A receiver signal is sampled at a sampling rate equivalent to a chip rate at which chips of a known signal are timed. The resulting receiver signal samples are segmented into receiver signal segments, which are filtered by respective matched filters that are matched to known signal segments segmented from the known signal. Indexes are assigned to elements of the resulting filter response sequences to define an array thereof. Frequency transforms are computed of elements of the filter response sequences in respective columns of the array. Indexes are assigned to elements of the resulting frequency response sequences to define another array thereof. Channel effects imparted on a radio signal are jointly estimated from characteristics of the other array at which at least one local maximum is located.

During optical performance monitoring in low SNR conditions, the detection of pilot data may be more difficult because the detector may mistake noise for the pilot data signal. Systems and methods are disclosed herein that try to address this problem. In one embodiment, a pilot tone detector processes the received signal to determine a maximum correlation peak, and then performs tracking of the correlation peak over time. Unlike the pilot data signal, noise is typically more transient in nature. Therefore, if a correlation peak does not actually correspond to the pilot data signal, but instead corresponds to noise, then the correlation peak typically disappears over time when tracked. A search for a new correlation peak may then be performed. When a correlation peak is determined that actually corresponds to the pilot data signal, then the correlation peak typically remains when tracked.

During optical performance monitoring in low SNR conditions, the detection of pilot data may be more difficult because the detector may mistake noise for the pilot data signal. Systems and methods are disclosed herein that try to address this problem. In one embodiment, a pilot tone detector processes the received signal to determine a maximum correlation peak, and then performs tracking of the correlation peak over time. Unlike the pilot data signal, noise is typically more transient in nature. Therefore, if a correlation peak does not actually correspond to the pilot data signal, but instead corresponds to noise, then the correlation peak typically disappears over time when tracked. A search for a new correlation peak may then be performed. When a correlation peak is determined that actually corresponds to the pilot data signal, then the correlation peak typically remains when tracked.