. GENERAL SPECIFICATIONS
Creator: Patrick Lindecker F6CTE (06/2003)
Description :
Baud rate : 31.25
Speed : 28 wpm
Modulation : DBPSK
Reception mode: indifferent (LSB or USB)
Character set : 56 "Varicode" characters " A..Z 0..9 <CR> <ESPACE> . , " : - = + ? $ ' ( ) ! / @ & # * with an error reset character and an idle character (displayed by ">").
Small characters are transformed in capital characters and special characters as
" é " are transformed in standard capital (in the example: " E ").
Shape of pulse : rectangular but the connection between 2 successive different bits is done by a decreasing sine then by a creasing sine (each of one during quarter of period)
Bandwidth : about 160 Hz
Demodulation : coherent,
Synchronization: automatic using the signal
Correction code: no
Convolution code: no
Interleaving: no
Repetition : each bit is repeated 13 positions later (so 0.42 s between 2 transmissions of the same bit). This diversity in time allows the correction of an erroneous bit. The synchronization is easy.
Automatic Frequency Correction: from +/-3 Hz to +/- 10 Hz depending on signal level,
Drift tolerance : 60 Hz/mn for PSKFEC31 (depending on signal level)
Lowest S/N for 2% errors: -13.5 dB (for white noise in a 3 kHz bandwidth)
Due to the FEC process, this mode permits to reduce appreciably the number of errors due to SW radio conditions, compared to BPSK31.
