Search NASA⌕ Search

Engineering topics

Peters, Robert

Publications and source records attributed to Peters, Robert.

10 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2015

Measurements of Integration Gain for the Cospas-Sarsat System from Geosynchronous Satellites

The GOES-R satellite is the first satellite to use a standard straight bent pipe transponder with no on-board re-modulation to support Search and Rescue (SAR) operations. Here, we report on the link measurements with a high fidelity satellite transponder simulator made up of satellite EDU (Engineering Design Units) components using an uplink from a beacon simulator and received by a GEOLUT (GEOsynchronous satellite Local User Terminal). We also report on the first ever measurements showing the performance gain obtained by the signal integration performed by the GEOLUT. In addition, a simulator made of commercially available off-the-shelf components assembled to develop the test plan was found to perform very close to the high fidelity simulator. In this paper, we describe what message integration is, how it is implemented in the particular satellite receiving station model used for this tests, and show the measured improvement in message decoding due to this integration process. These are the first tests to quantify the integration gain and are the first tests on the new SARSAT standard for the bent pipe (no onboard re-modulation) repeater used in GOES-R. An inexpensive satellite simulator to run test scripts built from off the shelf components was also found to have the same performance as a high fidelity simulator using actual satellite EDUs.

Klein-Lebbink, Elizabeth↗
NASA NTRS2015

Measurements of Integration Gain for the Cospas-Sarsat System from Geosynchronous Satellites

The GOES-R satellite is the first satellite to use a standard straight bent pipe transponder with no on-board re-modulation to support Search and Rescue (SAR) operations. Here, we report on the link measurements with a high fidelity satellite transponder simulator made up of satellite EDU (Engineering Design Units) components using an uplink from a beacon simulator and received by a GEOLUT (GEOsynchronous satellite Local User Terminal). We also report on the first ever measurements showing the performance gain obtained by the signal integration performed by the GEOLUT. In addition, a simulator made of commercially available off-the-shelf components assembled to develop the test plan was found to perform very close to the high fidelity simulator. In this paper, we describe what message integration is, how it is implemented in the particular satellite receiving station model used for this tests, and show the measured improvement in message decoding due to this integration process. These are the first tests to quantify the integration gain and are the first tests on the new SARSAT standard for the bent pipe (no onboard re-modulation) repeater used in GOES-R. An inexpensive satellite simulator to run test scripts built from off the shelf components was also found to have the same performance as a high fidelity simulator using actual satellite EDUs.

Klein-Lebbink, Elizabeth↗
NASA NTRS2008

Applying EVM to Satellite on Ground and In-Orbit Testing - Better Data in Less Time

Using Error Vector Magnitude (EVM) in satellite integration and test allows rapid verification of the Bit Error Rate (BER) performance of a satellite link and is particularly well suited to measurement of low bit rate satellite links where it can result in a major reduction in test time (about 3 weeks per satellite for the Geosynchronous Operational Environmental Satellite [GOES] satellites during ground test) and can provide diagnostic information. Empirical techniques developed to predict BER performance from EVM measurements and lessons learned about applying these techniques during GOES N, O, and P integration test and post launch testing, are discussed.

Peters, Robert↗
NASA NTRS2008

Analytic Calculation of Noise Power Robbing, NPR, and Polarization Isolation Degradation

Three Geostationary Operational Environmental Satellite (GOES) R transponders (services) required analysis and measurements to develop an accurate link budget. These are a) Search and Rescue transponder which suffers from power robbing due to thermal uplink noise, b) the Data Collection Platform Report which suffers from degradation due to NPR (Noise Power Ratio), and c) GOES Rebroadcast transponder which uses a dual circular downlink L band for which there was no depolarization data. The first two services required development of extended link budget to analytically calculate the impact of these degradations which are shown to have a significant impact on the link budget. The third service required measurements of atmospheric L band CP depolarization as there were no known previous measurements and results are reported her

Peters, Robert↗
NASA NTRS2007

Metrology Camera System Using Two-Color Interferometry

A metrology system that contains no moving parts simultaneously measures the bearings and ranges of multiple reflective targets in its vicinity, enabling determination of the three-dimensional (3D) positions of the targets with submillimeter accuracy. The system combines a direction-measuring metrology camera and an interferometric range-finding subsystem. Because the system is based partly on a prior instrument denoted the Modulation Sideband Technology for Absolute Ranging (MSTAR) sensor and because of its 3D capability, the system is denoted the MSTAR3D. Developed for use in measuring the shape (for the purpose of compensating for distortion) of large structures like radar antennas, it can also be used to measure positions of multiple targets in the course of conventional terrestrial surveying. A diagram of the system is shown in the figure. One of the targets is a reference target having a known, constant distance with respect to the system. The system comprises a laser for generating local and target beams at a carrier frequency; a frequency shifting unit to introduce a frequency shift offset between the target and local beams; a pair of high-speed modulators that apply modulation to the carrier frequency in the local and target beams to produce a series of modulation sidebands, the highspeed modulators having modulation frequencies of FL and FM; a target beam launcher that illuminates the targets with the target beam; optics and a multipixel photodetector; a local beam launcher that launches the local beam towards the multi-pixel photodetector; a mirror for projecting to the optics a portion of the target beam reflected from the targets, the optics being configured to focus the portion of the target beam at the multi-pixel photodetector; and a signal-processing unit connected to the photodetector. The portion of the target beam reflected from the targets produces spots on the multi-pixel photodetector corresponding to the targets, respectively, and the signal-processing unit centroids the spots to determine bearings of the targets, respectively. As the spots oscillate in intensity because they are mixed with the local laser beam that is flood illuminating the focal plane, the phase of oscillation of each spot is measured, the phase of sidebands in the oscillation of each spot being proportional to a distance to the corresponding target relative to the reference target A.

Dubovitsky, Serge↗
NASA NTRS2007

Alternative Controller for a Fiber-Optic Switch

A simplified diagram of a relatively inexpensive controller for a DiCon VX (or equivalent) fiber-optic switch -- an electromechanically actuated switch for optically connecting one or two input optical fibers to any of a number of output optical fibers is shown. DiCon VX fiber-optic switches are used primarily in research and development in the telecommunication industry. This controller can control any such switch having up to 32 output channels.

Peters, Robert↗
NASA NTRS2003

Adaptive Nulling: A New Enabling Technology for Interferometric Exoplanet

Deep, stable nulling of starlight requires careful control of the amplitudes and phases of the beams that are being combined. The detection of earth-like planets using the interferometer architectures currently being considered for the Terrestrial Planet Finder mission require that the E-field amplitudes are balanced at the level of approx. 0.1%, and the phases are controlled at the level of 1 mrad (corresponding to approx.1.5 nm for a wavelength of 10 microns). These conditions must be met simultaneously at all wavelengths across the science band, and for both polarization states, imposing unrealistic tolerances on the symmetry between the optical beamtrains. We introduce the concept of a compensator that is inserted into the beamtrain, which can adaptively correct for the mismatches across the spectrum, enabling deep nulls with realistic, imperfect optics. The design presented uses a deformable mirror to adjust the amplitude and phase of each beam as an arbitrary function of wavelength and polarization. A proof-of-concept experiment will be conducted at visible/near-IR wavelengths, followed by a system operating in the Mid-IR band.

planet detection↗
NASA NTRS2003

Absolute Distance Measurement with the MSTAR Sensor

The MSTAR sensor (Modulation Sideband Technology for Absolute Ranging) is a new system for measuring absolute distance, capable of resolving the integer cycle ambiguity of standard interferometers, and making it possible to measure distance with sub-nanometer accuracy. The sensor uses a single laser in conjunction with fast phase modulators and low frequency detectors. We describe the design of the system - the principle of operation, the metrology source, beamlaunching optics, and signal processing - and show results for target distances up to 1 meter. We then demonstrate how the system can be scaled to kilometer-scale distances.

modulation sideband technology for absolute rangin↗