News D-Flow Products Components Applications Technology Flow Level Analysis UFO ASIC Electronics Transducers Software Download PDF Download Sitemap Contact The UFO ASIC is more than a time measurement circuit. The UFO ASIC comprises almost all the electronics needed for accurate measurement of flow, level, and speed of sound measurement. The ASIC controls: 1. Transmission of an ultrasonic pulse. 2. Setting of the amplification with an automatic gain control. 3. Sampling of the zero level of the input signal. The time gap to sample the zero level is software selectable. 4. Detection of the received pulse. The detection voltage level is software selectable. 5. Selection of the chosen zero crossing. The software can select where the zero crossing measurement takes place. 6. Transmission of the next pulse and the selection of the sing-around loop for N number of pulses. All parameters are software selectable. 7. Typically < 5 picoseconds time resolution using sing-around averaging. 8. 300 picoseconds or better single-shot time resolution. 9. Data output. The time data is available for the micro-processor to read from the ASIC's readable registers through an 8-bit data bus. 10. The filter for the transducer frequency, which is external and enables use of a large number of different transducers. The internal structure of the UFO ASIC is given in the figure above. The analogue signals from the ultrasound transducers are received and fed to an amplifier. The signal is amplified to 1 V peak to peak, AGC. The signal path is then routed through an external band pass filter and finally detected in a trigger circuit, TRIGGER. Then the next sound transmission is issued to the desired transducers. The output signal from the trigger circuit is the sing-around signal. The number of sing-around loops completed, as counted by a loop counter, LOOPC, indicates the number of periods in the sing-around signal. The period time of this signal gives the sing-around frequency. The TIME METER component of the UFO measures the total time of N sing-around loops as programmed into UFO. This time, tx, can now be read by the microprocessor and used to calculate the flow. As indicated in the figure, the UFO ASIC can be regarded as a peripheral circuit to a microprocessor. UFO has a standard 8-bit bus communication interface with read, write, and chip select functionality. Via this interface, the 16 readable and the 16 writeable registers of UFO can be accessed. Via one register, the microprocessor can issue commands to the UFO. In this way, the microprocessor will start sing-around measurements in the upstream or downstream direction. When the UFO has completed such a measurement, an interrupt request is issued. Now the microprocessor can read sing-around period data and start the next measurement. Other commands that the processor can order the ASIC to do are: Setting initial parameters for different flow tube length, shapes and flow media. Calibration of the received signal through the AGC to obtain a 1V peak-to-peak signal. Calibration of the free running oscillator. Zero Calibration, to set the different delay times for each transducer and excitation stage. Time measurement using low-power mode. Package The D-Flow UFO ASIC is available in a MQFP 44 package.