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.

Techniques disclosed herein are directed toward make use of known wireless transmit station geometry (e.g., from a cell location database/almanac) to create an optimized search window, where the size of the search window is a function of an angle between a line from the center of the region of position uncertainty of the mobile device to the location of the reference transmit station, and a line from the center of the region of position uncertainty of the mobile device to the location of the remote transmit station. Techniques can be utilized for various types of wireless transmit stations not only in cell networks, but Global Navigation Satellite Systems as well.

Various embodiments provide methods, devices, and non-transitory processor-readable storage media for reducing subscription reacquisition times in single radio long term evolution (SRLTE) communication devices. In various embodiments, a processor of the SRLTE communication device may calculate an expected pilot slew error in response to a radio frequency (RF) resource of the SRLTE communication device becoming available to a first subscription following a declared system loss of the first subscription. The processor may determine a dynamic search window size based at least in part on the expected pilot slew error. The processor may find a pilot signal using the dynamic search window size. Using the pilot signal determined in this manner the processor may reacquire a network associated with the first subscription.

A receiver receives signals and noise over a frequency spectrum of a desired received signal. The desired received signal is spread using code division multiple access. The received signals and noise are demodulated to produce a demodulated signal. The demodulated signal is despread using a code uncorrelated with a code associated with the desired received signal. A power level of the despread demodulated signal is measured as an estimate of the noise level of the frequency spectrum.