Enigma ID M42 (catch-all MFA Moscow designator)

Spectrum image serdolik-spectrogram.png

Name Serdolik
Status Active
Voice N/A
Emission mode USB; MFSK-34, 40 Bd; OFDM-34, BPSK, 40 Bd; OFDM-34, QPSK, 40 Bd
Location Worldwide
Activity pages

Download audio sample

Known counterpart stations

Serdolik[1] is a currently semi-retired proprietary full duplex ARQ system used by the Russian Ministry of Foreign Affairs. From the early 2000s until the mid 2010s, it served as their most common two-way HF mode, replacing Morse code and RTTY; it has since been replaced by "Perelivt". At present, only a few embassies continue using Serdolik.

Its main waveform is 34-tone MFSK modulated at 40 Bd, which offers a gross data rate of 200 bit/s. The modem also contains a 34-carrier OFDM waveform, modulated at 40 Bd using either BPSK or QPSK, which offers higher speeds of 1200 bit/s and 2400 bit/s respectively.

As Serdolik is a full duplex system, the MFA Moscow and embassy sides take different frequencies. The Moscow side is usually a lot more powerful, and it's not uncommon for the embassy to be inaudible.


  1. Serdolik HF communication system - JSC Sozvezdie [accessed May 31st, 2018]
Your browser is out-of-date!

Update your browser to view this website correctly. Update my browser now