- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄383641 > MT884 (Mitel Networks Corporation) () PDF資料下載
參數(shù)資料
| 型號： | MT884 |
| 廠商： | Mitel Networks Corporation |
| 英文描述： | () |
| 中文描述： | （） |
| 文件頁數(shù)： | 2/11頁 |
| 文件大?。?/td> | 87K |
| 代理商： | MT884 |
MSAN-144
Application Note
A-230
Applications
Caller
applications. For example, an insurance company
could display all the relevant information about a
client's policies even before the phone is answered,
which would save time for both the company and the
customer. A hospital might use this capability to
bring up a patient's medical records when they call
in. A mail order company could display the buying
record of a customer and be ready to conduct
business by the time the first word is spoken.
ID
technology
has
many
commercial
There are many CID implementations. The chip can
be used in a small stand-alone unit (with an LCD)
connected to the line, or it can be built into a
telephone set. It can be used in a computer or on a
trunk card in a PBX. There is a growing interest in
CID from the companies that are designing the next
generation of answering machines.
The answering machine companies want to be able
to identify and record the number of callers who
hung up without leaving a message. In addition,
answering machine users want to be able to program
certain numbers that the user doesn't want to talk to
so that these calls can be sent directly to the
answering machine for recording and later reply.
CID technology will also be incorporated in FAX
machines and combination FAX/answering machines
to allow users to screen for junk Faxes.
Telephone companies view Caller ID as another
service to generate revenue. Consequently, the Bell
Operating Companies asked Bell Communications
Research (Bellcore) to prepare specifications that
show manufacturers how to build CID equipment.
These describe features and functions of equipment
or interfaces for possible use by any divested Bell
Operating Company or its regional affiliate. In the
Calling Number Delivery (CND) service, the
information about a calling party is embedded in the
silent interval between the first and second ring.
Besides CND, there are other telephone company
services that use the same transmission scheme.
For example, another service extends CND with call
waiting so that customers can tell who is calling on
the other line. This requires some handshaking
between the phone and the central office. Future
devices will incorporate this feature. Calling Name
Delivery (CNAM), another service using the same
scheme, displays the name of the caller, rather than
the number.
How it Works
The principle of CID is relatively simple. Coded
signalling information is sent during the period
between the first and second ring. Continuous
phase binary frequency shift keying (FSK) is used for
coding. The CID chip decodes analog information
and transforms it into a digital bit stream which is
available at the DATA pin. A micro-controller extracts
caller information from the digital stream.
A CID system has five important functions: line
termination during data reception, high voltage
isolation, common mode rejection, ring detection and
CID data reception. These functions, with the
exception of CID reception, are not built into most
CID devices, so a small amount of external circuitry
is required.
The receive data dynamic range of the CID detection
circuit is a critical requirement. On a long loop the
signal strength may be very low, but the CID device
must be able to detect it. Consequently, analog
performance as shown by the detect level and the
ability to perform in the presence of noise is very
important. The Mitel Calling Number Identification
Circuit (CNIC) for example, has a detect level of -
36dBm, specified over the entire temperature
range. The device is also specified to operate at a
typical 20dB S/N ratio. In addition, the MT8841 has
a user accessible input op-amp which can be
configured in a differential mode to reduce the
effects of common mode noise. The input gain may
also be changed easily (either increased or
decreased) to meet specific regulatory decode level
requirements. This is accomplished by changing the
resistor values of the input op-amp network.
According to the Bellcore specifications, the
Customer Premises Equipment (CPE) should
terminate the transmission line with the correct
impedance while data is being transmitted. The CPE
must detect the end of the first power ring and switch
in the termination. The termination is external to the
CID chip and is typically connected with a relay
during the period between the first and second ring
signals.
For
consumption, a power down mode is desirable. The
MT8841 has a power down pin (PWDN), which when
pulled high, forces the device into power down. This
is typically done after receiving a message. In this
mode, the CID device ceases to function and the
chip will not react to an input signal. Pulling the pin
to ground wakes up the chip so that it can receive the
FSK signal and start decoding.
applications
requiring
reduced
power
相關PDF資料 |
PDF描述 |
|---|---|
| MT8860 | DTMF DECODER |
| MT8860XC | DTMF DECODER |
| MT8860XE | DTMF DECODER |
| MT8865 | DTMF Filter |
| MT8865XC | DTMF Filter |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| MT8840 | 制造商:MITEL 制造商全稱:Mitel Networks Corporation 功能描述:ISO2-CMOS Data Over Voice Modem |
| MT8840-1 | 制造商:MITEL 制造商全稱:Mitel Networks Corporation 功能描述:ISO2-CMOS Data Over Voice Modem |
| MT8840AE | 制造商:Rochester Electronics LLC 功能描述: 制造商:MITEL / ZARLINK 功能描述: 制造商:Zarlink Semiconductor Inc 功能描述: |
| MT8840AS | 制造商:MITEL 制造商全稱:Mitel Networks Corporation 功能描述:ISO2-CMOS Data Over Voice Modem |
| MT8841 | 制造商:MITEL 制造商全稱:Mitel Networks Corporation 功能描述:CMOS Calling Number Identification Circuit |
發(fā)布緊急采購，3分鐘左右您將得到回復。