CPF107J データシートの表示（PDF） - YCL Electronics

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CPF107J

Asymmetric Digital Subscriber Line, POTS Splitter For ADSL CPE side

YCL Electronics  

Product Specification

4.6.2. Return loss for POTS splitter:

CPF107J

The Return Loss is measure of the driving point impedance variation introduced by the

filter, variation of the driving point impedance of the loop can affect POTS performance by

changing the sidetone balance of a telephone instrument or the front-end hybrid balance

of voiceband modem. Return loss measure the amount of energy that is lost due to

reflection which resulted from impedance mismatching at the interface. Return loss is

essentially defined as the ratio of the power incident upon a given transmission system to

the power reflected caused by impedance mismatch with respect to reference impedance

at the interface between source and device.

Return loss figure are a function of the impedance of the circuit involved and are therefore

frequency dependent.These impedance must be closely maintained in order to reduce the

possibility of undesirable reflection and echoes which in long distance circuit the

telephone user or destroy the data being sent.To perform the return loss test ,open ,short,

load calibration must be done prior measurement while the LCZ impedance Analyzer

being selected in impedance mode. Return loss is general expressed in decibels. General

Return loss equation as below :

Return loss = 20 log ZNL-r* - ZM / ZNL-r + ZMdB

Where ZNL-r = the reference impedance ZM = the measured impedance

The test setup is shown in drawing below:

Figure 2

Remote POTS Splitter

ZNL-r

LPF

Test Equipment

xDSL ZHP-r

ZNL-r

1: ZNL – r= 150 ohm + ( 72nF //(830ohms + 1uF))

2: ZHP-r is the impedance presented to the POTS connection by an ATU-R.

Data sheet subject to change without notice

RDPS-POTS415(R1)09/19/2002

SHEET 8 OF 10

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