參數(shù)資料
型號(hào)： MT8880CN-1
廠商： Mitel Networks Corporation
英文描述： ISO2-CMOS Integrated DTMFTransceiver
中文描述： ISO2 - CMOS集成DTMFTransceiver
文件頁(yè)數(shù)： 5/18頁(yè)
文件大?。?/td> 312K
代理商： MT8880CN-1
ISO
2
-CMOS
MT8880C/MT8880C-1
4-37
Increasing t
REC
improves talk-off performance since
it reduces the probability that tones simulated by
speech will maintain a valid signal condition long
enough to be registered. Alternatively, a relatively
short t
REC
with a long t
DO
would be appropriate for
extremely noisy environments where fast acquisition
time and immunity to tone drop-outs are required.
Design information for guard time adjustment is
shown in Figure 6. The receiver timing is shown in
Figure 9 with a description of the events in Figure 11.
Call Progress Filter
A call progress mode, using the MT8880C/C-1, can
be selected allowing the detection of various tones
which identify the progress of a telephone call on the
network. The call progress tone input and DTMF
input are common, however, call progress tones can
only be detected when CP mode has been selected.
DTMF signals cannot be detected if CP mode has
been selected (see Table 5). Figure 8 indicates the
useful detect bandwidth of the call progress filter.
Frequencies presented to the input, which are within
the ‘a(chǎn)ccept’ bandwidth limits of the filter, are hard-
limited by a high gain comparator with the IRQ/CP
pin serving as the output. The squarewave output
obtained from the schmitt trigger can be analyzed by
a microprocessor or counter arrangement to
determine the nature of the call progress tone being
detected. Frequencies which are in the ‘reject’ area
will not be detected and consequently the IRQ/CP
pin will remain low.
DTMF Generator
The DTMF transmitter employed in the MT8880C/C-
1 is capable of generating all sixteen standard DTMF
tone pairs with low distortion and high accuracy. All
frequencies are derived from an external 3.579545
MHz crystal. The sinusoidal waveforms for the
individual tones are digitally synthesized using row
and column programmable dividers and switched
capacitor D/A converters. The row and column tones
are mixed and filtered providing a DTMF signal with
low total harmonic distortion and high accuracy. To
specify a DTMF signal, data conforming to the
encoding format shown in Figure 7 must be written to
the transmit Data Register. Note that this is the same
as the receiver output code. The individual tones
which are generated (f
LOW
and f
HIGH
) are referred to
as Low Group and High Group tones. As seen from
the table, the low group frequencies are 697, 770,
852 and 941 Hz. The high group frequencies are
1209, 1336, 1477 and 1633 Hz. Typically, the high
group to low group amplitude ratio (pre-emphasis) is
2dB to compensate for high group attenuation on
long loops.
0= LOGIC LOW, 1= LOGIC HIGH
Figure 7 - Functional Encode/Decode Table
Figure 8 - Call Progress Response
The period of each tone consists of 32 equal time
segments. The period of a tone is controlled by
varying the length of these time segments. During
write operations to the Transmit Data Register the 4
bit data on the bus is latched and converted to 2 of 8
coding for use by the programmable divider circuitry.
This code is used to specify a time segment length
which will ultimately determine the frequency of the
tone. When the divider reaches the appropriate
count, as determined by the input code, a reset pulse
is issued and the counter starts again. The number
F
LOW
F
HIGH
DIGIT
D
3
D
2
D
1
D
0
697
1209
1
0
0
0
1
697
1336
2
0
0
1
0
697
1477
3
0
0
1
1
770
1209
4
0
1
0
0
770
1336
5
0
1
0
1
770
1477
6
0
1
1
0
852
1209
7
0
1
1
1
852
1336
8
1
0
0
0
852
1477
9
1
0
0
1
941
1336
0
1
0
1
0
941
1209
*
1
0
1
1
941
1477
#
1
1
0
0
697
1633
A
1
1
0
1
770
1633
B
1
1
1
0
852
1633
C
1
1
1
1
941
1633
D
0
0
0
0
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
A
A
A
A
A
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AAAA
AA
AA
AA
AA
AA
LEVEL
(dBm)
FREQUENCY (Hz)
-25
0
250
500
750
= Reject
= May Accept
= Accept
相關(guān)PDF資料
PDF描述
MT8880CP-1 ISO2-CMOS Integrated DTMFTransceiver
MT8880CS-1 ISO2-CMOS Integrated DTMFTransceiver
MT8880C Integrated DTMF Transceiver(雙音多頻信號(hào)（DTMF）收發(fā)器（帶電話程序?yàn)V波器）)
MT8885AE Integrated DTMFTransceiver with Power Down & Adaptive Micro Interface
MT8885AN Integrated DTMFTransceiver with Power Down & Adaptive Micro Interface
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MT8880CP 制造商:Microsemi Corporation 功能描述:
MT8880CP/CP-1 制造商:MITEL 制造商全稱:Mitel Networks Corporation 功能描述:Integrated DTMFTransceiver
MT8880CP1 制造商:Microsemi Corporation 功能描述: 制造商:Microsemi Corporation 功能描述:DTMF TXRX 3.58MHZ CMOS 5V 28PLCC - Rail/Tube 制造商:MICROSEMI CONSUMER MEDICAL PRODUCT GROUP 功能描述:IC TXRX DTMF 28PLCC 制造商:Microsemi Corporation 功能描述:IC TXRX DTMF 28PLCC
MT8880CP-1 制造商:MITEL 制造商全稱:Mitel Networks Corporation 功能描述:ISO2-CMOS Integrated DTMFTransceiver
MT8880CPR 制造商:Microsemi Corporation 功能描述: 制造商:Microsemi Corporation 功能描述:DTMF TXRX 3.58MHZ CMOS 5V 28PLCC - Tape and Reel
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