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Proceedings Paper

Time-To-Digital Converter For Fast, Accurate Laser Rangefinding
Author(s): Kari E. Maatta; Juha T. Kostamovaara; Risto A. Myllyla
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Paper Abstract

The construction and capability of a time-to-digital converter (TDC) intended for industrial laser rangefinding applications is described. The time interval T to be measured is split into three fractions T1, T12 and T2. T1 and T2 are the time fractions between the start pulse and the next clock pulse but one and between the stop pulse and the next clock pulse but one. T12 is thus synchronized with the clock and can be accurately digitized by a counter. The time difference Ti - T2 is digitized by an analogue interpolation circuit which consists of separate time-to-amplitude converters and A/D converters for the two time fractions. The measured time T is achieved by calculating the sum T12 + T1 - T2 and is a 16 bit digital word in which the lsb corresponds to about 40 ps. The measurement range of the TDC is 2.55 µs. The integral nonlinearity and single shot resolution were measured to be 5 ps (?-value) and 40 ps (?- value) respectively. Temperature stability is -3 ps/°C in a temperature range of 0°C - +50°C. A stability test over 14 hours indicated a peak to peak drift of about 10 ps, which includes the stabilities of the measuring instruments. The dead time of the TDC is about 10µs.

Paper Details

Date Published: 15 February 1989
PDF: 8 pages
Proc. SPIE 1010, Industrial Inspection, (15 February 1989); doi: 10.1117/12.949209
Show Author Affiliations
Kari E. Maatta, University of Oulu (Finland)
Juha T. Kostamovaara, University of Oulu (Finland)
Risto A. Myllyla, University of Oulu (Finland)


Published in SPIE Proceedings Vol. 1010:
Industrial Inspection
Donald W. Braggins, Editor(s)

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