US Patent 7620317 Programmable loss of signal detect hardware and method

A loss of signal assert and de-assert level programming mechanism in an optical transceiver coupled to a host computing system. A control module is connected to the host so as to receive the programmable loss of signal level. A post-amplifier detects when the receive power drops below a loss of signal level. However, in this case, instead of the loss of signal level being static, a loss of signal level adjustment mechanism changes the loss of signal level detected by the post-amplifier as directed by the programmable loss of signal level received from the host. The loss of signal assert and de-assert levels may be calibrated by comparing receive power to the threshold for assertion and de-assertion of the loss of signal.