Electrical pulse counters – pulse dividers – or shift registers: c – Applications – Measuring or testing
Patent
1991-12-19
1992-11-24
Howell, Janice A.
Electrical pulse counters, pulse dividers, or shift registers: c
Applications
Measuring or testing
377 33, 377 56, H03K 526
Patent
active
051669595
ABSTRACT:
A circuit for time stamping event signals, e.g. zero-crossings, using coarse and fine timers. The fine timer is a circuit section which subdivides a period from a phase-locked ring-oscillator into 2N subparts. An event signal is timed by latching a digital representation of a particular subpart. The digital representation of the subpart is an N-bit dual thermometer code which uniquely identifies each subpart with each adjacent subpart differing by only one bit. The subparts are made finer in time quantization than the propagation delay of one active element in the ring oscillator by the use of linear combiner elements. The dual thermometer code, encoded post-latching into a binary code, forms the "fine" timing part of a binary word representation of the event time. The event also latches the count states of a pair of lead-lag counters in a master-slave configuration counting ring oscillator periods. These counters change states respectively before and after the dual thermometer code turn-overs. Only one reading is chosen for recording as determined by the most significant bit of the fine code. The choice will always find an accurate and stable reading, and reject erroneous readings resulting from reading a counter in transition. The chosen counter reading, encoded to binary, forms the coarse timer for the binary word representation of the event time. The coarse and fine binary words are butt-joinable to form the complete binary timing representation without further arithmetic processing.
REFERENCES:
patent: 4764694 (1988-08-01), Winroth
patent: 4908784 (1990-03-01), Box et al.
"Phase Digitizing Sharpens Timing Measurements" by David C. Chu, IEEE Spectrum, Jul., 1988, pp. 28-32.
"Phase Digitizing: A New Method for Capturing and Analyzing Spread-Spectrum Signals" by David C. Chu, Hewlett-Packard Journal, Feb., 1989, pp. 28-35.
"Analysis of Spread Spectrum Signals Using a Time and Frequency Analyzer" by David C. Chu and R. F. Schneider, Hewlett-Packard brochure, Apr. 1988.
Chu David C.
Knotts Thomas A.
Hewlett--Packard Company
Howell Janice A.
Ouellette Scott A.
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