abstract: A combination laser system and global navigation satellite system has a laser detector positioned in a known and fixed relationship with the nominal phase center of an included global navigation satellite antenna. The outputs of the laser system and the global navigation satellite system are used together to determine position.

Abstract: A radar device has a light projecting circuit for projecting light to an object. Reflected light from the object is received by a first light receiving circuit and a second light receiving circuit and converted into signals. The first and second light receiving circuits each have an activity range in which the outputted signal is proportional to the logarithm of the quantity of received light. The activity range of the first light receiving circuit is lower than the activity range of the second light receiving circuit.

Abstract: A radar device includes a light projecting part for projecting light to an object, first and second light receiving elements each for outputting a signal according to the quantity of received light flux, and an optical system having a first optical path and a second optical path for guiding reflected light from the object respectively to the first light receiving element and to the second light receiving element. The optical system guides more light flux to the first optical path than to the second optical path corresponding to an incident light flux to the radar device.

Abstract: Vehicular arrangement for obtaining information about objects exterior to the vehicle includes at least one combined imaging and distance measuring system arranged along an edge or a side of the vehicle, each combined system including an infrared illuminator for directing infrared illumination outward from the vehicle, an imager sensitive to infrared illumination and visible light, the imager being arranged to form images of an environment around the vehicle and thereby enable identification of objects in the images, a radar or laser radar system arranged to simultaneously determine a distance between the vehicle and objects identified in images obtained by the imager with the identification of the objects in the images. A reactive system is arranged on the vehicle to consider both the identification of the objects and their distance from the vehicle and react accordingly.

Abstract: A target object detection system for detecting a target object using a detector and a tag on the target object; the tag includes a radio wave receiver receiving radio wave from the detector; a light receiver receiving a light signal from the detector; a receipt signal generator generating a receipt signal; and a transmitter which transmits the receipt signal to the detector; and the detector includes a radio wave transmitter transmitting radio wave to the surrounding area; a receiver receiving the receipt signal from the tag; a light emitter irradiating the light signal to a search region; a controller controlling the radio wave transmitter, the receiver, and the light emitter; and a target position measuring unit measuring a distance to the target object based on the intensity of the receipt signal, and regarding the irradiation direction of the light signal from the light emitter as the direction of the target-object.

Abstract: An image display apparatus includes a camera, a laser radar, a depression angle correction calculation device, a three-dimensional object detection device, and a viewpoint conversion device, which are installed in a vehicle. The laser radar detects changes in the condition of a road surface with respect to the camera The depression angle correction calculation device adds a correction angle to a depression angle of the camera. The viewpoint conversion device reduces the correction angle if the change in road surface condition detected by the laser radar is due to a three-dimensional object detected by the three-dimensional object detection device.

Abstract: A system is disclosed for administering a restricted flight zone using radar and lasers for detecting, tracking, warning and destroying airborne craft that enter restricted flight zones without authorization or that approach dangerously close to protected areas on the ground. The system comprises a support for positioning adjacent the surface of the Earth at a bottom of the zone, detecting and defending apparatus mounted on the support for detecting airborne objects in the zone and defending against the airborne objects in the zone, and controlling apparatus for controlling the detecting and defending means.

Abstract: An obstacle detection system determines a probability distribution of existence of an obstacle object corresponding to a distance in an irradiation direction of a transmission wave based on detected strength data per scanning-angle supplied from a radar device. A peak-value of the strength data becomes a maximum probability of existence of the obstacle. The probability distribution has a range gradually decreasing before and after the peak-value. Even if the position indicated by the maximum probability of existence of the obstacle object is different from an actual distance to the obstacle object, it hardly occurs that the probability of existence at an actual position of the obstacle object becomes zero. This eliminates occurrence of separation/association errors. Primary and secondary existence probability relationships made based on the probability distribution are combined. Using the combined one further decreases the error detection.