Television receiver

Abstract

A television receiver includes a tuner stage, a selective filter stage connected to the tuner stage, and a intermediate-frequency stage connected to the selective filter stage. A field-strength-detection stage is also provided, which generates a field strength signal proportional to the field strength of the received signal. The selective filter stage includes a transfer function that is modifiable by a control signal derived from the field strength signal.

1 . A television receiver comprising: 
 a tuner that receives a transmitted signal from an antenna;    a selective filter stage connected to the tuner;    an intermediate-frequency stage connected to the selective filter stage; and    at least one field-strength-detection stage that generates a field strength signal proportional to the field strength of the received signal, and which generates a control signal derived from the field strength signal, where the selective filter stage implements a transfer function that is modifiable by the control signal.    
     
     
         2 . The television receiver of  claim 1 , where the bandwidth of the selective filter stage is modified as a function of the control signal.  
     
     
         3 . The television receiver of  claim 1 , where the selective filter stage is implemented as a frequency trap, the slope of which is modifiable by the control signal.  
     
     
         4 . The television receiver of  claim 4 , where one chrominance signal and one luminance signal are contained in the received signal and where the frequency trap is dimensioned such that, in response to a higher field strength signal, spectral components of the chrominance signal are more strongly suppressed, while in response to a lower field strength signal noise signals in the spectral range of luminance and chrominance signal are reduced.  
     
     
         5 . The television receiver of  claim 1 , where a black-and-white signal is contained in the received signal and, in response to a low field strength signal, only black-and-white signals are transmitted by the selective filter stage.  
     
     
         6 . The television receiver of  claim 5 , where the received signal includes a video signal, and where a video signal is contained in the video signal and, in response to a low field strength signal, higher-frequency video signals are suppressed by the selective filter stage.  
     
     
         7 . The television receiver of  claim 1 , where the selective filter stage is controlled such that given a field strength signal above a certain threshold value there is no effect on the signal by the selective filter stage.  
     
     
         8 . The television receiver of  claim 1 , where in response to a degrading signal, the selective filter stage adapts the filter response continually or in steps.  
     
     
         9 . The television receiver of  claim 1 , where the at least one field-strength-detection stage evaluates the received signal and generates the field strength signal.  
     
     
         10 . The television receiver of  claim 1 , where the at least one field-strength-detection stage comprises the intermediate-frequency stage, where the intermediate-frequency stage generates the field strength signal.  
     
     
         11 . A television receiver comprising: 
 a tuner that receives a transmitted signal from an antenna;    a first selective filter stage connected to the tuner, the selective filter stage implementing a transfer function that is modifiable by one or more control signals derived from a field strength signal; and    an intermediate-frequency stage connected to the selective filter stage and generating a first control signal of the one or more control signals.    
     
     
         12 . The television receiver of  claim 11 , where the first selective filter stage modifies the bandwidth of the implemented transfer function based on the one or more control signals.  
     
     
         13 . The television receiver of  claim 1 , where the television receiver further comprises a second selective filter stage connected to the intermediate-frequency stage, the second selective filter stage being controlled by at least one of the one or more control signal.  
     
     
         14 . The television receiver of  claim 13 , where at least one of the first and second selective filter stages implements a frequency trap having a slope that is modifiable in response to the one or more control signals.  
     
     
         15 . The television receiver of  claim 14 , where one chrominance signal and one luminance signal are contained in the received signal, and where the frequency trap is dimensioned such that, in response to a higher field strength signal, spectral components of the chrominance signal are more strongly suppressed, while in response to a lower field strength signal noise signals in the spectral range of luminance and chrominance signal are reduced.  
     
     
         16 . The television receiver of  claim 13 , where a black-and-white signal is contained in the received signal and, in response to a low field strength signal, only black-and-white signals are transmitted by the first and second selective filter stages.  
     
     
         17 . The television receiver according to  claim 13 , where the received signal comprises a video signal, and where, in response to a low field strength signal, higher-frequency video signals are suppressed by one or more of the first and second selective filter stages.  
     
     
         18 . The television receiver according to  claim 13 , where in response to a degrading signal the first and second selective filter stages implement respective filter response one of either continually and in increments.  
     
     
         19 . The television receiver of  claim 13 , where the television receiver further comprises at least one additional signal-processing stage connected to and following the intermediate-frequency stage, where at least one of the one or more control signals is derived from at least one signal from the at least one additional signal-processing stage.  
     
     
         20 . A television receiver comprising: 
 a tuner that receives a transmitted signal from an antenna;    first selective filter means, connected to the tuner, for implementing a transfer function modifiable in response to one or more control signals; and    means for generating the control signal derived from a detected field strength of the received signal.    
     
     
         21 . The television receiver of  claim 20 , where the transfer function comprises a bandwidth modifiable in response to the one or more control signals.  
     
     
         22 . The television receiver of  claim 20 , where the means for generating a control signal derived from a detected field strength comprises an intermediate-frequency stage connected to the selective filter means.  
     
     
         23 . The television receiver of  claim 20 , where the means for generating a control signal derived from a detected field strength comprises a field strength detector connected to receive one of either an input to or an output from the tuner.  
     
     
         24 . The television receiver of  claim 4 , further comprising at least one additional selective filter means connected to the intermediate-frequency stage, the additional selective filter means responsive to the control signal.