Patent ID: RE40128

Claim:
A radar gauge adapted to sense fluid level in a tank, comprising: a radar gauge circuit adapted to receive a transmit frequency and a sample frequency controlling radar transmission and level sampling respectively, the radar gauge circuit generating a level output; a clock source generating first and second clock frequencies and having a control input setting a first frequency separation between the first and second clock frequencies; a separation sensing circuit coupled to the clock source and generating an evaluation output as a function of the first frequency separation; a controller receiving the evaluation output, the controller having a timer that measures the frequency separation and a control output feeding back to the control input that stabilizes the first separation as a function of timing the evaluation outputs, the controller further having a correction circuit that corrects the level output as a function of the first frequency separation; a divider circuit dividing the first and second clock frequencies and generating the transmit and the sample frequencies wherein the transmit and sample frequencies are separated from each other by a second frequency separation; and the separation sensing circuit further coupling to the divider circuit and generating a second evaluation output coupling to the controller as a function of the second frequency separation.