Tral telemetry system
트랄 원격측정 시스템
A Soviet multi-channel radio telemetry system developed by OKB MEI (Moscow Energy Institute) for the R-7 ICBM. Using pulse-time modulation, it transmitted 6,000 measurements per second across 48 channels, and in March 1956 it won a state comparative test against the rival RTS-7 to become the primary telemetry system for the R-7. Sputnik 2 was deliberately left attached to the core stage so that Tral could transmit biological data; the system later flew on Vostok 1 and other early crewed spacecraft.
In depth
Development
The Tral system was developed for the R-7 ICBM by the Special Works Sector of the Moscow Power Engineering Institute (MEI). Vladimir Kotelnikov had founded the sector in 1947 and appointed Aleksei Bogomolov as head of the work that produced Tral. In January 1955 the decision was taken to install the system on the R-7, and in March 1956 the young MEI team won the state comparative test against RTS-7, built for the same rocket by the influential electronics organization SKB-567 (chief designer Yevgeny Gubenko) under Mikhail Ryazansky. On 8 March 1958 the sector was reorganized as OKB MEI, with Bogomolov as chief designer and director.
Trials and service
In 1956 Tral was tested at Kapustin Yar on the M5-RD rocket, a flying laboratory for R-7 onboard systems. On 15 May 1957 it first operated during the failed first R-7 launch and delivered detailed information on the causes. On 21 August 1957 the R-7 made its first fully successful flight from Baikonur.
Sputnik and Vostok
During the launch of the first satellite in October 1957 Tral worked on the launch vehicle alone: the moment the engine cutoff signal arrived by telemetry determined how accurately the satellite had been placed in orbit. On Sputnik 2 the central-block set, Tral-Ts, was modified to relay the satellite's own telemetry as well, transmitting biological and engineering data for about a week from 3 November 1957. English-language accounts name this set Tral_D and record that it sent data to Earth for 15 minutes of each orbit. On the third Soviet satellite, launched in 1958, Tral was fully transistorized and a 2-megabit storage unit was added; the equipment worked for about a year. Vostok 1 carried two Tral sets on 12 April 1961: Tral-P1 with a ZU-O storage unit and Tral-T, which transmitted the television picture in Tral coding.
Ground stations and later variants
Early ground equipment was mobile, mounted in KUNG vans on ZIS-151 trucks, and in 1963 a compact receiving station, Tral-K, was developed for nuclear submarines. Variants such as Tral-P2, Tral-IOK and Tral-P1MA, P1MB and P1MV were produced for different spacecraft, and the family remained in service into the early 2000s.
Related historical events
Sources
- Wikipedia (RU) Russian Wikipedia: definitive article covering Tral's development at OKB MEI, competition with RTS-7, 48-channel architecture, PPM modulation, use on R-7/Sputnik/Vostok, and service life into the 2000s
- Wikipedia (EN) English Wikipedia: confirms Tral as the early Soviet PPM telemetry system developed by OKB-MEI
- Wikipedia (EN) English Wikipedia: Sputnik 2 used the Tral_D system to transmit engineering and biological data; the satellite was not separated from the Blok A to keep Tral operational
- mentallandscape.com Don P. Mitchell's independent reference: details Tral PTM encoding, 48 channels, 6000 measurements/sec, Tral-V/Tral-Ts/Tral-G variants on R-7
- nasa.gov Boris Chertok, Rockets and People Vol. II (NASA): Tral won unanimous expert commission vote over RTS-7 using cutting-edge electronics
- russianspaceweb.com Anatoly Zak, RussianSpaceWeb: flight controllers intentionally left the Tral telemetry system on the core stage active during Sputnik 1
- Wikipedia (RU)
- Wikipedia (EN)