Location detector for digital television appliances

A method of auditing operation of a television appliance, comprising:

• detecting an event that triggers an audit;
• generating a fingerprint value, wherein the fingerprint value is function of the television network characteristics at an authorized installation location;
• wherein the fingerprint value comprises a function of at least one of the following:
• at least one equalizer coefficient of an adaptive equalizer of the television appliance and at least one gain coefficient value of an AGC loop of the television appliance;
• comparing the fingerprint value with a stored reference value to determine if the fingerprint value is within a range of specified value limits of the stored reference value;
• if the fingerprint value is within specified limits of the stored reference value, permitting the television appliance to carry out a normal operational function and storing the fingerprint value for use as the stored reference values in a subsequent audit;
• and
• if the fingerprint value is outside of specified limits of the stored reference value, inhibiting the television appliance from carrying out a normal operational function.

A self auditing television appliance, comprising:

• means for detecting an event that triggers an audit;
• means for generating a fingerprint value, wherein the fingerprint value is function of the television network characteristics at an authorized installation location, and wherein the fingerprint is a function of at least one of a gain value of a variable gain amplifier and an equalizer coefficient of an adaptive equalizer of the television appliance;
• a memory that stores a reference value;
• a processor for comparing the fingerprint value with the stored reference value to determine if the fingerprint value is within a range of specified value limits of the stored reference value, wherein:
• if the fingerprint value is within specified limits of the stored reference value, the television appliance carries out a normal operational function;
• and
• if the fingerprint value is outside of specified limits of the stored reference value, means for inhibiting the television appliance from carrying out a normal operational function.

A self auditing television appliance, comprising:

• an AGC loop circuit having a plurality of variable gain amplifiers, where the gain value of one of a plurality of variable gain amplifiers is given by k, and H2, is the matrix of all gain values representing the state of the AGC circuit at one point in time can be represented by:
• H
• 2
• =
• [
• k
• 0
• k
• 1
• …
• k
• l
• ]
• where l is the number of AGC coefficients;
• an equalizer circuit having a plurality of equalizer coefficients, wherein an equalizer coefficient is represented by a±jb, then H1, the matrix of all equalizer coefficients representing the state of the system at one point in time can be represented by:
• H
• 1
• =
• [
• a
• 0
• b
• 0
• a
• 1
• b
• 1
• …
• …
• a
• n
• b
• m
• ]
• where n is the number of feedback coefficients and m is the number of feed forward coefficients;
• means for detecting an event that triggers an audit, wherein the event comprises one of power-up of the television appliance, rebooting of the television appliance, receipt of command from a source external to the television appliance, and expiration of a timer;
• means for generating a fingerprint value, wherein the fingerprint value is function of the television network characteristics at an authorized installation location, and wherein the fingerprint is given by Fingerprint(t)=Y(H1,H2);
• a memory that stores a reference value as a stored as a fingerprint value obtained during an activation process for the television appliance;
• a processor for comparing the fingerprint value with the stored reference value to determine if the fingerprint value is within a range of specified value limits of the stored reference value, wherein:
• if the fingerprint value is within specified limits of the stored reference value, the television appliance carries out a normal operational function;
• if the fingerprint value is outside of specified limits of the stored reference value, means for inhibiting the television appliance from carrying out a normal operational function and sending an output signal that produces an on-screen message with instructions on contacting a television supplier;
• and
• a memory for storing the fingerprint value in the memory for use as the stored reference values in a subsequent audit.