S05b was operated by Czech Office of Foreign Relations and Information (ÚZSI) under an ITU-registered callsign "OLX" (though officially assigned to ČTK, the press agency) and allocated frequencies. The language was Czech. It differs from the previous format S05a with different tuning signal and no null messages whatsoever. Last heard in 1996, replaced by S10d.
|VVV DE OLX OLX||424||73||57966 85288 30427 ...||Opakuji||73||57966 85288 30427 ...||Konec|
|In Morse code at 15 words per minute||3-figure ID||Amount of 5-figure groups in the message||5-figure single groups||"[I] Repeat"||Amount of 5-figure groups in the message||5-figure single groups||"End"|
|Repeated for 5 minutes||Repeated for 5 minutes|
S05b was transmitted almost 23 hours a day in 30-minute intervals.
The Czech Interior Ministry issued QSL cards to anyone interested under the following address:
Ministerstvo vnitra ČR
P. B. 21/SK
170 34 Praha 7