Abstract: Systems and methods are described for monitoring the surface flow velocity and volume discharge of rivers and channels using a VHF/UHF radar located in operative relationship with a riverbank. This frequency region allows precise estimation and removal of the Bragg wave velocity; it also is matched to the short wind-wave roughness periods existing on river surfaces so that operation is possible nearly all the time. Methods of bearing determination are also disclosed. Up/downriver surface velocity profiles vs. distance across the river may be constructed from maps of the radial velocity component from a single radar at thousands of points within the radar's coverage. Methods to compensate for Doppler aliasing under high flow conditions are also shown.

Abstract: Systems and methods are described for monitoring the surface flow velocity and volume discharge of rivers and channels using a VHF/UHF radar located in operative relationship with a riverbank. This frequency region allows precise estimation and removal of the Bragg wave velocity; it also is matched to the short wind-wave roughness periods existing on river surfaces so that operation is possible nearly all the time. Methods of bearing determination are also disclosed. Up/downriver surface velocity profiles vs. distance across the river may be constructed from maps of the radial velocity component from a single radar at thousands of points within the radar's coverage. Methods to compensate for Doppler aliasing under high flow conditions are also shown.

Abstract: Systems and methods are described for HF radar frequency sharing with GPS time modulation multiplexing. A method is provided that includes generating clock signals from the time information contained in a GPS signal. Radio frequency signals are transmitted and received in a sequence whose start times are dictated by the clock signals. The clock signals also control the modulation of the radio frequency signals. The radio frequency signals are modulated by using a sweep modulation. An apparatus to implement the method includes a GPS receiver, a state machine, a clock generator, a microprocessor, a memory chip, a signal synthesizer, and a digital data output device. The GPS receiver extracts time information from GPS signals. The state machine controls radar functions versus time. The microprocessor performs modulation multiplexing on radar signals.

Abstract: Systems and methods are described for HF radar frequency sharing with GPS time modulation multiplexing. A method is provided that includes generating clock signals from the time information contained in a GPS signal. Radio frequency signals are transmitted and received in a sequence whose start times are dictated by the clock signals. The clock signals also control the modulation of the radio frequency signals. The radio frequency signals are modulated by using a sweep modulation. An apparatus to implement the method includes a GPS receiver, a state machine, a clock generator, a microprocessor, a memory chip, a signal synthesizer, and a digital data output device. The GPS receiver extracts time information from GPS signals. The state machine controls radar functions versus time. The microprocessor performs modulation multiplexing on radar signals.