Low Power V.22 bis Modem
CMX868
DTMF Decoder
Notes
Min.
Typ.
Max.
Unit
Valid input signal levels
(each tone of composite signal)
10
10
-30.0
–
0.0
dBm
Not decode level
(either tone of composite signal)
Twist = High Tone/Low Tone
Frequency Detect Bandwidth
Frequency Not Detect Bandwidth
Max level of low frequency noise (i.e dial tone)
Interfering signal frequency <= 550Hz
Interfering signal frequency <= 450Hz
Interfering signal frequency <= 200Hz
Max. noise level wrt. signal
DTMF detect response time
DTMF de-response time
Status Register b5 high time
‘Will Detect’ DTMF signal duration
‘Will Not Detect’ DTMF signal duration
Pause length detected
–
-10.0
±1.8
–
–
–
–
–
-36.0
6.0
–
dBm
dB
%
±3.5
%
14
14
14
–
–
–
–
–
–
–
–
–
–
–
–
–
25.0
–
0
10.0
20.0
-10.0
40.0
30.0
–
–
–
–
15.0
dB
dB
dB
dB
ms
ms
ms
ms
ms
ms
ms
14,15
–
14.0
40.0
-
30.0
–
Pause length ignored
–
Notes:
14. Referenced to DTMF tone of lower amplitude.
15 Flat Gaussian Noise in 300-3400Hz band.
Receive Input Amplifier
Input impedance (at 100Hz)
Notes
Min.
10.0
Typ.
–
Max.
–
Units
Moh
m
Open loop gain (at 100Hz)
Rx Gain Control Block accuracy
–
10000
–
–
V/V
dB
-0.25
+0.25
ã 2004 CML Microsystems Plc
45
D/868/9
CMLMICRO [ CML MICROCIRCUITS ]
