FAQ about OTDRs

FirstFiber Technologies has compiled the following Frequently Asked Questions about OTDRs to help users better understand and maximize the use of their OTDRs. As a leading manufacturer of high-performance OTDRs, FirstFiber Technolgies always here to answer your questions and support your business growth.

How Long Does your OTDR can Reach?

As a professional manufacturer, we always like to remind our clients that the testing distance depends on the total loss of the fiber link, rather than just the length.
For example, using a standard single-mode fiber (G.652) at 1550nm

• Average fiber attenuation is about 0.2 dB/km.
• Splice loss and connector loss are roughly 0.5 dB to 1 dB total.

 
If you choose our 35dB OTDR and leave a 5dB safety margin

• Maximum Testable Loss=35dB−5dB=30dB
• Estimated Max Distance=30dB/0.2dB/km​=150km (on a clean, event-free fiber line).

 
Splitters introduce high loss, requiring higher dynamic range.

What wavelength does your OTDR support?

As a direct OTDR manufacturer, we offer highly flexible wavelength configurations depending on the model you choose,

• Standard Single-mode (SM): 1310nm / 1550nm (Most common for everyday fiber installation and maintenance).
• Multi-mode (MM): 850nm / 1300nm (For enterprise networks and data centers).
• PON/FTTH Tri-wavelength: 1310nm / 1550nm / 1625nm (or 1650nm) with a built-in filter.

Does your OTDR supports Live Testing (Online Testing)?

Yes, our PON/Live OTDR models support live fiber testing via the 1625nm (or 1650nm) port.
In a normal setup, you must shut down the active network (dark fiber) to test it, because standard 1310/1550nm OTDR laser signals will conflict with the customer's live data traffic. However, our Live OTDR uses a dedicated 1625nm/1650nm wavelength combined with an internal filter (attenuator). This filter blocks all incoming live traffic signals from damaging the OTDR's sensitive photodiode, allowing the OTDR to test the physical fiber while data is still running seamlessly.

Does your OTDR support Auto and Manual Pulse Width Set?

Our OTDR supports both Automatic and Manual pulse width settings.
We have designed our system to cater to technicians of all experience levels with two operational modes.

• Auto Mode (For Quick Testing)

• Manual / Expert Mode (For Advanced Troubleshooting)

Short pulse widths (e.g., 3ns, 5ns, 10ns) is  excellent for pinpointing closely spaced events or splitters in FTTx networks (small dead zone).
Long pulse widths (e.g., 10μs, 20μs) is good for penetrating long-distance fibers or high-loss links.

FirstFiber Technologies' OTDR Screen Visibility Under Direct Sunlight?

Yes, absolutely. Our OTDR screens are designed specifically for outdoor field environments and are perfectly readable under direct sunlight.

• High-Brightness

We use a high-luminescence display (industry-grade brightness). This allows technicians to read curves and data clearly even at noon.

• Adjustable Backlight

The software allows users to easily adjust the screen brightness. You can turn it to maximum for outdoor sunny days, or lower it to save battery when working indoors or at night.

How to Export Data from OTDR?

We provide multiple flexible ways to transfer your data from the device to your PC or phone.

• USB Flash Drive / Type-C Cable. You can copy files directly via a standard USB drive or by connecting the OTDR to your computer with a Type-C cable.
• TF/SD Card. Our OTDRs includes a removable memory card for large storage capacity.
• Bluetooth (Optional on specific models). Some of our models support Bluetooth transfer, allowing you to sync data to your phone.

Does your OTDR can generate report? and what format?

Yes, our OTDR completely supports data export and can generate standard professional testing reports.
Our OTDRs save raw data in .SOR format, which complies with the Telcordia (Bellcore) GR-196-CORE standard. This means you can open and analyze these files on any standard fiber analysis software worldwide.
We provide free PC Post-Processing Software. With just one click, you can batch-import your files and generate PDF reports.
You can contact us to get some sample reports.

How long is your OTDR Calibration Interval?

The recommended calibration interval for FirstFiber Technologies' OTDR is once every 2 years.
1. Factory Recalibration
You ship the device back to us. We will recalibrate it, perform firmware updates, and issue a new factory certificate.
2. Remote calibration
As a direct manufacturer, we also offer an exclusive, high-efficiency remote calibration method that can save you significant time and shipping costs.

• The Setup. You can take a "reference OTDR" (such as a brand-new FirstFiber OTDR or a well-known international brand like EXFO/Viavi) and your older OTDR.
• The Test. Use both machines to test the exact same fiber link under identical settings and export both .SOR data files.
• The Analysis. Simply email both .SOR files to us. Our R&D engineering team will analyze the trace differences, calculate the deviation, and create a customized software compensation package for your specific device.
• The Upgrade. You just need to upgrade your OTDR via a USB drive with our new firmware, and your machine's accuracy will be fully restored to factory standards.

This is a huge advantage of buying directly from FirstFiber Technologies—we can tweak the core software algorithms remotely to support your business.

Why I choose FirstFiber Technologies OTDR over Big Brands?

While we highly respect EXFO and VIAVI as industry pioneers, global telecom contractors and distributors increasingly choose FirstFiber Technologies for these critical reasons.
1. Drastic Cost Savings (Same Standards, 1/3 of the Price)
Big brands carry massive premiums for marketing and corporate overhead. A standard 35dB touchscreen OTDR from EXFO can easily cost $4,000 to $6,000+. FirstFiber Technologies delivers same testing precision and standard .SOR files for about 30% to 40% of their cost. For engineering teams deploying large-scale FTTH projects, choosing us means cutting equipment budgets by over 60% without sacrificing project quality.
2. Manufacturer-Direct Technical Support
When a big brand's OTDR has a software glitch or calibration drift, you must go through layers of local distributors, waiting weeks and paying high service fees. With FirstFiber Technologies, you talk directly to the factory. As mentioned before, we can analyze your .SOR files and send you custom firmware via email for remote calibration updates. No logistics hassle, no downtime.
3. Faster Delivery
Due to complex corporate structures, ordering from tier-1 brands often takes 4 to 8 weeks of lead time. As an agile manufacturer, FirstFiber Technologies maintains a steady stock of core components. We can dispatch standard orders within 3 to 7 working days.
4. Flexible Customization (OEM/ODM)
Big brands will never change their software interface or boot logo for you. We embrace it. We can pre-install your local language, flash your company logo on the boot screen, and customize the hardware packaging to help you build your own brand identity locally.

How do you guarantee the calibration and accuracy of your OTDRs? Do they come with a certificate?

Quality is our top priority. Every single unit undergoes factory calibration before shipment, and a Calibration Certificate is included inside the box. Our factory is ISO9001 certified, and our products hold CE and RoHS certifications to ensure they meet international standards.

Do you offer OEM/ODM services? Can you put our logo on your OTDRs?

Yes, we highly welcome OEM and ODM orders. We can customize the boot screen, print your logo on the OTDR housing, and even modify the user interface language to fit your local market.

How does your OTDR perform when testing through a 1:64 splitter in a PON network? Can it clearly identify events behind high attenuation?

Testing through high-ratio splitters is indeed the ultimate trial for any OTDR.
Our spitter OTDRs features a high dynamic range of 45dB and optimized pulse width options (up to 20μs). Combined with FirstFiber Technologies proprietary analysis algorithm, it can effectively penetrate a 1:64 splitter to detect events on the other side.

What is the sampling resolution and maximum number of sampling points of your OTDR? If I test a 100km link, will the resolution drop significantly?

Our CPU and acquisition board support up to 256,000 sampling points. This high density ensures that even when you test a long fiber link of 100km, our minimum sampling resolution remains at a very fine level, preventing any event omissions.
Your specs look similar to famous brand, but your price is much lower. Where exactly did you cut corners?
We respect EXFO/Viavi as industry pioneers, but a lower price doesn't mean cut corners. It means a different business model. As a direct manufacturer in China, we benefit from local partners and lower structural overhead. Moreover, big brands have massive marketing premiums. With FirstFiber Technologies, you are paying for the hardware performance and localized R&D, not the brand premium. We use high-quality lasers and PCB components ensuring our accuracy is at high level, but at a fraction of the cost.

If we integrate your OTDR module into our own monitoring system via software, can you provide the complete API/SDK?

Yes, we are highly supportive of system integration, and we offer a much more flexible solution than a standard SDK. We can provide our underlying TCP/IP communication protocol along with the 16-bit Hexadecimal (Hex) control command codes.
This means your developers can ignore any operating system dependencies or specific library constraints. Whether your monitoring system runs on Linux, Windows, or an embedded RTOS, your software can directly communicate with and control our OTDR hardware by sending standard network sockets. We will provide the protocol documentation detailing how to trigger a scan, set pulse widths, and retrieve the raw data stream.

If a software/firmware bug causes a critical error during a major telecom operators' acceptance test, how fast can your R&D team roll out a software/firmware patch? Do you have 24/7 technical support?

We treat critical field bugs with top priority. While we don't have 24/7 live call centers due to time zones, we have an Fast Response Protocol for Tier-1 Projects. If a critical bug is reported, our sales engineers will bridge you directly with our R&D software/firmware team within 12 hours. If verified as a firmware or software bug, we commit to delivering a customized beta patch/firmware update within 24 hours to ensure your acceptance test proceeds smoothly.

What is the dynamic range of your OTDR at an ultra-short pulse width like 3ns or 5ns? Don't tell me the 20µs max spec. I need to know the dynamic range for mapping micro-bends within a central office.

A very sharp question. Many suppliers hide this, but we prefer transparency. At a 3ns pulse width, our typical dynamic range is around 10dB to 15dB. This is achieved thanks to our high-frequency layout and optimized low-noise transimpedance amplifiers (TIA). It provides more than enough margin to clearly map out high-density patches and micro-bends within a 200 meter range in a Central Office, without getting drowned out by the noise floor that plagovs cheaper hardware.

At what precise temperature coefficient does your internal reference oscillator drift? If our field ambient temperature drops by 30°C within 4 hours, will the distance measurement accuracy (m) shift outside your stated formula?

That is an incredibly rigorous technical inquiry. Our time-base circuit relies on a temperature-compensated crystal oscillator, which has a stability temperature coefficient of ±1.5 ppm across our entire operating range of −10∘C to +50∘C. Even with a drastic 30∘C ambient drop, the maximum frequency drift remains well within the guard band of our distance calculation formula. The variance you experience will be negligible—far below the standard error introduced by the fiber's own Group Index (IOR) fluctuations due to temperature.

If two high-reflection events are separated by only 20cm, your event dead zone is 0.8m. How does your software interpret the overlapping reflection peaks? Will it show one merged event or can it apply a deconvolution algorithm to separate them?

Physically, at 20cm separation, the second reflection rides on the trailing edge of the first, falling inside our standard 0.8m event dead zone. On a standard trace, they merge into one fat peak. However, if our Advanced Deconvolution Algorithm is activated, the software treats the initial pulse shape as a known transfer function. It mathematically 'deconvolves' the overlapping electrical signals, analyzing the asymmetry of the peak. If the slope changes abruptly, the software recognizes the secondary inflection point and forces a split event, identifying two distinct reflections even. This feature will be included in our new OTDRs.

Your competitor's OTDR features a built-in Optical Spectrum Analyzer (OSA) module on the same handheld frame for checking DWDM channel power. If we choose your standalone OTDR, our technicians have to carry two separate devices. 

While an integrated OSA sounds high-tech, it introduces a severe high-risk point of failure for daily field deployment. A high-precision OSA grating is incredibly fragile and temperature-sensitive. Putting it in the same rugged handheld housing as a field OTDR means exposing a delicate laboratory-grade spectrometer to the harsh drops, vibrations, and dust of the trenches. If the OTDR port gets damaged, your expensive OSA is sidelined too. Our strategy of a dedicated high-performance OTDR paired with an ultra-portable CWDM Channel Tester provides the same operational efficiency, but with dual-device redundancy and a significantly lower replacement cost if a tool gets dropped in the field.