Active Hydrogen Maser VCH-2021

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VCH-2021 is the first successful realization of hydrogen maser with a single state selection system. It demonstrates absolutely record frequency stability for active H-masers.
Best technologies including internal stand-alone Cavity Auto Tuning system are inherited from the previous model VCH-1003M.
New option: optical output with wavelengths 1310 nm and 1550 nm.

Key Applications:
– National Time Keeping Service.
– Deep space tracking and navigation.
– VLBI systems.
– GNSS satellite monitoring.


Factory test results

Polyakov V., Timofeev Y. and Demidov N., “Frequency Stability Improvement of an Active Hydrogen Maser with a Single-State Selection System,” 2021 Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium (EFTF/IFCS), 2021, pp. 1-4, doi: 10.1109/EFTF/IFCS52194.2021.9604270.

Specifications

Output signals:
– sine: 5 MHz; 10 MHz, 100 MHz, 1±0.2 V RMS into 50 Ohms;
– pulse: 1 Hz, Amplitude: >2.5 V into 50 Ohms, width: (15±5) µs.
Rise time <2ns, positive polarity;
– optical: wavelengths 1310 nm and 1550 nm, modulated by 100 MHz and 1 Hz signals, respectively; power of optical radiation (0.1-1) mW.

Metrological characteristics are given in the table:

Averaging time, τ Frequency stability (Allan deviation) 5 MHz, 10 MHz, 100 MHz
Standard Option L
3 Hz measuring bandwidth 0.5 Hz measuring bandwidth 3 Hz measuring bandwidth
1 s 1.0·10 -13 5.0·10 -14 7.0·10 -14
10 s 1.5·10 -14 0.9·10 -14 1.0·10 -14
100 s 3.0·10 -15 2.5·10 -15 2.5·10 -15
1000 s 1.0·10 -15 * 1.0·10 -15 * 1.0·10 -15 *
1 hour 8.0·10 -16 * 8.0·10 -16 * 8.0·10 -16 *
1 day 1.0·10 -16 * 1.0·10 -16 * 1.0·10 -16 *
* Specified only under laboratory conditions: ambient temperature in the range ±0.1 °С, changing rate <0.3 °C/hour. ADEV at 1 day is specified for measurements with removed linear frequency drift

Frequency drift is no more 2.0·10 -15 per day at release and no more 3.0·10 -16 per day after 1 year of continuous operation.
Temperature sensitivity: ≤1.5·10 -15 / °C.
Magnetic sensitivity: ≤ 5·10 -15 /Gauss.
Frequency trim range: 1·10 -10 .
Frequency setting resolution: 10 -16 . Manual synchronization to external 1 PPS TTL signal in the range: ±15 ns.

Phase noise (SSB Phase Noise, dBc/Hz):

Standard Option L
Offset from carrier 5 MHz 10 MHz 100 MHz 5 MHz 10 MHz 100 MHz
1 Hz ≤−118 ≤−112 ≤−92 ≤−130 ≤−121 ≤−100
10 Hz ≤−135 ≤−129 ≤−109 ≤−148 ≤−135 ≤−115
100 Hz ≤−149 ≤−143 ≤−122 ≤−151 ≤−145 ≤−125
1 kHz ≤−156 ≤−149 ≤−122 ≤−158 ≤−150 ≤−130
10 kHz ≤−158 ≤−153 ≤−153 ≤−158 ≤−153 ≤−153
100 kHz ≤−158 ≤−153 ≤−153 ≤−158 ≤−153 ≤−153

Harmonic distortion: ≤−40 dBc (for 5 MHz output).
Non-harmonic distortion: <−100 dBc in the range from 10 Hz to 10 kHz.

Full data monitoring and functions control. Application software running under Microsoft Windows and Linux.

Operating temperature range: 10…30 °C.
Storage temperature range: −30…50 °C.
Power supply: AC(85÷264)V, (49÷51)Hz; DC(24÷27)V.
Power consumption: 150 V·A (AC), 100 W (DC).
Weight: <115 kg.
Weight in shipping container: <200 kg.
Dimensions (W×H×D): 445×950×625mm.
Warranty: 3 years (7 years extended).
Lifetime: 15 years.