Markku Lehtinen

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Matched filtering of quadriphase coded radar signals creates unwanted sidelobes, which may mask important information. This correspondence presents a method of eliminating these sidelobes in aperiodic quadriphase codes. This is done by using a mismatched filter. The signal-to-noise ratio (SNR) at the output of the mismatched filter is less than the SNR at(More)
In November 1995 a campaign of satellite radiotomography supported by the EISCAT incoherent scatter radar and several other instruments was arranged in Scandinavia. A chain of four satellite receivers extending from the north of Norway to the south of Finland was installed approximately along a geomagnetic meridian. The receivers carried out difference(More)
It is pointed out that observations of periodic nightglow structures give excellent information on atmospheric gravity waves in the mesosphere and lower thermosphere. The periods, the horizontal wavelengths and the phase speeds of the waves can be determined from airglow images and, using several cameras, the approximate altitude of the luminous layer can(More)
When statistical inversion of a lag profile is used to determine an incoherent scatter target, the posterior variance of the estimated target can be used to determine how well a certain set of transmission codes perform. In this work we present an incoherent scatter radar transmission code optimization search method suitable for different modulation types,(More)
We describe a radar transmission scheme with long phase coded pulses and non-uniform inter-pulse periods (IPPs) that gives a full range coverage while maintaining high radar duty cycle. In this scheme, the range ambiguity is mitigated using a combination of phase coding and nonuniform inter-pulse periods. To demonstrate the concept, we show initial results(More)
— The variances of matched and sidelobe free mis-matched filter estimators are given for arbitrary coherent targets in the case of aperiodic transmission. It is shown that mismatched filtering is often better than matched filtering in terms of estimation accuracy. A search strategy for finding general transmission codes that minimize estimation error and(More)
We present our effort for producing a highresolution 32-cm wavelength synthetic aperture radar map of the Moon using ground based measurements with the EISCAT UHF radar. We discuss coding, decoding, Doppler north-south ambiguity mitigation, focusing, and clock error mitigation. We also show preliminary results from a test measurement.
An accurate and physically defined system for measuring tremor in unanesthetized and unrestrained rats is described. The method is based on measuring the vibrations of an ordinary animal cage induced by the tremor of the animal inside it. The vibrations of the animal cage were recorded with a piezoelectric acceleration sensor and analyzed using a(More)