Abstract: A range detection apparatus comprising means for generating high frequency energy over a finite frequency range and for frequency modulating over a limited range of bandwidth the generated signal. A first path provides a phase reference while a second path provides for transmitting and receiving the signal. Along one of the two paths, the frequency modulated signal is phase shifted at a plurality of predetermined frequency values over a finite frequency range of bandwidth and at a predetermined plurality of phase-shifting values (greater than two) and at combinations of phase-shifting and frequency values to improve the relative range resolution. The signal in one path is phase compared to the signal in the second path to produce range measurement signals related to the combined phase shifts of the two paths, the results of the phase comparison, and the combinations of phase states of the phase shifts and frequencies of the frequency modulated signal.

Abstract: Disclosed is an in-furnace slag level measuring apparatus having a microwave radar for measuring a slag level in a convertor or the like. The level of a transmission signal or a reception signal is adjusted in accordance with the level of a detection signal so that the signal level in the microwave radar is adjusted to be constant. Further, the level measurement value and the detection signal are inputted and the level measurement values obtained in a predetermined time are subjected to averaging operation. In the averaging operation, when the detection signal is smaller than a set point, the averaging operation is performed while disregarding the level measurement value at that time.

Abstract: A radar system comprises a transmitter which essentially continuously transmits a modulated carrier wave signal and a receiver for receiving the carrier wave signal reflected at an object (echo signal). The carrier wave signal is modulated with a code-generating signal whose code frequency is determined for the range resolution of the radar. The code-generating signal is such that one bit in the code has a duration which is several times longer than the period of the carrier wave signal and several bits of the code form a block which is obtained by modulation of a carrier wave with constant frequency. The frequency of the carrier wave is changed between blocks so that the transmitter sends a block with a carrier wave frequency which is different from the carrier wave frequency or frequencies which the receiver is set up to receive. The receiver stores the transmitted code and correlates it with the received signal.

Abstract: A vehicle near obstacle detection system includes a plurality of radio frequency heads that can transmit and receive both frequency-modulated, continuous wave and two-frequency Doppler radar signals, such that the system operates in frequency-modulated, continuous wave radar mode and in two-frequency Doppler radar mode. The radio frequency heads used for transmitting the radar signals transmit their radar signals in accordance with commands from a system controller. The radio frequency heads are provided at various locations on the vehicle, directed at points around the vehicle which cannot easily be seen by the vehicle operator. The system controller switches between the two radar modes depending on which one is more appropriate to make use of one mode's strengths while avoiding the other mode's weaknesses. When there is no relative movement between objects and the vehicle, the frequency-modulated, continuous wave mode is used.

Abstract: A distance measuring method and apparatus in which first and second pseudo random signals which are the same in pattern but slightly different in period are generated to obtain a correlation output of the first and second pseudo random signals before transmission thereof as a reference correlation output, and the first pseudo random signal is directly transmitted toward a target or alternatively a carrier wave is modulated by the first pseudo random signal and transmitted toward the target. A correlation output of the signal reflected and received from the target and the second pseudo random signal is detected and the distance to the target is measured from the time interval between the reference correlation output and the received correlation output.

Abstract: A transmitter section of the arrangement includes an altimeter transmitter and a Doppler transmitter. The transmitters both provide frequency-modulated outputs. The altimeter transmitter is linear-FM while the Doppler transmitter is sine-FM.

Abstract: A range dispersion sensor operative to detect objects of a preselected height "h" operates on quarterwave interference principles. Electromagnetic energy is modulated at a first frequency f.sub.1 such that objects of the preselected height h disposed upon a background create a quarter-wave length reflector. A beam of electromagnetic energy reflected from an object of height h and its proximate background interferes destructively to create a null signal. Effects of non-uniform reflectivity are normalized by modulating the beam at a second frequency f.sub.2 selected to not create constructive or destructive interference effects with objects of the preselected height. The ratio of the two signals is taken thereby normalizing the effects of non-uniform reflectivity, and the resultant ratio is indicative of the height of the objects.

Abstract: A pulse doppler radar system for measuring the range to a target. The radar system alternately transmits a signal having a constant frequency and a signal modulated by a linearly-changing-frequency and receives an echo signal from a target. When a plurality of doppler frequencies derived from jet engine modulation are detected in the echo signal, the radar system is operable to obtain the number of frequency differences giving the same range value on the basis of the differences between the detected doppler frequencies, or to selectively use methods of range calculation according to the number of detected doppler frequencies.

Abstract: A laser radar system wherein a beam of continuous wave (CW) electromagnetic energy is generated with frequency modulation (FM) and amplitude modulation (AM) being imposed thereon to produce an amplitude and frequency modulated, continuous wave beam of energy. The AM-FM CW beam is transmitted toward a selected target, portions of the transmitted beam being reflected by the target and received along with portions of the transmitted beam reflected by unselected targets and atmospheric clutter. A first signal is produced in response to the frequency modulation on the received beam portions reflected by the selected target, such first signal representing the approximate range of the selected target and substantially resolving the selected target from unselected targets and atmospheric clutter and having a relatively long ambiguous range interval.

Abstract: A method an apparatus for measuring the distance to a target wherein FM wave is transmitted to the target and its reflected wave is received. A beat wave is then obtained using the thus-received wave and the FM wave. A sine wave is mixed with the beat wave and a first sideband wave of a plurality of sideband waves of the resultant mixed wave is obtained. Another sine wave is mixed with the sideband wave. Then, a second sideband wave of the thus-obtained mixed wave is separated and detected. In the above manner, phase modulation is applied directly to the above-described beat wave. Information pertaining to distance can then be obtained from the number of peaks of the thus-modulated beat wave. A microwave profile meter suitable for use in the determination of the surface profile of a burden in a blast furnace is also disclosed.