Smart flowmeter pre-amplifier

摘要

A flowmeter (M) measures fluid flow in a system and produces a train (Si) of digital pulses representing the measured flowrate. The frequency of the pulses is intended to be proportional to the flowrate. A preamplifier (10) controls generation of output pulses (Fn, Fq) of an output digital pulse train (So). The preamplifier first decodes the digital pulse train using a phase discriminator (14). Output pulses from the discriminator are counted (at 24 and 46) to count the number of pulses and their frequency of occurrence. A frequency multiplier (40) is responsive to the pulses and their occurrence to generate each pulse of the output pulse train. Generation of these pulses involves use of a scaling factor (Vcf) by which meter performance factors, drift, and the fluid flow environment are taken into account. Use of the scaling factor enables the timing and frequency of the generation of pulses comprising the output pulse train to both be controlled so these pulses are produced at a rate which is linearly proportional to the measured fluid flowrate. <IMAGE>