What is OTDR? Complete Beginner Guide (2026)

What is OTDR?

OTDR (Optical Time Domain Reflectometer) is a device used to test fiber optic cables by measuring signal loss, distance, and faults along the fiber link.

How does OTDR work?

OTDR sends a pulse of light into the fiber and measures the reflected signal to analyze:

• Fiber length
• Signal attenuation
• Fault locations

Key OTDR parameters

• Distance range
• Dynamic range
• Dead zone

👉 Dead zone is one of the most critical factors when choosing an OTDR.

How to read OTDR trace

An OTDR trace shows:

• Loss events
• Reflection points
• Fiber breaks

👉 Understanding the trace is essential for troubleshooting.

Common OTDR mistakes

• Using wrong wavelength
• Incorrect pulse width
• Ignoring dead zone

Best OTDR for beginners

For beginners, a compact and easy-to-use OTDR is recommended.

👉

COMWAY MAX-600-M1 — Professional Handheld OTDR for FTTH & Access Network Testing

The COMWAY MAX-600-M1 is a professional dual-wavelength handheld OTDR delivering 1310/1550nm testing with a 32/30dB dynamic range — all in a lightweight 1.0kg tablet-inspired design. With a 7-inch full touchscreen, 12-hour battery life, and built-in VFL, OPM, and light source, the MAX-600-M1 is the ideal all-in-one fiber test solution for FTTH commissioning, access network testing, and field maintenance at an exceptional value price of $1,169.

🔑 Key Features

• Dual Wavelength: 1310/1550nm — Standard SM fiber testing for FTTH and access networks
• Dynamic Range: 32dB / 30dB — Covers typical FTTH and metro access distances
• Minimum Event Dead Zone: 0.8m — Detect closely spaced events with precision
• 7-Inch Full Touchscreen — Large, clear display for easy trace analysis
• 12-Hour Operating Time — Full-day field testing on a single charge
• Built-in VFL, OPM & Light Source — Complete fiber test toolkit in one device
• Optional Fiber Inspection Probe Module
• Lightweight: 1.0kg | Compact: 215×152×64mm
• Wide Operating Temp: -10°C to +50°C
• Battery: 7.4V, 4,600mAh Li-ion | AC/DC 100–240V

📐 Technical Specifications

• Wavelengths: 1310nm / 1550nm
• Dynamic Range: 32dB (1310nm) / 30dB (1550nm)
• Event Dead Zone: ≥0.8m
• Display: 7-inch Full Touchscreen
• Battery: 7.4V, 4,600mAh | 12-hour life
• Weight: 1.0kg | Dimensions: 215×152×64mm
• Operating Temp: -10°C to +50°C
• Functions: OTDR + VFL + OPM + Light Source
• Connector Options: SC/APC | FC/APC | SC/UPC | FC/UPC

🏗️ Ideal Applications

FTTH/FTTB commissioning and acceptance · Access network fault location · Field maintenance and troubleshooting · Fiber link characterization · Telecom contractor and ISP use

💡 Best Value Professional OTDR

The MAX-600-M1 delivers the same 7-inch touchscreen platform and professional UI as the higher-spec MAX-600-M3, at a more accessible price point — making it the smart choice for technicians who need reliable OTDR performance for standard FTTH and access network applications.

✅ FAQ

Q1: What is the dynamic range of the COMWAY MAX-600-M1 and what distance can it test?
A: The MAX-600-M1 offers 32dB at 1310nm and 30dB at 1550nm, enabling fiber testing 
over distances of approximately 60–80km depending on fiber quality — ideal for FTTH 
access networks and short metro links.

Q2: What is the difference between the MAX-600-M1 and MAX-600-M3?
A: The MAX-600-M3 offers higher dynamic range (39/38dB vs 32/30dB) and adds a live 
1625nm wavelength for PON testing. The MAX-600-M1 is the best-value choice for 
standard FTTH and access network testing where 1625nm is not required.

Q3: Does the MAX-600-M1 include a power meter and VFL?
A: Yes. The MAX-600-M1 includes built-in VFL (Visual Fault Locator), optical power 
meter (OPM), and light source — plus an optional fiber inspection probe module.

Q4: What connector types are available?
A: Available in SC/APC, FC/APC, SC/UPC, and FC/UPC. Select your preferred connector 
type at checkout.

Q5: How long does the battery last on the MAX-600-M1?
A: The 4,600mAh Li-ion battery provides 12 hours of continuous operation — sufficient 
for a full day of field testing.

Q6: Is the MAX-600-M1 suitable for outdoor field use?
A: Yes. The MAX-600-M1 operates from -10°C to +50°C and is housed in a rugged, 
lightweight 1.0kg enclosure designed for field use.