Wavecom W61PC V7.5.0 - Manual (Page 187)

WAVECOM Decoder W61PC/LAN Manual V7.5 Transmission Modes  177
PSUBCOM will accommodate text (7-bit ASCII text), data (transparent data), status messages (transpar-
ent data) and data of higher level protocols like OVLS, identified by a protocol identification byte after the
time stamp.
Mobitex 1200 also has voice call ability.
MOBITEX-8000
Mobitex 8000 is a multiple access packet radio system for wireless communications developed from the
older Mobitex 1200 bps system. Mobitex 8000 operates in the UHF bands and is found around 420 and
900 MHz in a number of countries using direct 8 kbps GMSK modulation.
Parameter Value
Frequency range UHF
Operation modes Slotted Aloha TDMA system, full-duplex
Modulation GMSK
Symbol rate 8000 Bd
Shift ± 2 kHz
Receiver settings Narrow FM, BW = 15 kHz
Input AF, IF
Additional Info Mobitex Network Settings, Message Type
The Mobitex 8000 frames consist of a frame header with a unique synchronization word, base station
identification, traffic area identification and control flags followed by zero or more blocks of data, max 32
blocks. Each block consists of 18 bytes followed by two CRC bytes.
The data block bytes are protected by a 4-bit (12, 8) Hamming code so each data word is 12 bits long. For
further protection the data bits are interleaved. However, the frame header is not interleaved and does
not have a CRC sum appended.
Each system is identified by the unique 4 hexadecimal digit sync word. The sync word is inverted for mo-
bile-base communication.
Important: The sync word must be chosen for proper decoding in the Mobitex network settings and
depends on the Mobitex network provider.
The first data block contains addressing information, frame type id, number of blocks and other control in-
formation. Frames can either be data link frames used for the management of traffic or payload data
frames called MRM frames. The payload frames contain so called MPAKs, i.e. Mobitex Packets which can
have a total length of 512 bits. If the message is longer it is split into a number of sequences.
The first payload data block contains MPAK header information: source and destination addresses, sub-
scription flags, packet class and packet type information and a timestamp if they are transmitted in the
base-to-mobile direction. The remote terminals do not insert a time stamp, this is done by the network.
The system has two payload packet classes, PSUBCOM for subscriber packet switched communication and
DTESERV for service messages.
PSUBCOM will accommodate text (7-bit ASCII text), data (transparent data), status messages (transpar-
ent data) and higher protocol data identified by a protocol identification byte after the time stamp.
MODAT
The entire call number is transmitted by consecutive tones in decade sequence. When two identical digits
are to be transmitted consecutively, then an eleventh frequency is used as a repetition identifier.
Parameter Value
Frequency range VHF/UHF