SM34 Data Sheet #:

TM095

Page 20

Rev:

05 Date: 11/19/12

© Copyright 2012 The Connor-Winfield Corp. All Rights Reserved

Specifications subject to change without notice

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

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.

SM34 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 SM34

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 v.s. integration time as shown below.

Integration Time, (seconds)

TDEV (ns)

0.05

≤

100

10<

31.6x

1000

≤

N/A

The SM34 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)

MTIE (ns)

0.001326

≤S<0.0164

61,000xS

0.0164<S<1.97

925+4600xS

1.97

≤S

10,000

The SM34 will tolerate all reference input transients within the GR-1244 specification.

Free-run Frequency Accuracy – The ability of a clock to produce a frequency as close as possible to the nominal frequency in

the absence of a reference.

Hold Over Frequency Stability – A measure of a clock’s performance while in Hold Over mode over 24 hours, subjected to the

specified temperature variations.

Performance Specifications