The Passive Hydrogen Maser is a compact hydrogen maser with excellent frequency stability and utilises state-of-the-art technology. Full digital processing of the modulation and servo loop signals makes it ideal for high accuracy applications. An internal GPS/GLONASS option is available and provides automatic output signal frequency calibration.

Key applications:
– National Time Keeping Service
– Space tracking and navigation
– Verification of frequency signals
– Scientific research


Output signals:
Sine: 5 MHz; 10 MHz; 100 MHz, (1±0.2) V RMS into 50 Ω load.
Pulse: 2,048 MHz (square pulse), 1,5÷2,8 V (pp) into 75 Ω (ITU-T G.703 part13).
1Hz; 1/60 Hz, positive polarity pulse, width 10±0.1 μs, TTL level at 50 Ω, rise time: <10 ns.

Metrological characteristics are given in the table:

Relative frequency accuracy±3×10−13
(factory calibration)
(in option with GPS calibrator)
Output signals frequency correctorresolution
retuning range
Frequency stability
(Allan deviation at 25±1C°, environmental
effects are excluded)
1 s≤5.0×10−13
10 s≤2.0×10−13
100 s≤5.0×10−14
1 hour≤9.0×10−15
1 day≤4.0×10−15
Phase noise spectral density (dBc/Hz)
(5 MHz output)
Frequency offsetSpectral density (dBc/Hz)
1 Hz≤−105
10 Hz≤−130
100 Hz≤−145
1000 Hz≤−155
Manual synchronization to external 1 pps
TTL signal accuracy
≤±25 ns
Time synchronization to UTC using GPS≤±50 ns (using optional GPS calibrator)
Temperature sensitivity in temperature operating range
(10−35 C°)
≤±1×10−14 1/C°
Magnetic sensitivity≤±2×10−14 1/Oersted

Digital control and monitoring: all operating parameters on local LCD display, or also available remotely.
Interface: RS-232C; USB; LAN.
Power supply: 100–240 V AC, 50–60 Hz, or 22–30 VDC.
Power consumption: 120 VA AC, 100 W DC.
Options: 1. DC power supply 38.4–57.6 V (two inputs); 2. Internal battery for autonomous operation; 3. Internal GPS calibrator for automatic calibration.
Dimensions (W×H×D): 470 mm×200 mm×530 mm.
Weight: 33 kg.
Warranty: 3 years.
Life time: 15 years.