An apparatus and method for measuring power of carrier channel in question and power leaked from an adjacent channel (leakage power) of a transmitter, and calculating a ratio between the leakage power and the carrier power in the time domain using a digital signal processing technique. The power measurement apparatus includes a frequency mixer which receives a signal from a transmission channel in consideration, an A/D converter for converting an output of the frequency mixer to a digital signal, a Hilbert converter for converting the digital signal into a complex signal, a low pass filter for removing low frequency components from the output signal of the Hilbert converter, a bandpass filter for separating the output of the low pass filter into the carrier power and the leakage power, and a power processing unit for computing the ratio between the leakage power and the carrier power.

A radio controlled guidance and speed control system for a vehicle has spaced receivers for receiving magnetic energy signals from a movable energy source. The signals received vary in accordance with the position of the receivers with respect to the energy source, and are electrically processed to control separate motors driving two wheels of the vehicle for starting, stopping and direction controlling. The circuit for processing the received signals comprises a summing amplifier for speed control, two differential amplifiers for direction control and a gate connected to the summing amplifier through a comparator to provide a stop signal. The circuit provides for a gradual acceleration of the motors. One of the receivers is connected to the gate for developing a stop signal to prevent utilization of ambiguous signals from the other signal receivers.

A method for measuring the position, attitude and/or positional or attitudinal change of a fixed body in space, such as the lower jaw of a patient in a dental examination, utilizes signals obtained from a number of magnetic flux pickup blocks arranged at a distance from a magnetic field generator, the magnetic field generator being disposed on or a short distance from the fixed body and generating a defined irregular field. The pickup blocks detect the field flux, or the field flux alteration, during a measurement. In order to eliminate interference signals occurring in the region of the measuring system the signals from all of the pickup blocks are first added and the aggregate interference signals formed therefrom are respectively subtracted from the individual pickup block signals.