Wavecom W61PC V7.5.0 - Manual (Page 243)

WAVECOM Decoder W61PC/LAN Manual V7.5 Transmission Modes  233
identities etc.
In the current decoder version encrypted traffic similar to other traffic will trigger the indi-
cation “TRAFFIC” in the status box, and an option (see preceding paragraph) is available for
saving traffic to a text file containing cell information, destination address and payload data
(if an allocation is received). In case of encrypted traffic packets, the payload data is saved
together with the number of the slot, frame, multi-frame and hyper-frame being decoded
which constitute the Initial Value (IV) for the encryption algorithm. Saved data and meta-
information may be fed to an external decryption process. A sample of the text file contain-
ing encrypted voice and meta-data is shown below:
TMO: Main Freq: 393.912 MHz 383.912 MHz MCC: 000 MNC: 0000 LA: 15972 Security
class 3 and class 1
CN: 3756 CC: 2
Encrypted Channel Allocation Dest: 568463 Slot: 1 Frame: 11 Enc. Mode: 2
11011101000101010000000000101100110011101110010000100000111111101111100101100000
00001000000100001000000000000000000000000000000000000000000000000000000000000000
000000000000000000000000000000000000000000000000000000000000
2 8 40 5337 (slot – frame – multi-frame – hyper-frame)
10000101011111001100111010000101100011111011010010110000011000011111001100010000
00011001010010000110100001110010101010111010110110100101011001000010111110101101
10000111110011000111011100000001000011101100011010000111000011111100000001010100
001101010100
Constraints
WAVECOM’s implementation of TETRA is based on TETRA release 1 and will decode all TMO and DMO voice
and data traffic in real-time, albeit with certain constraints (referring to the TETRA reference protocol
stack and the appropriate ETSI standards):
Layer Constraints
Layer 1  Multiple Slot Transmission mode (MST) is not supported
 Only downlink bursts are supported in the current decoder version
Layer 2 Logical channels:
User plane, traffic channels:
 Circuit mode not supported
Control plane, control channels:
 All channels except Access Assignment Channel (AACH)
Protocol Data Units (PDU):
 Only downlink PDUs supported
Layer 3 At layer 3, control plane PDUs are user selectable
TWINPLEX
TWINPLEX (F7B) is a FSK modulation technique with four modulation frequencies. Two transmission chan-
nels V1 and V2 are obtained through a combination of the modulation frequencies.