Dayu Electronics: Can a Doppler Current Meter Perform Multi-Channel Simultaneous Transmission in Multi-Path Transit-Time Measurement?
Customer inquiry: When using a Doppler current meter for ultrasonic transit-time multi-path measurement, controlling 16 transducers and 8 paths, is it possible for several channels to transmit simultaneously?
Dayu Electronics frankly states that from a circuit perspective, multi-channel simultaneous transmission and reception is achievable. However, in pipes of DN400 or smaller, simultaneous transmission on multiple channels will inevitably cause ultrasonic signals to interfere with and mask each other. As long as you don't mind signal crosstalk, there is no technical issue.
1. Circuit Level: Capable of Simultaneous Transmission and Reception
In hardware design, simultaneous transmission and reception on 8 channels can be implemented by the circuit itself. There are no obstacles in the logic for transmit timing control and synchronous sampling of receive channels. So the answer to "can it be done" is affirmative.
2. Acoustic Level: Severe Signal Interference in Confined Spaces
The problem lies in the acoustic physics, not the circuit.
In a pipe like DN400, ultrasonic waves propagate in a limited space with complex wall reflections. If multiple channels transmit simultaneously, the ultrasonic signals from different paths will overlap, cross, and reflect in the water. Since sound waves cannot be isolated like electrical signals through physical wires, the signal received at the receiving end is a mixture of multiple transmitting sources, making it impossible to distinguish which echo corresponds to which transmitting source.
This is why in actual measurements, the more channels transmit simultaneously, the messier the waveform. The signal received by each transducer contains not only the component of its own transmitted wave reflected by particles, but also components from other channels that have strayed over. From a signal processing perspective, this is mutual interference and masking, and in severe cases, effective data cannot be extracted.
3. Recommendation: Time-Division Transmission, Not Simultaneous
In practical applications, it is more prudent to use time-division transmission for the 8 paths, where one channel completes transmission and reception before starting the next. Only one set of sound waves is transmitted per cycle, resulting in cleaner signals, simpler processing, and reliable data. Sacrificing a bit of time resolution yields stable and usable measurement results.
Of course, if there are special considerations in the customer's application scenario where multi-channel simultaneous transmission is truly required and the data quality degradation due to signal crosstalk is acceptable, we can provide customized implementation. However, for conventional transit-time measurement scenarios, we recommend the time-division transmission approach.
Summary: The circuit can do it, but acoustically it is not recommended. Simultaneous transmission within DN400 pipe diameters makes signal interference inevitable and data quality difficult to guarantee. The prudent approach is time-division transmission.
Fuzhou Dayu Electronics Technology Co., Ltd. specializes in ultrasonic technology R&D and manufacturing. Products include level gauges, flow meters, level difference gauges, open channel flow meters, transducers, etc., widely used in water conservancy, municipal, environmental protection, and industrial fields. Welcome water conservancy engineering companies, municipal maintenance units, system integrators, and design institutes to contact us for professional solutions.