Patent ID: 6628229
Filing Date: 2003-09-30
Classification: G01F,G01S

Abstract:
A product level transmitter, comprising:a first pullable oscillator circuit that provides a transmit frequency output; a second pullable oscillator circuit that provides a receive frequency output, the receive frequency output being offset from the transmit frequency output by a frequency offset; a first pulse generator receiving the transmit frequency output and providing microwave transmit pulses couplable to the product level; a second pulse generator receiving the receive frequency output and, providing microwave gating pulses; a gate receiving the microwave gating pulses and couplable to the product level for receiving microwave transmit pulses reflected back from the product level that are delayed by a reflection delay time, the gate providing a gated delayed pulse output; a controller receiving the gated delayed pulse output and providing a level output representative of the product level; and a reference crystal oscillator circuit that provides a reference frequency output that is coupled to the first and second pullable oscillators; and the transmit and receive frequency outputs are pulled as functions of the reference frequency output.