Level measuring device operating with microwaves

Abstract

The microwave measuring device, which preferably operates with microwave bursts, serves to produce a measured value (X H ) representing the level of the contents of a vessel ( 200 ). It comprises a transceiver unit ( 2 ) for generating a level-dependent intermediate-frequency signal (ZF) by means of a transmit signal (S 2 ) and a receive signal (E 2 ), and a transducer element ( 1 ) which in operation couples waves (S 2 ), particularly pulsed waves, into the vessel under control of the transmit signal (S 2 ) and converts echo waves (E 1 ) reflected from the contents ( 201 ) of the vessel into the receive signal (E 2 ). The intermediate-frequency signal (ZF) is fed to a control unit ( 3 ) of the level measuring device where it is stored in the form of a sampling sequence (AF) in a volatile data memory ( 33 ). In this manner, both amplitude information and phase information is available for the level measurement. The device is thus capable of measuring level with high accuracy, particularly accurately to a millimeter, and very fast.

What is claimed is:  
     
         1 . A level measuring device operating with microwaves, particularly with microwave bursts, for producing a level value (X H ). representative of a level in a vessel ( 200 ), said level measuring device comprising: 
 a transceiver unit ( 2 ) for generating a level-dependent intermediate-frequency signal (ZF) by means of a transmit signal (S 2 ) and a receive signal (E 2 );    a transducer element ( 1 ) 
 which in operation couples transmitted waves (S 1 ), particularly pulsed waves, into the vessel ( 200 ) under control of the transmit signal (S 2 ) and which converts echo waves (E 1 ) reflected from contents ( 201 ) of the vessel ( 200 ) into the receive signal (E 2 ); and  
   a control unit ( 3 ) with a volatile data memory ( 33 ) for storing, at least temporarily, a sampling sequence (AF) representing the intermediate-frequency signal (ZF).    
     
     
         2 . A level measuring device as set forth in  claim 1  which determines the level value (X H ) by means of amplitude information derived from the sampling, sequence (AF).  
     
     
         3 . A level measuring device as set forth in  claim 2  which determines the level value (X H ) by means of phase information derived from the sampling sequence (AF).  
     
     
         4 . A level measuring device as set forth in, any one of  claims 1  to  3  
 wherein the volatile data memory ( 33 ) holds, at least temporarily, a first signal sequence (SIN AF ), which represents a numerically performed multiplication of the sampling sequence (AF) by a digital sine-wave signal sequence, and/or;  
 wherein the volatile data memory ( 33 ) holds, at least temporarily, a second signal sequence (COS AF ), which represents a numerically performed multiplication of the sampling sequence (AF) by a digital cosine-wave signal sequence.  
 
     
     
         5 . A level measuring device as set forth in  claim 4   wherein the volatile data memory ( 33 ) holds, at least temporarily, a first quadrature-signal sequence (Q), which represents a numerically performed downconversion of at least a portion of the first signal sequence (SIN AF ), and/or    wherein the volatile data memory ( 33 ) holds, at least temporarily, a second quadrature-signal sequence (I), which represents a numerically performed downconversion of at least a portion of the second signal sequence (COS AF ).    
     
     
         6 . A level measuring device as set forth in  claim 4  or  5  
 wherein the volatile data memory ( 33 ) holds, at least temporarily, a first average-value sequence.({overscore (SIN AF )}), which serves in particular to generate the first quadrature-signal sequence (Q) and represents a variation of a time average of at least a portion of the first signal sequence, (SIN AF ), and/or  
 wherein the volatile data memory ( 33 ) holds, at least temporarily, a second average-value sequence ({overscore (COS AF )}), which serves in particular to generate the second quadrature-signal sequence (I) and represents a variation of a time average of at least a portion of the second signal sequence (COS AF ).  
 
     
     
         7 . A level measuring device as set forth in any one of  claims 4  to  6  wherein the volatile data memory ( 33 ) holds, at least temporarily, a data record (q j /i j ) which corresponds to a phase of a data record (af j ) of the sampling sequence (AF) and represents a numerical division of a data record (q j ) of the first quadrature-signal sequence (Q) by an essentially equal-locus data record (i j ) of the second quadrature-signal sequence (I).  
     
     
         8 . A level measuring device as set forth in  claim 7  wherein the volatile data memory ( 33 ) holds, at least temporarily, a first digital phase sequence (Q/I) which corresponds to a temporal phase variation of at least a portion of the intermediate-frequency signal (ZF).  
     
     
         9 . A level measuring device as set forth in any one of  claims 1  to  3  wherein the volatile data memory ( 33 ) holds, at least temporarily, a digital envelope (ENV) which represents a temporal amplitude variation of the intermediate-frequency signal (ZF).  
     
     
         10 . A level measuring device as set forth in  claim 9  wherein the volatile data memory ( 33 ) holds, at least temporarily, a data record (af j /env j ) which corresponds to a phase of a data record (af j ) of the sampling sequence,(AF) and represents a numerical division of said data record (af j ) by an essentially equal-locus data record (env j ) of the envelope (ENV).  
     
     
         11 . A level measuring device as set forth in  claim 9  or  10  wherein the volatile data memory ( 33 ) holds, at least temporarily, a second digital phase sequence (AF/ENV) which corresponds to a temporal phase variation of at least a portion of the intermediate-frequency signal (ZF).  
     
     
         12 . A level measuring device operating with microwaves, particularly with microwave bursts, for producing a level value (X H ) representative of a level in a vessel ( 200 ), said level measuring device comprising: 
 a transceiver unit ( 2 ) for generating a level-dependent intermediate-frequency signal (ZF) by means of a transmit signal (S 2 ) and a receive signal (E 2 );    a transducer element ( 1 ) 
 which in operation couples waves (S 1 ), particularly pulsed waves, into the vessel ( 200 ) under control of the transmit signal (S 2 ) and which converts echo waves (E 1 ) reflected from contents ( 201 ) of the vessel ( 200 ) into the receive signal (E 2 ); and  
   a control unit ( 3 ) 
 with a volatile data memory ( 33 ) for storing, at least temporarily, a digital phase sequence (AF/ENV) which represents a normalization of the intermediate-frequency signal (ZF) to an amplitude variation of the intermediate-frequency signal (ZF) and which corresponds to a temporal. phase variation of the intermediate frequency signal (ZF).  
   
     
     
         13 . A level measuring device as set forth in  claim 1  or  12  which comprises, a logarithmic amplifier ( 37 ) for the intermediate-frequency signal (ZF).