Inventor of MT63, Q15X25, Olivia
Co-Inventor of BPSKKraków, Poland; CERN Geneva, Switzerland
PSK31, developed by Peter Martinez G3PLX, based on the original conception of Paweł Jałocha SP9VRC who invented the SLOWBPSK, is a digital communications mode which is intended for live keyboard-to-keyboard conversations, similar to radioteletype. Its data rate is 31.25 bauds (about 50 word-per-minute), and its narrow bandwidth (approximately 60 Hz at -26 dB) reduces its susceptibility to noise. PSK31's ITU emission designator is 60H0J2B. It uses BPSK modulation without error correction or QPSK modulation with error correction (convolutional encoding and Viterbi decoding).
Q15X25 (or NEWQPSK) is a packet modem with a KISS/AX.25 interface designed for HF transmission of AX.25 packets and TCP/IP using Automatic Repeat reQuest (ARQ) and forward error correction (FEC). Q15X25 was developed by Paweł Jałocha SP9VRC for the Motorola DSP56002EVM digital signal processing evaluation board in the late 1990s. It operates like a packet radio terminal node controller (TNC). Its 15 tones are separated by 125 Hz, each QPSK modulated at a symbol rate of 83.33 bauds to provide a raw data rate of 2500 bit/s in an occupied bandwidth of 2000 Hz. Its emission designator is 2K00J2D. Signals can be found at 14 109.5 kHz upper sideband.
The MT-63 modem, using the MT-63 protocol by Paweł Jałocha SP9VRC, is constructed around a high speed DSP processor, either in a dedicated external DSP unit like the Motorola EVM, or in PC software using the PC sound card, transmits 64 tones spaced 15.625 Hz apart, in the 1 kHz bandwidth. The base-band signal occupies from 500 Hz to 1500 Hz. All 64 tones are differential bipolar phase shift keyed at 10 baud. Since the Walsh FEC code is 64 bit, the character rate is the same as the symbol rate, so the throughput with FEC is ten 7-bit ASCII characters/sec (about 100 WPM). There are two other bandwidths that can be used, 500 Hz, and 2 kHz, where the tone spacing and baud rate are halved or doubled, and the throughput halves or doubles respectively. Unless otherwise indicated, this description is of the default 1 kHz version.
"I developed the “Olivia” mode for weak signal QSO's. I have chosen the MFSK (Multi-Shift Frequency Keying) modulation, as it is a good FEC code in itself and its waveform has an almost constant envelope, so that the radio transmitter can work at its maximum power. As well MFSK passes well through the ionosphere made distortions. The disadvantage of MFSK is that it does not tolerate well coherent interferences and non-uniform frequency response of the transmission channel. Coherent noise is often present on HF and the amateur-grade receivers use low pass filters in the audio chain, thus the “Olivia” demodulator passes the audio first through a spectral preprocessor, which attempts to remove coherent signals and then equalizes the audio frequency response. This at least partially compensates for the MFSK deficiency in that matter."
See QSL cards with railway motifs at: