Vaisala Oy

Vaisala Oyj

Henry Andersson

Pentti Karhunen

Jarkko Korte

Juhana Jaatinen

Jussi Åkerberg

Reino Keränen

Juha Salmivaara

Petri Haapanen

Pauli Niska-Pudas

Elena Saltikoff

Rainer Sanmark

Timo Lyly

Paavo Toppila

Olli-Pekka Marstio

Eero Salasmaa

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

This publication discloses a radiosonde system, a radiosonde system receiver and a signal processing method for use in a radiosonde system. The radiosonde system comprises at least one radiosonde () with means for acquisition of position and/or weather data and means for downstream transmission of the data over a radio-frequency path, signal capture means () for reception of the weather and/or position data, and receiver means () for processing the received signals, the receiver means including RF circuit elements () for downconversion of the received signal frequency to a lower frequency known as the first intermediate frequency. According to the invention, the receiver means () include sampling means () performing sampling at the intermediate frequency, at least two digital mixer means () for selective filtration of desired frequency bands from the sampled signal, and processor means () for parallel signal processing at the desired frequency bands.

Radiosonde system, radiosonde system receiver and signal processing method in a radiosonde receiver

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

A method for measuring the velocity (v) of a moving target (A). Radio signals are transmitted by means of radio transmitter-receiver arrangements of both the measuring station (B) and the target station (A) and received at the opposite stations (A,B), the frequencies of which signal include Doppler shifts (fd) to be observed both at the measuring station (B) and in the measuring target (A). On the basis of the Doppler shifts (fd), the escape and/or approach velocity (v) of the target to be measured is determined relative to the measuring station (B). Radio signals are transmitted from the measuring station (B) and the target station (A), the frequencies of which signals deviate from each other by a relatively small frequency difference (fk) or by a Doppler frequency shift (fd), the absolute value of which small frequency difference remains at least as high as the absolute value of the largest expectable Doppler frequency shift (fd.sub.max). A difference frequency or difference frequencies (fb, fa) of the frequency including the Doppler shift (fd) and received at the measuring station (B) and the target station (A) and of the reference frequency of essentially the signal frequency range developed locally are formed in such a way that a low-frequency or possibly a zero-frequency signal at the target station is obtained as the difference frequency or frequencies (fb, fa). On the basis of the difference frequencies (fb, fa), the Doppler frequency shift (fd) is determined, by means of which the velocity (v) of the target (A) is obtained.

Method and device for measuring velocity of target by utilizing doppler

Method and device in the antenna and receiving system of a radio theodolite, wherein the radio signal arriving from the transmitter of the object (31) to be measured is received by means of at least three antennas (1 . . . n-1) in the antenna field (AK) as well as by means of a reference antenna (n). The signals received from said antennas are passed to the receiving system, being controlled and selected by an antenna-selection switch (10a). By means of said system, the phase differences between the signals of different antennas are detected and measured, on the basis of which phase differences it is possible to calculate the angles of incidence (.alpha.,.epsilon.) of the signals on the basis of the known coordinates of location of the antennas in the antenna field (AK). In the method an outer reference antenna (n+1) is used which does not belong to the antenna field (AK) proper. The phases of the antennas (1 . . . n-1) belonging to the antenna field proper and of the inner reference antenna (n) are measured in relation to the reference signal obtained from said outer reference antenna (n+1) and from the receiver (12) connected to same so that no calibration is required between the measurement branches and the reference branches.

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Espoo, Finland

Henry Andersson