Radio communication: PLUTO for registration of intercepted telex messages

PLUTO for registration of intercepted radio-telex messages (1966)

In 1966, the interception department of the Royal Air Force (45 LUVE) at Camp Blikkenburg, Zeist had also the need for a registration system for intercepted military radio telex messages from behind the former Iron Curtain. Therefore, TNO Waalsdorp developed PLUTO (Physical Laboratory Universal Telegraphs Receiving System), a device for the interception of mostly encrypted military telex messages. The device had a bit synchronisation system to extract the telex code from the intercepted radio link, of which the baud rate was unknown beforehand. This synchronisation had to be set very accurately in order to be able to bridge long signal interruptions due to fading. PLUTO contained the functions of the earlier PUNCHROPHYL and the SCRIBOPHYL.

A time clock was also made, which regularly supplied a modulated time signal to the many recording recorders linked to the RACAL radios. That timestamp was included in all messages registered by PLUTO, both in the directly punched paper tape and on the with recorders registered messages. On the right side of the printout, the clock time was printed so that the clock time of the message’s passage was also next to the registered time. The time clock was the first TNO-developed device based on wire-wrapped integrated circuits (TTL) from the SN7400 series. The registration recorders recorded the messages that were later processed using PLUTO’s decoder and control electronics and printed on an IBM model 73 typewriter. In addition, fault and time indications were recorded in the paper tape.

PLUTO: Met de radio werden Russische militaire zenders met digitale uitzendingen gezocht. Het bitformaat en datarate werd vastgesteld en vervolgens werd de data in een ponsband vastgelegd. Met de schrijfautomaat werd de ontvangen informatie op papier afgedrukt.
PLUTO: Russian military channels with telex traffic were searched for by radio. The bit format and data rate were determined and then telex data was recorded in a paper tape. The received information was printed on paper with the typewriter.


PLUTO: The recorded message traffic was printed on paper with the typewriter (improved SCRIBOPHYL)
PLUTO: The recorded telex messages were printed on paper with the typewriter (improved SCRIBOPHYL)


PLUTO: the newer SCRIBOPHYL control rack
PLUTO: the newer and more compact SCRIBOPHYL control rack using integrated components


The paper tape reader
The papertape reader


Central time clock of the PLUTO system
The central time clock of the PLUTO system