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What needs
Splitter in ADSL for?
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Splitter
is LPF(Low Pass Filter). Namely, LPF rejects the data
signal of high frequency and passes the voice signal
of low frequency.
When a mixture of PSTN(Public Switched Telephone Network)
Signal and ADSL Data Signal comes to CP(Customer Premises)
through the Subscriber line by ADSL Equipment, the signals
are mixed. So it requires a special equipment which
splits these two signals .
Though a human's audio frequency range is 20KHz, the
data signal of more than 30KHz does not harm to her
or his ears but while the data signal arrives at the
ears over the phone at the same time, it affects a physical
handicap such as a ringing in the ears.
Also, although the voice signal of ADSL Modem is low
frequency, while it is mixed with the data signal, the
baud rate is plummeted with data errors occurred. And
the ON/OFF HOOK and ringing signal of a phone are corrupted.
Therefore, Splitter is indispensible to prevent these
harms.
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What is the difference
between Splitter and Micro Filter?
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| Splitter is two kinds
of for CP or CO use as the device which uses Full
DMT(download speed: 8Mbps) method. Characteristic
Impedance is three kinds of north America type, Europe
type and Japan type. According to Characteristic Impedance,
it has a little different electrical feature, and
also Attenuation
should be less than -65dB at about 30KHz which is
the start point of ADSL.
Micro Filter is for CP use as the device which uses
G.Lite(Download speed: 1.5Mbps) method. Like Splitter,
according to Characteristic Impedance it has three
kinds of north America type, Europe type and Japan
type. General Attenuation should be less than -15dB
at about 25KHz which is the start point of UADSL.
Micro Filter is recommended to use on UADSL which
is download speed of about 1.5Mbps, and designed as
the "Splitterless" thing at the first time.
However, because of the ring signal, the noise of
a telephone call, the disconnection of data transmission,
finally Micro Filter was used. In addition, it is
being used for CP in the method of Full DMT with the
trend of the modern world.
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Is Splitter different
each country?
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country has the different Characteristic Impedance
of PSTN.
For example, we can not use Korean Splitter in Japan.
Because Korean Characteristic Impedance is 600§Ù and
Japan Characteristic Impedance is 150§Ù+(72nF//(830§Ù+1uF)).
Of course, we can use it in any other countries which
has the same Characteristic Impedance.
ITU-T standardizes four types of Characteristic Impedance,
G.992.1(Full DMT) type 1 Zcomplex(n) for Europe, type
2 for North America, type 3 for ISDN and type 4 for
Japan.
Namely, the North America type is 600§Ù and 900§Ù,
the Europe type is Complex(1):270§Ù+(750§Ù//150nF),
Complex(2) : 320§Ù+(1050§Ù//230nF), Complex(3) : 220§Ù+(820§Ù//115nF)
and 600§Ù.
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What kinds
of International Standard related to ADSL Splitter are
they ?
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| The typical
International Standard is ANSI T1.413 for North America,
ETSI 101 728 and ITU-T G.992.1 for Europe. It is a
little difference each country, but the base of specification
follows in accordance with the previous three standard.
ETSI 101 728 standardizes the base specification
of ADSL Splitter for each country in Europe. ITU-T
G.992.1 was established by the specification of ANSI
T1.413 and also is classified into three types, Europe,
North America, Japan.
ANSI : American National Standards Institute
ITU-T : International Telecommunications Union - Telecommunication
Standardization Sector
ETSI : European Telecommunications Standards Institute
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What is
PAM, LNA and DRA?
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| PAM
(Power Amplifier Module)
PA uses a specific chip or module because it is noise
source to have high thermal nature, integrated with
other elements.
PAM is module chip which makes to integrate MMIC
Die, In/Out Matching and Basic Bias Elements above
chip. There is not only MMIC Barechip in the package,
but also when it mounts Microstrip and LC elements
in system, we can use it if it has power supply and
a few elements without sophisticated matching process.
It generally called PAM, PA module which is mounted
in system.
LNA (Low Noise Amplifier)
An electric power received by RF Receiver has very
low power level because of Distortion and Noise. So
an amplifier needs amplification function which minimizes
the noise because the signal includes many noise components
from the outside.
LNA is designed to control operating point and matching
point, also it needs 1.5 ¡ 2.5 the value of NF(Noise
Figure).
Low noise amplifier should use the minimum of current
and temperature noise elements, which transistors
and registors have low NF. At the same time it must
get the maximum gain with Conjugation Matching.
DRA (Drive Amplifier, Driving
Amplifier)
Power Amplifier should send the high power signal
which is transmitted by the antenna at the Final-End.
Though it can not satisfy both of Gain and Power because
of Amplifier's feature, Amplifier can perform the
better result if either Gain or Power is concentrated
on. Especially, it is difficult to make high Gain
with high Power. But some case, transmitter needs
high Power and high Gain at the same time.
So the special Amplfier which has high Gain should
pull from back to operate PA. Finally, the Amplfier
of the Tx Final-End consists of the integration of
DA-PA.
Since DA is used with PA, it is standardized and
made with PA.
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