High-performance OTDR module for remote fibre test systems

The new AQ7277B from Yokogawa Europe is a high-performance optical time-domain reflectometer (OTDR) module for use with remote fibre-test systems (RFTS).

An RFTS is a test system designed to improve the efficiency of operation and maintenance management of optical fibre lines installed at a fibre-optic cable termination station by constantly monitoring individual fibres in the cable using the OTDR technology for continuous measurements. The system indicates the failure location on an electronic map and notifies the maintenance staff by means of e-mail or telephone.

As a result, it speeds up the identification and location of failures (such as increased loss, fibre breaks and water ingress) and facilitates restorative maintenance. It also enables the maintenance centre to test the installed equipment as a remote manual test during cable installation.

The ability to perform automatic testing of multiple fibres at once saves installation labour time and costs and reduces the overall work period required.

Today's regulatory regime has made it more important than ever for telecom carriers to proactively monitor and maintain their fibre networks. In particular, the huge penalties specified in service level agreements and quality of service commitments give carriers financial incentives to invest in maintaining their fibre networks.

"Detecting fibre degradation before failure while reducing mean time to repair is key to succeeding in today's competitive business environment", says Terry Marrinan, Vice-President, Test & Measurement, Europe & South East Asia, for Yokogawa Test & Measurement Europe: "and the time saved by using an RFTS to locate and isolate the first fibre break can pay for itself by yielding a full return on investment and achieving a higher level of customer satisfaction through improved quality of service."

The hardware of the AQ7277B OTDR module is based on Yokogawa's established AQ7280 OTDR, with its superior optical performance in terms of short dead zone (0.6 m typical) and high dynamic range (up to 50 dB). Moreover, its size is reduced by 60% compared to its predecessor, which improves its integration into the RFTS. Now its dimensions are 230 mm (W) × 50 mm (H) × 140 mm (D), and weight is approximately 1 kg.

There are two models in the AQ7277B family, both equipped with an Ethernet (10BASE-T/100BASE-TX) interface as standard. The AQ7277B-B01 takes measurements at 1650 nm, a wavelength which does not affect the communication wavelengths of 1310/1490/1550 nm. It is equipped with a built-in cutoff filter to isolate it from wavelengths lower than 1650 nm, and so can perform accurate measurements on "live" lines (where active communication signals are travelling). This model is also optimised for testing passive optical networks (PON), and can measure through the high-port-count splitters used in modern PON systems.

The AQ7277B-B02 is designed for monitoring long-distance optical fibres - greater than 200 km in real-life environmental conditions - -being capable of a 50 dB dynamic range. It operates at a wavelength of 1550 nm.