Apparatus and methods for signal generation, reception, and calibration involving quadrature modulation and frequency conversion. An acoustic extension is mounted to the enclosure and is external of the enclosure. In one aspect, only one of the feedback paths from the quantizer output is DC coupled, and at least one other of the feedback paths is DC-coupled, which reduces the signal levels in the loop filter integrators. The scintillator array includes at least one complementary scintillator row of at least one complementary scintillator element, and the at least one complementary scintillator row is optically coupled to the at least one photosensor row and the at least one complementary scintillator element is optically coupled to the at least one photosensor element. The processing portions of the remaining texture pipelines may not be not triggered. The wavelength selective switch sets as a cutoff band at least one of predetermined bands on the low and high frequency sides, narrows a transmission band of the input signal light to be wavelength-multiplexed, deletes an overlapped band of optical spectra, and outputs the transmission signal light, thereby suppressing crosstalk.