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參數(shù)資料
| 型號： | MT8885 |
| 廠商： | Mitel Networks Corporation |
| 英文描述： | Integrated DTMF Transceiver with Power Down and Adaptive Micro Interface(雙音多頻信號（DTMF）收發(fā)器（帶電源關(guān)閉和自適應(yīng)微接口）) |
| 中文描述： | 集成雙音多頻收發(fā)器的斷電和自適應(yīng)微型接口（雙音多頻信號（DTMF）的收發(fā)器（帶電源關(guān)閉和自適應(yīng)微接口）） |
| 文件頁數(shù)： | 6/25頁 |
| 文件大?。?/td> | 190K |
| 代理商： | MT8885 |
MT8885
Preliminary Information
4-56
Figure 9 - Description of Timing Events
EXPLANATION OF EVENTS
A)
TONE BURSTS DETECTED, TONE DURATION INVALID, RX DATA REGISTER NOT UPDATED.
B)
TONE #n DETECTED, TONE DURATION VALID, TONE DECODED AND LATCHED IN RX DATA REGISTER.
C)
END OF TONE #n DETECTED, TONE ABSENT DURATION VALID, INFORMATION IN RX DATA REGISTER
RETAINED UNTIL NEXT VALID TONE PAIR.
D)
TONE #n+1 DETECTED, TONE DURATION VALID, TONE DECODED AND LATCHED IN RX DATA REGISTER.
E)
ACCEPTABLE DROPOUT OF TONE #n+1, TONE ABSENT DURATION INVALID, DATA REMAINS UNCHANGED.
F)
END OF TONE #n+1 DETECTED, TONE ABSENT DURATION VALID, INFORMATION IN RX DATA REGISTER
RETAINED UNTIL NEXT VALID TONE PAIR.
EXPLANATION OF SYMBOLS
V
in
DTMF COMPOSITE INPUT SIGNAL.
ESt
EARLY STEERING OUTPUT. INDICATES DETECTION OF VALID TONE FREQUENCIES.
St/GT
STEERING INPUT/GUARD TIME OUTPUT. DRIVES EXTERNAL RC TIMING CIRCUIT.
RX
0
-RX
3
4-BIT DECODED DATA IN RECEIVE DATA REGISTER
b3
DELAYED STEERING IN STATUS REGISTER (BIT 3) INDICATES THAT VALID FREQUENCIES HAVE BEEN
PRESENT/ABSENT FOR THE REQUIRED GUARD TIME THUS CONSTITUTING A VALID SIGNAL. ACTIVE LOW
FOR THE DURATION OF A VALID DTMF SIGNAL.
b2
RECEIVE DATA REGISTER FULL (BIT 2) IN STATUS REGISTER INDICATES THAT VALID DATA IS IN THE
RECEIVE DATA REGISTER. THE BIT IS CLEARED AFTER THE STATUS REGISTER IS READ.
IRQ/CP
INTERRUPT IS ACTIVE INDICATING THAT NEW DATA IS IN THE RX DATA REGISTER. THE INTERRUPT IS
CLEARED AFTER THE STATUS REGISTER IS READ.
t
REC
MAXIMUM DTMF SIGNAL DURATION NOT DETECTED AS VALID. TYPICALLY 20MS.
t
REC
MINIMUM DTMF SIGNAL DURATION REQUIRED FOR VALID RECOGNITION. TYPICALLY 40MS.
t
ID
MINIMUM TIME BETWEEN VALID SEQUENTIAL DTMF SIGNALS. TYPICALLY 40MS.
t
DO
MAXIMUM ALLOWABLE DROPOUT DURING VALID DTMF SIGNAL. TYPICALLY 20MS.
t
DP
TIME TO DETECT VALID FREQUENCIES PRESENT.
t
DA
TIME TO DETECT VALID FREQUENCIES ABSENT.
t
GTP
GUARD TIME, TONE PRESENT.
t
GTA
GUARD TIME, TONE ABSENT.
DTMF signals cannot be detected if CP mode has
been selected (see Table 7). 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 MT8885 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 by using
row and column programmable dividers and
switched capacitor D/A converters. The row and
column tones are mixed and filtered to provide a
DTMF signal with low total harmonic distortion and
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 8 - Call Progress Response
LEVEL
(dBm)
FREQUENCY (Hz)
-25
0
250
500
750
= Reject
= May Accept
= Accept
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MT8888CE-1 | Integrated DTMFTransceiver with Intel Micro Interface |
| MT8888CN-1 | CB 3C 3#16S SKT RECP WALL |
| MT8888CS-1 | Integrated DTMFTransceiver with Intel Micro Interface |
| MT8888C | Integrated DTMFTransceiver with Intel Micro Interface |
| MT8888CC | Integrated DTMFTransceiver with Intel Micro Interface |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MT8885AE | 制造商:MITEL 制造商全稱:Mitel Networks Corporation 功能描述:Integrated DTMFTransceiver with Power Down & Adaptive Micro Interface |
| MT8885AE1 | 制造商:Microsemi Corporation 功能描述:DTMF TXRX 3.58MHZ CMOS 5V 24PDIP - Rail/Tube 制造商:MICROSEMI CONSUMER MEDICAL PRODUCT GROUP 功能描述:IC TXRX DTMF 20PDIP 制造商:Microsemi Corporation 功能描述:IC TXRX DTMF 20PDIP |
| MT8885AN | 制造商:Microsemi Corporation 功能描述:DTMF TXRX 3.58MHZ CMOS 5V 24SSOP - Rail/Tube |
| MT8885AN1 | 制造商:Microsemi Corporation 功能描述:DTMF TXRX 3.58MHZ CMOS 5V 24SSOP - Rail/Tube |
| MT8885ANR | 制造商:Microsemi Corporation 功能描述: |
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