April 2, 2026, 3:11 pm | Read time: 2 minutes
A mysterious shortwave transmitter has been regularly broadcasting sequences of numbers in Persian since late February. Radio amateurs noticed the signals shortly after the start of the Iran war. The structured messages are reminiscent of past secret communications and lead to a possible location in southern Germany. However, who is behind the transmissions and their purpose remains unclear.
On February 28, just hours after the start of the Iran war, radio amateurs first discovered unusual broadcasts on the frequency 7,910 kHz. As reported by “Spiegel,” the signals were broadcast twice daily in the following days and weeks. The messages are written in Persian and always begin with a keyword that can be translated as “Attention.” This is followed by sequences of numbers in clearly structured blocks, sometimes lasting more than two hours.
The nature of the transmission appears systematic and suggests targeted communication. However, the content itself remains incomprehensible without the appropriate key.
Trail Leads to Stuttgart Area
The properties of shortwave helped narrow down the origin of the signals. Shortwaves are reflected at higher atmospheric layers and can thus cover great distances. Near the transmitter, however, the signal is particularly strong. This characteristic was used by radio amateurs from the international project Priyom for location tracking.
The analysis suggests that the transmitter originates from Germany, specifically from an area between the Panzerkaserne Böblingen and the Patch Barracks of the U.S. Army in Stuttgart-Vaihingen. Measurements point to a nearby forest area where the signal was received particularly clearly and strongly.
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Reminder of Cold War Number Stations
The observed transmissions are reminiscent of so-called number stations, which were especially common during the Cold War. These typically involved state entities or intelligence agencies sending coded sequences of numbers that could only be deciphered with the appropriate key. This method was long considered a relic of the past, but it seems to still be in use.
Who is specifically behind the current transmitter remains unknown. Neither the involved radio amateurs nor the reporting entities could identify those responsible. Official institutions such as the U.S. military, the Federal Network Agency, or the Ministry of Defense have not commented on the events.
Since March 25, 2026, the signal continues to be broadcast, albeit with significantly reduced power. Whether the transmissions still serve an operational function or are part of a larger security policy context remains unclear.