Radar-based method for measuring a level of material in a container
Described is a radar-based method for measuring a level of material in a container. Microwaves are emitted to a surface of the material by a radar level gauge, echo waves reflected from the surface are received and the received echo waves are converted into an echo function which is stored and evaluated to establish a useful echo and to determine a position of the echo. The echo function is generated and stored with a first higher resolution for a selected first portion of the entire level measurement range of the radar level gauge. Further, the echo function is generated and stored with a second lower resolution or no echo function is generated and stored for the remaining second portion of the entire level measurement range.
1. A radar-based method for measuring a level of material in a container, comprising:
emitting microwaves to a surface of the material by a radar level gauge;
receiving echo waves reflected from the surface of the material using the radar level gauge;
converting the received echo waves into an echo function over time;
storing the echo function; and
establishing a useful echo and determining a position of the useful echo by evaluating the stored echo function;
wherein the echo function is converted and stored with a first higher resolution for a selected first portion of the entire level measurement range of the radar level gauge, and
wherein the echo function is converted and stored with a second lower resolution or no echo function is converted and stored for the remaining second portion of the entire level measurement range.
2. The method according to claim 1 , wherein the first portion of the entire level measurement range is centered around the last determined position of the useful echo.
3. The method according to claim 2 , wherein the useful echo is established in one of two consecutive measurement cycles.
4. The method according to claim 3 , further comprising:
establishing another useful echo in the other measurement cycle of the two consecutive measurement cycles by converting, storing and evaluating another echo function with the first or another higher resolution for a selected third portion of the entire level measurement range of the radar level gauge and wherein the other echo function is converted and stored with the second or another lower resolution or no echo function is converted and stored for a remaining fourth portion of the entire level measurement range.
5. The method according to claim 4 , wherein the third portion of the level measurement range is centered around the last determined position of the other useful echo.
6. The method according to claim 1 , wherein the useful echo is established in one of two consecutive measurement cycles.
7. The method according to claim 6 , further comprising:
establishing another useful echo in the other measurement cycle of the two consecutive measurement cycles by converting, storing and evaluating another echo function with the first or another higher resolution for a selected third portion of the entire level measurement range of the radar level gauge and wherein the other echo function is converted and stored with the second or another lower resolution or no echo function is converted and stored for a remaining fourth portion of the entire level measurement range.
8. The method according to claim 7 , wherein the third portion of the level measurement range is centered around the last determined position of the other useful echo.
9. A pulse radar level gauge, comprising:
a microwave transducer configured to generate microwave pulses, the microwave transducer being arranged in a tank containing a material and a top surface of the material providing a reflective surface to reflect the microwave pulses;
a transmitter;
a microprocessor, the microwave transducer being coupled to the microprocessor via the transmitter, and the microprocessor controlling the transmitter to excite the microwave transducer to emit the microwave pulses;
a receiver configured to receive an electric signal based upon reflected microwave pulses or echo pulses, the receiver having an amplifier and an envelope detector; and
a converter configured to generate a digital echo profile,
wherein the microprocessor executes an algorithm to identify a true echo from the top surface of the material and to calculate a range of the reflective surface.
10. The pulse radar level gauge according to claim 9 , wherein the microprocessor operates under a control program stored in a read-only memory (ROM), utilizing parameters stored in non-volatile random access memory (NVRAM) and provided with a working memory being a random access memory (RAM).
11. The pulse radar level gauge according to claim 9 , further comprising:
an interface controlled by the microprocessor for an export of data and an import of operating parameters.