Referring to FIG. 1, a passive optical network (PON) 100 provides for the optical transmission of data between a central office and one or more users. Typically, the central office comprises an optical line terminal (OLT) 105 or optical transceiver that transmits and receives optical data via fiber optic media between the OLT 105 and a user node (e.g., 125a, 125b, . . . or 125n), which utilizes a transceiver often referred to as either an optical network unit (ONU) or optical network terminal (ONT).
In the optical network 100, the OLT 105 and the ONU(s) 125a-n attempt to keep their respective transceivers transmitting optical signals at consistent power levels. However, in addition to (1) the distance between the transceivers and (2) the proper functioning of components in the transceivers and in the network 100, there exist other factors which may result in variations in the power levels of optical signals received by the receiver 110, 130 of an OLT 105 or ONU 125, respectively. By way of illustration and not limitation, some reasons for link loss include variations in transmitter operation, the presence of intervening components 140 (e.g., cables, splitters, couplers, etc.), and the use of splices. For example, link loss may result from variations in the power level of the optical signals received by the OLT 105 and ONU(s) 125a-n. If the OLT 105 and/or ONU(s) 125a-n receive optical signals at improper power levels (for example, too high or too low), the data may not be properly communicated or processed. To ensure proper and/or consistent communication, it is advantageous to ensure that the power level of the input optical signals remain within the dynamic range of the receiver of the OLT 105 and ONU(s) 125.
An inaccurately detected and/or processed optical signal by the OLT 105 and/or ONU(s) 125a-n can lead to erroneous processing of the received data by receiver circuitry 110, 130a-n. Increasing the gain of a signal may improve the detection and/or processing of the optical signal and/or the accuracy of the received data. However, large signals do not need much gain; in fact, it may not be desirable to increase the gain of a strong signal, as it may cause saturation during subsequent stages of processing the signal.
In order to determine if the optical transceiver is functioning correctly, various operational parameters relating to the optical signal may be monitored. In optical transceivers, the detection of input and/or output power may allow users to monitor information of the transceiver and ensure adequate performance and proper operation. However, the measurement for received signal strength must be performed relatively quickly. Traditional power measurement circuitry for determining received signal strength may be relatively slow, and its accuracy may diminish in instances of low current and/or short optical data transmission time frames. Further, any filter added to the power supply of the photodetector can slow down the response time of the power measurement circuitry. Typical power measurement circuitry also tends to be linear, and thus, may have a limited dynamic range.
This “Discussion of the Background” section is provided for background information only. The statements in this “Discussion of the Background” are not an admission that the subject matter disclosed in this “Discussion of the Background” section constitutes prior art to the present disclosure, and no part of this “Discussion of the Background” section may be used as an admission that any part of this application, including this “Discussion of the Background” section, constitutes prior art to the present disclosure.