Home
Up
W-CODE-LT
W-CODE-CL
W-CODE-SAT
PACTOR
CLOVER 2
CLOVER2000 | | PACTOR3PACTOR3
| Parameter | Value | | System | Half-duplex synchronous ARQ | | Center frequency | In the range (−2900, 2900) Hz; automatic frequency control (AFC): +/−50 Hz | | Speed | 100.0 Baud | | Modulation | DBPSK, DQPSK; 2, 6, 14, 16, or 18 tones | | Additional Info | ITA-5 with block coding, CRC is displayed |
PACTOR-III is an adaptive transmission mode that provides higher throughput and improved robustness compared to PACTOR-I and –II, both of designed for operation within a bandwidth of 500 Hz. To achieve the improved features, PACTOR-III uses up to a maximum of 18 tones spaced 120 Hz, thus occupying a maximum bandwidth of 2160 Hz. Six so-called Speed Levels (SL) are specified, which are predefined combinations of modulation type (DBPSK or DQPSK), channel coding and number of tones (2, 6, 14, 16, or 18) as well as positions of tones. For all Speed Levels, the modulation rate of each tone is 100 Baud.
B = DBPSK, Q = DQPSK) for the 6 Speed Levels (SL).
| TN | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | | | | | | | | B | | | | | | | B | | | | | | | SL=1 | | | | | | B | | | | | | | B | | | | | | | SL=2 | | | | B | | B | | B | | | B | | B | | B | | | | | SL=3 | | | B | B | B | B | B | B | B | B | B | B | B | B | B | B | | | | SL=4 | | | Q | Q | Q | Q | Q | Q | Q | Q | Q | Q | Q | Q | Q | Q | | | | SL=5 | | Q | Q | Q | Q | Q | Q | Q | Q | Q | Q | Q | Q | Q | Q | Q | Q | | | SL=6 | Q | Q | Q | Q | Q | Q | Q | Q | Q | Q | Q | Q | Q | Q | Q | Q | Q | Q | | TF | 480 | 600 | 720 | 840 | 960 | 1080 | 1200 | 1320 | 1440 | 1560 | 1680 | 1800 | 1920 | 2040 | 2160 | 2280 | 2400 | 2520 |
As propagation conditions change, PACTOR-III is able to select the most suitable speed level.
Each frame consists of the user data, a status byte, and two CRC bytes. This input bit stream is then bit-interleaved and convolutionally encoded. After that, the symbol mapping for the different channels is done, and the resulting signals are applied to the DxPSK modulators. To extract the data from a PACTOR-III signal, the signal is demodulated with the appropriate number of DxPSK-demodulators, according to the speed level.
The center frequency must be adjusted to the center between the lowest and highest tone in use. AFC (automatic frequency control) is always enabled. After demodulation and bit synchronization, the symbols of the channels are combined to one bit stream, which is de-interleaved and passed through a Viterbi-decoder. The CRC is used to check whether transmission errors occurred. After successful synchronization, it may take several tens of seconds before any text is output in the GUI.
In PACTOR-III, the data may be transmitted as ASCII without compression or can be compressed with HUFFMAN or PSEUDO-MARKOV compression (PMC). In addition, run length encoding (RLE) is included.
|
|
|
|
