|Enigma ID||M42 (catch-all MFA Moscow designator)||
|Emission mode||USB; 34-tone MFSK, 40 Bd, 40 Hz; 34-carrier OFDM, BPSK or QPSK, 40 Bd, 50 Hz|
|Known counterpart stations|
Serdolik (Сердолик, English: Carnelian) is a proprietary full duplex HF communication system. Its main waveform is 34-tone 40 Bd MFSK, which offers the gross data rate of 200 bit/s. Once an MFSK link is established, it also allows optional use of one of two 34-carrier OFDM waveforms, which offer the speeds of 1200 bit/s and 2400 bit/s respectively.
Serdolik is used exclusively by the Russian Ministry of Foreign Affairs. From the early 2000s until the mid 2010s, it served as their main HF mode, replacing Morse code and RTTY; it has since been replaced again, by "Perelivt". At present, only a few embassies continue using Serdolik as the primary mode, but it's still maintained at other diplomatic missions as a backup mode.
- Serdolik HF communication system - JSC Sozvezdie [accessed 31 May 2018]