TRANSISTORIZED DIGITAL CLOCK WITH SERIAL BINARY-CODED READOUT
NAVAL RESEARCH LAB WASHINGTON DC
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A transistorized digital clock and coder unit has been developed which is being used as part of the time standard equipment at the U. S. Naval Space Surveillance Stations in Hawkinsville, Georgia, Red River, Arkansas, and Raymondville, Texas, which were instrumented in 1965. This unit is powered by a 24-v battery supply and is capable of 24 hours of emergency service in case of commercial power failure. Decimal digits are read out in binary format at a rate of one decimal digit per second. Each group of pulses comprising a decimal digit is clearly separated from the next pulse group. Once the code is learned, it is much easier to recognize than the one formerly used in the Space Surveillance system. The transistorized circuitry used in this unit has resulted in a considerable reduction in size and power input 12 w as compared with the vacuum tube unit which has been used for a similar purpose in other Space Surveillance stations. Also, the error in coding due to aging of components has been eliminated since only two levels must be distinguished in the binary logic as compared with the ten voltage levels of the decimal logic in the earlier equipment. The new unit employs two cascaded gates, one switching at 0.1-sec intervals and the other at 1.0-sec intervals.
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