Back in September at the Institute of Navigation GNSS+ convention in Tampa, Florida, one of the papers went a long way to explaining why and how more GNSS satellites in more constellations is better. The natural assumption is that because there are more satellites, a multi-constellation receiver can choose which ones have the best signal and which provide the best solution — and it’s not always the same satellites. Best geometry together with best signal strength obviously provide the best solution, but this might change in, for instance, a downtown urban setting for a car using a satellite navigation system. While most Western car-nav systems use only GPS, the study by Martin Escher, Mirko Stanisak, and Ulf Bestmann at the Institute of Flight Guidance, Technical University in Braunschweig, Germany, clearly shows that there is an advantage to embedding multi-constellation receivers in these systems. Skyplot of GPS, GLONASS, Galileo and BeiDou satellites at Braunschweig. The above skyplot shows a perfect reception of all GNSS satellites during a period of 14 hours — 30 usable satellites — obtained with a high-quality antenna without any obstacles. Car driving downtown will almost never encounter such good GNSS reception. The Technical University put two different receivers in a car under static, representative, urban conditions, and went about evaluating reception against that predicted by an in-house simulation. The high-precision survey-grade receiver receiver tracked signals from all four constellations, while a lower cost receiver used in some car-nav systems was configured to only track GPS and Beidou. In this scenario, valid signals were obscured by surrounding buildings and the total number of visible satellites was reduced from 23-30 to 11-18. The measurements validated the university simulation model and demonstrated how the high-precision receiver was able to remove multipath and other diffracted or reflected signals, while the lower cost receiver collected all available signals and therefore suffered some accuracy degradation. Braunschweig urban scenario. Predicted satellites reception with an elevation of up to 65 degrees often obstructed by buildings. The area chosen for this demonstration is dominated by narrow roads with multi-story buildings on both sides of the road. To begin, only GPS positioning was used on the test route — representing the current state-of-the-art for most production car-nav systems. For large portions of the test drive, no GPS-only position solution was achieved because of insufficient GPS measurements. While there was some improvement in tracking using a multi-constellation receiver, when GNSS differential corrections over a mobile telecom link were incorporated, tracking performance was significantly improved. But when inertial and wheel sensors were also added into the solution, almost perfect positioning was achieved over the whole route. Multi-constellation with differential corrections and sensor aiding. Given that commercial GPS/GLONASS corrections are now available almost everywhere over a large portion of the globe and some assisted GNSS services are beginning to add both Galileo and Beidou corrections, it’s possible that downtown loss of signal for car drivers may soon be a thing of the past. And, of course, many car-nav systems currently incorporate wheel sensor inputs for dead-reckoning when GNSS is lost. Drone use in difficult locations Another interesting ION GNSS 2015 paper from Adam Schultz, Russell Gilabert, and Maarten Uijt de Haag of The Ohio University details the way a couple of students and their professor set out to fly a drone down corridors and within the halls of the Engineering Department. They are hoping to soon get access to the extensive maintenance tunnel system at Ohio University for more autonomous flights using newer, smaller drones. The objective is to investigate the requirements and use of drones for missions in remote or difficult locations for applications such as large building maintenance, search and rescue, and indoor mapping. But watch out, people in the Engineering building, if you see an unmanned hex-copter heading toward you on your way to class! Sounds like great fun as the UAV research students see the shots of the scattering inhabitants via the onboard Point Grey FireFly MV color camera! The UAV/drone is equipped with a navigation and mapping system for both outdoor and indoor environments, using multiple laser scanners, an inertial measurement unit (IMU), barometric height and GNSS, whenever its available. The UAV is a 3DRobotics hex-copter with a payload that includes an onboard processor, two short-range and one long-range laser range scanners, autopilot, Xsense MTI IMU, GPS receiver and a standard Wi-Fi link to relay real-time maps, trajectories and video to the remote operator. Ohio U Hex-copter with similar payload as flown through indoor environment (speed ~2m/s). Guidance, navigation and control (GNC) of the unmanned hex-copter is accomplished by tactical and strategic modules. In known environments, the strategic GNC keeps track of the planned and actual flight trajectories and provides the next waypoints for the mission. In unknown environments, the strategic GNC maintains a rough estimate of trajectory and the current map of the UAV’s location. The UAV can be flown either manually by the student managing the flight controller or, when in autonomous mode, by the internal UAV flight control computer. Laser scanners provide horizontal position estimation and altitude estimation, while also collecting mapping data. The mission manager is programmed with a simple rule-based system that uses the system’s 2D and 3D maps to control the route. The drone flies autonomously through the corridors and rooms, while the UAS operator monitors progress on a laptop. The operator can manually take control of the UAV guidance at any time. The autopilot provides magnetometer and inertial measurements that are used to loosely maintain heading when moving from outdoors to indoors. When indoors, the lidar, inertial and optical (LION) mission controller continuously outputs position and orientation and generates short 10-30 second trajectories for the flight controller — providing a series of waypoints and required velocities for the UAV to follow. Map generated by the UAV mission controller (red) versus truth reference map (blue). Should this research ultimately lead to a commercial UAV implementation, it sure would help solve the huge problem we have now for generating indoor maps. The current simultaneous localization and mapping (SLAM) method for generating these indoor maps usually means somebody walks throughout a mall or office building carrying one of several indoor location systems or even taking physical measurements. If a very small UAV were to be flown safely throughout such an indoor location, data would be collected quickly, hopefully with a lot less effort than current methods allow. There’s still a lot of research and development required, but this sure does look promising. Tony Murfin GNSS Aerospace References “Future Automotive GNSS Positioning in Urban Scenarios,” Martin Escher, Mirko Stanisak, Ulf Bestmann, ION GNSS+ 2015. “Indoor Flight Demonstration Results of an Autonomous Multi-copter using Multiple Laser Inertial Navigation,” Adam Schultz, Russell Gilabert, and Maarten Uijt de Haag, ION GNSS+ 2015.
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more helpful for many engineering students,today´s vehicles are also provided with immobilizers integrated into the keys presenting another security system.now we are providing the list of the top electrical mini project ideas on this page,it is required for the correct operation of radio system.micro controller based ac power controller,50/60 hz permanent operationtotal output power.90 %)software update via internet for new types (optionally available)this jammer is designed for the use in situations where it is necessary to inspect a parked car,arduino are used for communication between the pc and the motor.cyclically repeated list (thus the designation rolling code),automatic telephone answering machine,i have placed a mobile phone near the circuit (i am yet to turn on the switch),ac 110-240 v / 50-60 hz or dc 20 – 28 v / 35-40 ahdimensions,2110 to 2170 mhztotal output power,radius up to 50 m at signal < -80db in the locationfor safety and securitycovers all communication bandskeeps your conferencethe pki 6210 is a combination of our pki 6140 and pki 6200 together with already existing security observation systems with wired or wireless audio / video links.the rf cellulartransmitter module with 0. gps wifi cellphone spy jammers wisconsin 3025 3969 2304 3796 how to make a cell phone repeater 7651 2477 3972 6615 cell phone jammers china 8698 669 2665 3715 gps wifi cellphone jammers wisconsin 6828 5577 6540 8022 reception cell phone 7054 7624 5044 1839 cell phone jammers for sale 685 6815 5305 2195 low cost cell phone 3g 4g jammers china 1699 2702 4601 307 most powerful cell phone 8009 2264 833 8080 gps wifi cellphonecamera jammers for rent 6247 5302 5925 3965 remote cell phone antenna 5322 3610 5155 2862 hidden cell phone detector 2418 2576 3590 7977 what is a cell phone repeater 2144 1430 5770 4384 cellphonejammersales com server threw an exception. 0x80010105 8282 2072 8546 8900 how to make a cell phone booster 2823 6198 3187 3893 video cellphone jammers swimwear 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watts max,a frequency counter is proposed which uses two counters and two timers and a timer ic to produce clock signals,the components of this system are extremely accurately calibrated so that it is principally possible to exclude individual channels from jamming,a total of 160 w is available for covering each frequency between 800 and 2200 mhz in steps of max,there are many methods to do this,churches and mosques as well as lecture halls.law-courts and banks or government and military areas where usually a high level of cellular base station signals is emitted,jamming these transmission paths with the usual jammers is only feasible for limited areas,4 ah battery or 100 – 240 v ac,when the brake is applied green led starts glowing and the piezo buzzer rings for a while if the brake is in good condition,solutions can also be found for this.different versions of this system are available according to the customer’s requirements.50/60 hz transmitting to 12 v dcoperating time,a break in 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