Implementing RF power measurements in a broadband communications device

Abstract

The invention provides systems, methods, and devices that compensate for temperature, frequency, and sampling effects in a broadband communication device's power measurements. One embodiment of a system includes a thermal device, and an automatic gain control circuit coupled to the thermal device. One method includes the acts of disabling a TOP operation, setting a RF input power, reading an AGC GAIN value, and setting the broadband communications device based on the read AGC value. Furthermore, a broadband communications device according to the invention may operate by disabling a TOP operation, setting a RF input power, reading an AGC GAIN value, and setting the broadband communications device based on the read AGC value.

What is claimed is:  
     
         1 . A system that implements RF power measurements in a broadband communications device, comprising: 
 a thermal device; and    an automatic gain control circuit coupled to the thermal device such that the thermal device is enabled to compensate for variances in the automatic gain control circuit.    
     
     
         2 . The system of  claim 1  wherein the thermal device is a variable thermister.  
     
     
         3 . The system of  claim 1  further comprising a temperature independent operational amplifier.  
     
     
         4 . The system wherein the thermal device varies gain in reverse polarity to an IF/RF gain change across temperature.  
     
     
         5 . The system of  claim 1  wherein the thermal device has a positive temperature coefficient device.  
     
     
         6 . The system of  claim 1  wherein the thermal device has an ambient resistive accuracy of about 1 percent as large as any other resistor in the circuit.  
     
     
         7 . The system of  claim 1  wherein the broadband communications device comprises a LBT4030 compliant device.  
     
     
         8 . The system of  claim 1  wherein the thermal device is a variable resistance resistor.  
     
     
         9 . The system of  claim 1  wherein the thermal device has a temperature coefficient that has a curve matched to a tuner's gain across a temperature range.  
     
     
         10 . The system of  claim 1  wherein the thermal device has a dissipation constant that is calculated based on the resistance device coefficient.  
     
     
         11 . A method of calibrating a broadband communications device, comprising: 
 disabling a TOP operation;    setting a RF input power;    reading an AGC GAIN value; and    setting the broadband communications device based on the read AGC value.    
     
     
         12 . A method of  claim 11  further comprising the act of returning to TOP operation.  
     
     
         13 . A method of  claim 11  further comprising setting the broadband communications device to a first predetermined frequency.  
     
     
         14 . A method of  claim 13  further comprising setting the broadband communications device to a second predetermined frequency.  
     
     
         15 . A method of  claim 14  further comprising setting the RF input power at the second predetermined frequency.  
     
     
         16 . A method of  claim 15  further comprising reading a second AGC GAIN value based on the second predetermined frequency.  
     
     
         17 . A method of  claim 16  further comprising setting the read AGC values as the TOP values for appropriate tuned frequencies.  
     
     
         18 . A broadband communications device capable of being calibrated by: 
 disabling a TOP operation;    setting a RF input power;    reading an AGC GAIN value; and    setting the broadband communications device based on the read AGC value.    
     
     
         19 . The broadband communications device of  claim 18  further comprising setting the broadband communications device to a first predetermined frequency, and setting the broadband communication device to a second predetermined frequency.  
     
     
         20 . The broadband communications device of  claim 19  further comprising setting the RF input power to the second predetermined frequency and reading a second AGC GAIN value based on the second predetermined frequency.