Method for testing a communication channel

Abstract

A method of evaluating the characteristics of a subscriber loop associated with a customer modem comprises the steps of receiving line probing data from the modem and analyzing the line probing data to determine the circuit characteristics of the subscriber loop which relate to communication rate performance. The method generates a gain slope value as a function of the line probing data which is indicative of the length of the subscriber loop. The method also generates a loaded slope value as a function of the line probing data which is indicative of an inductive load on the subscriber loop. The method also generates an A/D value as a function of the line probing data which is indicative of an analog-to-digital and digital-to-analog conversion on the subscriber loop. The method then outputs an expected communication rate for the subscriber loop as a function of the gain slope, loaded slope, and A/D values, thereby providing a circuit analysis of the customer subscriber loop.

1. A method of evaluating a modem-linked communication channel comprising:
 receiving line probing data from said modem;   generating a first line value as a function of said line probing data, said first line value relating to a first circuit characteristic of said communication channel;   determining a loaded slope value of said communication channel by calculating said line probing data and subtracting the signal strength of said communication channel at 2850 Hz from the signal strength of said communication channel at 3300 Hz;   indicating the load status of said communication channel as a function of said loaded slope value; and   outputting a message as a function of said first line value, said message being indicative of the first circuit characteristic of said communication channel.   
     
     
       2. The method of  claim 1  further comprising determining an A/D value of said communication channel by calculating the difference between the signal strength of said communication channel at 2850 Hz and the signal strength of said communication channel at 3750 Hz, and the step of outputting the message includes indicating whether an A/D and a D/A conversion are present in said communication channel as a function of said loaded slope value and said A/D value. 
     
     
       3. A method of evaluating a modem-linked communication channel comprising:
 receiving line probing data from said modem;   generating a first line value as a function of said line probing data, said first line value relating to a first circuit characteristic of said communication channel;   generating a notch filter value of said communication channel as a function of said line probing data;   indicating a reduced communication rate for said communication channel as a function of said notch filter value; and   outputting a message as a function of said first line value, said message being indicative of the first circuit characteristic of said communication channel.   
     
     
       4. A method of evaluating the characteristics of a subscriber loop associated with a customer modem, the method comprising:
 receiving line probing data from said customer modem;   generating a gain slope value as a function of said line probing data, said gain slope value being indicative of the length of said subscriber loop;   generating a loaded slope value as a function of said line probing data, said loaded slope value being indicative of an inductive load on said subscriber loop;   generating an A/D value as a function of said line probing data, said A/D value being indicative of an analog-to-digital and digital-to-analog conversion on said subscriber loop; and   outputting an expected communication rate for said subscriber loop as a function of said gain slope, loaded slope, and A/D values.   
     
     
       5. The method of  claim 4  further comprising generating a notch filter value as a function of said line probing data, said notch filter value being indicative of a predetermined amount of signal attenuation at a predetermined frequency on said subscriber loop; and
 outputting the expected communication rate for said subscriber loop as a function of said notch filter value. 
 
     
     
       6. The method of  claim 4  wherein generating the gain slope value includes subtracting the signal strength of said subscriber loop at 1050 Hz from the signal strength of said subscriber loop at 3000 Hz, and when said gain slope value is greater than or equal to approximately 7 dB, outputting the expected communication rate includes indicating the length of said subscriber loop as the function of said gain slope value. 
     
     
       7. The method of  claim 6  wherein generating the loaded slope value includes subtracting the signal strength of said subscriber loop at 2850 Hz from the signal strength of said subscriber loop at 3300 Hz. 
     
     
       8. The method of  claim 7  wherein generating the A/D value includes subtracting the signal strength of said subscriber loop at 2850 Hz from the signal strength of said subscriber loop at 3750 Hz; and
 when said loaded slope value is less than 4 dB, said A/D value is greater than or equal to 17 dB and the expected communication rate is between 19.2 kbps and 26.4 kbps, and 
 when said loaded slope value is less than 4 dB, said A/D value is greater than or equal to 16 dB and the expected communication rate is between 19.2 kbps and 24.0 kbps, and 
 when said loaded slope value is less than 4 dB, said A/D value is greater than or equal to 16 dB and the expected communication rate is between 40 kbps and 53 kbps. 
 
     
     
       9. The method of  claim 4  wherein receiving the line probing data from said customer modem includes:
 establishing a communications link between said customer modem and a terminal associated with a network service provider by way of said subscriber loop; 
 entering a command level of said customer modem such that said customer modem will respond to a predetermined command; and 
 transmitting said predetermined command from said terminal to said customer modem to display said line probing data on said terminal. 
 
     
     
       10. The method of  claim 4  wherein receiving the line probing data from said customer modem includes:
 establishing a communications link between said customer modem associated with a terminal and a network service provider by way of said subscriber loop; 
 entering a command level of said customer modem such that said customer modem will respond to a predetermined command; and 
 transmitting said predetermined command from said terminal to said customer modem to display said line probing data on said terminal. 
 
     
     
       11. A modem adapted to receive line probing data comprising signal frequency versus attenuation data and evaluate the characteristics of a subscriber loop, said modem comprising a microprocessor programmed to perform the following steps:
 generating a gain slope value indicative of the length of said subscriber loop associated with said modem;   generating a loaded slope value as a function of said line probing data, said loaded slope value being indicative of an inductive load on said subscriber loop;   generating an A/D value as a function of said line probing data, said A/D value being indicative of an analog-to-digital and digital-to-analog conversion on said subscriber loop; and   outputting an expected communication rate for said subscriber loop as a function of said gain slope, loaded slope, and A/D values.   
     
     
       12. A modem adapted to receive line probing data comprising signal frequency versus attenuation data and evaluate the characteristics of a subscriber loop, said modem comprising a microprocessor programmed to perform the following steps:
 generating a first value as a function of said line probing data, said first value corresponding to a circuit characteristic of said subscriber loop associated with said modem;   generating a notch filter value as a function of said line probing data, said notch filter value being indicative of a predetermined amount of signal attenuation at a predetermined frequency on said subscriber loop; and   outputting an expected communication rate for said subscriber loop as a function of said notch filter value.   
     
     
       13. A method of determining a subscriber loop characteristic, comprising:
 acquiring frequency versus attenuation data associated with a subscriber loop; and   determining a subscriber loop condition using a modem in response to attenuation values associated with a predetermined frequency range from the frequency versus the attenuation data,   wherein the subscriber loop condition comprises a condition other than a loaded loop condition or an unloaded loop condition,   wherein the subscriber loop condition comprises a loaded bridge tap condition,   wherein the predetermined frequency range associated with the loaded bridge tap condition extends from approximately 1250 Hz to approximately 2850 Hz, and   wherein an attenuation greater than 4 dB within the predetermined frequency range is indicative of the loaded bridge tap condition.    
     
     
       14. The method of claim 13, wherein the frequency versus the attenuation data includes line probe data associated with the modem.  
     
     
       15. The method of claim 13, wherein the frequency versus the attenuation data is received from the modem coupled to the subscriber loop.  
     
     
       16. A device comprising:
 a processor adapted to:
 acquire frequency versus attenuation data associated with a subscriber loop; and 
 analyze the frequency versus the attenuation data to perform an unloaded long loop condition test, a loaded loop condition test, a plurality of A/D conversions condition test, and a loaded bridge tap condition test, 
 wherein a subscriber loop condition of the subscriber loop comprises a loaded bridge tap condition, 
 wherein a predetermined frequency range associated with the loaded bridge tap condition extends from approximately 1250 Hz to approximately 2850 Hz, and 
 wherein an attenuation greater than 4 dB within the predetermined frequency range is indicative of the loaded bridge tap condition.  
   
     
     
       17. The device of claim 16, wherein the device is a modem coupled to the subscriber loop and wherein the frequency versus the attenuation data includes line probe data.