SM3 Datasheet, PDF (19/36 Pages) Connor-Winfield Corporation – ULTRA MINIATURE STRATUM 3 MODULE

Performance Specifications
Performance Definitions
Jitter and Wander – Jitter and wander are defined respectively as “the short-term and long-term variations of the significant instants
of a digital signal from their ideal positions in time”. They are therefore the phase or position in time modulations of a digital signal relative
to their ideal positions. These phase modulations can in turn be characterized in terms of their amplitude and frequency. Jitter is defined
as those phase variations at rates above 10Hz, and wander as those variations at rates below 10Hz.
Fractional frequency offset and drift – The fractional frequency offset of a clock is the ratio of the frequency error (from the nominal
or desired frequency) to the desired frequency. It is typically expressed as (n parts in 10^X), or (n x 10-^X). Drift is the measure of a clock’s
frequency offset over time. It is expressed the same way as offset.
Time Interval Error (TIE) – TIE is a measure of wander and is defined as the variation in the time delay of a given signal relative to an
ideal signal over a particular time period. It is typically measured in nS. TIE is set to zero at the start of a measurement, and thus
represents the phase change since the beginning of the measurement.
Maximum Time Interval Error (MTIE) – MTIE is a measurement of wander that finds the peak-to-peak variations in the time delay of
a signal for a given window of time, called the observation interval (t). Therefore it is the largest peak-to-peak TIE in any observation
interval of length t within the entire measurement window of TIE data. MTIE is therefore a useful measure of phase transients, maximum
wander and frequency offsets. MTIE increases monotonically with increasing observation interval.
Time Deviation (TDEV) – TDEV is a measurement of wander that characterizes the spectral content of phase noise. TDEV(t is the
RMS of filtered TIE, where the bandpass filter is centered on a frequency of 0.42/t.
SM3 Performance
Input Jitter Tolerance – Input jitter tolerance is the amount of jitter at its input a clock can tolerate before generating an indication of
improper operation. GR-1244 and ITU-813 requirements specify jitter amplitude v.s. jitter frequency for jitter tolerance. The SM3 device
provides jitter tolerance that meets the specified requirements.
Input Wander Tolerance – Input wander tolerance is the amount of wander at its input a clock can tolerate before generating an
indication of improper operation. GR-1244 and ITU-813 requirements specify input wander TDEV vs. Integration Time as shown below.
Integration Time, (seconds)
0.05 ≤ τ < 10
10 < τ < 1000
1000 ≤ τ
TDEV (ns)
100
31.6 x τ ^0.5
N/A
The SM3 device provides wander tolerance that meets these requirements.
Phase Transient Tolerance – GR-1244 specifies maximum reference input phase transients that a clock system must tolerate without
generating an indication of improper operation. The phase transient tolerance is specified in MTIE(nS) v.s. observation time from .001 to
100 seconds, as shown below.
Observation time S (Seconds)
0.001326 ≤S < 0.0164
0.0164 < S < 1.97
1.97 ≤ S
MTIE (ns)
61,000 x S
925 + 4600 x S
10,000
The SM3 will tolerate all reference input transients within the GR-1244 specification.
Free Run Frequency Accuracy – Free Run frequency accuracy is the maximum fractional frequency offset while in Free Run mode.
It is determined by the accuracy of the internal clock.
Hold Over Frequency Stability – Hold Over frequency stability is the maximum fractional frequency offset while in Hold Over mode.
It is determined by the stability of the internal clock.
Data Sheet #: TM052 Page 19 of 36 Rev: 03 Date: 11/07/08
© Copyright 2008 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice