Product Specification
CPF105C
Data sheet subject to change without notice
RDPS-POTS328(R2)08/12/2002
SHEET 7 OF 10
4.5 . Test method :
4.5.1. Insertion loss :
The insertion loss of a device connected into a given transmission system is defined as
the ratio, expressed in dB, of the load power available(before and after insertion)
delivered to the output network beyond the point of insertion at a given frequency.In
general , the insertion loss of a device inserted in a given transmission system mainly
caused by internal component resistive loss while all of the impedance between source ,
load and device interface having been matched. To perform the insertion loss
measurement ,thru calibration must be done prior the testing . General Insertion loss
equation can be expressed as following
Insertion loss = 20 log
V1 / V2 dB where
V1 = the measured voltage value of load without LPF in circuit.
V2 = the measured voltage value of load with LPF in circuit.
The test setup is shown in drawing below. :
4.5.2. Return loss :
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
Z
L + ZM / ZL - ZMdB
Where Z
L = the reference impedance
Z
M = the measured impedance
The test setup is shown in drawing below:
Z
M
phone
LPF
LCZ meter
600ohms
line
600
Ω
Low pass
filter
ZHP-r
600
Ω
Phone
Line
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