參數(shù)資料
型號(hào)： MT88L89
廠商： Mitel Networks Corporation
英文描述： 3V Integrated DTMF Transceiver with Adaptive Micro Interface(3V 集成雙音多頻信號(hào)（DTMF）接收器（帶自適應(yīng)微接口）)
中文描述： 3V的雙音多頻收發(fā)器集成自適應(yīng)微型接口（3V的集成雙音多頻信號(hào)（DTMF）的接收器（帶自適應(yīng)微接口））
文件頁(yè)數(shù)： 7/28頁(yè)
文件大?。?/td> 210K
代理商： MT88L89
MT88L89
4-129
Figure 9 - Spectrum Plot
Scaling Information
10 dB/Div
Start Frequency = 0 Hz
Stop Frequency = 3400 Hz
Marker Frequency = 697 Hz and
1209 Hz
high accuracy. To specify a DTMF signal, data
conforming to the encoding format shown in Table 1
must be written to the transmit Data Register. Note
that Table 1 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 (twist) is 2 dB to compensate for high group
attenuation on long loops.
Figure 10 - 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
of time segments is fixed at 32, however, by varying
the segment length as described above, the
frequency can also be varied. The divider output
clocks another counter, which addresses the
sinewave lookup ROM.
The lookup table contains codes which are used by
the switched capacitor D/A converter to obtain
discrete and highly accurate DC voltage levels. Two
identical circuits are employed to produce row and
column tones, which are then mixed by using a low
noise summing amplifier. A bandwidth limiting filter is
incorporated and serves to attenuate distortion
products above 8 kHz. Figure 9 shows that the
distortion products are very low in amplitude.
Burst Mode
In certain telephony applications it is required that
DTMF signals being generated are of a specific
duration determined either by the particular
application or by any one of the exchange transmitter
specifications currently existing. Standard DTMF
signal timing can be accomplished by making use of
the Burst Mode. The transmitter is capable of issuing
symmetric bursts/pauses of predetermined duration.
This burst/pause duration is 51 ms
±
1 ms which is a
standard interval for autodialer and central office
applications. After the burst/pause has been issued,
the appropriate bit is set in the Status Register to
indicate that the transmitter is ready for more data.
The timing described above is available when DTMF
mode has been selected. However, when CP mode
(Call Progress mode) is selected, the burst/pause
duration is doubled to 102 ms
±
2 ms. Note that when
CP mode and Burst mode have been selected,
DTMF tones may only be transmitted and not
LEVEL
(dBm)
FREQUENCY (Hz)
-25
0
250
500
750
= Reject
= May Accept
= Accept
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MT88L89AC 制造商:MITEL 制造商全稱:Mitel Networks Corporation 功能描述:3V Integrated DTMFTransceiver with Adaptive Micro Interface
MT88L89AE 制造商:MITEL 制造商全稱:Mitel Networks Corporation 功能描述:3V Integrated DTMFTransceiver with Adaptive Micro Interface
MT88L89AN 制造商:Microsemi Corporation 功能描述:
MT88L89AN1 制造商:Microsemi Corporation 功能描述:DTMF TXRX 3.58MHZ CMOS 3V 24SSOP - Rail/Tube
MT88L89ANR1 制造商:Microsemi Corporation 功能描述:DTMF TXRX 3.58MHZ CMOS 3V 24SSOP - Tape and Reel 制造商:MICROSEMI CONSUMER MEDICAL PRODUCT GROUP 功能描述:IC TXRX DTMF 3V 24SSOP 制造商:Microsemi Corporation 功能描述:IC TXRX DTMF 3V 24SSOP
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