Overview
GL’s Universal T1 E1 Cards have pulse shape measurement capability. Software has been developed to determine if the pulse shape
fits within a “pulse mask” as specified by standards ITU G.703 and ANSI T1.102-1993. The software is available in both visual and tabular
formats. Tabular formats are convenient for automation and scripted test environments.
It is quite common for T1 E1 signals, within a central office environment or an enterprise telecom room, to NOT meet pulse mask
requirements due to interference, too long or short cable lengths, improper impedances, or simply poor transmitter design. In such cases,
pulse mask compliance is very useful in diagnosing problems.
Background
In T1 E1 transmission systems, signals are dropped, inserted, and accessed at the electrical level at a point called DSX patch panel or
at some similar point. To reliably receive, monitor, or access these signals, they must first conform to a standard that establishes parameters
such as pulse width, rise time, amplitude, allowable undershoot and overshoot. If the pulse meets the pulse mask, then a properly designed
receiver should be able to decode the bits transmitted. See diagram below.
Main Features
- Plots the pulse measured within a predefined template.
- Compares the incoming T1/E1 pulses against the pulse mask display.
- For T1 pulses, the x-axis measures time in unit intervals (UI), while for E1 pulse, the x-axis measures time in nanoseconds (ns),
- The y-axis measures the normalized amplitude in volts.
Operation
T1 Pulse Mask
The transmit data path is selected and measured at the end of the transmission line for each T1 line. The specification for T1 requires
that the T1 signal must fit within the pulse mask at the end of the line when transmitting an isolated pulse. Regardless of the way the T1
device is configured. The amplitude of the isolated signal at time zero should be within 20% of 3.0 volts. If the amplitude requirement is met,
then the signal is scaled linearly to determine if it fits the pulse mask.
Plots a pulse against the mask, with the pulse mask x-axis measures time in unit intervals (UI), where 1UI is the nominal time to transmit
one T1 bit - 648ns. The y-axis measures pulse voltage in normalized amplitude: the pulse voltage is scaled to fit the mask.
E1 Pulse Mask
The specification for E1 requires that all the pulses meet the template and not just an isolated pulse. Another difference is the fact that that
pulses are measured at transmitter output, rather than after some length of cable, while T1 pulses must meet the template for the entire line length.
There are two types of cables used in E1 mode: 75 Ohm coax cable and a 120 Ohm twisted pair. Both cables have different nominal amplitudes
associated with them. For the 75 Ohm coax cable, the amplitude must be 2.37V ± 10% at T0. For the 120 Ohm twisted pair, the amplitude must be
3.0V ± 10%.
WCS Pulse Mask
The Pulse Mask compliance testing can be performed through commands with the Windows Client-Server application. The pulse mask can be
remotely controlled using simple commands by client applications. Some of the commands supported are CheckPulseMask, validate pulse, stop
pulse mask validation, and others.
For complete information, click here to visit WCS Pulse Mask web page.
Buyer's Guide
Please Note: The XX in the Item No. refers to the hardware platform, listed at the bottom of the Buyer's
Guide, which the software will be running on. Therefore, XX can either be HDT, HDE, HUT, HUE, UTA or UEA depending
upon the hardware.
| Item No. |
Item Description |
| XX012 |
Pulse Shape and Jitter Measurement
Easy, accurate, visual
pulse shape and jitter measurement for T1 E1 signals |
| |
|
| |
Related Hardware |
| HTE001 |
Universal T1/E1 Card |
