GMSK Modem Data Pump
Page 16 of 37
MX909A PRELIMINARY INFORMATION
Ref. Figure 9 and Figure 10
Task
Any
Typical (bit-times)
1
t
Time from writing first task (modem in 'idle' state) to
application of first transmit bit to Tx Low Pass filter
Time from application of first bit of task to TX Low
Pass Filter until BFREE goes to a logic 1
1
t
2
T7H
TQB
TDB
TSB
T7H
TQB
TDB
TSB
T7H
TQB
TDB
TSB
SFH
R3H
RDB
RSB
SFH
R3H
RDB
RSB
Any
36
24
20
1
56
32
240
8
18
6
218
6
56
24
240
8
14
18
218
6
t
3
t
4
t
5
t
6
t
7
Time to transmit all bits of task
Max time allowed from BFREE going to a logic 1 for
next task (and data) to be written to the modem
Time to receive all bits of task
Maximum time between first bit of task entering
de-interleave circuit and task being written to modem
Time from last bit of task entering de-interleave
circuit to BFREE going to a logic '1'
1
Data to Data Buffer
1
2
3
Task to Command Register
1
2
3
t4
t4
t4
IBEMPTY Bit
BFREE Bit
t2
t2
t2
t3
t3
t3
t1
Bits to Tx Lowpass Filter
Modem Tx Output
from Task 2
from Task 3
from Task 1
Figure 9: Transmit Mode Timing Diagram
Modem Rx Input
Bits to De-Interleave Circuit
for Task 1
t5
for Task 2
for Task 3
t5
1
t5
2
3
Data from Data Buffer
Task to Command Register
1
2
3
t6
t6
t6
t7
t7
t7
BFREE Bit
Figure 10: Receive Mode Timing Diagram
¤2001 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. # 20480134.005
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