Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
191 words
In a process for measuring the level of liquid in a tank according to the radar principle in which a microwave signal is transmitted in the direction of the liquid level and the bottom of the tank from a transmitting antenna located above the liquid level, received signals including perhaps spurious signals, a measuring signal reflected from the liquid level and a bottom signal reflected from the bottom of the tank are received by a receiving antenna and the measuring and bottom signals from the receiving antenna are detected and processed by receiver means associated with the antenna, the actual distance between the transmitting antenna and the receiving antenna, respectively, and the tank bottom distance being known, and the permittivity and permeability numbers ε r and μ r for the liquid in the tank being known at least approximately, the steps of determining from said bottom signal the transit time for said bottom signal,and mathematically determining the actual liquid level in the tank at least approximately from said transit time, the known actual bottom distance and the at least approximately known permittivity and permeability numbers ε r and μ r .
Claim 2
Dependent Claim
191 words
In a process for measuring the level of liquid in a tank according to the radar principle in which a microwave signal is transmitted in the direction of the liquid level and the bottom of the tank from a transmitting antenna located above the liquid level, received signals including perhaps spurious signals, a measuring signal reflected from the liquid level and a bottom signal reflected from the bottom of the tank are received by a receiving antenna and the measuring and bottom signals from the receiving antenna are detected and processed by receiver means associated with the antenna, the actual distance between the transmitting antenna and the receiving antenna, respectively, and the tank bottom distance being known, and the permittivity and permeability numbers ε r and μ r for the liquid in the tank being known at least approximately, the steps of determining from said bottom signal the transit time for said bottom signal,and mathematically determining the actual liquid level in the tank at least approximately from said transit time, the known actual bottom distance and the at least approximately known permittivity and permeability numbers ε r and μ r .
Claim 3
Dependent Claim
97 words
The process according to claim 1, wherein the mathematical determination is made according to the equation ##EQU3## l s being the apparent liquid level l being the actual liquid level, h s being the apparent bottom distance, h being the actual bottom distance, d being the free space above the liquid level, c 1 being the rate of propagation of the microwave signal in the air, c.sub.η being the rate of propagation of microwave signal in the liquid, ε r being the permittivity number of the liquid, and μ r being the permeability number of the liquid.
Claim 4
Dependent Claim
45 words
The process according to claim 1 or 2, including the step of, in a spectrum of the received signals (measuring signal and spurious signals), identifying one of the signals as the measuring signal by means of the mathematically determined value for the actual liquid level.
Claim 5
Dependent Claim
74 words
The process according to claim 3, including the steps of: by taking account of the error band widths of the permittivity and permeability numbers ε r and μ r and the bottom signal, determining mathematically the value for the actual liquid level with a certain error band width, wherein said certain error band width defines a recognition window for the measuring signal, and determining which of the received signals is within the recognition window.
Claim 6
Dependent Claim
25 words
The process according to claim 1 or 2, wherein the microwave signal transmitted by the transmitting antenna is modulated with pulse modulation or frequency modulation.