CMX860D6 Просмотр технического описания (PDF) - MX-COM Inc
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CMX860D6 Datasheet PDF : 38 Pages
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Telephone Signaling Transceiver
13
CMX860 Advance Information
10
0
-10
-20
dB
-30
-40
-50
-60
0
0.5
1
1.5
2
2.5
3
3.5
4
kHz
Figure 9: Response of the Call Progress Filter
The Answer Tone detector measures both amplitude and frequency of the received signal and sets bit 6 or bit
7 respectively of the Status Register when a valid 2225Hz or 2100Hz signal is received.
4.7 Rx Modem Filter and Equalizer
When the receive part of the CMX860 is operating as a modem, the received signal is fed to a bandpass filter
to attenuate unwanted signals and to provide fixed compromise line equalization. The line equalizer may be
enabled or disabled by bit 10 of the General Control Register and compensates for one quarter of the relative
amplitude and delay distortion of ETS Test Line 1.
A typical response of this filter, including the line equalizer is shown in Figure 10. The effect of external
components (see Figure 5 and Figure 6) should also be considered in determining the overall response.
10
0
-10
-20
-30
dB
-40
-50
-60
0
0.5
1
1.5
2
2.5
3
3.5
4
kHz
Figure 10: V.23/Bell 202 Rx Filters
The signal level at the output of the Receive Modem Filter and Equalizer is measured in the Modem Energy
Detector block, compared to a threshold value, and the result controls bit 10 of the Status Register.
The output of the Receive Modem Filter and Equalizer is also fed to the FSK demodulator.
4.8 FSK Demodulator
The FSK demodulator recognizes individual frequencies as representing received ‘1’ or ‘0’ data bits:
The FSK demodulator produces a serial data bit stream which is fed to the Rx USART block, see
Figure 11. This bit stream is also monitored for continuous ‘1010’s and for continuous 1’s. The outputs of
these pattern detectors control bits 9 and 7 respectively of the Status Register.
ã2000 MX-COM, Inc.
www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054
Doc. # 20480222.002
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.
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