Abstract: A method and an apparatus for detection of flaws in lumber is provided, in which the lumber is subjected to microwave radiation of equal intensity in turns simultaneously from two microwave radiation means in phase opposition and from an intermediate microwave radiation means and between the turns from none of said microwave radiation means. The microwave radiation transmitted through the lumber is measured and the level of the measured signals in pulse form is adjusted in such a way that the mean value of the pulse train equals a reference value. The level of the pulse train when no radiation is transmitted is adjusted to zero and the level of the pulses when said two microwave radiation means in phase opposition radiate is used as a measure of the size of the flaw in the lumber.

Abstract: A method and apparatus for detecting grain direction in wood particularly in lumber by means of high frequency radio energy like microwave radiation. The grain direction in lumber can be detected so that knots will cause no significant error to the measuring result. The knots are detected by the method according to the invention in so far as they contain deviations of grain direction. The microwave radiation is either passed through or reflected from the piece of lumber. Radiation energy is transmitted with the aid of a transmitting antenna with a certain direction of polarization and a signal of grain direction is obtained by detecting microwave field by a receiving antenna whose direction of polarization plane forms an angle of 90.degree. with the direction of polarization plane of transmitting antenna.

Abstract: A system for arrangement of operations and connections between a computer or the like involved with a process and a control station needed by the process operator for communication with the computer and for control of the process in case of failure in the computer operation, and for arrangement of the communication between these devices and the process, wherein there are parallel measurement signal channels leading from the process to the computer and the control station and, similarly, parallel control signal channels leading from said devices to the process, respectively, and wherein, additionally, the control station is provided with separate push buttons or the like for at least each measurement of interest, with which push buttons the display of the measurement signal as well as the corresponding control signal may be switched on to the control station, and with which a message concerning the selected measurement may be delivered to the computer.