Simplified frequency-domain filter adaptation window

A physical layer transceiver for a data channel, the physical layer transceiver comprising:

• receiver circuitry configured to receive signals that arrive on the data channel;
• transmit circuitry configured to transmit signals onto the data channel;
• and
• adaptive filter circuitry coupled to the receiver circuitry and the transmit circuitry and configured to filter the data channel by operating on input frequency-domain data samples to output filtered data samples, the adaptive filter circuitry comprising:
• error sample generation circuitry configured to generate error samples representing a difference between a target response and the filtered data samples, the error sample generation circuitry comprising:
• comparison circuitry configured to generate error signals representing a difference between a target response and the filtered data samples, and
• combining circuitry configured to combine the error signals with processed signals derived from the input frequency-domain data samples to provide the samples of a gradient of a cost function to be minimized;
• arithmetic-only circuitry configured to approximate a windowing function to operate on the cost function gradient samples to provide windowed error samples;
• and
• output sample generation circuitry configured to operate on the windowed error samples to provide the output filtered data samples.