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- Author or Editor: P. K. Govind x
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Abstract
Wind-profiling systems that use the retransmission of Omega navigation signals are described. Sources of error affecting the composite performance of the Omega system are highlighted, with emphasis on their effect on velocity estimates. Finally, the question of processing noisy phase data from the Omega system to yield optimal estimates of wind velocities is debated.
Abstract
Wind-profiling systems that use the retransmission of Omega navigation signals are described. Sources of error affecting the composite performance of the Omega system are highlighted, with emphasis on their effect on velocity estimates. Finally, the question of processing noisy phase data from the Omega system to yield optimal estimates of wind velocities is debated.
Abstract
A windfinding dropsonde instrumentation system is described, with examples of its operational use in the GARP Atlantic Tropical Experiment conducted during the summer of 1974. Deployed from an aircraft flying typically at ∼10 km altitude, the dropsonde transmits vertical profiles of horizontal wind, pressure, temperature and humidity while descending on a parachute at ∼5 m s−1. The temperature sensor in the dropsonde is a 95-mil bead thermistor, the humidity sensor a standard carbon strip hygristor, and the pressure sensor an improved aneroid cell. Winds are determined by tracking the sonde using the 13.6 kHz Omega navigation signals received by an Omega receiver and retransmitted over a telemetry link. The telemetered data from a dropsonde are received, and recorded on-board the aircraft, using a computerized system configured to permit processing of two sondes descending simultaneously (one operating on 404.5 MHz, the other on 405.5 MHz).
Abstract
A windfinding dropsonde instrumentation system is described, with examples of its operational use in the GARP Atlantic Tropical Experiment conducted during the summer of 1974. Deployed from an aircraft flying typically at ∼10 km altitude, the dropsonde transmits vertical profiles of horizontal wind, pressure, temperature and humidity while descending on a parachute at ∼5 m s−1. The temperature sensor in the dropsonde is a 95-mil bead thermistor, the humidity sensor a standard carbon strip hygristor, and the pressure sensor an improved aneroid cell. Winds are determined by tracking the sonde using the 13.6 kHz Omega navigation signals received by an Omega receiver and retransmitted over a telemetry link. The telemetered data from a dropsonde are received, and recorded on-board the aircraft, using a computerized system configured to permit processing of two sondes descending simultaneously (one operating on 404.5 MHz, the other on 405.5 MHz).
Abstract
The paper presents a technique for designing a self-optimizing filter to combine noisy measurements of the same physical quantity as measured by different instruments into a single time-series representative of the measured quantity (signal). The procedure minimizes the output power (sum of the squared amplitudes) of a filter that is run over the data, subject to a set of constraints on filter coefficients to characterize signal information. Practical applications of such a data-adaptive weighting algorithm are also illustrated.
Abstract
The paper presents a technique for designing a self-optimizing filter to combine noisy measurements of the same physical quantity as measured by different instruments into a single time-series representative of the measured quantity (signal). The procedure minimizes the output power (sum of the squared amplitudes) of a filter that is run over the data, subject to a set of constraints on filter coefficients to characterize signal information. Practical applications of such a data-adaptive weighting algorithm are also illustrated.
Abstract
Design highlights, system performance and operational use of the Portable Automated Mesonet (PAM) are featured. PAM consists of a trailer-mounted base station and a network of remote sampling stations for surface mesoscale research. PAM differs from unautomated systems in that the data are sampled synchronously, averaged locally and transmitted digitally via a telemetry link to the base station where real-time data from the entire network are displayed.
The base station uses minicomputer control for polling remotes, logging data, checking data quality and displaying data. Displays include tabular listings, time plots, vector wind plots and contours. Remote stations measure pressure, temperature, humidity, rain, wind speed and wind direction, and include flexibility for future expansion. A programmable microprocessor at each remote station controls communications, data sampling and data averaging. Averaged data are reported to the base station when the base station interrogates the remote station (typically once a minute).
System performance was evaluated in a group intercomparison experiment prior to field operation in support of the National Hail Research Experiment (NHRE '76). Real-time display of PAM was used to identify surface mesoscale circulations influencing thunderstorm development during NHRE '76.
Abstract
Design highlights, system performance and operational use of the Portable Automated Mesonet (PAM) are featured. PAM consists of a trailer-mounted base station and a network of remote sampling stations for surface mesoscale research. PAM differs from unautomated systems in that the data are sampled synchronously, averaged locally and transmitted digitally via a telemetry link to the base station where real-time data from the entire network are displayed.
The base station uses minicomputer control for polling remotes, logging data, checking data quality and displaying data. Displays include tabular listings, time plots, vector wind plots and contours. Remote stations measure pressure, temperature, humidity, rain, wind speed and wind direction, and include flexibility for future expansion. A programmable microprocessor at each remote station controls communications, data sampling and data averaging. Averaged data are reported to the base station when the base station interrogates the remote station (typically once a minute).
System performance was evaluated in a group intercomparison experiment prior to field operation in support of the National Hail Research Experiment (NHRE '76). Real-time display of PAM was used to identify surface mesoscale circulations influencing thunderstorm development during NHRE '76.
