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Cermetek Microelectronics, Inc.
CH1788 Surface Mount PLCC 2400bps Modem
2006 Cermetek Microelectronics, Inc.
Page 21
Document No. 607-0018 Revision A6 (01/06)
Table 7. CH1788 System Data Mode Compatibility Specifications.
Parameter Specification Parameter Specification
Asynchronous
2400, 1200 bps character
asynchronous.
300 bps asynchronous
Receive Carrier
Frequencies
V.22 bis, V.22,
212A
Originate 2400Hz ± 7Hz
Answer 1200Hz ± 7Hz
Asynchronous
Speed Range
TXD may /-2.5% from
modem output. Offsets will be
corrected by adding/ deleting stop
bits.
Bell 103
Answer ‘space’ 2020Hz ± 7Hz
Answer ‘mark’ 2225Hz ± 7Hz
Originate ’space’ 1070Hz ± 7Hz
Originate ‘mark’ 1270Hz ± 7Hz
Asynchronous
Format
10 bits, including start, stop,
parity.
Receiver
Sensitivity
Carrier detect ON threshold
-43dBm
Carrier detect OFF threshold
-48dBm
Telephone Line
Interface
Two-wire full duplex over public
switched network. On-chip hybrid
and billing delay timers.
Billing Delay
2.0 to 3.0 seconds
Transmit level
V.22 bis, 16 point QAM at 600
baud. V.22 and 212A, 4 point
DPSK at 600 baud. 103 Binary
phase coherent FSK.
Power -9.6dB
max-QAM
-7.4dB max.-DPSK
-5.3dB max-FSK
Self Test Pattern
Generator
Alternate ‘ones’ and ‘zeros’ and
error detector, to be used along
with most loopbacks. A number
indicating the bit errors detected
is sent to DTE.
Line
Equalization
Fixed compromise equalization,
transmit. Adaptive equalizer for
DPSK/QAM, receive.
Transmit Carrier
Frequencies V.22
bis, V.22, 212A
Originate 1200Hz ± .01%
Answer 2400Hz ± .01%
Diagnostic
Available
Local analog loopback.
Local analog loopback.
Remote digital loopback.
Request remote digital loopback.
Local interface loopback modem
with self-test.
Bell 103
Originate ’space’ 1070Hz ± .01%
Originate ‘mark’ 1270Hz ± .01%
Answer ‘space’ 2020Hz ± .01%
Answer ‘mark’ 2225Hz ± .01%
Call Progress
Tones Detected
Computer
Interface
With speaker or quiet screen
messages (No dial tone, busy,
ring-back, modem answer tone
and voice).
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