Fiber-optic modem VCH-608 is designed for receiving and transmitting signals of atomic clocks through a fiber optic communication line (FOCL).
The signals are:
− 1 PPS with delay compensation can be shifted with 100ps step;
− sine 5, 10, 100 MHz with phase instability compensation.
Reception/transmission of high precision signals via the FOCL is provided using a pair of modems: one is configured as a Transmitter and installed at the end of the FOCL where the signal source is located, the second – as a Receiver and installed at the opposite end of the FOCL. To extend the distance, modified VCH-608 can be used as repeators. One, two or four fibers can be used for time and frequency transfer, depending on modem modification.
Key applications:
− metrology;
− time scale comparison systems;
− production and testing of high precision oscillators and devices based on them;
− scientific research.
Specifications
The optical characteristics of the modem correspond to Class 1 of laser safety, according to IEC 60825-2-2013.
The permissible loss of optical power in the FOCL between modems is 25 dB (corresponds to the length of the optical fiber 70 – 110 km).
The type of optical connectors is FC/APC.
Input electrical signals:
− sinusoidal: 5, 10, 100 MHz, root mean square (RMS) voltage value — (1 ± 0.2) V at a load of 50 Ω;
− pulse: 1 PPS, amplitude ≥ 2.5 V at a load of 50 Ω, pulse duration — (15 ± 5) microseconds, front duration < 3 ns, polarity – positive.
Output electrical signals:
− sinusoidal: 5 MHz, 10 MHz, 2.048 MHz, 100 MHz, RMS voltage value — (1 ± 0.2) V at a load of 50 Ω;
− pulse: 1PPS, amplitude ≥ 2.5 V at a load of 50 Ω, pulse duration — (15 ± 5) microseconds, front duration < 3 ns, polarity – positive.
Metrological characteristics
| Averaging time, τ | Allan deviation noise floor |
|---|---|
| 1 s | 8.0∙10 −14 |
| 10 s | 1.0∙10 −14 |
| 100 s | 2.0∙10 −15 |
| 1 hour | 1.0∙10 −16 |
The error of synchronization when transmitting 1 PPS time signal is no more than 200 ps.
Dimensions (H×W×D) – 140×483×328 mm.
