Pulsed radar level gauge with feedback of transmit pulse

A pulsed level gauge for determining a filling level of product in a tank, said level gauge comprising:

• a frequency generator for generating a Tx frequency signal and a Rx frequency signal;
• a pulse generator connected to said frequency generator and configured to generate a transmit signal in the form of a pulse train having a pulse repetition frequency equal to said Tx frequency, and a pulse duration;
• a propagation device connected to said pulse generator and configured to direct said microwave transmit signal, ST, into said tank towards said product and return a microwave return signal, SR, resulting from a reflection caused by a surface of said product;
• a receiver connected to said propagation device and configured to receive the microwave return signal SR reflected from the tank;
• sampling circuitry connected to the receiver and to the frequency generator, and configured to sample the received signal with a sampling frequency equal to the Rx frequency in order to provide a time expanded tank signal including a fiducial pulse and a surface echo;
• and
• processing circuitry for determining said filling level based on the time expanded tank signal,
• impedance increasing circuitry arranged to ensure that an input impedance of the receiver provides matching to said propagation device such that a detectable portion of the transmit pulse is received by the receiver;
• and
• a delay line arranged between said receiver and said propagation device, said delay line configured to introduce a delay greater than said pulse duration,
• such that said time expanded signal includes a transmitted pulse in addition to the fiducial pulse and the surface echo, wherein the processing circuitry is configured to detect the transmitted pulse, and use information about the transmitted pulse in the level detection, wherein processing of the fiducial pulse and the surface echo are compensated based on this information.