Constellation adjustment based on detected encoding and encoding conversion for modem connections

For a signal processing application, a circuit for adjusting a signal representing a modem constellation, the signal transmitted through a telecommunication channel between source and destination modems and subjected to at least two of a plurality of line encoding algorithms, comprising:

• a detector adapted to detect:
• i) the two line encoding algorithms based on a set of test levels included in the signal to identify encoding conversion compensation values, wherein the source modem transmits the signal with a constellation based on one line encoding algorithm and the destination modem transmits to the source modem with a constellation based on an other line encoding algorithm, wherein each of the encoding algorithms encodes one of the set of test levels to generate a substantially equivalent value, and one or more remaining test levels received by at least one of the source and destination modems are normalized based on the one of the test levels for comparison with a decision metric;
• ii) a superimposed information channel in the signal to identify channel compensation values;
• and
• iii) line attenuation of the signal to identify gain compensation values;
• and
• a demodulator adapted to adjust the constellation at the destination modem in accordance with the encoding conversion, channel, and gain compensation values,
• wherein the circuit is adapted to compensate the test levels of the signal based on at least one of i) the encoding conversion compensation values and ii) the gain compensation values.

A computer-readable medium having stored thereon a plurality of instructions, the plurality of instructions including instructions which, when executed by a processor cause the processor to implement a method of adjusting a signal representing a modem constellation, the signal transmitted through a telecommunication channel between source and destination modems and subjected to at least two of a plurality of line encoding algorithms, the method comprising the steps of:

• (a) detecting the two line encoding algorithms based on a set of test levels included in the signal to identify encoding conversion compensation values, wherein the source modem transmits the signal with a constellation based on one line encoding algorithm and the destination modem transmits to the source modem with a constellation based on an other line encoding algorithm, wherein each of the encoding algorithms encodes one of the set of test levels to generate a substantially equivalent value, and step (a) comprises the step of normalizing, based on the one of the test levels, one or more remaining test levels received by at least one of the source and destination modems for comparison with a decision metric;
• and
• (b) detecting a superimposed information channel in the signal to identify channel compensation values;
• (c) detecting line attenuation of the signal to identify gain compensation values;
• (d) compensating the test levels of the signal based on at least one of i) the encoding conversion compensation values and ii) the gain compensation values;
• and
• (e) adjusting the constellation at the destination modem in accordance with the encoding conversion, channel, and gain compensation values.

For a signal processing application, a method of adjusting a signal representing a modem constellation, the signal transmitted through a telecommunication channel between source and destination modems and subjected to at least two of a plurality of line encoding algorithms, the method comprising the steps of:

• (a) detecting the two line encoding algorithms based on a set of test levels included in the signal to identify encoding conversion compensation values, wherein the source modem transmits the signal with a constellation based on one line encoding algorithm and the destination modem transmits to the source modem with a constellation based on an other line encoding algorithm;
• (b) detecting a superimposed information channel in the signal to identify channel compensation values;
• (c) detecting line attenuation of the signal to identify gain compensation values;
• (d) compensating the test levels of the signal based on at least one of i) the encoding conversion compensation values and ii) the gain compensation values;
• and
• (e) adjusting the constellation at the destination modem in accordance with the encoding conversion, channel, and gain compensation values,
• wherein step (a) detects the two line encoding algorithms by the steps of:
• (a1) generating the signal comprising a set of test levels, wherein each of the test levels is selected based on the relative difference between each of the plurality of encoding algorithms when encoding the test level, and each of the plurality of encoding algorithms encode one of the set of test levels to generate a substantially equivalent value;
• and
• (a2) comparing a combination of each of the set of test levels transmitted through the communication channel to a decision metric, wherein the decision metric is based on a measure of the difference between one or more of the set of test levels prior to being transmitted through the communication channel to the corresponding one or more of the set of test levels after the signal is transmitted through the communication channel, the one test level employed to normalize the remaining test levels for the comparison;
• and
• (a3) detecting the line encoding according to one of a plurality of encoding algorithms based on the comparison of the combination with the decision metric.

For a signal processing application, a circuit for adjusting a signal representing a modem constellation, the signal transmitted through a telecommunication channel between source and destination modems and subjected to at least two of a plurality of line encoding algorithms, comprising:

• a detector adapted to detect:
• i) the two line encoding algorithms based on a set of test levels included in the signal to identify encoding conversion compensation values, wherein the source modem transmits the signal with a constellation based on one line encoding algorithm and the destination modem transmits to the source modem with a constellation based on an other line encoding algorithm;
• ii) a superimposed information channel in the signal to identify channel compensation values;
• and
• iii) line attenuation of the signal to identify gain compensation values;
• and
• a demodulator adapted to adjust the constellation at the destination modem in accordance with the encoding conversion, channel, and gain compensation values,
• wherein the circuit is adapted to compensate the test levels of the signal based on at least one of i) the encoding conversion compensation values and ii) the gain compensation values, and
• wherein the detector detects the two line encoding algorithms by:
• (1) generating the signal comprising a set of test levels, wherein each of the test levels is selected based on the relative difference between each of the plurality of encoding algorithms when encoding the test level, and each of the plurality of encoding algorithms encode one of the set of test levels to generate a substantially equivalent value;
• and
• (2) comparing a combination of each of the set of test levels transmitted through the communication channel to a decision metric, wherein the decision metric is based on a measure of the difference between one or more of the set of test levels prior to being transmitted through the communication channel to the corresponding one or more of the set of test levels after the signal is transmitted through the communication channel, the one test level employed to normalize the remaining test levels for the comparison;
• and
• (3) detecting the line encoding according to one of a plurality of encoding algorithms based on the comparison of the combination with the decision metric.