SR625 Frequency Counter with Rb Timebase0 pages

Frequency Counters
SR625 — Frequency counter with rubidium timebase

SR625 Time Interval & Frequency Counter
· Rubidium atomic timebase
· 2 GHz prescaler input
· 11-digit frequency resolution (1 s)
· 10 minute warm-up period
· 10 MHz Rb timebase output
· Statistical analysis & Allan variance
· Hardcopy to printers and plotters
· GPIB and RS-232 interfaces

The SR625 Frequency Counter is a NIST traceable frequency
counting standard for calibrating base stations, transmitters
and many other types of communication systems. It combines
the high resolution and wide variety of features found in the
SR620 counter with the atomic accuracy of a rubidium timebase.
Low Drift, High Accuracy
The SR625 Frequency Counter consists of a frequency counter
(SR620), a high-accuracy rubidium timebase (PRS10), and a
2 GHz input prescaler. The combination of the SR620 and the
prescaler allows direct frequency measurements up to 2 GHz,
with twelve digits of resolution in a 100 s measurement.
The rubidium timebase ensures excellent short-term
stability (<2 × 10–11 Allan variance (1 s)) and long-term drift
(<5 × 10–11/month).
Simple, Portable Operation

· SR625 ... $6,950 (U.S. list)

The SR625’s warmup time is less than ten minutes, making
it ideal for field applications. An additional back-panel output
provides a rubidium stabilized 10 MHz signal which can
be used to drive other test equipment (e.g., synthesizers or
spectrum analyzers). The standard GPIB and RS-232 interfaces
allow for complete control and data acquisition from any
laboratory computer. The SR625’s performance makes it the
standard for remote applications or laboratory calibration.

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