Abstract: Devices, systems and methods are provided for the transmission of scalar longitudinal waves via a monopole antenna. A balun may attach to a shield at a base end of a monopole antenna to form a cylindrical shell shape with a closed end at the contact location and an open end facing the tip end of the monopole antenna. The open end may form an aperture between a distal shield end and a distal balun end, and the lengths of the shield and balun may be equal. A shielded portion and an antenna portion of the center conductor may be encased by a spherical transmitter. The center conductor may extend through the aperture, toward the tip end, and through a gap formed between the terminating end of the shield at the distal end of the shielded portion and the first end of the antenna portion encased by an antenna tube.

Abstract: Methods, and systems of use, for sensor calibration. The method may comprise calibrating an attitude accelerometer of a sensor using an elliptical-fitting method, which may be based on calibration positions. The method may further calibrate a magnetometer of the sensor using a dot-product invariance (DPI) method, which may be based on the calibration positions. The method may comprise determining a magnetometer-calibration status of the magnetometer based on a chi squared distribution test method and a root mean square error (RMSE) method of dot-products generated by the DPI method. The method may further comprise calibrating an acoustic accelerometer of the sensor using the DPI method, which may be based on relative-values of a shape matrix. The method may comprise scaling an acoustic accelerometer of the sensor using a hydrophone. The system may comprise a sensor-error engine configured to perform steps of the disclosed methods.

Abstract: The invention is a sewer plug which is inserted into a sewer main line and positioned over a tributary or sewer feed line coming into the sewer main line. The sewer plug has an inflatable collar which is inflated once the device is in place. The inflation of the device causes blockage of the feeder line, but allows the flow through the sewer main line to continue. The device is positioned using lines attached to the device which are pulled from an upstream and a downstream manhole access. The device can be positioned by moving at a measured distance between the two manhole accesses, or by the use of a video camera, which can be attached to the device, and which enables a user to view the sewer tributary line during positioning. When the device is no longer used, it may be deflated and pulled out of the sewer main line.