The Generator is designed to provide pulses with preset attenuation levels and time intervals between them. Used for verification of Optical Time Domain Reflectometers (OTDR).


The Generator principle of operation is based on optical pulse generation with the preset attenuation and time intervals between them which are measured by OTDR.

The Generator comprises a Mainframe and three Built-in Units operating at different wavelengths. In the external triggering mode the Generator is used to test pulse Reflectometers. The external triggering mode is performed in the following manner:

the probing pulse of the Reflectometer under test applied through directional optical coupler and a 20 dB attenuator is fed to optico-electric converter. The fixed attenuator is used to match the Reflectometer pulse power (in the range from 15 to 20 dB) with operating power range of the opto-electronic converter (from –35 to 0 dBm). Further the electric pulse triggers the control circuitry which in a preset time forms two electrical pulses with a preset width and delay between them.

Electrical pulses are applied to the electro-optical converter where they are converted into optical pulses which passing through step and additional attenuators and an optical coupler are returned to a Reflectometer. The attenuators are used to change the reflected pulse amplitude. Two pulses reflectogram is displayed on a Reflectometer screen. Then the distance to the 1st pulse front, the distance between front and the attenuation at the pulse peak are measured in different points of the Reflectometer range. The obtained results are compared to the values calculated from the Generator time delays.

In the interval triggering mode the Generator operates in the same manner but the count down of the 1st pulse delay in a new generation cycle begins from the 2nd pulse decay. So in such a way pulse pair is generated without external triggering.

In the non-modulated optical emission mode the Generator is used as a regulated optical emission power source.

The Generator is equipped with standard «FC-PC» fiber-optic connectors.


Operating wavelengths: 0.85±0.05, 1.31±0.05, 1.55±0.05 mm

Repeatable distances range: 10–5·105 m

Repeatable distance absolute error: ±(0.2+10–5 L), where L – repeatable distance in m

Repeatable attenuation range: 0–25 dB

Basic permissible absolute error of the attenuation repeatability in the 0–25 dB: 0.02А, where A – repeatable attenuation in dB


Operating temperature range: 10–35 °С

Relative humidity at 30 °С: up to 90 %

Power: 220±22 V, 50±1 Hz

Power consumption: not more than 80 VA

Dimensions: 368x392x130 mm

Weight: 15 kg