Browse Topic: Altimeters

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Altitude Alerting Devices and SystemsARP1061B (Current)4/14/2020
This SAE Aerospace Recommended Practice (ARP) provides performance criteria for Altitude Alerting Devices and Systems. These devices can be self-contained or receive remote altitude information and can have integral or remote barometric corrections. Only the generation of the alerting signals is covered by this recommended practice and not the details of the visual or audio alerts operated by these signals. It is recommended that the system’s operational correspondence between the selected altitude settings of the Altitude Alerting Device and the Altitude Level Indication normally used to control the aircraft should not exceed ±250 ft RSS throughout the operating range of the device.
A-4 Aircraft Instruments Committee
Digital Beamforming InterferometryTBMG-270246/1/2017
NASA Goddard Space Flight Center has developed a new radar approach that uses a single phased array antenna and a single-pass configuration to generate interferograms, known as Digital Beamforming Interferometry. A digital beamforming radar system allows the implementation of nonconventional radar techniques, known as Digital Beamforming Synthetic Aperture Radar Multimode Operation (DBSAR).
A 16-Beam, Non-Scanning, Swath-Mapping Laser Altimeter InstrumentTBMG-2327911/1/2015
The purpose of this work was to develop and demonstrate technologies for a next-generation, efficient, swath-mapping space laser altimeter. The Lidar Surface Topography (LIST) mission concept allows simultaneous measurements of 5-meter-spatial-resolution topography and vegetation vertical structure with decimeter vertical precision in an elevationimaging swath several kilometers wide from a 400-km-altitude Earth orbit. To advance and demonstrate needed technologies for the LIST mission, the Airborne LIST Simulator (ALISTS) pathfinder instrument was developed. ALISTS is a micropulse, single photon-sensitive waveform recording system based on a new and highly efficient laser measurement approach utilizing emerging laser transmitter and detector technologies.
Stackfile DatabaseTBMG-154791/1/2013
This software provides storage retrieval and analysis functionality for managing satellite altimetry data. It improves the efficiency and analysis capabilities of existing database software with improved flexibility and documentation. It offers flexibility in the type of data that can be stored. There is efficient retrieval either across the spatial domain or the time domain. Built-in analysis tools are provided for frequently performed altimetry tasks.
Grand Prize WinnerTBMG-1511411/1/2012
The Sensordrone, an invention that dramatically extends the sensing capabilities of smartphones and tablets, came out of the Consumer Products category, but could well have been entered in almost all of the categories because of its versatility. The keyfob- sized device includes sensors that enable consumers to run a variety of medical applications — from blood pressure monitoring to temperature sensing to breath alcohol testing. But, in addition to medical uses, the device is open to a wide range of applications, depending on whether it’s for home safety use, medical use, industrial, or construction use. It could be used to monitor carbon monoxide, humidity, light, and weather, or as an altimeter, barometer, stud-finder, data-logger, and more.
Grand Prize WinnerTBMG-1515011/1/2012
Mark Wagner, Ben Madoff, and Mark Rudolph Sensorcon, Buffalo, NY
Multi-Scale Three- Dimensional Variational Data Assimilation System for Coastal Ocean PredictionTBMG-132594/1/2012
A multi-scale three-dimensional variational data assimilation system (MS-3DVAR) has been formulated and the associated software system has been developed for improving high-resolution coastal ocean prediction. This system helps improve coastal ocean prediction skill, and has been used in support of operational coastal ocean forecasting systems and field experiments. The system has been developed to improve the capability of data assimilation for assimilating, simultaneously and effectively, sparse vertical profiles and high-resolution remote sensing surface measurements into coastal ocean models, as well as constraining model biases.
High-Rate Data-Capture for an Airborne Lidar SystemTBMG-130543/1/2012
A high-rate data system was required to capture the data for an airborne lidar system. A data system was developed that achieved up to 22 million (64-bit) events per second sustained data rate (1408 million bits per second), as well as short bursts (
Laser Systems Will Enable NASA Satellite to Measure Sea IceTBMG-107698/1/2011
Flight lasers and test laser Fibertek Herndon, VA 703-471-7671
Test Port for Fiber-Optic-Coupled Laser AltimeterTBMG-105507/1/2011
A test port designed as part of a fiber-optic-coupled laser altimeter receiver optical system allows for the back-illumination of the optical system for alignment verification, as well as illumination of the detector(s) for testing the receiver electronics and signal-processing algorithms. Measuring the optical alignment of a laser altimeter instrument is difficult after the instrument is fully assembled. The addition of a test port in the receiver aft-optics allows for the back-illumination of the receiver system such that its focal setting and boresight alignment can be easily verified. For a multiple-detector receiver system, the addition of the aft-optics test port offers the added advantage of being able to simultaneously test all the detectors with different signals that simulate the expected operational conditions.
Miniaturized Ka-Band Dual-Channel RadarTBMG-95524/1/2011
Smaller (volume, mass, power) electronics for a Ka-band (36 GHz) radar interferometer were required. To reduce size and achieve better control over RF-phase versus temperature, fully hybrid electronics were developed for the RF portion of the radar’s two-channel receiver and single-channel transmitter. In this context, fully hybrid means that every active RF device was an open die, and all passives were directly attached to the subcarrier. Attachments were made using wire and ribbon bonding. In this way, every component, even small passives, was selected for the fabrication of the two radar receivers, and the devices were mounted relative to each other in order to make complementary components isothermal and to isolate other components from potential temperature gradients. This is critical for developing receivers that can track each other’s phase over temperature, which is a key mission driver for obtaining ocean surface height.
Target Assembly to Check Boresight Alignment of Active SensorsTBMG-95454/1/2011
A compact and portable target assembly (Fig. 1) has been developed to measure the boresite alignment of LRO’s Lunar Orbiter Laser Altimeter (LOLA) instrument at the spacecraft level. The concept for this target assembly has evolved over many years with earlier versions used to test the Mars Observer Laser Altimeter (MOLA), the Geoscience Laser Altimeter System (GLAS), and the Mercury Laser Altimeter (MLA) space-based instruments. These earlier laser altimeters were single ranging channel instruments, but as demonstrated with the five-channel LOLA instrument, the target assembly can simultaneously measure the co-boresite alignment of multiple transmitter laser beams and receiver channels (Fig. 2).
FPGA Sequencer for Radar Altimeter ApplicationsTBMG-89961/1/2011
A sequencer for a radar altimeter provides accurate attitude information for a reliable soft landing of the Mars Science Laboratory (MSL). This is a field-programmable-gate-array (FPGA)-only implementation. A table loaded externally into the FPGA controls timing, processing, and decision structures. Radar is memory-less and does not use previous acquisitions to assist in the current acquisition. All cycles complete in exactly 50 milliseconds, regardless of range or whether a target was found.
Piecewise-Planar Parabolic Reflectarray AntennaTBMG-51615/1/2009
The figure shows a dual-beam, dual- polarization Ku-band antenna, the reflector of which comprises an assembly of small reflectarrays arranged in a piecewise-planar approximation of a parabolic reflector surface. The specific antenna design is intended to satisfy requirements for a wide-swath spaceborne radar altimeter, but the general principle of piecewise-planar reflectarray approximation of a parabolic reflector also offers advantages for other applications in which there are requirements for wide-swath antennas that can be stowed compactly and that perform equally in both horizontal and vertical polarizations.
RADIO ALTIMETERARINC707-7 (Current)4/6/2009
This standard provides the desired characteristics of a RALT intended for installation in all types of commercial transport aircraft. Its primary function is to determine the aircraft's height above terrain for visual display to the pilot (essentially ground level to 2500 feet), and for use by the AFCS during automatically controlled approaches and landings.
Airlines Electronic Engineering Committee
Simulating the Phoenix Landing Radar SystemTBMG-31849/1/2008
A computer program called “phxlrsim” simulates the behavior of the radar system used as an altimeter and vel - ocimeter during the entry, descent, and landing phases of the Phoenix lander spacecraft. The simulation includes modeling of internal functions of the radar system, the spacecraft trajectory, and the terrain. The computational models incorporate representations of nonideal hardware effects in the radar system and effects of radar speckle (coherent scatter of radar signals from terrain).
Ka-Band Radar Terminal Descent SensorTBMG-228610/1/2007
The terminal descent sensor (TDS) is a radar altimeter/velocimeter that improves the accuracy of velocity sensing by more than an order of magnitude when compared to existing sensors. The TDS is designed for the safe planetary landing of payloads, and may be used in helicopters and fixed-wing aircraft requiring highaccuracy velocity sensing.
NASA Institute Studies and Identifies Martian Land FormationsTBMG-11641/1/2007
The Lunar and Planetary Institute (LPI) in Houston is part of the Universities Space Research Association, and is a NASAfunded institute that conducts research in the lunar, planetary, and terrestrial sciences on behalf of university science departments and NASA. The most recent project between the University of Houston (UH) and the LPI seeks to identify and characterize the natural landscape structures of Mars, such as the inside of craters, valley networks, and the outside and inside rims of craters and inter-crater plains. Identifying these structures is important because rocks, minerals, and geologic landforms hold clues to past water activity on Mars. Understanding the history of water on Mars is a part of NASA’s long-term Mars Exploration Project.
Robust Control for the Mercury Laser AltimeterTBMG-16845/1/2006
Mercury Laser Altimeter Science Algorithms is a software system for controlling the laser altimeter aboard the Messenger spacecraft, which is to enter into orbit about Mercury in 2011. The software will control the altimeter by dynamically modifying hardware inputs for gain, threshold, channel- disable flags, range- window start location, and range- window width, by using ranging information provided by the spacecraft and noise counts from instrument hardware. In addition, because of severe bandwidth restrictions, the software also selects returns for downlink. To reduce mission risk, the software incorporates three different modes of operation. The three modes are denoted as fixed, range-driven, and closedloop (or adaptive). The fixed mode provides fixed hardware inputs for all but the threshold. The range-driven mode receives and utilizes ranging information from the spacecraft regarding its slant range to the planet or asteroid. The adaptive mode is capable of improving upon the ranging information provided by the spacecraft by use of a closed-loop range-estimation algorithm. The software is sufficiently robust that it could be used on other missions, and in fact, this has already been proposed.
Program Analyzes Radar Altimeter DataTBMG-35812/1/2004
A computer program has been written to perform several analyses of radar altimeter data. The program was designed to improve on previous methods of analysis of altimeter engineering data by (1) facilitating and accelerating the analysis of large amounts of data in a more direct manner and (2) improving the ability to estimate performance of radar-altimeter instrumentation and provide data corrections. The data in question are openly available to the international scientific community and can be downloaded from anonymous file-transfer-protocol (FTP) locations that are accessible via links from altimetry Web sites. The software estimates noise in range measurements, estimates corrections for electromagnetic bias, and performs statistical analyses on various parameters for comparison of different altimeters. Whereas prior techniques used to perform similar analyses of altimeter range noise require comparison of data from repetitions of satellite ground tracks, the present software uses a high-pass filtering technique to obtain similar results from single satellite passes. Elimination of the requirement for repeat-track analysis facilitates the analysis of large amounts of satellite data to assess subtle variations in range noise.
Software for Global Forecasting of Winds and WavesTBMG-32345/1/2002
The WorldWinds™ software system generates high-resolution global weather forecasts, with emphasis on wind and ocean-wave vectors, in nearly real time. WorldWinds™ was developed primarily to serve organizations and individuals needing accurate forecasts for scientific, safety, or economic reasons. WorldWinds™ accepts input data from multiple satellite sources: the TOPEX altimeter, the ERS-2 scatterometer, the QuikScat scatterometer, and the SSM/I microwave radiometer. The software takes those parts of the data that pertain to wind, wave, and other weather observations, combines them with observational data from National Weather Service, and feeds them into two numerical models of weather: the Penn State MM5 model and the Harris Quasi-Lagrangian model. These models generate superior forecasts of wind and wave vectors and other weather variables for periods from 12 to 72 hours. World- Winds™ is unique in that it can forecast winds over the entire surface of the Earth, producing a seamless global weather map every hour of every day. Data can be given at spatial grid intervals that range from 120 to as little as 3 km. Both spatial and temporal scales can be adjusted to satisfy the needs of clients.
Small Lidar Altimeter Would Operate at Low Light LevelsTBMG-703212/1/2000
A lidar apparatus called a microaltimeter has been proposed for use aboard a spacecraft in orbit around the Earth for mapping land and sea surfaces, including such features of special interest as ice, tree canopies, and flood plains. The microaltimeter is short for "microlaser altimeter" and is so named because it uses a very compact, low-energy, subnanosecond pulse, solid-state microlaser as its source and relatively small (typically 10 to 20 cm in diameter) telescopes, resulting in a factor of 100 reduction in telescope weight and volume, as compared to conventional spaceborne laser altimeters. Operating at thousands of pulses per second, the surface sampling rate is approximately 100 times higher than that of prior spaceborne laser altimeters having the same transmitter power-aperture product.
Data-Acquisition System Takes 8-Bit Samples at 1 GHzTBMG-3004810/1/1999
A unique data-acquisition system converts analog input voltages to 8-bit digital data at a rate as high as 109 samples per second (1 GHz), stores the data, and makes the data available for further processing. The system is compact, is highly resistant to ionizing radiation, consumes relatively little power, and is made from commercially available components. Designed for original use as part of a spaceborne laser altimeter, such data-acquisition systems could be adapted to potential terrestrial use as general-purpose high-speed analog-to-digital converters in electronic test equipment and scientific instruments, and as memory devices for storing data to be processed in digital signal-processing systems.
Pressure Altimeter SystemsAS8009A (Historical)10/29/1996
This Aerospace Standard (AS) specifies minimum performance requirements for primary pressure altimeter systems other than air data computers. This AS covers altimeter systems that measure and display altitude as a function of atmospheric pressure. The pressure transducer may be contained within the instrument display case or located remotely. Requirements for air data computers are specified in AS8002. Some requirements for nontransducing servoed altitude indicators are included in AS791. The instrument system specified herein does not include aircraft pressure lines. Unless otherwise specified, whenever the term "instrument" is used, it is to be understood to be the complete system of pressure transducer compponents, any auxiliary equipment, and display components. The test procedures specified herein apply specifically to analog type instruments. Digital instruments or automatic test instrumentation may require other test procedures. Such differing procedures shall be justified prior to use.
A-4 Aircraft Instruments Committee
AIR DATA COMPUTER - MINIMUM PERFORMANCE STANDARDAS8002A (Historical)9/1/1996
This SAE Aerospace Standard (AS) covers air data computer equipment (hereinafter designated the computer) which when connected to sources of aircraft electrical power, static pressure, total pressure, outside air temperature, and others specified by the manufacturer (singly or in combination) provides some or all of the following computed air data output signals (in analog and/or digital form) which may supply primary flight instruments: Pressure Altitude Pressure Altitude, Baro-Corrected Vertical Speed Calibrated Airspeed Mach Number Maximum Allowable Airspeed Overspeed Warning Total Air Temperature In addition, the computer may supply one or more of the following signals: Pressure Altitude, Digitized Equivalent Airspeed True Airspeed Static Air Temperature Altitude Hold Airspeed Hold Mach Hold Angle of Attack Flight Control Gain Scheduling Others
A-4 Air Data Subcommittee
Effects of Digital Altimetry on Pilot Workload84148910/1/1984
A series of VOR-DME landing approaches were flown in the NASA Langley Research Center fixed-base full- workload simulator to evaluate the effects of using a digital altimeter on pilot's scanning behavior and workload. Six pilots executed two sets of landing approaches, using a counter-drum-pointer altimeter (CDPA) on one set and a digital altimeter (DA) on the other set. The DA consisted of five, 7-segment LED digits, 0.28 inches high. Pilot scanning data were collected with Langley's oculometer system. The oculometric data were reduced to dwell percentages, average dwell times, transition matrices, dwell time histograms, and were statistically analyzed. The results showed differences in pilot scanning behavior with the DA versus the CDPA. Although the average dwell time on the DA was slightly shorter, there were more transitions to altitude information with the DA. The average dwell time on the attitude indicator was 0.2 seconds shorter after looking at the CDPA than if the previous look had been on the DA, which seems to indicate that after looking at the DA, the pilots had to think about the digital altitude information. Pilot comments were generally negative toward the DA because of (1) the lack of needle motion cues, (2) the pilot could not form a mental picture of his altitude when using the DA, and (3) the pilot had to perform mental arithmetic to estimate the distance to his assigned altitude.
Harris, Randall L., Glover, Bobby J.
Pressure Altimeter SystemsAS8009 (Historical)5/1/1979
This SAE Aerospace Standard (AS) specifies minimum performance requirements for primary pressure altimeter systems other than air data computers. This document covers altimeter systems that measure and display altitude as a function of atmospheric pressure. The pressure transducer may be contained within the instrument display case or located remotely. Requirements for air data computers are specified in AS8002. Some requirements for nontransducing servoed altitude indicators are included in AS791. The instrument system specified herein does not include aircraft pressure lines. Unless otherwise specified, whenever the term "instrument" is used, it is to be understood to be the complete system of pressure transducer components, any auxiliary equipment, and display components. The test procedures specified herein apply specifically to analog type instruments. Digital instruments or automatic test instrumentation may require other test procedures. Such differing procedures shall be justified prior to use.
A-4 Aircraft Instruments Committee
Pressure Altimeter System, Minimum Safe Performance StandardAS942 (Historical)6/1/1971
A-4 Aircraft Instruments Committee
REVIEW OF AIRCRAFT INSTRUMENT PROBLEMS6003731/1/1960
GEBHARDT, G. T.
DESIGN OF INSTRUMENT DIALS FOR EASE OF READING4802201/1/1948
THIS survey of psychological research in the field of reading aircraft and other instruments shows that the majority of serious errors cannot be eliminated by mere improvements in visibility, such as could be obtained by increases in size or illumination. Rather, it is said, we must find methods of indication that actually simplify the interpretational processes interposed between the seeing of an instrument and the making of an appropriate control action. For instance, it appears that most errors in the reading of such instruments as the altimeter can be eliminated by the use of a single-pointer instrument with a counter to indicate the number of revolutions of the pointer.
GRETHER, WALTER F.
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