Wavecom W74PC User Manual

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Transmission Modes WAVECOM Decoder W74PC, W-PCI/e, W-CODE, W-CLOUD Manual V9.1.0
Parameter
Value
Symbol rate
62.5 Bd per carrier (max. 32 carriers)
Receiver Settings
LSB/USB (automatic polarity recognition)
Input format(s)
AF, IF
Additional Info
AFC, Adaptive number of carriers, compression
GW-OFDM-Modulation and Protocol
GlobeWireless-OFDM employs a dynamic increase and decrease in the number of OFDM carriers; the num-
ber of carriers can vary between 12 and 32. Each carrier is modulated with DQPSK.
The main specifications of GW-OFDM are:
 12 to 32 subcarriers
 DQPSK modulation
 62.5 Hz subcarrier spacing (symbol duration 16ms)
 Cyclic prefix / guard interval duration 2ms
 700-2700 Hz occupied bandwidth
 Pilot tone for synchronization and frequency tracking
The system ensures error free data exchange with an ARQ protocol – if a reception error occurs, the in-
formation receiving station (IRS) can request the retransmission of the corrupted packet from the infor-
mation sending station (ISS). To reduce the peak-to-average power ratio, a scrambler is used. Different
compression algorithms are used to achieve efficient data throughput.
Decoder
There are long packets containing data and short packets containing control or request information for the
ARQ process.
The decoder can recognize and decode the following packet types:
Packet type
Function
Source
IDLE
Idle frame
ISS
DATA
Data frame
ISS
RQ
Frame with Acknowledge(ACK) or
Not Acknowledge(NAK)
IRS
OVER
ISS requests to become IRS
ISS
FORCED OVER
IRS accepts the OVER
IRS
END
ISS indicates end of Transmission
ISS
END ACK
IRS acknowledges end of trans-
mission
IRS
MYCALL
Contains selcall of the calling sta-
tion
Not specified
RQ, FORCED OVER and END ACK are short packets. The others are long packets.
The decoded packet types are shown in the upper status bar.
In the next lower status bar the following information is shown:
 Number of carriers/channels
 For long packets: Number of channels with CRC OK and CRC FAILED
 For RQ packets: Number of channels with ACK, NAK, and wrongly decoded channels (UNKN)
Due to the compression employed by GW-OFDM, decoded data is not available until the end of a transmis-
sion. The end of a transmission is indicated by an END or END ACK packet, or after a timeout of several
seconds. After a transmission ends, the decoded data packets are put together and further processed to a
text file which contains information about the transmitting station and which can further contain com-

Wavecom W74PC Specifications

General

Brand	Wavecom
Model	W74PC
Category	Media Converter
Language	English