Multi-Task Testing with the VIAVI MTS-5800 — Running BERT and Optical Spectrum Analysis from One Platform

Traditionally, verifying 100 G wavelengths required two engineers and two separate instruments. This case study explores how a regional carrier reduced testing time by 40% by combining Layer 1 BERT and Layer 0 Optical Spectrum Analysis into a single workflow using the VIAVI MTS-5800.

Background

A regional carrier was upgrading its metro transport network to 100 G and 400 G wavelengths using coherent DWDM technology. Each new site required validation of both the electrical layer (Ethernet/OTN performance) and the optical layer (spectrum and channel power) before hand-over to the NOC.

Traditionally, this meant sending two different engineers — one carrying a BERT tester for service verification, and another with an optical spectrum analyser to confirm channel alignment and optical signal levels. This duplication increased testing time, coordination effort, and operational costs.

To streamline field operations, the carrier equipped its engineering team with VIAVI’s MTS-5800 platform, which can host multiple interchangeable modules — allowing one engineer to perform both layer-1 BERT and optical testing simultaneously from a single portable unit.

The Challenge

At each network hub, engineers needed to:

• Validate bit-error performance on new 100 G Ethernet links to verify clean transmission.
• Measure optical spectrum and power levels on a separate DWDM span to ensure proper channel setup.
• Complete all tests within tight commissioning windows, often at remote locations with limited staffing.

Using separate instruments created several challenges:

• Increased setup time — each tool required independent power, calibration, and configuration.
• Coordination delays, since BERT and OSA results had to be compared after testing.
• Physical bulk and transport costs, with multiple test sets in the field.

The engineering team wanted a way to perform both electrical and optical measurements in parallel, without compromising accuracy or workflow.

The Solution: VIAVI MTS-5800 with Nano-OSA Module

The VIAVI MTS-5800 offers a modular test platform that supports multiple functions through swappable interfaces. For this project, engineers configured the instrument with:

• A 100 G Ethernet test module for BERT and service verification.
• A Nano-OSA module inserted in the optical test slot for real-time spectrum analysis.

During site commissioning, one engineer connected the 100 G interface to the live Ethernet circuit to run a BER test using PRBS patterns. At the same time, the Nano-OSA port monitored a separate DWDM link to measure channel wavelengths, OSNR (Optical Signal-to-Noise Ratio), and total power.

Both applications ran concurrently under the MTS-5800’s unified test environment, with results logged automatically to VIAVI StrataSync® for central storage and reporting.

The Results

This dual-testing approach delivered major operational benefits:

• Testing time reduced by more than 40 %, as one visit and one engineer completed both tasks.
• Improved accuracy, since electrical and optical measurements were taken under identical environmental conditions.
• Instant fault correlation, allowing engineers to confirm whether any BER issues were optical-layer related.
• Simplified logistics, with one lightweight test set replacing two separate instruments.

The carrier’s team could now verify end-to-end service integrity and optical health in a single workflow — critical for efficient turn-ups in multi-vendor DWDM networks.

Conclusion

By leveraging the modular flexibility of the VIAVI MTS-5800, the network engineer transformed what was once a two-person, multi-tool task into a single-technician, multi-layer test.

Running a BERT on one circuit while simultaneously using the Nano-OSA module to verify optical performance on another allowed faster site commissioning, reduced travel, and higher productivity.

For carriers expanding to 100 G and 400 G DWDM infrastructure, the MTS-5800 provides a compact, all-in-one solution that bridges the gap between optical and Ethernet testing — proving that one instrument really can do the work of two.