Vaisala Oyj

Vaisala Oy

Pentti Karhunen

Henry Andersson

Petri Haapanen

Juha Salmivaara

Jarkko Korte

Reino Keränen

Alan D Siggia

Sebastian Torres

Juhana Jaatinen

Timo Lyly

Olli-Pekka Marstio

Richard Passarelli

Pauli Niska-Pudas

Elena Saltikoff

Rainer Sanmark

Paavo Toppila

A method for extension of unambiguous range and velocity of a weather radar. To avoid pulse overlaying, the pulse repetition time of a single pulse can be extended such that any return echo will arrive at the radar before the next pulse is transmitted. When pulse repetition time is increased, the maximum unambiguous range increases while the maximum unambiguous velocity decreases. The pulse overlaying can be avoided if consecutive pulses are sent on different frequencies that are far enough from each other to allow separation of pulses arriving simultaneously at the radar. When different frequencies are used an unknown phase difference is generated by distributed atmospheric targets to the return signals. This normally prevents use of the shorter pulse repetition time for velocity calculation.

Method for extension of unambiguous range and velocity of a weather radar

The present invention relates to a method and apparatus for simultaneous transmission of horizontal (H) and vertical (V) channels in a dual polarized weather radar. The goal of the invention is accomplished by placing the receiver, duplexer and polarizer equipment above the azimuth rotary joint but below elevation rotary joints. The elevation rotary joints and other associated signal paths are calibrated by using a low power signal on the radar's operating frequency that is fed into couplers above the elevation rotary joints.

Simultaneous dual polarization radar system with pedestal mounted receiver

An antenna system and method for measuring azimuth and elevation angles of an active, signal sending radiosonde. The system includes a first passive antenna group having at least two antenna arrays, the direction pattern of which is wide at least in elevation plane for measuring azimuth angle based on the phase differences between the antenna arrays, a second passive antenna group having at least two antenna arrays, the direction pattern of which is wide at least in elevation plane for measuring the elevation angle based on the phase differences between the antenna arrays and the rotational position of the antenna field, and at least one third antenna having high gain for receiving the telemetry signal, the direction pattern of which element is narrow in azimuth plane and wide in elevation plane. The first and second antenna groups form a solid antenna field which is fixedly tilted in a predetermined elevation position.

Antenna system and method for measuring the azimuth and elevation angles of an active, signal sending radiosonde

The present invention relates to a method and apparatus for pointing the beams () of a wind profiler comprising a stationary antenna matrix () with several individual antenna elements (). According to the method an input signal is fed to the antenna matrix (), and the phase of the input signal is adjusted for the individual antenna elements () in order to point the beam () of the profiler. In accordance with the invention separate feeder lines for each beam are used for feeding the signals to the antenna elements (), and the phase differences between the individual antenna elements () are controlled with hybrid coupler elements ().

Method and apparatus for pointing the beam of a wind profiler

Method and apparatus for measurement of the velocity of a moving target (20) in radio frequencies. From the measurement station (10) and from the target station (20), radio signals (S.sub.1,S.sub.2) are transmitted that are in different frequency ranges, as compared with each other, so that the receivers at the measurement station (10) and at the target station (20) are not subjected to interference. The radio signals (S.sub.1,S.sub.2) are received at stations (20,10) opposite to their transmission stations (10,20). The oscillator of the target station (20) is locked with the frequency transmitted by the measurement station (10) by means of a phase-locked loop (PLL). The frequency of said oscillator is passed to the transmitter part of the target station (20). The signal (S.sub.2) transmitted by the target station (20) is received at the measurement station (10). The Doppler shift (fd) of the frequency of the signal (S.sub.1) transmitted from the measurement station (10) and of the signal received at the measurement station is measured, and the velocity (v) of the moving target to be measured is determined on the basis of the Doppler shift.

Method and device for measurement of the velocity of a moving target by

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Vantaa, Finland

Pentti Karhunen