Sandbox:SITOR-A

SITOR-A is one of two modes of SITOR, which stands for Simplex Teletype Over Radio. Based on CCIR 476-4. It was formerly used to transmit maritime short messages, however the maritime industry is gradually moving away from using this mode in favor of PACTOR. AMTOR is a type of SITOR used by amateur radio operators.

SITOR-A has been seed with shifts of 170 Hz, 300 Hz, 400 Hz, and 850 Hz. SITOR-A is most commonly used with 170 Hz shift and 100 Bd.

Samples

100 Bd 170 Hz Shift
<html5media>File:SITOR-A_Cairo_MFA_100_bd_170_Hz_shift_Jan_29_2016_9989.7kHz.mp3</html5media>

Frequencies

One of the biggest users of SITOR-A is not a maritime service - it's the Egyptian Embassy/MFA Cairo. The current version of the 2014 Digital Digest by Mike Chace-Ortiz (Spectrum Monitor editor) has an extensive description of this network. Also see the Utility DXers Forum on Groups.io for current frequency information

Video Examples

• Reception and decoding of a SITOR-A signal ("RCVB" Egyptian station )

Decoding Software

Hobby Level Software

• MultiPSK
• MultiMode (for Macs)
• Sorcerer
• TrueTTY

Professional Equipment/Software

• Go2decode
• Go2Monitor
• Hoka Code 3-32P
• Hoka 300-32
• Hoka 300-32P
• Krypto500
• Wavecom W-Code
• Wavecom W-Spectra
• WinRadio Universal FSK Decoder

Additional Links

• HF Digital "Tower of Babel"
• shoc Database: SITOR-A
• WAVECOM Database: SITOR-A
• Reading and Decoding the Transmissions of MFA Cairo (PDF) via UDXF website