Apparatus and method for measuring the distance to an object

A method for measuring the distance of an object, comprising:

• a) emitting a pulse-shaped signal from a transmitter to the object;
• b) receiving an echo pulse (3;
• 21, 22) of the pulse-shaped signal;
• c) measuring a time difference between the transmission of the pulse-shaped signal and reception of the echo pulse (3;
• 21, 22) of the echo;
• d) measuring a phase difference between the transmitted pulse-shaped signal and the echo pulse (3;
• 21, 22);
• e) determining a distance as the measured distance of the object, which distance is compatible with the measured time difference and the measured phase difference after taking into account the propagation speed of the signal;
• characterized in that the echo received in step b) is logarithmized by a cascade of saturable limiters (14-1, . . . 14-n), the output signals of which are detected and added to obtain the logarithm, that step c) is performed on the logarithmized echo pulse (5;
• 21, 22), and that step d) is performed on the output signal (18) of the last limiter (14-n) of the cascade.

A circuit arrangement for measuring the distance of an object based on the echo of a pulse-shaped signal reflected from the object, comprising:

• a first measurement circuit (8) to measure the time difference between the transmission of the pulse-shaped signal and reception of an echo pulse (3;
• 21, 22);
• a second measurement circuit (8) to measure a phase difference between the transmitted pulse-shaped signal and the echo pulse (3;
• 21, 22);
• and
• an evaluation circuit (8) to determine a distance as the measured distance of the object, which distance is compatible with the measured time difference and the measured phase difference after taking into account the propagation speed of the signal, characterized in that a logarithmation circuit to logarithmize the echo pulse is placed before each signal input (9, 19) of the first and second measurement circuit.

A circuit arrangement for measuring the distance of an object based on the echo of a pulse-shaped signal reflected from the object, comprising:

• a first measurement circuit (8) to measure the time difference between the transmission of the pulse-shaped signal and reception of an echo pulse (3;
• 21, 22);
• a second measurement circuit (8) to measure a phase difference between the transmitted pulse-shaped signal and the echo pulse (3;
• 21, 22);
• and
• an evaluation circuit (8) to determine a distance as the distance of the measured object, which distance is compatible with the measured time difference and the measured phase difference after taking into account the propagation speed of the signal, characterized by a logarithmation circuit (400) which includes a cascade of saturable limiters (14-1, . . . 14-n), detectors (15-1, . . . , 15-n), and a summation circuit (16-2, . . . 16-n), where the output of each limiter (14-1, . . . , 14-(n−1)) is connected, except the last one (14-n), to the input of a following limiter (14-2, . . . , 14-n) and to an input of a detector (15-1, . . . , 15-n), and where the outputs of the detectors (15-1, . . . , 15-n) are connected to the inputs of a summation circuit, the output (17) of which supplies the logarithmized echo signal (5) to the first measurement circuit (8), and where the output (18) of the last limiter (14-n) supplies an input signal for the second measurement circuit (8).

A radar fill level measurement sensor for measuring the level of material in a container, said sensor comprising:

• means for generating an electromagnetic pulse, for transmitting said electromagnetic pulse, and for detecting reflected electromagnetic pulses and providing an intermediate frequency signal indicative of said reflected electromagnetic pulses;
• a logarithm detector circuit that receives said intermediate frequency signal and provides a logarithmic output signal indicative of the logarithm of said intermediate frequency signal;
• and
• means, responsive to said logarithmic output signal, for determining the fill level of the material within the container, and for providing a fill level measurement signal indicative thereof.

A radar fill level measurement sensor for measuring the level of material in a container, said sensor comprising:

• an antenna that transmits an electromagnetic pulse, and receives reflected electromagnetic pulses from the material and the container, and provides an electrical received signal indicative thereof;
• a transmit/receive circuit that generates said electromagnetic pulse, and receives said electrical received signal and generates an intermediate frequency signal indicative thereof;
• a logarithm detector circuit that receives said intermediate frequency signal and provides a logarithmic output signal indicative of the logarithm of said intermediate frequency signal;
• and
• a processor that receives and processes said logarithmic output signal to determine the fill level of the material within the container, and provides a fill level measurement signal indicative thereof.