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參數(shù)資料
| 型號(hào)： | MT8972 |
| 廠商： | Mitel Networks Corporation |
| 英文描述： | () |
| 中文描述： | （） |
| 文件頁數(shù)： | 1/5頁 |
| 文件大?。?/td> | 27K |
| 代理商： | MT8972 |
A-1
These are some of the questions that have been
frequently asked regarding the DNIC and associated
technological implications.
1. What is the line code and transmit signal
level
The line code used is biphase with differential
encoding. The amplitude of the signal on the line is
1.2 V
p-p
±3%. Assuming a line termination of 120
ohms, this corresponds to a transmit power level of
+1.0 dBm.
2. What does the Power Spectral Density graph
of the transmitted line look like
The spectral density graph shows a peak response
of -24dBV at 0.75fb. This would be at 120 kHz when
transmitting at 160 kHz, and 60 kHz when using 80
KHz. There are zeros at 0, and 2fb. The secondary
lobes have at least 36dB additional attenuation
relative to the spectral peak.
3. What is the maximum line length the DNIC
can operate over
The maximum line length of the DNIC is a function of
the type of cable that is used. Gauge as well as
composition affects the loop length achievable. A
more reliable means of specifying range is by using
allowable dB of attenuation. In this way one value
can be specified, and from this value the achievable
range over the various loop configurations can be
derived. The DNIC is capable of handling typically 40
dB of total attenuation. This corresponds to 34 dB of
cable attenuation, and 6 dB loss in the termination
impedance. From transmission theory for line
attenuation, this works out to a limit in excess of 4
km on 24 AWG for 160 kHz operation.
4. What is the limiting factor in the loop range
specification
The maximum loop length of the DNIC is limited by
the signal attenuation and noise on the line. The
calculation is done by dividing the total tolerable line
attenuation (in dB), by the attenuation factor for each
gauge
of
wire
and
interference (ISI) can also be the limiting factor in
certain loop configurations. Near end crosstalk
(NEXT) is thought of as being the limiting factor for
frequency.
Intersymbol
echo-cancelling schemes as a whole. The loop
range is further limited by the characteristics of the
line. Bridged taps, noise, and severe impedance
mismatches can result in a shorter range.
5. What are the associated signal noise ratios
and error rate figures for the listed specs
The SNR is a measure of the receiver tolerance. This
value is also a function of the data transmission rate
and loop length. At 160 kbit/s transmission on 24
AWG, the DNIC has a SNR of better than 10 dB for
any loop length between 500 metres and 2 km. This
is for a BER of 10
-6.
6. What does "Channel Quality" in the transmit
C-channel indicate
The channel quality gives an indication of the relative
signal to noise ratio. The two bits in the transmitted
C-channel allow for four possible values of channel
quality. The further the value is away from 0, the
higher is the SNR (i.e., the better the performance).
The actual value cannot be directly translated into an
equivalent SNR, but rather it only provides a
qualitative measurement of transmission quality.
7. What does the ”ATTACK“ feature do
The ATTACK feature allows for faster convergence of
the echo canceller RAM when powering up. Instead
of incrementing / decrementing the LSB of a
particular RAM value, ATTACK disables several least
significant bits, making the effective step size of the
echo canceller larger.
8. What is the convergence time of the echo
canceller without "ATTACK" ..with "ATTACK"
Under normal operating conditions, the ATTACK
feature is disabled except for power up. At power up
ATTACK is turned on for a certain specified period of
time, then it is deactivated, letting the RAM converge
normally.
ISSUE 3
October 1989
MSAS-42
MT8972 DNIC Questions and Answers
ISO-CMOS ST-BUS
FAMILY
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MT8976 | Ultraframer DS3/E3/DS2/E2/DS1/E1/DS0 |
| MT8976 | Ultraframer DS3/E3/DS2/E2/DS1/E1/DS0 |
| MT8976AC | Ultraframer DS3/E3/DS2/E2/DS1/E1/DS0 |
| MT8976AE | Ultraframer DS3/E3/DS2/E2/DS1/E1/DS0 |
| MT8976AP | Ultraframer DS3/E3/DS2/E2/DS1/E1/DS0 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MT8972B | 制造商:MITEL 制造商全稱:Mitel Networks Corporation 功能描述:ISO2-CMOS ST-BUS⑩ FAMILY Digital Subscriber Interface Circuit Digital Network Interface Circuit |
| MT8972BC | 制造商:MITEL 制造商全稱:Mitel Networks Corporation 功能描述:ISO2-CMOS ST-BUS⑩ FAMILY Digital Subscriber Interface Circuit Digital Network Interface Circuit |
| MT8972BE | 制造商:MITEL 制造商全稱:Mitel Networks Corporation 功能描述:ISO2-CMOS ST-BUS⑩ FAMILY Digital Subscriber Interface Circuit Digital Network Interface Circuit |
| MT8972BP | 制造商:MITEL 制造商全稱:Mitel Networks Corporation 功能描述:ISO2-CMOS ST-BUS⑩ FAMILY Digital Subscriber Interface Circuit Digital Network Interface Circuit |
| MT8976 | 制造商:MITEL 制造商全稱:Mitel Networks Corporation 功能描述:ISO-CMOS ST-BUS⑩ FAMILY T1/ESF Framer Circuit |
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