Specifications
19A705178
REV NO. TITLE
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ROCKWELL MODEM TEST
SPECIFICATION/PURCHASE PART DRAWING
CONT ON SHEET SH NO. FIRST MADE FOR
F. C. F. O.
MADE BY
R Sager
APPROVALS
DCB
M. R. P. D.
DIV OR DEPT.
19A705178
ISSUED
Nov. 19, 1986
11-18-86
LYNCHBURG
LOCATION
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REVISIONS
L30
PRINTS TO
No.
V.29
(bps)
V.27
bis/ter
(bps)
Gearshift
(bps)
RTS-CTS
Response Time
(milliseconds) Comments
1
2
3
4
5
FT/9600
FT/7200
FT/4800
FT/4800
FT/2400
23
24
23
22
30
Proprietary
Fast Train
6
7
8
9
10
11
12
13
9600
7200
4800
4800 long
2400 long
4800 short
2400 short
253
253
253
708
943
50
152
67
14
15
16
17
18
19
20
9600
7200
4800
4800 long
2400 long
4800 short
2400 short
438
438
438
913
1148
255
272
Preceded
by Echo
Protector
Tone for
lines using
echo
suppressers
1. For short echo protector tone, subtract I55 ms from values of RTS-CTS
response time.
2. V.21 (300 bps FSK). RTS-CTS, response time is <35 ms.
Turn-Off Sequence
For V.27 bis/ter, V.27FT and 2400/4800 bps Gearshift
configurations, the turn-off sequence consists of
approximately 10 ms of remaining data and scrambled ones
followed by a 20 ms period of no transmitted energy (V.27
bis/ter only). For V.29 and V.29FT, the turn-off sequence
consists of approximately 8 ms of remaining data and
scrambled ones.
Clamping
Received Data (RXD) is clamped to a constant mark (one)
when the Received Line Signal Detector (RLSD) is off.
Response Times Of Clear To Send (CTS)
The time between the off-to-on transition of Request To
Send (RTS) and the off-to-on transition of Clear to Send
(CTS) is dictated by the length of the training sequence and
the echo protector tone. if used. These times are given in
the Turn-on Sequences table. If training is not enabled.
RTS/CTS delay is less than 2 baud times.
The time between the on-to-off transition of RTS and the
on-to-off transition of CTS in the data state is a maximum
of 2 baud times for all configurations.
Receive Line Signal Detector (RLSD)
Response
For Fast Train and Gearshift configurations, the receiver
enters the training state upon detecting a significant
increase in the received signal power. If the received line
signal power is greater than the selected threshold level at
the end of the training state, the receiver enters the Data
state and RLSD is activated. If the received line signal
power is less than the selected threshold level at the end of
the training state, the receiver returns to the idle state and
RLSD is not activated.
Also, in Fast Train and Gearshift configurations, the
receiver initiates the turn-off delay upon detecting a
significant decrease in the received signal power. If the
received signal power is less than the selected threshold at
the end of the turn-off delay, the receiver enters the idle
state and RLSD is deactivated. If the received signal power
were greater than the selected threshold at the end of the
turn-off delay, the receiver returns to the data state and
RLSD is left active.
For CCITT configurations, the receiver enters the training
detection state when the received line sign power crosses
the selected threshold level. RLSD is activated at the end of
the training sequence. For V.21 Channel, a separate
received line signal detector (FRLSD) is provided. FRLSD
is activate when energy above -43 dB is present at the
receiver’s audio input (RXA). The FRLSD off-to-on
response time is 15 ±1.5ms and the on-to-off response time
is 25 ±1.5ms.
The RLSD on-to-off response times are:
RLSD On-To-Off
Configuration Response Time (ms)
V.29 Fast Train 6.5 ±1
V.27 Fast Train 8 ±1
Gearshift 6 ±1
V.29 30 ±9
V.27 bis/ter 10 ±5
RLSD response times are measured with a signal at least 3
dB above the actual RLSD on threshold or at least 5 dB
below the actual RLSD off threshold.