GPON OLT SFP Class C+ Transceiver | 2.5G/1.25G | 32dB Budget | Tx 1490nm

Overview

The GPON OLT SFP Class C+ Transceiver is the industry-standard upgrade for Gigabit Passive Optical Networks (GPON), offering significant performance improvements over legacy Class B+ modules. Designed for Optical Line Terminals (OLT), this module operates under the ITU-T G.984.2 standard, delivering asymmetric data rates of 2.488 Gbps downstream and 1.244 Gbps upstream.

The “Class C+” rating signifies an enhanced optical power budget of approximately 32dB. This additional headroom allows Service Providers to comfortably support 1:64 split ratios over 20km distances, or to extend reach in networks with older cabling or higher insertion loss. It features a high-performance 1490nm DFB laser transmitter and a highly sensitive 1310nm APD receiver, ensuring robust connectivity for residential and commercial FTTH deployments.

Key Features

• Enhanced Link Budget: Class C+ specification provides ~32dB optical budget, superior to the ~28dB of Class B+.
• Optimized Split Ratios: Reliably supports 1:64 split ratios, maximizing subscriber density per OLT port.
• Standard Compliance: Fully meets ITU-T G.984.2 and SFP MSA standards.
• High-Speed Transmission: 2.5Gbps Down / 1.25Gbps Up throughput.
• Integrated Diagnostics: SFF-8472 compliant Digital Diagnostic Monitoring (DDM) for real-time health checks.
• Burst-Mode Rx: 1310nm APD receiver capable of handling rapid burst traffic from multiple ONUs.

Applications

• FTTH/FTTB Networks: Ideal for standard residential fiber rollouts requiring reliable 1:64 splitting.
• Network Upgrades: A drop-in replacement for Class B+ modules to fix “low light” issues on fringe customer premises.
• Video Surveillance: High-bandwidth upstream for passive optical LANs (POL) supporting IP camera backhaul.
• Triple-Play Services: Ensures stable delivery of Voice (VoIP), Data, and High-Definition IPTV.

Specifications

Class B+ vs. Class C+

While Class B+ was the early standard for GPON, Class C+ has become the preferred choice for new deployments. The primary difference lies in the transmit power and receiver sensitivity:

• Class B+: Lower power budget (~28dB). Often limited to 1:32 splits or shorter distances.
• Class C+: Higher power budget (~32dB). Enables 1:64 splits at full 20km range, providing a “safety buffer” for patch panel losses and connector aging.

FAQ

1. Can I use a Class C+ module in a port configured for Class B+?

Yes, Class C+ modules are backward compatible with standard GPON deployments. They simply provide a stronger signal. However, you should check if your OLT requires a specific configuration profile to recognize the specific transceiver vendor ID.

2. Do I need special ONUs for Class C+?

No. Standard GPON ONUs work with both Class B+ and Class C+ OLT modules. The improvement is entirely on the OLT side (stronger transmission and better listening sensitivity), which benefits the entire link regardless of the ONU type.

3. What is the difference between Class C+ and Class C++?

Class C+ is the mid-tier upgrade (approx 32dB budget). Class C++ is the high-power tier (approx 35dB budget), designed for extreme scenarios like 1:128 splits or very long distances. For most standard 1:64 networks, Class C+ is the most cost-effective solution.

4. Does this module support DDM/DOM?

Yes, it supports Digital Diagnostic Monitoring. You can view parameters like Tx power, Rx power, temperature, and voltage directly via the OLT’s command-line interface (CLI).

5. Is the connector SC/APC or SC/UPC?

This module uses SC/UPC (Blue). Connecting an SC/APC (Green) patch cord can damage the optical interface and will cause significant signal loss. Always use blue SC/UPC connectors.