Wavecom W 4010 User Manual page 20

The ARQ-M2-242 and ARQ-M4-242 systems correspond to the CCIR recommendation REC. 242. This system
combines two or four data channels in a single transmission. It uses a 7-bit code with which transmission er-
rors can be recognized. All characters of the ITA-3 alphabet have a 4 to 3 ratio. The Time-Division-Multiplex
(TDM) system operates full duplex and the error-correction procedure operates like ARQ-M2, complying with
Rec. 342-2.
The software preselects 96 Baud for ARQ-M2-242 and 192 Baud for ARQ-M4- 242. Additionally the [F2] key
can be used to manually change the Baud rate. The [F3] key is used to select sub-channels A & B, respec-
tively A, B, C, and D, or automatic selection of a busy channel.
[F1] SPEED CHECK
[F2] BAUD RATE SELECTION
[F3] POLARITY SELECTOR
[F4] FORWARD SEQUENCE
[F4]+[F3]
DUP-ARQ is a new system of semiduplex data transmission. The system additionally has an automatic chan-
nel selection: before starting the transmission, the best possible short-wave channel is chosen and during
the transmission regularly checked. Within a frequency range, the system can select from 5 different chan-
nels using steps of 400 Hz. DUP-ARQ uses the channel like a simplex system: both stations alternately send
5-character blocks and a Hamming check sum. If a transmission error appears, a nonacknowledgement is
sent and the last data block is repeated. A frequency offset often occurs between stations A and B because
of the automatic channel selection. If only one station is sending data, the other sends an idle bit-pattern. If
errors occur, block repetition (RQ) cycles are initiated.
The software uses 125 Baud as a default since this is the most common speed, but the [F2] key can be used
to change the speed. The polarity (sideband) is changed with the [F3] key and causes no loss of synchroni-
zation.
[F1] SPEED CHECK
[F2] BAUD RATE SELECTION
[F3] MODE RECALL
[F4] FORWARD SEQUENCE
[F4]+[F3] REVERSE SEQUENCE
The POL-ARQ is a duplex system with two transmission frequencies, usually operating at a speed of 100
Baud. The system uses the errorcorrecting SITOR-ARQ alphabet. If only one station is sending data, the oth-
er sends an idle bitpattern. If errors occur, block repetition (RQ) cycles are initiated.
The [F2] key can be used to change the speed, while the [F3] key recalls the operating mode POL-ARQ with
operational menu.
[F1] SPEED CHECK
[F2] BAUDRATE SELECTOR
[F3] MODE RECALL
[F4] FORWARD SEQUENCE
[F4]+[F3]
The idle condition is easily recognized by means of the signal's regular mark/space shift (about 40/60 %).
However, in idle condition it is neither possible to synchronize nor to measure the Baud rate.
REVERSE SEQUENCE
3.6 SOFTWARE MODUL C
REVERSE SEQUENCE
DUP-ARQ
Measure Baud rate
Configure Baud rate
Configure polarity
go to next operating mode
go to previous operating mode
POL-ARQ
Measure Baud rate
Configure Baud rate
Retrieves the operating mode
go to next operating mode
go to previous operating mode
FEC-A
Displays the baud rate
Selects Baud rates manually
Redisplay of the mode as well as resynchronization
go to next operating mode
go to previous operating mode
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