44results about How to "Large return loss" patented technology

The invention discloses a substrate integrated waveguide leaky-wave antenna with a big circular polarization beam scanning range, belongs to the field of microwave antenna engineering, and solves a problem that a conventional circular polarization leaky-wave antenna is small in circular polarization beam scanning range. The antenna is of a three-layer structure, wherein the top and the bottom are metal layers, and the central part is a dielectric base material layer. The top metal layer and the bottom metal layer are electrically connected through two rows of metalized via holes, and the top metal layer forms a microstrip, a substrate integrated waveguide converter and N antenna units through etching. Each antenna unit comprises one longitudinal seam and a pair of lateral seams, and the longitudinal seam and the lateral seam pair respectively provide the loading of parallel capacitance and series inductance, can achieve the inhibition of the stop band of the leaky-wave antenna, and achieve the backward, lateral and forwarding continuous scanning of a beam. The longitudinal seam and the lateral seam pair also respectively provide independent controllable lateral polarization and longitudinal polarization radiation, thereby achieving the big circular polarization beam scanning range.

The invention discloses a large-mode-area single-mode fiber connector and a manufacture method. The large-mode-area single-mode fiber connector comprises an insertion pin; a connecting and fixing head is arranged at the periphery of the insertion pin; a single-mode fiber is formed in the center hole of the insertion pin; the single-mode fiber is fused with a graded-refractive-index lens, wherein the graded-refractive-index lens is made by carrying out thermal diffusion on a step-type multimode fiber; and a color ring is formed on a rubber tail sleeve of the single-mode fiber. The manufacture method of the large-mode-area single-mode fiber connector comprises the following steps of: carrying out thermal diffusion on the step-type multimode fiber so as to achieve the element doping of a fiber core, and forming the graded-refractive-index lens with a refractive index reducing outwards along the radial direction; fusing the graded-refractive-index lens with the single-mode fiber, cutting the graded-refractive-index lens and fixedly connecting the graded-refractive-index lens into the center hole of the insertion pin, aligning the outer end of the graded-refractive-index lens with the end face of the insertion, grinding and polishing the end face of the insertion pin; and printing the color ring on the rubber tail sleeve, and configuring the connecting and fixing head for the insertion pin. The large-mode-area single-mode fiber connector and the manufacture method have the advantages that: the large-mode-area single-mode fiber connector is simple in structure and easy to manufacture, the end face of the large-mode-area single-mode fiber connector is easily ensured to be clean, the light-passing area is large, and the matching connection with the traditional other fiber movable connectors can be achieved.

The invention discloses Gold wire bonding capacitance compensation in a three-dimensional encapsulated circuit. The invention involves a microwave multilayer circuit dielectric substrate. A capacitance compensation structure is arranged on a first layer transmission wire on the surface of the microwave multilayer circuit dielectric substrate. A capacitance compensation structure is arranged on a middle layer transmission wire in the vertical direction of the microwave multilayer circuit dielectric substrate. The transmission lines are in interconnection through gold wire bond wires. According to the invention, a problem of impedance matching of gold wire bonding in the three-dimensional encapsulated circuit is solved effectively. Space of the multilayer circuit is utilized fully for design of the capacitance compensation structure for parasitic inductance effect of gold wire bonding, especially the capacitance compensation structure added in the vertical direction. Compared with a prior art, area required for capacitance compensation merely on the surface layer transmission wire can be reduced. By adopting the structure provided by the invention, microwave transmission characteristics between transmission wires and chips and between transmission wires and transmission wires in a multi-chip circuit can be improved.

The invention discloses an anti-multipath-interference broadband low-axial-ratio global-navigation-satellite-system (GNSS) antenna comprising four rectangular radiating units, corresponding four triangular matching connection units, four via holes, a microstrip line power divider phase-shift network, a feed via hole, a dielectric substrate, a circular plate type floor, four via hole round units, a feed via hole round unit, and a metal cylinder. The four rectangular radiating units and the four triangular matching connection units form a centric symmetric structure and are arranged right above the dielectric substrate. The four via holes pass through the dielectric substrate to realize communication between the triangular matching connection units and the port of the microstrip line power divider phase-shift network. The microstrip line power divider phase-shift network is arranged at the back of the dielectric substrate. The feed via hole is used for connecting the microstrip line power divider phase-shift network with a conductor arranged inside a coaxial feeder. The circular plate type floor is arranged at the front side of the dielectric substrate and the edge of the circular plate type floor is connected with the metal cylinder. The anti-multipath-interference broadband low-axial-ratio GNSS antenna disclosed by the invention has characteristics of good anti-multipath-interference performance, broadband, low axial ration, wide beam, and small size and the like.

The invention relates to a 2*2MEMS optical switch based on a double optical fiber elliptical light spot collimator. The optical switch is characterized in that: (1) the optical switch is formed by coupling a pair of the double optical fiber elliptical light spot collimators with an MEMS micro-mirror; (2) a beam waist light spot of an exit light beam of the double optical fiber elliptical light spot collimator is an elliptical light spot, that is, the radii of the light spots in two vertical directions are unequal; (3) a collimating lens of the optical fiber collimator comprises a cylindrical surface, and a circular light spot is changed into the elliptical light spot; (4) the surface of the collimating lens is plated with an anti-reflection film to increase return loss; (5) the elliptical light spot collimator is a double optical fiber collimator, and an input optical fiber is a double optical fiber; (6) the MEMS micro-mirror is an MEMS comb drive actuated micro-mirror; and (7) the MEMS micro-mirror is arranged at the beam waist of the exit light beam of the elliptical light spot collimator, and the drive direction corresponds with the minor axis of the light spot. In the optical switch, the requirement of the 2*2 optical switch for the MEMS micro-mirror drive stroke can be greatly reduced, and the stroke of microns can immediately obtain sufficiently low optical signal crosstalk.

The invention provides a coupled toroidal resonator based miniaturized differential band-pass filter. The coupled toroidal resonator based miniaturized differential band-pass filter comprises two centrally-symmetrical mutually-coupled toroidal resonators, wherein each toroidal resonator comprises four micro-strip line combinations. The first toroidal resonator comprises a rectangular ring composed of a first micro-strip line, a second micro-strip line, a third micro-strip line and a fourth micro-strip line, a first output port and a second output port, wherein the first micro-strip line is located above the rectangular ring and is vertically symmetrical to the third micro-strip line, the second micro-strip line and the fourth micro-strip line are respectively located on the left side and right side of the first micro-strip line and are both connected with the first micro-strip line and the third micro-strip line, the first output port is connected with the first micro-strip line, and the second output port is connected with the third micro-strip line. The coupled toroidal resonator based miniaturized differential band-pass filter has lower difference mode pass band insertion loss, higher return loss, a steep edge selection characteristic and a higher common-mode rejection characteristic.

An ultra-wideband tri-trap antenna comprises a dielectric substrate. The upper surface and the lower surface of the dielectric substrate are respectively coated with a radiation patch and a conductive layer. The radiation patch comprises a patch front end in the diameter decreasing and a micro-strip feeder line connected to the tail of the patch front end. The conductive layer comprises a base plate with arc-shape edge and a split ring reflector arranged above the base plate with arc-shape edge. The arc-shaped edge of the base plate with arc-shape edge protrudes upwards. The base plate with arc-shape edge is provided with a U-shaped groove with a downward opening. The split ring reflector comprises an upper ring with a rectangular opening, a lower ring with a rectangular opening and symmetrical branches arranged outside the rings. According to the ultra-wideband tri-trap antenna, straight grooves in both inner side edges of the U-shaped groove and wave grooves outside the U-shaped groove are used for trapping the frequency band of a wireless local area network and the C-band respectively, and the non-base plate area at the bottom of the antenna is used for trapping the downlink band of the X-band through the split ring reflector with double openings and the branches. The ultra-wideband tri-trap antenna has the advantages of being novel in overall structure, small in size, high in trap quantity, good in trap form and the like.

The invention relates to a cable processing technology, in particular to a production method for a light low-attenuation wrinkled coaxial cable. The technical scheme is that the production method for the light low-attenuation wrinkled coaxial cable sequentially comprises the following steps: (1) preparing an inner conductor; (2) wrapping an insulator, first enabling the inner conductor to enter an inner thin layer extruder to enable an inner thin layer to be formed outside the inner conductor; enabling the inner conductor where the inner thin layer is wrapped to enter a foaming insulating layer extruder to form an insulating layer; and forming an outer thin layer outside the foaming insulating layer through an outer thin layer extruder; (3) preparing an outer conductor; and (4) wrapping a sheath, and using a plastic extruder to enable a sheath material to be wrapped outside the outer conductor to form the sheath. The wrinkled coaxial cable prepared in the method has the advantages of being low in attenuation, uniform in impedance and large in return loss.

The invention discloses a wide-range cavity filter with an adjustable frequency band. The wide-range cavity filter comprises an input port and an output port, wherein the input port and the output port are arranged on the same side of a cuboid resonant cavity, two rectangular windows are arranged at the central position of the resonant cavity, two cuboid resonant rods are arranged on two symmetric sides of the rectangular windows, two pairs of resonant discs are respectively arranged above the two cuboid resonant rods, two resonant discs arranged below the two cuboid resonant rods are separately connected with two cuboid resonant rods, and two cylindrical tuning screw rods are separately connected with the two resonant discs arranged above the two cuboid resonant rods. The corresponding area of the two pairs of resonant discs can be changed by rotating the tuning screw rods for achieving adjustable frequency band of the cavity filter. The wide-range cavity filter with the adjustable frequency band, disclosed by the invention, is simple in structure, relatively wide bandwidth, relatively small insertion loss and relatively high return loss can be achieved in pass-band width, the effect of adjustable frequency band in a wide range is achieved, and the cavity filter has favorable promotion prospect.

The invention provides a defected ground structure (DGS) asymmetrical coplanar waveguide type tri-band antenna, which comprises a substrate, a radiation patch unit, a metal grounding plate and an impedance-matching input transmission line. The radiation patch unit, the metal grounding plate and the impedance-matching input transmission line are arranged on the surface of the substrate. The metal grounding plate is provided with a rectangular slot, an inverted right-angled triangular slot and an arc-shaped slot. The radiation patch unit is composed of three radiation patches, namely a homogeneous type fold line combined radiation patch A, a radiation patch C and a non-homogeneous type fold line combined radiation patch C. The bottoms of the three radiation patches are overlapped. The middle parts of the bottoms of the three radiation patches are connected with one end of the impedance-matching input transmission line. The other end of the impedance-matching input transmission line is connected with the bottom end of the substrate. The three radiation patches and the impedance-matching input transmission line are symmetrical relative to the Y-axis of the substrate. The DGS asymmetrical coplanar waveguide type tri-band antenna is very concise, compact and novel in structure, and better in applicability. Meanwhile, the effective area of the radiation patches is increased, and the antenna performance is improved.

The invention discloses a narrow-band difference band-pass filter based on a terminal short circuit self-coupling annular resonator. The narrow-band difference band-pass filter comprises a terminal short circuit self-coupling annular resonator and two coupling micro band lines. Micro band line design with distribution parameters is adopted. The narrow-band difference band-pass filter has the advantages of light weight, high reliability, excellent property, good temperature stability, large-scale production, low cost, and the like, is wide in application prospect in radar of different frequency bands, communication and future high-velocity data wireless communication, and can be particularly used in corresponding systems with harsh requirements on weight, property and reliability.

The invention discloses an electronically-controlled adjustable optical attenuator. On the basis of the microfluidic technology, a sandwich structure is adopted; the first layer is a cover plate (1), an outlet (10) for a power line (9) is left, and piezoelectric ceramic (6) is embedded in an inner groove (12), and the piezoelectric ceramic (6) is bonded with the cover plate (1); the second layer is a square transparent dielectric layer (2) and comprises a microfluidic channel (3) on the diagonal line, an incident fiber collimator (4), an emergent light fiber collimator (5), the piezoelectric ceramic (6), an insulated piston sheet (7) bonded with the piezoelectric ceramic together, a liquid storage pipe (8) and the power line (9), the upper end of the microfluidic channel (3) is sealed with air by using an elastic thin film, the other end is filled with liquid and communicated with the liquid storage pipe (8), and the liquid refractive index is the same as or similar with that of the square transparent dielectric layer (2); and the third layer is a base (11). The piezoelectric ceramic is controlled to be extended and retracted by voltage, the matching liquid in the microfluidic channel (3) is driven to flow, the position of the matching liquid in the microfluidic channel (3) is controlled, the light intensity coupling efficiency between two fiber collimators is thus mediated, and controllable attenuation adjustment on the light is realized.

The invention discloses a 5G broadband Wilkinson power divider, and relates to the technical field of microwave transmission devices. The 5G broadband Wilkinson power divider positioned on a dielectric layer comprises an input port and first and second output ports arranged in the dielectric layer, an input and output matched first branch line is arranged between the input port and the first output port, an input and output matched second branch line is arranged between the input port and the second output port, and first, second and third isolating resistors are arranged successively along the signal transmission direction between the first and second branch lines. The Wilkinson power divider works in the frequency band of 1.45GHz-5.35GHz, the bandwidth of the Wilkinson power divider canbe broadened effectively, and 5G work frequency band can be covered.

The invention relates to a 2*2MEMS optical switch based on a double optical fiber elliptical light spot collimator. The optical switch is characterized in that: (1) the optical switch is formed by coupling a pair of the double optical fiber elliptical light spot collimators with an MEMS micro-mirror; (2) a beam waist light spot of an exit light beam of the double optical fiber elliptical light spot collimator is an elliptical light spot, that is, the radii of the light spots in two vertical directions are unequal; (3) a collimating lens of the optical fiber collimator comprises a cylindrical surface, and a circular light spot is changed into the elliptical light spot; (4) the surface of the collimating lens is plated with an anti-reflection film to increase return loss; (5) the ellipticallight spot collimator is a double optical fiber collimator, and an input optical fiber is a double optical fiber; (6) the MEMS micro-mirror is an MEMS comb drive actuated micro-mirror; and (7) the MEMS micro-mirror is arranged at the beam waist of the exit light beam of the elliptical light spot collimator, and the drive direction corresponds with the minor axis of the light spot. In the optical switch, the requirement of the 2*2 optical switch for the MEMS micro-mirror drive stroke can be greatly reduced, and the stroke of microns can immediately obtain sufficiently low optical signal crosstalk.

The invention discloses a substrate integrated waveguide filter with independently adjustable double bands. The substrate integrated waveguide filter comprises a resonant cavity and a perturbation body on the resonant cavity, wherein the resonant cavity comprises a ground plane, a dielectric plate, a top-layer surface and metal wall via holes; the top-layer surface and the ground plane are located at the upper part and the lower part of the dielectric plate; the metal wall via holes are distributed in the periphery of the resonant cavity in an array at equal distances to form a wall; the hole pitch between two metal wall via holes is smaller than or equal to 2.5 times of the diameter of each metal wall via hole; the perturbation body comprises a perturbation trough, perturbation metal via holes and connecting troughs; the perturbation trough is located at the center position of the top-layer surface of the resonant cavity; the connecting troughs are symmetrically arranged about the perturbation trough; the perturbation metal via holes in each resonant cavity are symmetrical about the perturbation trough and correspondingly located in the connecting troughs; and the numbers of the connecting troughs and the perturbation metal via holes are even numbers. The SIW filter with the independently adjustable double bands has the advantages of being simple in structure, relatively large in return loss, independently adjustable in double bands and simple in operation.

The invention discloses a narrow-band differential bandpass filter based on a terminal short-circuit self-coupling ring resonator, which comprises a terminal short-circuit self-coupling ring resonator and two coupling microstrip lines. The present invention adopts microstrip line design. The invention has the advantages of light weight, high reliability, excellent performance, good temperature stability, and low mass production cost. It has broad application prospects for radars in various frequency bands, communications, and future high-speed data wireless communications, especially for weight, In the corresponding system with strict requirements on performance and reliability.

The invention relates to an adjustable attenuator with high echo loss and large dynamic range based on a zero-refraction metamaterial. The adjustable attenuator comprises a T-shaped coaxial air line with three ports, an internal conductor is fractured at the port opposite to a matched load port, a rotation rod is arranged at the fracture position, one end of the rotation rod is rotatably connected with the internal conductor in a mechanical manner, the other end of the rotation rod rotates at any angle between the internal conductor and an outer conductor, the zero-refractive-index metamaterial is filled between the T-shaped junction, the internal conductor and the outer conductor, the metamaterial covers the rotation rod, and an air slot is reserved for a rotation area of the rotation rod. According to the attenuator, the attenuation can be controlled, and large dynamic adjusting range is provided; by employing the novel inserted metamaterial, the refractive index is zero, the echo loss of incident signals is increased, the reflectivity can be effectively reduced, interference with an input port front-end circuit is prevented, and the performance of the attenuator is effectively enhanced.

The invention discloses Gold wire bonding capacitance compensation in a three-dimensional encapsulated circuit. The invention involves a microwave multilayer circuit dielectric substrate. A capacitance compensation structure is arranged on a first layer transmission wire on the surface of the microwave multilayer circuit dielectric substrate. A capacitance compensation structure is arranged on a middle layer transmission wire in the vertical direction of the microwave multilayer circuit dielectric substrate. The transmission lines are in interconnection through gold wire bond wires. According to the invention, a problem of impedance matching of gold wire bonding in the three-dimensional encapsulated circuit is solved effectively. Space of the multilayer circuit is utilized fully for design of the capacitance compensation structure for parasitic inductance effect of gold wire bonding, especially the capacitance compensation structure added in the vertical direction. Compared with a prior art, area required for capacitance compensation merely on the surface layer transmission wire can be reduced. By adopting the structure provided by the invention, microwave transmission characteristics between transmission wires and chips and between transmission wires and transmission wires in a multi-chip circuit can be improved.

The invention relates to a cable processing technology, in particular to a production method for a light low-attenuation wrinkled coaxial cable. The technical scheme is that the production method for the light low-attenuation wrinkled coaxial cable sequentially comprises the following steps: (1) preparing an inner conductor; (2) wrapping an insulator, first enabling the inner conductor to enter an inner thin layer extruder to enable an inner thin layer to be formed outside the inner conductor; enabling the inner conductor where the inner thin layer is wrapped to enter a foaming insulating layer extruder to form an insulating layer; and forming an outer thin layer outside the foaming insulating layer through an outer thin layer extruder; (3) preparing an outer conductor; and (4) wrapping a sheath, and using a plastic extruder to enable a sheath material to be wrapped outside the outer conductor to form the sheath. The wrinkled coaxial cable prepared in the method has the advantages of being low in attenuation, uniform in impedance and large in return loss.

The invention provides an asymmetrical coplanar waveguide triple-band antenna with defective ground structure, which includes a substrate, a radiation patch unit, a metal ground plate, and an impedance matching input transmission line. The surface of the substrate has a radiation patch unit, a metal ground plate and an impedance matching input transmission line; the metal ground plate has a rectangular groove, an inverted right-angled triangle groove and an arc groove; the radiation patch unit includes a uniform broken line combined radiation patch A and Radiation patch C, non-uniform broken-line combination type radiation patch B Three radiation patches, the bottom of the three radiation patches overlap, the middle of the bottom is connected to one end of the impedance matching input transmission line, and the other end of the impedance matching input transmission line is connected to the bottom of the substrate The three radiating patches and the impedance-matched input transmission lines are all symmetrical to the y-axis of the substrate. The structure of the invention is very simple, compact and novel, has high applicability, and at the same time expands the effective area of ​​the patch and improves the performance of the antenna.

The invention relates to a multichannel 2x2 photoswitch. A relay is inlaid in a bottom box; plug holes are respectively formed in two opposite side surfaces of the bottom box; an N-core optical collimator is fixedly arranged in each plug hole; N can be 4, 8, 12 or 16; and the central axes of the collimators on the two sides of the bottom box are superposed to each other. The rear end of a swinging plate hinged to the relay is positioned above a coil; a cantilever arm is fixed at the front end of the swinging plate; and n=N / 4 prisms are fixedly arranged at the front end of the cantilever arm. When the multichannel 2x2 photoswitch is in an initial state, the prisms are positioned below light paths of the collimators, and light paths of the collimators at an inputting end and an outputting end are communicated to each other directly. When the relay is electrified, the swinging plate is raised, the prisms on the cantilever arms are placed in the light paths of the optical collimators, outputting light of the optical collimator of the inputting end is refracted and reflected by the prisms and then enters another light path of the outputting end, and each prism can switch 4 light paths. Each optical collimator is inserted in a plug tube fixedly connected to the corresponding plug hole and is fixed, and a plug sleeve sleeves each optical collimator so as to protect the optical collimator. The bottom box is closed by a cover plate, various seams are sealed in a metalized manner, and the bottom box is filled with nitrogen. The multichannel 2x2 photoswitch is simple in structure, low in loss, convenient to adjust, high in precision and long in service life.

The invention discloses a substrate integrated waveguide leaky-wave antenna with a big circular polarization beam scanning range, belongs to the field of microwave antenna engineering, and solves a problem that a conventional circular polarization leaky-wave antenna is small in circular polarization beam scanning range. The antenna is of a three-layer structure, wherein the top and the bottom are metal layers, and the central part is a dielectric base material layer. The top metal layer and the bottom metal layer are electrically connected through two rows of metalized via holes, and the top metal layer forms a microstrip, a substrate integrated waveguide converter and N antenna units through etching. Each antenna unit comprises one longitudinal seam and a pair of lateral seams, and the longitudinal seam and the lateral seam pair respectively provide the loading of parallel capacitance and series inductance, can achieve the inhibition of the stop band of the leaky-wave antenna, and achieve the backward, lateral and forwarding continuous scanning of a beam. The longitudinal seam and the lateral seam pair also respectively provide independent controllable lateral polarization and longitudinal polarization radiation, thereby achieving the big circular polarization beam scanning range.

The invention discloses a three-dimensional integrated filter based on glass through holes. The filter comprises a first layer, a second layer, a third layer and a fourth layer, wherein the first layer comprises first metal plates and first metal wires, and the plurality of first metal plates are connected with the first metal wires; the second layer comprises a dielectric substrate and a second metal plate, the dielectric substrate is arranged above the first metal plates and the first metal wires, and the second metal plate is arranged in the dielectric substrate; the third layer comprises aglass substrate and glass through holes, the glass substrate is arranged above the second layer, and the glass through holes penetrate through the glass substrate; the fourth layer comprises a thirdmetal plate and a second metal wire, the second metal wire is arranged above the third layer and defines a second area structure, and the third metal plate is arranged in the second area structure. According to the invention, a three-dimensional spiral inductor and a plate capacitor are constructed based on the glass through holes, and an equivalent filter structure formed by series-parallel connection of the three-dimensional spiral inductor and the plate capacitor is compact in structure, small in size, convenient to integrate and flexible in design.

The invention relates to a cable, particularly relates to a radio frequency coaxial cable, and belongs to the technical field of cable manufacturing. The radio frequency coaxial cable comprises an internal conductor, insulating layers, an external conductor and a sheath. The internal conductor is a silver-plated copper wire. The conductor is extruded by the insulating layers. There are two insulating layers, wherein the internal layer is solid perfluorinated ethylene-propylene, and the external layer is solid polyethylene. The external diameter of the insulating layers is 1.90-5.08cm. The insulating layers are longitudinally wrapped by the aluminum foil external conductor which is provided with, from inside to outside, a copper wire braiding shielding layer, a copper tape shielding layer and a copper wire braiding shielding layer. The external copper wire braiding shielding layer is extruded by the sheath. The cable is excellent in shielding performance, wide in use frequency band, stable in performance and attenuation is low.

The invention discloses a miniaturized dual-band-pass filter based on a stacked dielectric integrated waveguide, which includes upper, middle and lower stacked dielectric integrated waveguide resonators. The upper and lower dielectric integrated waveguide resonators have the same structure and are placed in opposite directions, they are symmetrical about the center of the filter, and couple energy to each other through the middle dielectric integrated waveguide resonator. Compared with microstrip lines, the present invention has higher Q value and higher power carrying capacity, and has smaller passband insertion loss, larger return loss, steep edge selection characteristics and larger passband gap. The isolation degree achieves the optimization purpose of miniaturization, and the processing and testing are convenient, the structure is simple, and the cost is low.

An integrated system for optical fiber testing equipment is provided with an optical switch, three sets of equipment connection ports and two sets of sample connection ports. electrical connection. Each group of device connection ports is composed of a device data input lead fiber and a device data output lead fiber, and one end of the device data input lead fiber and the device data output lead fiber is respectively connected to the optical switch. Each group of sample connection ports is composed of a sample test signal input lead fiber and a sample test signal output lead fiber, and one end of the sample test signal input lead fiber and the sample test signal output lead fiber is respectively connected to the optical switch. Through the reasonable integration of resources through the optical path switching mode, multiple instruments can be connected to each other, and the optical fiber is connected at one time, and the tests of different optical fiber indicators are completed successively, which can improve the work efficiency of operators and the use efficiency of test equipment.