What is the function of OTDR launch cable box？

In the construction and maintenance of optical communication networks, the testing accuracy of fiber optic links directly determines the reliability and stability of the network. Traditional OTDR (Optical Time Domain Reflectometer) can generate testing blind spots ranging from tens to hundreds of meters due to strong reflection signals (such as connector end faces and fusion points) and pulse widths during the testing process, resulting in inaccurate capture of information such as near end fiber losses and events. OTDR launch cable box, as a professional testing equipment, transfers the testing blind spot to a controllable range by connecting a specific length and low loss optical fiber, ensuring the authenticity and reliability of the test results of the tested link.

What is OTDR launch cable box?

To understand it, one must first understand an inherent challenge in OTDR testing: blind spots.

Blind spot: When the powerful optical pulse emitted by OTDR first enters the fiber optic cable, the receiver will be "blinded" and take some time to recover. Within this distance (event blind spots and attenuation blind spots), OTDR cannot accurately identify and measure fiber events (such as connectors and fusion points).

Solution:

OTDR testing launch cable box (also known as false fiber box) is an auxiliary equipment designed specifically for OTDR testing. Its core function is to connect an launch cable fiber between the OTDR and the tested fiber. The OTDR launch cable box is a high-quality fiber of known length and performance (usually 1-3 kilometers) wound in a box. Limit the blind spots caused by strong reflection in OTDR within the launch cable line range to avoid affecting the testing accuracy of the tested link.

Technical Specifications:

Fiber type: Supports single-mode (9/125 μ m), multi-mode (62.5/125 μ m, 50/125 μ m, OM3, OM4)

Length range: Standard length 500m, 1km, 2km, customizable (up to 5km)

Connector types: SC/UPC, SC/APC, FC/UPC, LC/UPC, etc., compatible with different device interfaces

Loss index: Single mode ≤ 0.5dB/km, multi-mode ≤ 3.5dB/km

Environmental adaptability: Operating temperature range of -40 ℃ to+85 ℃, waterproof, dustproof and explosion-proof, suitable for field operations

Box/Disc Design: The mainstream products adopt a box structure, which is compact in size (such as 250x15x65mm) and lightweight (about 0.75kg)

How does it operate?

The operation of OTDR launch cable box is based on the principle of optical reflection and loss compensation, and its core steps are as follows:

1. Connect the launch cable cable and transfer blind spots

The optical pulse emitted by OTDR first enters the optical fiber inside the launch cable box. Due to the lack of a direct fusion point between the launch cable cable and the tested fiber, strong reflected signals (such as connector end faces) only affect the launch cable cable portion and will not mask the near end events of the tested link.

2. Loss compensation to ensure accurate data

The loss of launch cable fiber optic cables must be strictly controlled within the standard range. OTDR automatically deducts the loss of the launch cable line through a built-in algorithm, and finally displays the actual loss value of the tested link.

Computational logic:

Total test loss=measured link loss+launch cable line loss

OTDR display value=total test loss - launch cable line loss

3. Standardized operating procedures

Connect the device: Connect the output port of the OTDR to the input port of the launch cable box, and connect the output port of the launch cable box to the measured optical fiber.

Set parameters: Enter the launch cable cable length and type (single-mode/multi-mode) in OTDR, and the device will automatically compensate for losses.

Start test: emit light pulses, OTDR records the reflected signal and generates a test curve.

Analysis results: Check key data such as fusion point loss and event point location of the tested link.

Why must it be used?

1. Eliminate blind spots and improve testing accuracy

The limitations of traditional OTDR: During direct testing, events such as fusion points and micro bends within tens of meters of the near end may be masked by blind spots, leading to misjudgments.

The effect of the launch cable box: blind spots are transferred to the end of the launch cable line, and the near end event detection rate of the tested link reaches 100%.

2. Protect OTDR:

By reducing backward reflection, the transmission cable box can protect the OTDR receiver from potential damage. High power reflection can overload the optical components of OTDR, thereby affecting its performance and accuracy. The transmission cable box serves as a protective barrier, allowing the OTDR to maintain its optimal working condition for a longer period of time.

3. Complies with industry standards:

Multinational telecommunications standards (such as ITU-T G.650) explicitly require the use of launch cable boxes for critical link testing to ensure consistency and reliability of OTDR measurements.

4. Assist in troubleshooting:

Accurate and reliable measurements are crucial in diagnosing fiber optic network faults. The launch cable box assists in troubleshooting by providing accurate data, enabling technicians to efficiently identify and solve problems.

Conclusion

The OTDR launch cable box solves the blind spot problem in fiber optic testing through technical means. Its low loss design, standardized operation, and wide adaptability make it an indispensable testing equipment in the field of optical communication. Whether it is telecommunications infrastructure, data centers, or fiber optic network deployment in smart cities, choosing OTDR launch cable boxes means choosing more efficient testing processes, more reliable link quality, and lower operational risks.

The stability of communication begins with every precise test.

Consult now to obtain ZG Technology OTDR launch cable box technology solution!