Designed to measure relative frequency deviation of 5 and 10 MHz signals under test from 5 MHz reference signal.

Mathematical processing allows to determine and display relative systematic frequency variation, rms frequency difference, rms relative frequency deviation, rms relative two sample frequency deviation.

The Comparator measures time shift of external or auxiliary time scales in relation to the main time scale; forms 1 and 10 MHz signals from a reference 5 MHz signal; main and auxiliary (delayed) time scales signals with a pulse repetition rate of 1 s; displays current time in hours, minutes and seconds.


5 or 10 MHz external signal frequency deviation in relation to 5 MHz reference signal is based on measurement of pulse width produced by a relative frequency difference multiplier. The duration (T) is connected with a relative frequency deviation (Df/f0) with a relation:

T=To(1 ±k ·Δf/f0)

where To – time interval set (1, 10 or 100 s), k=104 – multiplication factor of the relative frequency difference multiplier.

The main time scale formation is based on division of a high stability signal

(10 MHz to 1 Hz) using a 7-decade frequency divider. The Instrument uses a digital method of the delayed time scale formation using code comparators.

The Instrument provides measurement results and current time transmission over

the IEC 625 interface bus.

Together with the CH1-81/2, CH1-81/3 Standards the CHK7-51 Frequency Comparator forms the CH1-82/2 Time and Frequency Standards respectively. The CH1-81 is powered directly from the CHK7-51.


rms relative frequency deviation measurement accuracy:

1 s: < 1.10–11

10; 100 s: < 1.10–12

External and delayed time scale shift measurement accuracy in relation

to the main time scale: not more than ±0.1 µs

Main and delayed time scale signal delay measurement range:

0–999999.9 µs with 0.1±0.05 µs step

Time scale to external time scale synchronization accuracy: not more than ±0.1 ms


Operating temperature range: 0–50 °C

Relative humidity: up to 98 % at 25 °C

Power: 220±22 V, 50±1 Hz; 220±11 V, 400 ±10 Hz; 22–30 V

Power consumption: 40 VA

Dimensions: 459x308x129 mm

Weight: 10 kg