Caballero P., Lopez-Ferber, M., Williams, T. (eds.). 2001. Los Baculovirus y sus Aplicaciones como Bioinsecticidas en el Control Biologico de Plagas [Baculoviruses and their Application as Bioinsecticides in Biological Control of Pests]. PHYTOMA-Espaiia, Universidad Publica de Navarra, Valencia. 2001. ISBN 84-9320256-0-5, 518 pp. Price: $35.80

The ultrasonic flowmeter which is described in this paper, measures the transit of time of an ultrasonic pulse. This device consists of two ultrasonic transducers and a high resolution time interval measurement module. An ultrasonic transducer emits a characteristic wave packet (transmit mode). When the transducer is in receive mode, a characteristic wave packet is formed and it is connected to the time interval measurement module inputs. The time interval measurement module allows registration of transit time differences of a few pulses in the packet. In practice, during a single measuring cycle a few time-stamps are registered. Moreover, the measurement process is also synchronous and, by applying the statistics, the time interval measurement uncertainty improves even in a single measurement. In this article, besides a detailed discussion on the principle of operation of the ultrasonic flowmeter implemented in the FPGA structure, also the test results are presented and discussed