| 摘要 |
Methods and apparatus are provided for performing jitter measurements in a transceiver module. In one embodiment (Fig. 2) the transceiver monitors the jitter of a signal produced in the transmitting section of the transceiver. In this embodiment a high-speed monitor photodiode 50 provides optical feedback to jitter measurement circuitry 80. In an alternative embodiment the transceiver monitors the jitter contained in a received signal which originated at an external device. In this case a receiver photodiode (82, Fig. 4) of the transceiver feeds the jitter measurement circuitry (160, Fig. 4). In one embodiment the jitter measurement circuit uses a frequency detector in the form of a phase-locked loop (PLL) (see Fig. 3). The transceiver may include a processor for correlating jitter measurement values to the amount of jitter contained in the signal. The invention provides the advantage that there is no need to use expensive test equipment that must be inserted into and removed from the network in order to obtain jitter measurements. In addition, because the measurement can be obtained at any time without any interruption in communications over the network, jitter performance can be monitored more closely and more frequently to facilitate better and earlier diagnosis of problems that can lead to failures in the network. |
