| |
|
|
| |
 |
What needs Splitter
in ADSL for?
|
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.
|
|
|
What is the difference between
Splitter and Micro Filter?
|
|
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.
|
|
|
Is Splitter different each
country?
|
|
Each 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.
|
|
|
What kinds of
International Standard related to ADSL Splitter are they ?
|
|
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
|
|
|
|
|
What is PAM, LNA
and DRA?
|
|
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.
|
|
| |
|
|
