WAVECOM Decoder W74PC, W-PCI/e, W-CODE, W-CLOUD Manual V9.1.0
Transmission Modes
229
Digit
Hz
Digit
Hz
2
1160
A
970
3
1270
B
810
4
1400
C
2800
5
1530
D
885
6
1670
E
2600
7
1830
F
680
Tone duration: 70 ms.
ROBUST-PACKET
Robust-Packet (RPR, Robust Packet Radio) is a data transmission mode devised from Special Communica-
tions Systems GmbH & Co. KG. It is optimized for the deployment in the short wave band. To accommo-
date the characteristics of this frequency range, for example fading and multipath propagation, a eight
carrier OFDM was used.
Parameter
Value
Frequency range
HF
System
OFDM, FEC, CRC
Modulation
OFDM with DQPSK and DBPSK
Center frequency
1500 Hz
Shift
420 Hz
Symbol rate
200 Bd and 600 Bd adaptive
Receiver settings
Data, CW, LSB or USB
Input format(s)
AF
Additional Info
AX.25 data, APRS
Dependent on the speed level (r200 or r600) every carrier is DBPSK or DQPSK at a rate of 50 Bd modulat-
ed. Just like in PACKET-RADIO the AX.25-protocol comes into operation. The decoder module detects the
speed level and the size of the transmitted packet automatically and shows the result. The payload of one
packet can be up to 256 Byte. The real length of one data packed depends on the amount of data to be
send. There are 25 different packages. One for connect/disconnect and respectively 12 for the two speed
levels with their variable packet length.
To make the transmission as robust as possible, there are several modifications applied onto the AX.25-
data stream before the transmission. The call signs are compressed with a special algorithm, the data
stream is scrambled, redundancy is added and it is interleaved over the full frame length.
The decoder output is divided in signaling information (call signs with SSIDs, package-identifier and AX.25
control word) and data. It is possible to represent the data as ITA5-US and HEX.
Further description to the signaling information can be found in the AX.25 Link Access Protocol for Ama-
teur Packet Radio.
The package-identifier specifies the used layer 3 protocol.
In the following table, all possible package identifiers are given:
Package-Identifier PID
Hexadecimal
value PID
binary value
Layer 3 Protocol
**
xx01xxxx
AX.25 layer 3 implemented
