1200/2400/4800bps MSK Modem
5
MX469
Signal
Type
Description
P
DW
D3
17
18
15
RX Sync
output A flywheel squarewave output. This clock will
synchronize to incoming RX MSK data. (See Figure 4
and Figure 6).
16
19
16
input
A logic ‘1’ on this pin selects the 1200bps option; tone
frequencies are one cycle of 1200Hz represents a logic
‘1’, one-and-a-half cycles of 1800Hz represents a logic
‘0’. A logic ‘0’ on this pin selects the 2400bps option;
tone frequencies are one-half cycle of 1200Hz represents
a logic ‘1’, one cycle of 2400Hz represents a logic ‘0’.
This pin has an internal 1Mꢂ pull-up resistor.
Operational Data Rate Configurations are illustrated in
Table 3
1200/ 2400 BPS
Select
18
20
17
4800 BPS Select
input
input
A logic '1' on this pin combined with a logic '0' on the
1200/2400 BPS Select pin will select the 4800 option
(1Mꢂ pulldown resistor). Tone frequencies are: one-half
cycle of 2400Hz represents a logic '1', one cycle of
4800Hz represents a logic '0'. This state can only be
achieved using a 4.032MHz Xtal input. Operational Data
Rate Configurations are illustrated in Table 3
19
20
22
21
23
24
18
19
20
Clock Rate
A logic input to select and allow the use of either a
1.008MHz or 4.032MHz Xtal/clock. Logic ‘1’ =
4.032MHz, logic ‘0’ = 1.008MHz. This input has an
internal pulldown resistor (1.008MHz).
Carrier Detect
Time Constant
output Part of the carrier detect integration function. The value
of C4 connected to this pin will affect the carrier detect
response time and therefore the noise performance (See
Figure 2, Note 3).
V
DD
power Positive supply. A single 5-volt supply is required.
No Internal Connection.
4, 4, 6,
N/C
21
17,
22
Table 1: Signal List
RX Enable
=
=
=
RX Function
Clock Data Output
Carrier Detect
Rx Sync Out
Enabled
1
0
Enabled
Enable
0
Enabled
0
Powersave
1 or 0
Table 2: RX Enable Control Functions
XTAL/CLOCK Frequency
Clock Rate pin
1.008MHz
4.032MHz
0
1
0
0
1
1
1
0
1
0
1
1200/2400 Select Pin
4800 Select Pin
0
0
0
0
Data Rate (bps)
1200
2400
1200
2400
4800
Table 3: Operational Data Rate Configuration
ꢀ1998 MX-COM, Inc.
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054
Doc. # 20480081.010
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