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Technical description digimode: SIM-PSK31  
Name of program: SIM-PSK31
Development: 2012
Designer: BEN NIZAR REJEB
Origin: Tunisia
Date of first distribution: October 2012
Methods: BPSK 31 and 63bps (125 bps expected)
Modulation: DBPSK "Differential Binary Phase Shift Keying."
Pulse shape: BPSK31 similar to classic.
Bandwidth: about 60 Hz
Demodulation Differential (coherent demodulation tests are planned)
Synchronization: on the signal
Correction of errors: By character FEC (Forward Error Correction)
tolerate one error bit per character
Convolutional code:NO (makes slow sync)
Interlace:YES
Repeat: YES, but only for some messages structured as CQCQ, QRZ, QRA LOC NAME, QTH,
Maximum drift:20 Hz / min (depending on the signal level)
Lower limit of intelligibility:-15.5 DB in text mode until 17dB message mode (in the presence of white noise over a bandwidth of 3 kHz)
Reception mode: indifferent (LSB or USB) Note: The frequency adjustment is simplified by staying USB on all bands
Character set: 53 "fixed code" A.. Z 0 .. 9 <CR> <SPACE>. , - = +? '()! / @ # *
No character reset on error or wait character ().
lowercase characters are converted to uppercase

Special characters:Special characters such as "" characters are transformed into "standard" case (in this example: "E") with the possibility to display lowercase locally.
Posts:Messages used by radio amateurs are coded and structured.
Speed:187 char / min (31.25 wpm)
Principle:coding "varicode" representing whole sentences "structured."
SIM = S tructured I ntegrated M essage BPSK31.

Structure: variable length coding, 10 to 100 bits
depending on the characters ... words ... phrases
Availability: www.on4nb.be/sim.htm since October 2012.
Benefits

Varicode optimized more reliable through the use of interlaced frames
Error correction: FEC.
Squelch based digital coherent signals received.
Transmission through very fast encoding full sentences.
5 dB gain on analog PSK (decodes signals imperceptible on a waterfall).
Mode "Split": using a transmission frequency independent of the receiving frequency (in the same band).
Automatically centered on the frequency selected by a mouse click.
Viewing "eye diagram".
No special installation.
Evolution permanently according to the demands of OM's
Link to DX-cluster and PSK-Reporter:
(Announcement in real time via the internet presence of the station using the SIM mode, and when it is received.)

Eye diagram
Instant confirmation of the correct setting:

Signal Type: conformity of modulation, PSK, QPSK, FSK, etc..
Speed ??Compliance bitrate .... 62.5 ... 31.25 Hz (125 ...)
Accuracy: bit synchronization, immediate detection of a shift in the diagram.
Monitoring: decoding quality, visible distortions instead of diamonds straight
Diagnosis: identifying defects. A click on the track and here is how this Diagram of the eye for proper reception


The presence of diamonds confirms that it is indeed a PSK
The frequency is correct (cursor centered) no interference.
Good bit synchronization signal (diamonds are stable, they do not slip)



Mode Menu
SIM31
Mode Audio Sample
FFT Window Screenshot