The main improvement of MULTIPSK 4.45
PSK125R/250R/500R modes coding/decoding
The “R” means “Robust”, this because the modulation is the PSKxyzF one, at which it is added an interleaving.
The PSKR modes (initially created on the Fldigi program) are fast, robust and sensitive.
The advised frequencies are 1838, 3570, 7070, 14070, 18101, 21070 and 28120 kHz.
These modes are in freeware, so without time limitation. See general specifications below.
Other improvements: new POCSAG.TXT file for correspondences “Address – Name” managed by the user.
PSK125R/250R/500R modes description
Created by: John (Jean-Yves) Douyere (VK2ETA) and David Freeze (W1HKJ) in 2009 on Fldigi
Baud rate : 125 for PSK125R, 250 for PSK250R, 500 for PSK500R
Speed : 84 wpm (average) for PSK125R, 168 wpm for PSK250R, 336 wpm for PSK500R
Modulation : DBPSK
Reception mode: indifferent (LSB or USB)
Character set : ASCII characters + almost all ANSI extended characters + a backspace character (“Varicode” characters)
Shape of pulse : raised cosine
Bandwidth : about 260 Hz for PSK125R, 500 Hz for PSK250R, 1000 Hz for PSK500R
Synchronization: automatic using the signal
Correction code: no
Convolution code: R(Rate)=1/2, K (Constraint length)=7 with Viterbi type decoder, both coder outputs being sent successively,
Interleaving : on 82 bits with 40 diagonal interleavers in series, on a square elementary matrix 2×2 for PSK125R, on 162 bits with 80 interleavers for PSK125R,on 322 bits with 160 interleavers for PSK500R Drift tolerance : 2 Hz/sec (depending on signal-to-noise ratio) for PSK125R, 4 Hz/s Hz for PSK250R, 8 Hz/s for PSK500R
Pmean/Ppeak: 0.79
Lowest S/N: – 9 dB for PSK125R, – 6 dB for PSK250R, – 3 dB for PSK500R
