78P2351-DB/CMI Maxim Integrated Products, 78P2351-DB/CMI Datasheet - Page 13

• Manufacturer Part Number: 78P2351-DB/CMI
• Description: BOARD DEMO 78P2351 COAX CABLE
• Manufacturer: Maxim Integrated Products

Specifications of 78P2351-DB/CMI

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Design Guidelines for TERIDIAN 78P235x LIUs
SAMPLE TRANSMIT PULSE SHAPE RESULTS
There are generally two methods for specifying and measuring the transmit pulse signal integrity. Pulse Mask
Templates originate from ITU-T G.703 and Eye Diagrams originate from ANSI T1-102. Telcordia GR-253-CORE
refers to both and provides a better description on how to use the eye diagrams.
Pulse Template
The Pulse Template specifies the characteristics of singular pulses. It defines the precise shape of the pulse
including rise time, fall time, amplitude and overshoot. It takes into account the affect of inter-symbol interference
from successive pulses and reflection from improper terminations.
To perform pulse template measurements, the oscilloscope must be able to isolate the pulse under evaluation, be
it binary 1 or 0. The Tektronics TDS 784 is one oscilloscope that has the ability to trigger on CMI signals,
capturing only the pulses of interest. The signal can be acquired using average or sample mode depending on the
parameters to be evaluated. Average mode provides the clearest indication of pulse shape and allows
measurement of continuous anomalies such as reflection and inter-symbol interference. Sample mode will
provide information on spurious signal noise and occasional violations of the pulse template. As noted in G.703, it
is important to eliminate the effects of low frequency jitter or wander when making pulse mask measurements.
Therefore it is not recommended to use long persistent acquisition methods (DPO) for performing pulse template
measurements.
Instrumentation Variations
These measurements were taken on the Tektronics TDS 784D oscilloscope. Generally auto set will properly
select the proper acquisition method and set time and voltage scales. However, often these settings come up
incorrect and will need to be adjusted. Different scopes will default to different acquisition modes depending on
model. It is important to carefully monitor all scope settings when performing pulse shape measurements.
 2008 Teridian Semiconductor Corp.
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