Receivers, methods, and computer program products for an analog modem that receives data signals from a digital modem

A method for demodulating, in a receiver, a data signal transmitted from a digital source at a network sampling rate that is synchronized with a network clock, comprising the steps of:

• sampling the data signal to produce digital samples at a first local sample rate that is synchronized with a local clock;
• interpolating the digital samples to produce first and second estimates for each of the digital samples using a polyphase interpolator;
• interpolating, using a linear interpolator, the first and second estimates to produce interpolated digital samples having a second local sample rate that is synchronized with the network clock;
• equalizing the interpolated digital samples to produce equalized digital samples;
• and
• decoding the equalized digital samples to generate detected symbols therefrom.

A method as recited in 15, wherein the identifying step comprises the steps of:

• establishing a plurality of alphabet thresholds corresponding to valid data symbols;
• computing an average value for the equalized digital samples corresponding to a particular alphabet threshold;
• and
• updating the particular alphabet threshold with the average value.

A computer program product for demodulating, in a receiver, a data signal transmitted from a digital source at a network sampling rate that is synchronized with a network clock, comprising:

• a computer readable storage medium having computer readable code means embodied therein, the computer readable code means comprising:
• first logic configured to sample the data signal to produce digital samples at a first local sample rate that is synchronized with a local clock;
• second logic configured to interpolate the digital samples to produce first and second estimates for each of the digital samples, the second logic configured to interpolate comprising:
• third logic configured to use a polyphase interpolator to produce the first and second estimates;
• fourth logic configured to interpolate the first and second estimates to produce interpolated digital samples having a second local sample rate that is synchronized with the network clock, the fourth logic configured to interpolate comprising:
• fifth logic configured to use a linear interpolator to produce the interpolated digital samples;
• sixth logic configured to equalize the interpolated digital samples to produce equalized digital samples;
• and
• seventh logic configured to decode the equalized digital samples to generate detected symbols therefrom.