SLDA058 March   2021 TUSS4470

 

  1.   Trademarks
  2. 1Review of Ultrasonic Sensing Range Performance Factors
    1. 1.1 Physical Parameters
    2. 1.2 Transducer Characteristics
    3. 1.3 AFE Device Configuration
  3. 2Methods Overview
    1. 2.1 Introduction
    2. 2.2 Hardware Configuration
      1. 2.2.1 Transducers
      2. 2.2.2 Experimental Setup: Air-Coupled Level Sensing
      3. 2.2.3 Experimental Setup: Water-Coupled Level Sensing
      4. 2.2.4 TUSS4470 EVM Hardware Configuration
      5. 2.2.5 TDC1000-C2000EVM Hardware Configuration
    3. 2.3 Firmware Configuration
      1. 2.3.1 TUSS4470 Power Configuration
      2. 2.3.2 TUSS4470 220 kHz Configuration
      3. 2.3.3 TDC1000 220kHz Configuration
      4. 2.3.4 TDC1000 220kHz Configuration
      5. 2.3.5 TDC1000 1 MHz
  4. 3Short Range Air-Coupled Test Results
    1. 3.1 TUSS4470
    2. 3.2 TDC1000
  5. 4Mid-Range Air-Coupled Test Results
    1. 4.1 TUSS4470
      1. 4.1.1 Concept
      2. 4.1.2 TUSS4470 35 V Results
    2. 4.2 TDC1000
  6. 5Short Range Water-Coupled Test Results
    1. 5.1 TUSS4470
    2. 5.2 TDC1000
  7. 6Resistive Damping Device Comparison
    1. 6.1 TUSS4470
    2. 6.2 TDC1000
  8. 7Summary
  9. 8References
  10.   A Appendix A
    1.     A.1 TUSS4470: Filter Capacitor Selection
    2.     A.2 TUSS4470: Shematic
  11.   B Appendix B
    1.     B.1 TDC1000 Misc.
    2.     B.2 TDC1000-C2000EVM Schematic

1.2 Transducer Characteristics

A transducer's diameter, mechanical packaging and quality factor also have a measurable impact on transmission range. In one common definition, the quality factor of a mechanical-electrical oscillator is proportional to the reciprocal of its resonant half power bandwidth. The Q-factor can be described similarly by the ratio of energy stored to energy dissipated per cycle of the oscillation. For example, a perfect transducer would have an infinitely narrow bandwidth and an infinite Q-factor, and the BVD model of this theoretical transducer is a lossless LC oscillator. Thus, a transducer with a higher Q-factor will have a longer oscillation decay than a transducer with a lower Q-factor

The damping of a commercial transducer is related to the resistance of the BVD model (RLC circuit). The BVD model's damping resistance corresponds to the overall damping characteristic of the transducer, which is a function of the transducer packaging, such as the enclosure and backing material surrounding the piezo element, as well as trace electrical resistance.

GUID-20210317-CA0I-QNTX-NS6Z-VQWPFSQMP913-low.png Figure 1-3 Transducer BVD Model

The ring down period of a transducer is the length of time that the transmit signal takes to decay, also known as the blind-zone in reference to a plotted signal. The reflected ultrasonic pulse cannot be received within the ring down period. One method for reducing the ring down time is to increase the resistance of the RLC model of the transducer by mechanical or electrical means (utilizing mechanical damping or a parallel damping resistor).

GUID-715A8891-F1F4-4D4C-A457-76E0530A3227-low.gif Figure 1-4 Monostatic Ring Decay