Abstract: A novel microwave sensor (10, 60, 70, 90, 200, 250, 280) provides low-cost, robust measurement of the electrical properties of fluid substances. The sensor is suitable for use in an industrial vessel or pipe and employs parallel electrical transmission paths (12,14) that differ in electrical or physical length. The electrical length of each transmission path, which may be a two-way path caused by placing a reflective element in each path, is further determined by the electrical properties of the material under test. The frequency (f) of the signal being applied to the sensor is varied in a known manner such that the difference in the electrical lengths (&Dgr;L) of the transmission paths (12, 14) is caused to correspond to an odd integral multiple of a half wavelength. When the frequency is so adjusted and the signals that have traversed the transmission paths are allowed to coherently interfere with one another, then a minimum resultant signal or null is obtained.

Abstract: Computationally efficient DTMF detection methods and apparatus are presented that meet all of the ITU recommendations using the modified non-uniform DFT. The system of the present invention employs a high band filter block and two low band filter blocks to detect power at the 8 DTMF tones. The frame length of the high band filter blocks is one half the length of the low band filter blocks. The frame lengths are chosen to meet the ITU frequency selectivity requirements for all DTMF frequencies. The frames of the two low band filter blocks are staggered to produce outputs alternately, and are aligned with respect to the frame of the high band filter block to produce low band filter block outputs that coincided with the high band filter block outputs without the need for signal buffering. A system of power level tests are employed in conjunction with a system of timing tests to ensure that all ITU timing and frequency constraints are met.

Abstract: Computationally efficient DTMF detection methods and apparatus are presented that meet all of the ITU recommendations using the modified non-uniform DFT. The system of the present invention employs a high band filter block and two low band filter blocks to detect power at the 8 DTMF tones. The frame length of the high band filter blocks is one half the length of the low band filter blocks. The frame lengths are chosen to meet the ITU frequency selectivity requirements for all DTMF frequencies. The frames of the two low band filter blocks are staggered to produce outputs alternately, and are aligned with respect to the frame of the high band filter block to produce low band filter block outputs that coincided with the high band filter block outputs without the need for signal buffering. A system of power level tests are employed in conjunction with a system of timing tests to ensure that all ITU timing and frequency constraints are met.

Abstract: An integrated guidance system for use in swath guidance applications combines the display of swath navigation information with swath guidance system information. A processor receives information from an external positioning system such as a Global Positioning System receiver and generates course correction data derived from swath parameters selected by the user from a displayed menu of options using a control interface that is integrated with the display and processor or is located externally. The swath navigation information is displayed graphically and numerically. The entire apparatus is compact and mountable within the operative view of the user as he operates the equipment to be guided, thereby reducing hazard and navigational error.

Abstract: Methods and apparatus are presented for precise measurement of mechanical position comprising combination of a plurality of coarse position signals to obtain substantial cancellation of spatial harmonics, generating a digital course position from a resolver system responsive to non-time harmonic signals, and providing precise incremental position signals from memory locations addressed by digital coarse position words.

Abstract: A method and apparatus for demodulating and decoding an MSK signal utilizing synchronous accumulation and simultaneous synchronization of reference carrier and MSK data clocks enables a GPS correlator channel in a multi-channel GPS receiver to be used for processing MSK signals. The PRN code epochs are synchronized with the MSK data clocks and the process of de-spreading with a PRN code is disabled in order to obtain coherent MSK demodulation without corrupting the MSK signal with a PRN code within the channel.