A method and apparatus for the detection of optical channels in an optical signal and their reliable discrimination against optical amplifier noise, i. The sulfur recovery unit may include an acid gas supply, which may supply acid gas, an oxygen supply, which may supply oxygen, a fuel supply, which may supply fuel. The first layers each consist of a homogenous thermoplastic film of a polyolefin copolymer, polyester, or a polyester copolymer. A send buffer is coupled to the transmitter. The ADC may be on a device-under-test. The start of the preamble is considered likely to be the initial location of the interval that corresponds to the metric having the lowest value.