When using an Optical Time Domain Reflectometer (OTDR), choosing the proper launch and receive cables is crucial for accurate test results. These cables, also called fibre launch leads or dead zone eliminators, help compensate for the OTDR’s initial blind spot and ensure you can see faults or loss at the start and end of the fibre link.  

To get the best results, use high-quality fibre launch cables that match the type of fibre under test (single-mode or multimode) and are long enough to eliminate dead zones. 
 

Choosing the Right Launch and Receive Cables 

Here’s what you should consider: 

Match the Fibre Type 

Single-mode (OS1/OS2) – Typically, yellow cables are used for long-distance fibre runs. 

Multimode (OM1/OM2/OM3/OM4/OM5) cables are usually orange or aqua cables designed for shorter data center or campus links. 

Choose the Right Length 

To ensure proper trace visibility, a launch cable should be at least 150 meters for multimode fibre and at least 500 meters for single-mode fibre. 

A receive cable is not always required, but it helps measure loss at the far end of the fibre. 
 

Select Quality Connectors 

Match the connector type to your fibre: SC, LC, ST, or FC. 

Consider APC (angled) connectors for high-precision single-mode testing. 

Use Durable and Portable Solutions 

Look for ruggedised launch boxes that protect the fibre during field use. 

Some brands offer compact, spool-based solutions that fit neatly into test kits. 

Why Does This Matter? 

Imagine testing a fibre link without a launch cable. You’d miss any connector losses at the start of the run. Worse yet, without a receive cable, you wouldn’t get a clear view of the end-of-link loss. That’s like trying to judge a marathon runner’s time but only seeing their mid-race performance—helpful, but not the full picture. 
 

FAQs  

Why do I need a launch cable for my OTDR? 

A launch cable eliminates the OTDR’s dead zone, ensuring you can see any faults or loss at the start of the fibre link. 

Can I use a standard patch cord instead of a launch cable? 

No, standard patch cords are too short to eliminate the dead zone. A proper launch cable is more extended and designed for testing purposes. 

How do I know what length of launch cable to use? 

It depends on the fibre type. Multimode launch cables should be at least 150m, while single-mode launch cables should be at least 500m. 

Do I always need a receive cable? 

Not always, but it helps detect loss at the far end of the fibre link, especially in bidirectional testing. 

What happens if I use the wrong fibre type in my launch cable? 

Your OTDR test results will be inaccurate, leading to potential misdiagnosis of fibre issues. Always match the fibre type to your installation. 
 

 

Final Thoughts 

Choosing the proper launch and receive cables for your OTDR is essential for reliable fibre testing. You'll get precise test results and avoid costly troubleshooting by ensuring you use the correct fibre type, length, and connectors.