DB929B Datasheet, PDF (22/51 Pages) CML Microcircuits – Full Data Packet Framing

4-Level FSK Modem Data Pump
Page 22 of 50
MX929B PRELIMINARY INFORMATION
4.5.2.19 TSID: Transmit Station ID
This task takes three ID bytes from the Data Block Buffer, calculates and appends the 6-bit CRC0 checksum,
translates the result to 4-level symbols (with FEC) and transmits the resulting 22 symbols preceded and
followed by 'S' symbols.
Once the modem has read the data bytes from the Data Block Buffer, the BFREE and IRQ bits of the Status
Register will be set to '1'.
4.5.2.20 RESET: Stop any current action
This task takes effect immediately, and terminates any current action (task, AQSC or AQLEV) the modem
may be performing and sets the BFREE bit of the Status Register to '1', without setting the IRQ bit. It should
be used after V_DD is applied first to set the modem into a known state.
Note: Due to delays in the RRC filter, it will take several symbol times for any change caused by RESET to
appear at the TXOUT pin.
4.5.2.21 Task Timing
The following table and figures describe the duration of tasks and timing sequences for Tx and Rx operation.
Task
t₁ Modem in idle state. Time from writing first task to application of first Any
transmit bit to Tx RRC filter
t₂ Time from application of first symbol of the task to the Tx RRC
filter until BFREE goes to a logic ‘1’
T24S
TSID
THB/TIB/TLB
T4S
t₃ Time to transmit all symbols of the task
T24S/TSID
THB/TIB/TLB
T4S
t₄ Max time allowed from BFREE going to a logic '1' (high) for next
task (and data) to be written to modem
T24S
TSID
THB/TIB/TLB
T4S
t₅ Time to receive all symbols of task
SFS
SFP
RSID
RHB/RILB
R4S
t₆ Maximum time between first symbol of task entering the de-
interleave
circuit and the task being written to modem
SFS
SFP
RSID
RHB/RILB
R4S
t₇ Maximum time from the last bit of the task entering the de interleave Any
circuit to BFREE going to a logic '1' (high)
Time
(symbol times)
1 to 2
5
6
16
0
24
69
4
18
17
52
3
25 (minimum)
48 (minimum)
23
69
4
21
21
15
51
3
1
©2001 MX-COM, INC.
www.mxcom.com Tel: [phone] 744 5050 Fax: [phone]
Doc. # 20480171.003
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA All trademarks and service marks are held by their respective companies.